Shift Range Control Device Abnormality Handling
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Solution Overview
Problem
Existing shift range control devices face challenges in appropriately switching the shift range when communication between control units is incomplete or when an abnormality occurs, leading to potential failure in selecting the correct control unit for range switching.
Innovation Solution
A shift range control device with multiple control units for each motor winding, including a motor rotation angle signal acquisition unit, an output shaft signal acquisition unit, a drive control unit, and an abnormality determination unit, which switches the shift range by controlling the motor drive. When an abnormality occurs, the device determines if the output shaft is rotating before a standby time elapses and adjusts the energization of the motor winding accordingly to prevent erroneous switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple control units are provided for each motor winding to improve reliability, then the system can handle abnormalities better, but the device complexity increases
Solution Approach 1:
The control system is divided into multiple independent control units (first control unit and second control unit), each capable of independently controlling the motor. This segmentation allows the system to maintain functionality even when one control unit experiences an abnormality, thereby improving reliability while managing complexity through modular design.
Solution Approach 2:
The system dynamically changes the operational parameters by switching between feedback control mode (when encoder is normal) and open control mode (when encoder abnormality is detected). This parameter change allows the system to adapt to abnormal conditions without requiring complete system redesign, balancing reliability improvement with acceptable device complexity.
2Measurement precision
If feedback control is used to improve precision, then the shift range switching accuracy is improved, but when encoder abnormality occurs the system reliability deteriorates
Solution Approach 1:
The control system dynamically switches between feedback control and open control based on the operational state. When the encoder is functioning normally, feedback control is used for precise shift range switching. When encoder abnormality is detected, the system transitions to open control, maintaining reliability by adapting to the changed conditions rather than failing completely.
Solution Approach 2:
The system uses feedback control when the encoder is normal to achieve precise shift range switching by continuously monitoring the motor position. When encoder abnormality is detected, the feedback loop is discontinued and open control is implemented, preventing the system from using unreliable feedback information that would compromise reliability.
3Productivity
If the motor is controlled to rotate quickly to improve productivity, then the shift range switching speed is improved, but when encoder abnormality occurs the control precision deteriorates
Solution Approach 1:
The system dynamically adjusts the control method based on encoder status. During normal operation, feedback control enables both high-speed switching and high precision. When encoder abnormality occurs, the system transitions to open control, maintaining productivity through continued operation while accepting reduced precision, thus balancing both requirements under different operational conditions.
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
Ensures appropriate switching of the shift range even with encoder abnormalities, by using feedback or open control methods based on the status of the output shaft, thereby preventing obstruction of feedback control and ensuring reliable range switching.
Implementation Method 1
a motor rotation angle signal from a motor rotation angle sensor that detects a rotation position of the motor
Implementation Method 2
an output shaft signal from an output shaft sensor that detects a rotation position of the output shaft
Implementation Method 3
The motor shaft rotates by energizing the motor windings
Data Source
AI summary
A shift range control device includes a plurality of control units provided for each of motor windings. When a motor rotation angle sensor is normal, a drive control unit controls an energization of the motor winding of its own system by using a motor rotation angle signal. When the motor rotation angle sensor has an abnormality and it is determined that an output shaft is rotating before a standby time elapses, the drive control unit does not energize the motor winding of its own system. When it is determined that the output shaft is not rotating even after the standby time has elapsed, the drive control unit controls the energization of the motor winding of its own system without using the motor rotation angle signal.