Shift Range Control Apparatus Reducing Cogging Torque
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Solution Overview
Problem
In shift range switching systems, the cogging torque generated by permanent magnet motors can prevent the shaft from rotating to the stop allowable range due to the imbalance between cogging torque and external forces, such as detent spring forces, leading to issues with shift range switching.
Innovation Solution
A shift range control apparatus that includes a drive controller and a polarity determination device, which controls the motor to apply a cancellation current reducing the magnetic flux density of the stator, thereby decreasing the cogging torque and allowing the engaging member to fit into recesses according to the shift range, using a motor with a stator wound by a coil and a rotor rotated by the coil's energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a permanent magnet motor is used in the shift range switching system, then the motor can provide sufficient driving force, but the cogging torque generated by the permanent magnet prevents the shaft from rotating to the stop allowable range
Solution Approach 1:
The patent changes the magnetic flux density parameter by applying cancel energization current to the coil. This current reduces the magnetic flux density generated by the permanent magnet, thereby decreasing the cogging torque. The drive controller adjusts the coil current parameters to achieve the desired reduction in cogging torque while maintaining sufficient driving force for shaft rotation.
2Power
If the motor size is increased to overcome cogging torque, then sufficient driving force can be achieved, but the device complexity and size increase
Solution Approach 1:
The patent replaces the mechanical solution of increasing motor size with an electrical control solution. By applying cancel energization current to the coil, the system electrically reduces the cogging torque without requiring a larger motor. This substitution maintains the original motor size while achieving the necessary driving force to overcome reduced cogging torque.
3Manufacturing precision
If cancel energization control is applied to reduce cogging torque, then the detent roller can fit into the desired recess, but additional control complexity is introduced
Solution Approach 1:
The drive controller implements feedback control by monitoring the shaft position and determining when to apply cancel energization current. The controller uses the detected shaft position to decide when the detent roller needs assistance to fit into the recess, applying current only at the appropriate moment. This feedback mechanism achieves precise positioning without requiring continuously complex control.
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 apparatus effectively reduces cogging torque, enabling the detent roller to fit into the desired recess, stabilizing the shaft position and allowing proper shift range switching without the need for increasing motor size, by performing cancel energization control to balance detent and cogging torques.
Implementation Method 1
a motor including a stator (11) wound by a coil (12) and a rotor (13) rotated by the energization of the coil (12)
Implementation Method 2
controls the motor to apply a cancellation current reducing the magnetic flux density of the stator (11), thereby decreasing the cogging torque
Data Source
AI summary
A shift range control apparatus controls driving of a motor in a shift range switching system provided with the motor and a shift range switching mechanism. A drive controller controls the driving of the motor to fit an engaging member in a recess according to a shift range in response to that the shift range is switched. A polarity determination device determines a polarity of a stator, which faces a rotor. The drive controller causes the engaging member to move to the recess according to the shift range, and then performs cancel energization control to energize a coil with a cancellation current which is a current reducing the magnetic flux density of the stator according to the polarity of the stator.