Shift-by-Wire Actuator Integrated Controller Position Sensing
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Solution Overview
Problem
Conventional shift-by-wire (SBW) devices face issues with mechanical and electrical errors due to the absence of mechanical components, leading to potential control failures and increased costs from separate controllers and inhibitor switches, as well as reduced accuracy in position sensing.
Innovation Solution
An integrated SBW device with a motor, hollow rotor shaft, reduction gear, and controller that senses the position of the manual shaft using an encoder magnet, eliminating the need for an inhibitor switch and directly transmitting torque to the manual shaft, thereby reducing component count and minimizing position errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If mechanical components are eliminated in SBW method, then weight of transmission is reduced and layout configuration is simple, but emergency situation such as being unable to control actuator due to electric and/or electronic signal error may occur
Solution Approach 1:
The patent merges the controller with the SBW actuator into an integrated unit. The controller is positioned inside the actuator housing and directly controls the motor, eliminating the need for separate mechanical linkages and external controllers. This integration reduces the number of mechanical components and wiring harnesses, thereby reducing weight while maintaining control reliability through direct electronic control.
Solution Approach 2:
The patent introduces a position sensor as an intermediary element that provides feedback on the actuator's position to the controller. This feedback mechanism enables the controller to monitor and adjust the actuator's position accurately, ensuring reliable control even without mechanical linkages. The position sensor acts as a mediator between the motor and the control system, enabling precise control through electronic signals.
2Reliability
If separate controller and inhibitor switch are used in conventional SBW, then control function is achieved, but number of components increases and costs increase
Solution Approach 1:
The patent combines the controller and inhibitor switch functions into a single integrated controller unit. The controller internally manages both the shift control logic and the inhibitor switch functionality, eliminating the need for separate physical components. This integration reduces the number of parts, simplifies the system architecture, and lowers costs while maintaining all necessary control functions.
Solution Approach 2:
The integrated controller performs multiple functions: it controls the motor operation, monitors position sensor feedback, manages shift stage transitions, and implements inhibitor switch logic. By making the controller universal and multi-functional, the patent eliminates the need for separate dedicated components for each function, thereby reducing overall system complexity and component count.
3Measurement precision
If position of manual shaft is sensed indirectly in conventional SBW, then shift stage information is obtained, but position sensing accuracy is reduced due to backlash errors
Solution Approach 1:
The patent extracts the position sensing function from the mechanical linkage system and implements it directly on the actuator shaft. The position sensor is mounted to detect the position of the actuator shaft directly, eliminating the need to sense position through the manual shaft and detent plate mechanism. This extraction of the sensing function from the mechanical chain eliminates backlash errors and improves position sensing accuracy.
Solution Approach 2:
The patent replaces the mechanical position sensing method (using inhibitor switch and mechanical linkages) with an electronic sensing method. The position sensor uses magnetic or optical fields to detect the actuator shaft position directly, substituting mechanical contact and transmission with non-contact electronic measurement. This substitution eliminates mechanical backlash and wear, providing more accurate position feedback.
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 integrated solution reduces the number of components, lowers costs, and enhances position sensing accuracy by directly sensing the manual shaft's position, minimizing backlash errors and improving shift control reliability.
Implementation Method 1
a motor which generates torque using force of an electromagnet formed by applying current
Implementation Method 2
a reduction gear which receives the torque of the motor, converts the generated torque, and transmits the converted torque to an output shaft
Implementation Method 3
an output shaft shaft which has one end provided with an encoder magnet... and a controller which is disposed inside the housing and senses a position of the output shaft from the encoder magnet
Data Source
AI summary
The present invention relates to a shift-by-wire (SBW) device and, more specifically, to an actuator and reduction gear structure of a shift-by-wire device. A shift-by-wire device according to the present invention comprises: a housing; a motor which generates torque by means of an applied current; a hollow rotor shaft; a reduction gear which receives the transmission of the torque of the motor, converts same and transmits same to an output; an output shaft which passes through inside the rotor shaft, has an encoder magnet provided on one end thereof, has the other end directly connected to a manual shaft, and transmits the torque increased by means of the reduction gear to a detent plate; and a controller disposed inside the housing and for detecting the position of the output from the encoder magnet.