Shift-by-Wire Detent Torque Control for Gear Rattle Reduction
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Solution Overview
Problem
The existing shift-by-wire systems experience gear rattling noise due to backlash elimination issues when switching shift positions, particularly because the backlash elimination on the counter-turning direction is not adequately managed, leading to increased noise and inefficiency.
Innovation Solution
The proposed shift-by-wire system initiates backlash elimination on the counter-turning direction using the reversed rotating electrical machine torque before the detent torque finishes backlash elimination on the same side, reducing the necessary backlash elimination amount and minimizing gear rattling noise by controlling the rotating electrical machine torque based on the detent torque and angular velocity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the detent torque reverses from counter-turning direction to turning direction to switch shift position, then the shift position switching is achieved, but gear rattling noise occurs due to backlash elimination issues
Solution Approach 1:
The control unit initiates backlash elimination on the counter-turning direction side using reversed rotating electrical machine torque before the detent torque finishes backlash elimination on the same side. This preliminary action reduces the necessary backlash elimination amount and minimizes gear rattling noise by controlling the rotating electrical machine torque based on detent torque and angular velocity changes
Solution Approach 2:
The control unit changes the torque parameter of the rotating electrical machine from driving torque to reversed torque at an appropriate timing during the shift position switching process. This parameter change allows the reversed torque to assist in eliminating backlash on the counter-turning direction side, reducing gear rattling noise while achieving smooth shift position switching
2Object-generated harmful factors
If the rotating electrical machine torque is reversed early to eliminate backlash, then gear rattling noise is reduced, but the shift position switching time is extended
Solution Approach 1:
The control unit monitors detent torque and angular velocity changes in real-time during the shift position switching process. Based on this feedback, the control unit determines the appropriate timing to reverse the rotating electrical machine torque and controls the torque reversal to occur at the optimal moment, reducing gear rattling noise while minimizing the impact on switching time
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 approach effectively reduces gear rattling noise by minimizing the period of increased speed in the backlash portion and optimizing the backlash elimination process, thereby enhancing the efficiency and quietness of shift position switching.
Implementation Method 1
a shift-by-wire system configured to switch a shift position by transmitting a torque output from a rotating electrical machine to a detent plate via a gear pair that is a gear device
Implementation Method 2
a detent torque generated in a detent plate by a push of an engagement portion
Data Source
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AI summary
A shift-by-wire system configured to switch shift positions includes a detent plate (46), a detent spring (56), a rotating electrical machine (32), a gear device (76), and an electronic control unit (30). The electronic control unit (30) provided in the shift-by-wire system is configured to control a rotating electrical machine torque. The electronic control unit (30) is configured to reverse the rotating electrical machine torque after the electronic control unit (30) makes the rotating electrical machine (32) output the rotating electrical machine torque for turning the detent plate (46) in a turning direction to switch the shift position, then the detent torque generated in the detent plate (46) by a push of the engagement portion (58) is reversed in the turning direction from a counter-turning direction opposite to the turning direction, and before backlash elimination in a backlash portion of the gear device (76) by the reversed detent torque is finished.