Shift-by-Wire Parking Torque Limiting for Sprag Protection
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Solution Overview
Problem
Shift-by-Wire (SBW) type shift levers in vehicles can cause damage to the parking sprag when the accelerator pedal is operated while the vehicle is not stopped, due to applied impacts.
Innovation Solution
A vehicle control system that includes an inputter for receiving acceleration pedal signals and road gradient information, a controller to determine gradient load torque and acceleration torque, and a driving device to limit the driver's requested torque, thereby preventing damage to the parking sprag by shifting the shift lever to the P-stage when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shift lever is shifted to P-stage while the accelerator pedal is pressed, then the vehicle can be quickly parked, but the parking sprag may be damaged due to applied impact
Solution Approach 1:
The controller performs preliminary actions by determining gradient load torque and acceleration torque before the parking sprag engages, and limits the driver's requested torque based on these calculations. This preliminary torque limitation prevents excessive impact forces from being applied to the parking sprag during the shifting process, thereby protecting it from damage while still allowing quick parking when the vehicle is stationary.
Solution Approach 2:
The controller changes the torque parameter dynamically by limiting the driver's requested torque based on calculated gradient load torque and acceleration torque. This parameter modification ensures that the torque applied during P-stage engagement remains within safe limits, preventing damage to the parking sprag while maintaining the ability to execute parking commands efficiently.
2Reliability
If the driver's requested torque is limited based on gradient load torque and acceleration torque, then the parking sprag is protected from damage, but the system complexity increases
Solution Approach 1:
The patent replaces a purely mechanical torque transmission system with an electronically controlled system. The controller calculates gradient load torque and acceleration torque, then electronically limits the driver's requested torque before it reaches the transmission. This substitution allows for precise torque management to protect the parking sprag while using software-based control rather than complex mechanical mechanisms.
Data Source
AI summary
A vehicle in which a shift lever of a Shift-by-Wire (SBW) type is used, the vehicle may include an inputter configured to receive pressing force of an acceleration pedal of the vehicle, a shift command to a P-stage of the shift lever, and gradient information related to a road on which the vehicle drives; a controller configured to: when the pressing force of the acceleration pedal of the vehicle is generated and the shift command to the P-stage is input to the controller, determine a gradient load torque and an acceleration torque of the vehicle, and limit a driver's requested torque based on the determined gradient load torque and the determined acceleration torque; and a driving device connected to the controller and configured to shift the shift lever to the P-stage when the driver's requested torque is limited.