Steer-By-Wire Belt Tooth Jump Detection in Ball Screw Steering
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Solution Overview
Problem
The existing steer-by-wire steering systems experience tooth jumping in the belt transmission mechanism due to reverse input loads, leading to wear and reduced efficiency, necessitating a method to detect and address this anomaly.
Innovation Solution
A steering device with two ball screw parts, two ball nuts, two motors, and toothed belt transmission mechanisms, equipped with detectors to monitor the rotation angles of the motors and a controller to detect tooth jumping by comparing the absolute positions calculated from these angles, thereby preventing excessive wear and maintaining torque transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If toothed pulleys and toothed belt are employed to transmit rotation without slippage, then torque transmission efficiency is improved, but tooth jumping occurs under reverse input loads causing wear and reduced quietness
Solution Approach 1:
The control unit detects the occurrence of tooth jumping in advance by monitoring the relationship between motor rotation amount and steering rod displacement amount. When tooth jumping is detected, the control unit preemptively adjusts motor control to prevent further damage, rather than waiting for actual wear to occur.
Solution Approach 2:
The system continuously monitors the correlation between motor rotation and steering rod displacement to detect tooth jumping conditions. This feedback mechanism allows the system to identify when belt teeth are skipping over pulley teeth and adjust operation accordingly to prevent wear.
2Strength
If the steering rod movement is physically restricted to prevent end striking, then structural integrity is improved, but tooth jumping occurs due to inertial forces continuing to rotate the motor and pulley
Solution Approach 1:
The control unit monitors the relationship between motor rotation amount and steering rod displacement amount to detect when the steering rod is physically restricted. When tooth jumping is detected under these conditions, the system adjusts motor control to prevent belt tooth wear.
Solution Approach 2:
When tooth jumping is detected, the control unit preemptively applies counteracting forces through motor control adjustment to offset the inertial forces causing the tooth jumping, preventing further belt damage while maintaining the physical restriction on the steering rod.
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 solution effectively detects tooth jumping, preventing belt wear and maintaining the quietness and efficiency of the steering system by controlling the motors to counteract the inertial forces and reduce the occurrence of tooth jumping.
Implementation Method 1
two ball screw mechanisms 12a, 12b having different lead directions
Implementation Method 2
two ball nuts 15, 16 respectively fastened to the two ball screw parts 12a, 12b
Implementation Method 3
the teeth of the pulleys mesh with the teeth of the belt to transmit the rotation of the motor to the steering rod without slippage
Implementation Method 4
two detectors 30a, 30b configured to respectively detect rotation angles of the two motors 17, 18
Data Source
AI summary
A steering device includes a steering rod that includes two ball screw parts, the steering rod being configured to steer a steerable wheel by moving linearly, two ball nuts respectively fastened to the two ball screw parts, two motors each configured to generate a drive force, two transmission mechanisms each including a toothed belt, the two transmission mechanisms being configured to transmit the drive force of each one of the two motors to a corresponding one of the ball nuts, two detectors configured to respectively detect rotation angles of the two motors, and a controller configured to control each of the two motors. The controller is configured to detect tooth jumping of the belts using the rotation angles of the two motors that are detected by the two detectors.