Electric Parking Brake Cable Tension Control for Slope Reliability
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Solution Overview
Problem
Existing electric parking brake systems face challenges in maintaining appropriate braking torque on slopes due to differences in torque application direction, leading to inefficiencies when the vehicle is on an uphill or downhill slope, despite equal inclination angles.
Innovation Solution
The system controls the tension of the cable in the electric parking brake mechanism based on the slope inclination, setting a higher target tension for downhill slopes than uphill slopes to maintain consistent braking torque, utilizing an inclination-based tension control unit and maintaining mechanism to ensure the friction member pushing force is appropriate for both scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cable tension is set to the same value for both uphill and downhill slopes with equal inclination angles, then the system structure is simple, but the braking torque differs due to torque application direction, leading to inadequate braking performance
Solution Approach 1:
The patent applies different cable tension values for different slope directions (uphill vs downhill) even when inclination angles are equal. The tension control unit sets higher tension for downhill slopes and lower tension for uphill slopes, making the braking system's tension parameter direction-dependent to match the different torque application directions and ensure reliable braking performance in both scenarios.
Solution Approach 2:
The patent changes the cable tension parameter based on slope direction. The tension control unit adjusts the cable tension value as a variable parameter depending on whether the vehicle is on an uphill or downhill slope, ensuring optimal braking torque is achieved for each direction while maintaining simple control logic.
2Reliability
If the cable tension is increased for downhill slopes to compensate for lower braking torque, then braking reliability improves, but energy consumption increases
Solution Approach 1:
The patent applies higher cable tension specifically for downhill slopes where braking torque is naturally lower, while using lower tension for uphill slopes where braking torque is sufficient. This localized adjustment ensures braking reliability is maintained only where needed (downhill) rather than uniformly increasing tension in all conditions, thereby minimizing unnecessary energy consumption.
3Use of energy by moving object
If the cable tension is decreased for uphill slopes to reduce energy consumption, then energy efficiency improves, but braking torque may be insufficient on steep uphill slopes
Solution Approach 1:
The patent dynamically adjusts the cable tension parameter based on slope direction, setting it to a lower value for uphill slopes to reduce energy consumption while maintaining sufficient braking torque, and to a higher value for downhill slopes to ensure adequate braking performance when needed.
4Device complexity
If the same cable tension is used for both uphill and downhill slopes, then the control system is simple, but the braking torque varies due to different torque application directions
Solution Approach 1:
The patent makes the cable tension parameter direction-dependent by applying different tension values for uphill and downhill slopes. The tension control unit determines the slope direction and sets appropriate tension levels, ensuring consistent and reliable braking torque is achieved in both directions while keeping the control logic straightforward and easy to implement.
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 allows for effective maintenance of the vehicle at a standstill on various slopes by adjusting cable tension, minimizing braking torque differences and ensuring reliable braking performance regardless of the slope direction.
Implementation Method 1
an electric motor; a motion conversion mechanism that converts the rotation of a rotating shaft of the electric motor into the linear motion of an output member
Implementation Method 2
a shoe which is fitted to a backing plate that is a non-rotating body so as to be movable relative to the backing plate, and which has a friction member on the outer peripheral face, and a pushing mechanism that pushes the shoe against the friction face to suppress the rotation of the drum
Data Source
AI summary
In an electric parking brake system including a tension control unit that controls the friction member pushing force in a brake by controlling the tension of a cable, the target tension is set to a larger value when a vehicle is maintained at a standstill on a downhill slope than when the vehicle is maintained at a standstill on an uphill slope.