Electronic Parking Brake Clamping Control Without Motor Temperature Sensors
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Solution Overview
Problem
Conventional electronic parking brake systems lack temperature sensing capabilities, leading to inconsistent clamping forces due to motor temperature variations, which results in increased product size, cost, and reduced durability due to the need for excessive margin settings to accommodate all temperature conditions.
Innovation Solution
An electronic parking brake system that estimates motor temperature without a temperature sensor by analyzing voltage drops and current resistance, adjusting clamping force calculations based on magnetic flux density and torque changes to maintain consistent performance across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is installed to detect motor temperature, then measurement precision of motor temperature is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses voltage drop as an intermediary parameter to indirectly measure motor temperature. Instead of directly measuring temperature with a sensor, the system measures voltage drop across the motor terminals, which correlates with temperature-induced resistance changes. This intermediary measurement approach avoids adding temperature sensors while still providing temperature information for control adjustments.
Solution Approach 2:
The patent replaces the physical temperature sensor measurement system with an electrical measurement system. By measuring electrical parameters (voltage drop, current) and using them to infer temperature, the system substitutes a complex mechanical/thermal sensing mechanism with a simpler electrical measurement approach that uses existing motor terminals.
2Reliability
If a temperature sensor is installed to detect motor temperature, then reliability of clamping force control is improved, but manufacturing cost increases
Solution Approach 1:
The motor itself serves the dual function of both actuation and temperature sensing. The motor's electrical characteristics (resistance changes with temperature) are utilized to provide temperature information without requiring separate sensing components. This self-service approach reduces manufacturing cost while maintaining reliability of clamping force control across temperature variations.
Solution Approach 2:
The motor terminals serve multiple functions: they are used for both driving the motor and for temperature measurement. By making the measurement system universal with the actuation system, the patent eliminates the need for separate temperature sensors, thereby reducing component count and manufacturing cost while ensuring reliable temperature-compensated clamping force control.
3Adaptability or versatility
If excessive margin is set for clamping force to accommodate all temperature conditions, then adaptability is improved, but product size and weight increase
Solution Approach 1:
The patent implements dynamic adjustment of clamping force based on real-time temperature estimation. Instead of using a static excessive margin to cover all temperature conditions, the system dynamically modifies the target clamping force according to the estimated motor temperature. This allows the system to adapt to temperature changes without requiring oversized hardware components.
Solution Approach 2:
The patent changes the control parameter (target clamping force) based on temperature conditions. By adjusting the clamping force target according to estimated motor temperature, the system achieves adaptability across different temperature environments without needing to oversize the mechanical components, thereby reducing product weight and size.
4Reliability
If excessive margin is set for clamping force to accommodate all temperature conditions, then reliability is improved, but product cost increases
Solution Approach 1:
The patent performs preliminary temperature estimation and compensation calculations before executing the clamping force application. By estimating the motor temperature and adjusting the target clamping force in advance, the system ensures reliable clamping force consistency without needing to oversize components with excessive margins, thereby reducing manufacturing costs.
Solution Approach 2:
The patent implements a feedback control mechanism where the estimated motor temperature is used to adjust the target clamping force. This feedback approach ensures that the clamping force remains consistent across temperature variations by continuously adapting the control target, eliminating the need for excessive design margins and reducing overall system cost.
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 ensures precise control of clamping force, reducing the need for excessive margin settings, thereby minimizing product size, cost, and enhancing durability by optimizing hardware design for specific temperature and voltage conditions.
Implementation Method 1
an electric motor provided to rotate the spindle member
Implementation Method 2
estimates a motor temperature depending on a voltage drop amount of the electric motor
Implementation Method 3
estimate a first magnetic flux density based on the first motor temperature
Data Source
AI summary
An electronic parking brake system including: an electronic parking brake (EPB) including a piston provided to press a pair of brake pads disposed on opposite sides of a brake disk rotating together with a wheel of a vehicle, a nut member provided to press the piston, a spindle member provided to move the nut member, and an electric motor provided to rotate the spindle member, and a controller electrically connected to the electric motor, wherein the controller identifies whether a requested parking operation is an initial parking operation, estimates a motor temperature depending on a voltage drop amount of the electric motor in the case of not being the initial parking operation, estimates a clamping force required for parking depending on the motor temperature, and ends the parking operation when the clamping force reaches a target clamping force.