Electric Linear Actuator Clearance Control for Brake Wear
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Solution Overview
Problem
Existing electric brake systems face challenges in adjusting the clearance between brake pads and a brake disk during normal braking operations, as existing solutions either require special procedures or are prone to instability due to temperature fluctuations and load sensor inaccuracies.
Innovation Solution
An electric linear motion actuator equipped with a load sensor, temperature compensation means, and a clearance control mechanism that calculates and adjusts the target rotational angle of the electric motor to set the clearance to a predetermined value, ensuring accurate and stable adjustment during normal braking operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clearance between the friction pads and the brake disk is set to be small, then the response time to braking is improved, but the friction pads may contact the brake disk due to run-out, generating resistance and causing abnormal wear
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the clearance between the brake pads and brake disk based on detected run-out conditions. The system changes the clearance parameter from a fixed value to a variable value that adapts to actual operating conditions, thereby optimizing both response time and preventing abnormal wear.
2Reliability
If the clearance between the friction pads and the brake disk is set to be large, then the risk of abnormal wear is reduced, but the response time to braking increases
Solution Approach 1:
The system dynamically changes the clearance parameter based on detected conditions. When run-out is detected, the clearance is adjusted to a larger value to prevent abnormal wear. When run-out is not present, the clearance is reduced to improve response time. This dynamic parameter adjustment resolves the contradiction between wear prevention and response speed.
3Measurement precision
If a load sensor is used to detect the magnitude of the load, then the clearance can be adjusted based on actual conditions, but the measurement becomes unstable when the load is near zero
Solution Approach 1:
The patent applies preliminary anti-action by detecting run-out conditions before they cause measurement instability. The system proactively identifies conditions that would lead to unstable load sensor readings and adjusts the clearance accordingly, preventing the instability problem from occurring in the first place.
Solution Approach 2:
The system uses feedback from the load sensor to continuously monitor brake pad contact conditions and adjusts the clearance based on this feedback. When the load sensor detects conditions indicating proper clearance (stable readings with appropriate load), the system maintains or adjusts the clearance to optimize performance while avoiding the instability region near zero load.
4Manufacturing precision
If a special procedure is applied to set the clearance by applying current to the electric motor and stopping it, then the clearance can be adjusted, but the procedure is time-limited and cannot be performed during normal braking operations
Solution Approach 1:
The patent applies self-service by enabling the clearance adjustment function to serve itself during normal braking operations. The system uses the existing braking operation to perform clearance adjustment without requiring a separate special procedure. The clearance is adjusted automatically based on load sensor detection during regular brake application and release, making the system self-sufficient and eliminating time loss.
5Measurement precision
If the differentiated value of the load sensor output is used to pinpoint timing, then the clearance can be set with reference to brake pad position, but the differentiated value becomes unstable when the load is near zero
Solution Approach 1:
The system applies preliminary anti-action by detecting run-out conditions and adjusting clearance before the load sensor enters the unstable near-zero region. This prevents the differentiation instability from occurring, as the clearance is already optimized based on proactive detection of running conditions.
Solution Approach 2:
The system uses feedback from the load sensor to monitor braking conditions and adjusts clearance timing based on this feedback. When the load sensor indicates conditions approaching the unstable region, the system modifies its timing detection strategy or adjusts clearance proactively, preventing instability in the differentiated value.
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
Enables precise adjustment of clearance between brake pads and the brake disk during normal braking, improving response time and reducing wear and fuel consumption by compensating for temperature influences and ensuring accurate load detection.
Implementation Method 1
a load sensor for detecting the magnitude of a load with which the linear motion member is pressed against the object
Data Source
AI summary
An electric linear motion actuator is provided which can set the clearance during normal braking operation of an electric brake system. The linear motion actuator includes a load sensor for detecting the magnitude of the load with which a friction pad is pressed against the brake disk, a temperature sensor for compensating for the influence of temperature on the load sensor, and an electronic control unit. The electronic control unit is adapted to calculate a target rotational angle from the position of the electric motor corresponding to the magnitude of the load detected by the load sensor to the position of the electric motor where the clearance is at a predetermined value, and control the electric motor to rotate the electric motor by the target rotational angle.