Electric Parking Brake Control Using Motor Current Pressure Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional brake control devices fail to accurately estimate fluid pressure in hydraulic brakes when the fluid pressure detection value is not correctly detected by the fluid pressure sensor, leading to potential surplus braking forces.
Innovation Solution
A brake control device that estimates fluid pressure in hydraulic brakes using a current detection value from the electric motor, allowing for adjustment of the electric parking brake force to prevent surplus braking, even if the fluid pressure sensor malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluid pressure sensor is used to detect brake fluid pressure, then the electric parking brake force can be adjusted to prevent surplus braking, but the system becomes vulnerable to sensor malfunction and detection errors
Solution Approach 1:
The patent creates a virtual copy of the fluid pressure sensor by using the motor current detection value to estimate the brake fluid pressure. Instead of relying solely on the physical sensor, the system generates an alternative pressure indication through electrical measurement, which can be used when the sensor fails or provides inaccurate readings.
Solution Approach 2:
The patent replaces the mechanical/fluid-based pressure sensing system with an electrical measurement system. By measuring the current through the motor that drives the brake mechanism, the system substitutes a direct fluid pressure measurement with an indirect electrical parameter measurement, thereby eliminating dependency on the fluid pressure sensor.
2Object-affected harmful factors
If the electric parking brake force is reduced based on fluid pressure detection, then surplus braking force is prevented, but the system cannot cope with sensor detection failures
Solution Approach 1:
The patent prepares for potential sensor failures by establishing an alternative pressure estimation method in advance. The motor current-based estimation system is ready to take over immediately when the fluid pressure sensor malfunctions, providing a cushion against the harmful effects of sensor failure and ensuring continuous reliable operation.
3Measurement precision
If a fluid pressure sensor is installed to monitor brake fluid pressure, then accurate brake force control is achieved, but the detection precision is compromised when the sensor malfunctions
Solution Approach 1:
The patent makes the motor current serve multiple functions: it is used both for controlling the motor operation and for estimating the brake fluid pressure. This multi-functional use of the current detection system provides a universal measurement that works both during normal operation and when the dedicated pressure sensor fails, enhancing overall system robustness.
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 accurate estimation and reduction of surplus braking forces by modifying the electric parking brake force based on estimated fluid pressure, ensuring safe and controlled braking operations even without a functioning fluid pressure sensor.
Implementation Method 1
an electric parking brake capable of generating an electric braking force, which is a braking force different from the hydraulic braking force, on the wheel by a wheel brake mechanism driven by a motor
Implementation Method 2
a hydraulic brake capable of generating a hydraulic braking force, which is a braking force converted from a fluid pressure to a wheel of the vehicle
Data Source
AI summary
A brake control device to be applied to a vehicle having a hydraulic brake generating a hydraulic braking force, which is a braking force converted from a fluid pressure to a wheel of the vehicle, and an electric parking brake generating an electric braking force, which is a braking force different from the hydraulic braking force, on the wheel by a wheel brake mechanism driven by a motor. The brake control device includes an electric parking brake controller for determining a current target value, which is a target value of an electric current through the motor, by using a target braking force, and for controlling the electric parking brake by using the current target value. The electric parking brake controller is configured to estimate the fluid pressure in the hydraulic brake by using a current detection value, which is a detection value of an electric current through the motor.