Electric Brake Thrust Force Control via Function Update
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Solution Overview
Problem
Conventional electric brake apparatuses face challenges in accurately calculating thrust force due to changes in mechanical components over time, leading to reduced vehicle stability during brake operations, especially when these changes occur on both left and right wheel sides.
Innovation Solution
The electric brake apparatus includes a caliper moved by an electric motor through a transmission mechanism, a control unit with a thrust force estimation unit that calculates thrust force based on electric current, and an update unit that corrects and updates the electric current/thrust force conversion function by comparing estimated and reference thrust forces at specific rotational positions, ensuring accurate control despite mechanical changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric brake apparatus uses a fixed electric current/thrust force conversion function to calculate thrust force, then the control system is simple and does not require additional sensors, but the calculation accuracy deteriorates over time due to mechanical component changes
Solution Approach 1:
The system performs preliminary calibration to establish the electric current/thrust force conversion function, and then periodically updates this function based on detected changes in mechanical components. This preliminary action and subsequent updates maintain calculation accuracy without requiring continuous sensor feedback during normal operation.
Solution Approach 2:
The system uses feedback from detecting devices that monitor changes in mechanical portions (such as brake pad wear and grease viscosity changes) to automatically update the electric current/thrust force conversion function. This feedback mechanism maintains thrust force calculation accuracy despite mechanical component degradation over time.
2Productivity
If the electric brake apparatus does not update the conversion function, then the device operation is simple and fast, but vehicle stability deteriorates when mechanical components change
Solution Approach 1:
The system performs periodic updates of the electric current/thrust force conversion function based on detected mechanical component changes, rather than continuous updates. This periodic action maintains vehicle stability while minimizing interference with normal brake operations and maintaining operational speed.
3Measurement precision
If the electric brake apparatus uses a thrust force sensor to directly detect thrust force, then the thrust force measurement is accurate, but the device complexity and cost increase
Solution Approach 1:
The system replaces the mechanical thrust force sensor with an electrical measurement approach. By measuring electric current and using the electric current/thrust force conversion function (which is updated based on mechanical portion changes), the system achieves accurate thrust force detection without requiring direct mechanical sensors, thereby reducing device complexity and 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 solution maintains high accuracy in brake control and stabilizes vehicle performance by continuously updating the electric current/thrust force conversion function, accounting for wear and changes in brake pads and mechanical components, thus preventing a reduction in vehicle stability during braking.
Implementation Method 1
an electric motor unit (18) including an electric motor (19)
Data Source
AI summary
An electric brake apparatus compares an estimated thrust force corresponding to a predetermined rotational position of an electric motor, which is calculated from an electric current/thrust force conversion function, with a reference thrust force based on a rotational position/thrust force table indicating a relationship between the rotational position of the electric motor and a thrust force of a piston to correct and update the electric current/thrust force conversion function, thereby maintaining a predetermined control accuracy despite wear of a brake pad and other changes over time.