Brake System Motor Stopping Current Control
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Solution Overview
Problem
Conventional electric power brakes face challenges in maintaining appropriate braking force across varying temperatures due to a small torque constant at high temperatures, which can result in inadequate braking force if the set current value is only adjusted proportionally to atmosphere temperature.
Innovation Solution
A brake system that includes a motor, a current detection unit, a storage unit, and a control unit to set and manage the motor stopping current based on the idle running current, ensuring the rate of change of the motor stopping current relative to the idle running current is adjusted to maintain consistent braking force across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the set current value is changed proportional to the atmosphere temperature, then the braking force can be maintained at low temperatures, but the predetermined braking force cannot be obtained at high temperatures due to small torque constant
Solution Approach 1:
The motor stopping current is dynamically adjusted based on the detected idle running current, which varies with temperature. The control unit changes the motor stopping current in a non-proportional manner according to the idle running current magnitude, allowing the system to adapt to temperature changes while maintaining appropriate braking force across different temperature conditions
Solution Approach 2:
The invention changes the parameter of motor stopping current based on the idle running current detected at different temperatures. By storing correspondence relations between idle running current and motor stopping current, and adjusting the rate of change differently for small versus large idle running currents, the system optimizes braking force across the temperature range without requiring proportional adjustment
2Device complexity
If a constant motor stopping current is used, then the control system is simple, but the braking force becomes inadequate at high temperatures due to torque constant reduction
Solution Approach 1:
The system uses the idle running current, which is already detected during normal operation, to automatically determine the appropriate motor stopping current. The control unit refers to stored correspondence relations between idle running current and motor stopping current, allowing the system to self-adjust without requiring external temperature sensors or complex control algorithms
Solution Approach 2:
The control unit continuously monitors the idle running current and uses this feedback to adjust the motor stopping current accordingly. By establishing a feedback loop where the idle running current information is used to determine the motor stopping current, the system maintains appropriate braking force while keeping the control logic relatively simple
3Reliability
If the motor stopping current is increased to compensate for high temperature torque constant reduction, then adequate braking force is obtained at high temperatures, but excessive braking force occurs at low temperatures
Solution Approach 1:
The invention applies different adjustment strategies for different operating conditions. When the idle running current is small (indicating high temperature), the motor stopping current is increased with a smaller rate of change. When the idle running current is large (indicating low temperature), the motor stopping current is maintained or adjusted with a larger rate of change. This localized quality adjustment prevents excessive braking force at low temperatures while ensuring adequate braking force at high temperatures
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
The system effectively generates appropriate braking force regardless of temperature changes, reducing the risk of excessive braking force and enabling a downsized, low-cost, and reliable configuration by considering resistance and torque constant variations.
Implementation Method 1
a motor that moves the piston with the supply of power source
Implementation Method 2
presses pressing members to a rotary member to control the rotation of the rotary member
Data Source
AI summary
An object of the present invention is to obtain a brake system that can generate appropriate braking force without influence of temperature. A brake system includes: a piston that presses pressing members; a motor that moves the piston; a current detection unit that detects current flowing in the motor; a storage unit that stores a correspondence relation between idle running current and motor stopping current; a motor stopping current setting unit that sets the motor stopping current using the storage unit and the idle running current; and a control unit that stops to supply the current to the motor when the current flowing in the motor reaches the motor stopping current. The correspondence relation is set so that the rate of change of the motor stopping current relative to the idle running current becomes smaller when the idle running current is small than that when it is large.