Magneto-Rheological Brake Torque Control Using Residual Yoke Magnetism
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Solution Overview
Problem
Existing brake systems using magneto-rheological fluids face challenges in controlling the initial torque when applying a weak brake force, leading to uncomfortable operation feel due to variations in torque when the coil is not energized, and require complex feedback control and additional components, increasing costs and layout restrictions.
Innovation Solution
An operating device utilizing a magneto-rheological fluid with a magnetic field generation system including a coil and yoke, where a residual magnetic field is maintained by the magnetization means, and the rotational torque control means adjusts the current to the coil based on this field, allowing for a desired constant initial torque without the need for magnetic sensors or feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If feedback control using a magnetic sensor is implemented to suppress variation in initial torque, then the operation feel can be controlled, but the device complexity and manufacturing cost increase due to additional sensors and control circuits
Solution Approach 1:
The yoke material itself provides the solution through its hysteresis characteristics. The residual magnetic field in the yoke automatically generates a stable initial torque without requiring external sensors or control systems. The material's inherent magnetic properties serve the control function that would otherwise require complex electronic systems.
Solution Approach 2:
The invention changes the magnetic parameters of the yoke by selecting materials with specific hysteresis characteristics. By controlling the residual magnetic field strength and direction through material selection and magnetization treatment, the initial torque is stabilized without requiring active control systems.
2Force
If a coil is energized to apply strong brake force, then the braking performance is improved, but the initial torque variation when the coil is not energized causes uncomfortable operation feel
Solution Approach 1:
The yoke is pre-magnetized to establish a residual magnetic field before the brake is activated. This preliminary magnetization creates a stable baseline torque condition that eliminates initial torque variations when the coil is first energized, providing smooth operation feel from the start.
Solution Approach 2:
The invention converts what would normally be considered waste - the residual magnetic field in the yoke - into a beneficial effect. Instead of the residual field causing unwanted initial torque, it is utilized to provide stable and predictable initial torque conditions, improving operation feel.
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 reduces costs and complexity by stabilizing the operation feel and controlling initial torque effectively, achieving a constant resistance force without the need for additional sensors or feedback control circuits, thereby enhancing user experience and reducing manufacturing costs.
Implementation Method 1
a magneto-rheological fluid disposed in contact with the rotor and giving a resistance force to rotation by action of a magnetic field passing through the rotor
Implementation Method 2
a coil generating the magnetic field when energized
Implementation Method 3
a yoke forming a magnetic path for the magnetic field passing through the rotor
Implementation Method 4
the magnetization means supplying a current to energize the coil such that a residual magnetic field in the yoke is held at a predetermined magnitude
Data Source
AI summary
An operating device according to the present invention includes magnetic field generation means. The magnetic field generation means includes a coil generating a magnetic field when energized, and a yoke forming a magnetic path for the magnetic field passing through a rotor. A control unit includes magnetization means and rotational torque control means. The magnetization means supplies a current to energize the coil such that a residual magnetic field in the yoke is held at a predetermined magnitude. The rotational torque control means adjusts a current value applied to the coil in accordance with the magnitude of the residual magnetic field in the yoke. An absolute value of a maximum value of the current value applied to the coil by the rotational torque control means is smaller than an absolute value of a current value applied by the magnetization means.