MRF Brake Isolation in Hydraulic Flow Control for Low-Weight Systems
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Solution Overview
Problem
Existing hydraulic fluid systems using magneto-rheological (MR) fluid are limited by the high weight and density of MR fluid, which is not compatible with aerospace applications requiring low fluid weight and contaminant-free recirculation.
Innovation Solution
A hydraulic fluid system is designed with a separate MRF brake that contains a fixed quantity of magneto-rheological fluid, preventing its recirculation, and an integrated configuration with a hydraulic motor, allowing for controlled viscosity and braking torque through electrical control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If magneto-rheological fluid is used to manipulate fluid pressure relationship in hydraulic system, then braking torque control is improved, but fluid weight increases due to high density of MR fluid
Solution Approach 1:
The hydraulic system is segmented into two separate circuits: a first hydraulic circuit containing MR fluid for braking torque control, and a second hydraulic circuit containing conventional hydraulic fluid for actuator operation. This segmentation allows the heavy MR fluid to be isolated to only the brake assembly where it is needed, rather than circulating throughout the entire hydraulic system, thereby minimizing the overall weight penalty while maintaining effective braking torque control.
Solution Approach 2:
The MR fluid is extracted from the main hydraulic circuit and confined exclusively to the brake assembly. A small quantity of MR fluid (approximately 10 mL) is contained within the brake, separated from the larger volume of conventional hydraulic fluid in the second circuit. This extraction eliminates the need for heavy MR fluid to circulate through the entire system, reducing overall fluid weight while preserving braking performance.
2Stress or pressure
If magneto-rheological fluid is recirculated in hydraulic system, then fluid pressure control is improved, but fluid contamination increases
Solution Approach 1:
The hydraulic system is divided into two independent circuits: the first circuit with MR fluid in the brake assembly and the second circuit with conventional hydraulic fluid serving the actuators. This segmentation prevents contaminated MR fluid from recirculating through the actuator circuit, as the brake assembly acts as an isolated containment system where MR fluid remains stationary or is locally recirculated without entering the main hydraulic loop.
Solution Approach 2:
The MR fluid is extracted from the recirculating hydraulic circuit and confined to the brake assembly. This extraction eliminates the contamination pathway that would otherwise exist if MR fluid circulated through the entire hydraulic system, as the MR fluid is now isolated in a separate, non-recirculating containment system.
3Force
If magneto-rheological fluid is used in aerospace applications, then braking performance is improved, but fluid weight increases which is incompatible with aerospace requirements
Solution Approach 1:
The hydraulic system is segmented into two separate circuits: a first hydraulic circuit containing MR fluid for braking torque control, and a second hydraulic circuit containing conventional hydraulic fluid for actuator operation. This segmentation allows the heavy MR fluid to be isolated to only the brake assembly where it is needed, rather than circulating throughout the entire hydraulic system, thereby minimizing the overall weight penalty while maintaining effective braking torque control.
Solution Approach 2:
The MR fluid is extracted from the main hydraulic circuit and confined exclusively to the brake assembly. A small quantity of MR fluid (approximately 10 mL) is contained within the brake, separated from the larger volume of conventional hydraulic fluid in the second circuit. This extraction eliminates the need for heavy MR fluid to circulate through the entire system, reducing overall fluid weight while preserving braking performance.
4Measurement precision
If magneto-rheological fluid is used to control viscosity through electrical signals, then braking torque control precision is improved, but device complexity increases
Solution Approach 1:
The brake assembly uses an electromagnet instead of a mechanical adjustment mechanism to control braking torque. Electrical current applied to the electromagnet modifies the viscosity of the MR fluid, thereby controlling the braking torque applied to the wheel assembly. This substitution of electrical control for mechanical adjustment improves precision while the integrated design keeps the overall device complexity manageable.
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 manages braking torque and fluid pressure in aerospace applications by isolating the magneto-rheological fluid within the MRF brake, ensuring low fluid weight and contaminant-free operation.
Implementation Method 1
magneto-rheological (MR) fluid has a high weight/density and includes ferromagnetic particles
Implementation Method 2
MR fluid has a high weight/density and includes ferromagnetic particles
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A hydraulic fluid system is disclosed and that utilizes a hydraulic motor (30) or gear pump and a magneto-rheological fluid (MRF) brake (50) that is interconnected with an output of the hydraulic motor (30). The MRF brake (50) may utilize a rotatable rotor that is disposed within a magneto-rheological fluid and that is interconnected with an output (e.g., a rotatable output shaft) of the hydraulic motor. An electrical control signal may be provided to the MRF brake (e.g., to a magnetic coil) to adjust the viscosity of the magneto-rheological fluid, and thereby a braking torque exerted on the output of the hydraulic motor.