Drum Brake Abutment Sensing for Accurate Small-Travel Load Measurement
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Solution Overview
Problem
Existing drum brake systems lack a measurement device capable of providing sufficient measuring accuracy and precision for the elastic flexibility over small distances, which is essential for controlling a spreader device with electric motor, particularly in determining braking forces acting on the abutment during braking.
Innovation Solution
A drum brake design featuring a cylinder with guided pistons, high spring rate springs, and sensors such as Hall sensors or AMR sensors, which are mounted on the pistons or in a sensor housing, allowing precise measurement of forces acting on the pistons through small movement distances, with the abutment securely attached to the steering knuckle using screws or a riveted joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If elastic flexibility is used to determine braking forces, then measurement capability is provided, but measuring accuracy is insufficient for small distance movements
Solution Approach 1:
The patent changes the parameter of spring stiffness (spring rate) to be very high, which allows the elastic element to provide sufficient measurement signal even with minimal compression distances. This parameter change enables accurate force measurement while maintaining compact dimensions.
Solution Approach 2:
The patent replaces traditional mechanical measurement approaches with magnetic field-based sensors (Hall sensors or AMR sensors). These sensors detect the position of magnets on the pistons through non-contact measurement, enabling high-precision measurement of small movements without mechanical contact.
2Volume of moving object
If high spring rate is used to achieve small travel distances, then compact design is enabled, but measurement precision must be maintained
Solution Approach 1:
The patent uses magnetic sensors (Hall sensors or AMR sensors) to replace mechanical measurement systems. These sensors can accurately measure the position of magnets on the pistons even when the pistons move only small distances, thereby maintaining measurement precision in a compact design.
Solution Approach 2:
The patent employs magnets on the pistons that create a magnetic field detectable by the sensors. This change in measurement approach allows for high-precision detection of small displacements caused by high spring rate compression.
3Ease of operation
If elastic abutment design is used, then braking forces can be supported flexibly, but orientation precision with respect to steering knuckle is insufficient
Solution Approach 1:
The patent introduces a hollow peg as an intermediary element that projects from the cylinder and penetrates an opening in the carrier plate to be received in a receiving space in the steering knuckle. This peg serves as a precision alignment feature that defines the orientation of the entire abutment assembly relative to the steering knuckle, while the elastic flexibility is maintained through the spring-loaded piston mechanism.
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 solution enables precise measurement of braking forces with high accuracy, ensuring effective control of the brake actuator and actuation, while maintaining a compact design with minimal actuation distance, thus enhancing the overall performance of the drum brake system.
Implementation Method 1
The springs have a high spring rate. At high spring rates, small movement distances of the pistons are sufficient to determine the forces acting on the pistons with sufficient measuring accuracy from a movement distance.
Implementation Method 2
Typically, the elements that can be sensed consist of magnets, and the sensors consist of sensors that are sensitive to magnetic fields, these being, for example, Hall sensors or AMR sensors, which are based on the anisotropic magnetoresistive effect.
Implementation Method 3
Hall sensors or AMR sensors, which are based on the anisotropic magnetoresistive effect.
Data Source
AI summary
A drum brake having a brake drum, brake shoes, a carrier plate and a load measurement device in the region of an abutment is mountable on a steering knuckle. The abutment has a cylinder in which two pistons are guided, on the outer end faces of which the abutment ends of the brake shoes rest and the inner end faces of which are each supported by a spring on a step in the cylinder. A hollow peg projects from the outside of the cylinder and penetrates an opening in the carrier plate, such that it can be received in a receiving space in the steering knuckle resting on the carrier plate or in a reinforcement element fixed on the steering knuckle.