Drum Brake Abutment Force Sensing for Precise Torque Control
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Solution Overview
Problem
Existing drum brake systems lack accurate control and regulation due to varying frictional forces between brake shoes, leading to incomplete measurement of total forces and braking torques, which affects the performance of electric actuators.
Innovation Solution
An elastic abutment with elastic spring action is introduced, allowing for automatic, currentless force limitation through deformation measurement, using strain gauges, Hall sensors, or AMR sensors to detect mechanical stresses and changes in leg inclination or distance, providing accurate force and torque data for actuator control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load sensor is arranged on the abutment to measure supporting forces, then force measurement capability is provided, but measurement precision is insufficient due to varying frictional forces affecting the supporting force accuracy
Solution Approach 1:
A magnetic field is introduced as an intermediary between the mechanical deformation and the sensor. The abutment's deformation changes the air gap in a magnetic circuit, which alters the inductance of a coil. This magnetic field intermediary allows precise measurement of the abutment's deformation without direct mechanical contact, solving the problem of inaccurate force measurement caused by frictional forces.
Solution Approach 2:
The direct mechanical measurement approach (using load sensors that measure supporting forces) is replaced with an electromagnetic measurement system. Instead of mechanically measuring forces that are affected by friction, the system measures the electrical inductance change caused by magnetic field variation, which directly reflects the abutment's deformation and thus the total braking torque.
2Stability of the object's composition
If the abutment is made rigid for structural stability, then structural stability is improved, but the ability to detect total forces through deformation is lost
Solution Approach 1:
The abutment is designed with differentiated local properties: the overall structure maintains rigidity for stability, while specific localized regions (where the coil is positioned) are designed to be elastically deformable. This allows the abutment to exhibit controlled local deformation under load that can be detected by the magnetic measurement system, while maintaining overall structural stability.
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 enables precise control of brake forces and torques, preventing excessive application forces and improving parking brake functionality by compensating for temperature changes, thus enhancing braking performance and reducing the need for additional adjustments.
Implementation Method 1
an elastic abutment (5) with elastic spring action is present as a whole as a solid component that is elastically deformable under load
Implementation Method 2
These mechanical stresses can preferably be detected by strain gauges on the anvil
Implementation Method 3
the sensor or sensors being of the type with which the changing under the load Inclination of the legs can be detected
Implementation Method 4
based on the anisotropic magnetoresistive effect AMR sensors, including the legs are provided with magnets that act as a signal generator for the Hall sensor or AMR sensor
Implementation Method 5
the inductance of the plunger coil is depends on the width of the measuring gap
Data Source
Figure 1
Figure 2~3
AI summary
In particular for controlling electromechanically actuatable brakes it is necessary to detect the forces acting on the abutment (5) of the brake shoes (2, 3). According to the invention, the abutment (5) is therefore formed from a solid material which deforms under load, wherein measurement devices are provided which detect this deformation. A particular embodiment lies in providing the abutment (5) with two limbs (11, 12), on which the brake shoes (2, 3) are supported. The changing distance between the two brake shoes under load is determined by detecting the distance between extension rods (22, 23) on the limbs (11, 12) by means of a measurement device consisting of magnets (24, 25) and Hall sensors or AMR sensors.