Drum Brake Abutment Gap Sensing for Accurate Braking Torque
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Solution Overview
Problem
Existing drum brake systems lack precise control over braking forces and torques due to inaccurate measurement of frictional forces acting on brake shoes, which affects the regulation of electric actuators.
Innovation Solution
An elastically deformable abutment is designed between the brake shoes, equipped with sensors to detect deformation and measure the braking torque, using strain gauges or Hall/AMR sensors to record changes in a measuring gap or arm inclination, allowing for accurate determination of braking forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load sensor is installed on the abutment to measure the support force of one brake shoe, then force measurement capability is provided, but the measurement precision is insufficient because frictional forces vary and the support force does not accurately reflect total braking forces
Solution Approach 1:
The patent introduces an elastically deformable abutment as an intermediary element between the brake shoes and the fixed mounting. This abutment deforms under the combined action of both brake shoes, and the deformation is measured by sensors. The abutment acts as a mediator that converts the complex force interactions into a measurable deformation signal that reflects the total braking force, resolving the issue of inaccurate force measurement.
Solution Approach 2:
The patent replaces the direct mechanical force measurement approach with a deformation measurement approach. Instead of trying to measure forces directly with load sensors that are affected by varying frictional forces, the system uses the elastic deformation of the abutment as a proxy measurement. This substitution allows for more accurate determination of total braking forces through strain gauges or other deformation sensors.
2Measurement precision
If contact forces are detected without abutment deformation by sensors detecting rotational bearing forces, then measurement is possible, but the measurement does not reflect the total magnitude of forces acting on the drum brake
Solution Approach 1:
The elastically deformable abutment serves as an intermediary that accumulates and integrates the forces from both brake shoes into a single deformation response. This deformation represents the total magnitude of forces acting on the drum brake, including both frictional and normal forces, thereby preventing information loss about the complete force state.
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 measurement of braking forces and torques, enhancing the control of the braking effect and improving the regulation of the electric actuator in drum brakes.
Implementation Method 1
the abutment as a whole is designed as a solid component that is elastically deformable under load
Implementation Method 2
Strain gauges can be used to determine the deformation of the abutment; these are applied to the abutment
Implementation Method 3
Hall sensors or AMR sensors based on the anisotropic magnetoresistive effect are used, for example, to determine the measuring gap size
Implementation Method 4
Hall sensors or AMR sensors based on the anisotropic magnetoresistive effect are used
Data Source
Figure 1~2
Figure 3~4
AI summary
In particular for the control of electromechanically actuatable brakes of the self-energizing brake type, it is necessary to sense the forces acting on the abutment (6) of the brake shoes (2, 3). The abutment (6) is therefore formed from a solid material that deforms under load, and measurement devices are provided, which sense this deformation. The shape of the abutment (6) is selected in such a way that the abutment has measurement gaps, the size of which changes when the abutment is loaded. The size of the measurement gaps can be sensed by means of Hall sensors or AMR sensors, for example.