Drum Brake Screw Layout for Service and Parking Brake Integration
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Solution Overview
Problem
The existing drum brake and electronic parking brake systems require separate screws and components for service braking and parking braking, leading to increased complexity, manufacturing costs, and a cumbersome layout.
Innovation Solution
A drum brake system where a service brake and a parking brake share a single screw, utilizing a bolt screw and nut piston for service braking and a press nut for parking braking, with the press nut being movable to prevent self-locking during service braking and self-locking during parking braking, achieved through a combination of motors and motive power transfer apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate screws and components are provided for service braking and parking braking, then the braking functions can be independently performed, but the number of components increases and the layout becomes complicated
Solution Approach 1:
The patent combines the service brake screw and parking brake screw into a single integrated screw structure. The screw has different functional sections: a first screw portion for service braking that allows self-locking prevention, and a second screw portion for parking braking that enables self-locking. This merging eliminates the need for separate screws and their associated boosting components, reducing part count while maintaining independent braking functions.
Solution Approach 2:
The single screw structure serves multiple functions: it acts as both the service brake actuator and the parking brake actuator. By incorporating different structural features in different portions of the same screw (different lead angles, different self-locking characteristics), the component achieves multi-functionality, eliminating the need for separate dedicated components for each braking mode.
2Force
If separate boosting components are provided for service braking and parking braking, then the force requirements for each braking mode can be met, but the manufacturing cost increases
Solution Approach 1:
The patent merges the force boosting functions into a single integrated mechanism. The shoe reaction force boosting structure works together with the screw mechanism to provide the necessary mechanical advantage for both service and parking braking. This eliminates the need for separate boosting components for each braking mode, reducing manufacturing complexity and cost while maintaining adequate braking force.
3Ease of operation
If a high-lead screw or ball-screw is used for service braking to prevent self-locking, then the service braking function works properly, but the screw cannot maintain the braking state for parking
Solution Approach 1:
The screw is segmented into functionally distinct portions: a first screw portion with a first lead angle designed for service braking where self-locking prevention is desired, and a second screw portion with a second lead angle designed for parking braking where self-locking is required. This segmentation allows each portion to have optimized characteristics for its specific function, resolving the contradiction between service braking operability and parking brake state maintenance.
Solution Approach 2:
Different portions of the screw have different local qualities in terms of lead angle and self-locking characteristics. The first portion has a larger lead angle for easier service braking operation without self-locking, while the second portion has a smaller lead angle for reliable self-locking during parking braking. This local differentiation of properties allows the single screw to satisfy contradictory requirements at different locations.
4Reliability
If a screw with self-locking capability is used for parking braking, then the braking state can be maintained, but the service braking operation becomes difficult
Solution Approach 1:
The screw is divided into segments with different self-locking characteristics. The first screw portion is designed with a larger lead angle that prevents self-locking, enabling smooth service braking operation. The second screw portion is designed with a smaller lead angle that provides self-locking capability for reliable parking brake state maintenance. This segmentation resolves the contradiction by applying different designs to different functional zones of the same component.
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 configuration reduces the number of components, simplifies the layout, lowers manufacturing costs, and allows for stable parking braking with a significantly lower load requirement compared to traditional systems, enabling a more compact and efficient design.
Implementation Method 1
a nut piston combined by bolt-nut fastening with a circumference of the bolt screw and to be movable toward a direction in which the nut piston presses against a shoe, in conjunction of the rotation of the bolt screw
Implementation Method 2
the press nut being configured to be movable toward the bolt screw due to the drive of the second motor to be brought into contact with the bolt screw, and being configured to prevent the nut piston from being pushed due to a reaction force of the shoe
Implementation Method 3
a press nut being combined by the bolt-nut fastening with a circumference of the nut piston, being configured to be movable toward an axial direction in conjunction with drive of a second motor
Data Source
AI summary
The present disclosure relates to a drum brake. The drum brake includes a bolt screw being rotated in conjunction with drive of a first motor, a nut piston being combined by a bolt-nut fastening with a circumference of the bolt screw and being moved toward a direction in which the nut piston presses against a shoe, in conjunction of the rotation of the bolt screw, and a press nut being combined by the bolt-nut fastening with a circumference of the nut piston, being moved toward an axial direction in conjunction with drive of a second motor, being brought into contact with the bolt screw, and thus preventing the nut piston from being pushed due to a reaction force of the shoe.