Parking Brake Piston Assembly With Load Transfer Stroke Compensation
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Solution Overview
Problem
The existing parking brake apparatuses face challenges in generating sufficient braking force, especially for large vehicles, due to the limited service life of elastic members, which are prone to damage and stroke loss, and are constrained by the in-wheel space.
Innovation Solution
The apparatus incorporates a bolt screw, pistons, screw nuts, elastic members, and a load transfer unit that distributes the displacement of the screw nut beyond a set distance to the piston, reducing the load on the elastic member, thereby increasing its service life and maintaining braking force consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the elastic member is enlarged to increase service life and compensate for stroke loss, then the braking force stability is improved, but the in-wheel space is insufficient to accommodate the larger elastic member
Solution Approach 1:
The displacement compensation function is segmented between two components: the elastic member (disc spring) that handles initial displacement, and the load transfer unit (nut protrusion pressing part) that handles additional displacement beyond the set distance. This segmentation allows the elastic member to remain compact while still achieving the compensation function through collaborative operation with the load transfer unit.
Solution Approach 2:
The load transfer unit acts as an intermediary mechanism between the screw nut and the piston. When the screw nut moves beyond the set distance, the load transfer unit transmits the additional displacement to the piston, thereby compensating for stroke loss without requiring the elastic member to be enlarged.
2Reliability
If the elastic member is enlarged to compensate for stroke loss, then the braking force generation is improved, but the device complexity increases
Solution Approach 1:
The load transfer unit serves multiple functions: it acts as a displacement transmission mechanism, a load distribution element, and a stroke loss compensation device. By integrating these functions into a single component (the nut protrusion pressing part), the patent avoids increasing device complexity while improving braking force generation.
Solution Approach 2:
The load transfer function is merged with the existing screw nut structure. The nut protrusion pressing part is formed as an integral part of the screw nut, combining the fastening function with the load transfer function, thereby avoiding additional separate components and reducing overall structural complexity.
3Duration of action of moving object
If the elastic member is enlarged to increase service life, then the stroke loss compensation is improved, but the manufacturing difficulty increases
Solution Approach 1:
The load transfer unit is designed with a predetermined set distance from the piston, allowing the elastic member to be manufactured to standard specifications. The preliminary positioning of the load transfer unit ensures that it engages at the correct displacement point, eliminating the need for custom-manufactured large elastic members.
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 enhances the service life of the elastic member by distributing additional displacement to the load transfer unit, reducing the load on the elastic member and maintaining consistent braking force, even under increased vehicle weight or slope conditions.
Implementation Method 1
one or more elastic members disposed around the screw nut within the piston, and elastically deformed, in response to a displacement of the screw nut while the screw nut is moved by a set distance, to press the piston toward a shoe
Implementation Method 2
one or more screw nuts accommodated in the piston, screwed to an end of the bolt screw, and moved along with the rotation of the bolt screw
Implementation Method 3
When the actuator is driven to rotate a worm shaft, a piston moves while a worm wheel engaged with the worm shaft is rotated
Data Source
AI summary
A parking brake apparatus including a bolt screw rotated by a driving force transmitted from an actuator, one or more pistons disposed at one side or both sides of the bolt screw, one or more screw nuts accommodated in the piston, screwed to an end of the bolt screw, and moved along with the rotation of the bolt screw, one or more elastic members disposed around the screw nut within the piston, and elastically deformed, in response to a displacement of the screw nut while the screw nut is moved by a set distance, to press the piston toward a shoe, and a load transfer unit disposed in the piston, and configured to transmit, to the piston, a displacement of the screw nut when the screw nut moves more than the set distance, thereby pressing the piston toward the shoe.