Electric Brake Restriction Pin Load Distribution
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Solution Overview
Problem
Existing electric brake devices face challenges in preventing deformation of the piston sliding surface of the cylinder body due to load transmission from restriction pins, which can lead to deformation and damage of the piston and seal members.
Innovation Solution
The electric brake device incorporates a restriction pin secured perpendicular to the cylinder body with a clearance between the pin and the cylinder body's inner wall, and an abutting portion on the piston to distribute the load, reducing the risk of deformation and enhancing sliding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a restriction pin is inserted into the cylinder body to restrict backward movement of the piston, then the minimum hydraulic pressure is ensured, but the piston sliding surface of the cylinder body may be deformed due to load transmission
Solution Approach 1:
A restriction groove is introduced as an intermediary structure between the restriction pin and the cylinder body's inner peripheral wall. The restriction pin fits into this groove, which is formed radially outward from the effective inner diameter of the cylinder body. This intermediary groove receives and transmits the load from the restriction pin away from the piston sliding surface, preventing deformation of the sliding surface while maintaining the restriction function.
Solution Approach 2:
The load transmission path is shifted from the radial dimension (affecting the piston sliding surface) to another dimension by forming the restriction groove radially outward from the effective inner diameter. This dimensional shift moves the load application point away from the critical piston sliding surface region, allowing the restriction function to be maintained without harmful deformation.
2Device complexity
If the restriction pin is secured directly to the cylinder body, then the structure is simplified, but excessive force is applied to the restriction pin and the cylinder body
Solution Approach 1:
The restriction function is segmented into two parts: the restriction pin that restricts piston movement and the restriction groove that receives the pin and distributes the load. The groove is formed radially outward from the effective inner diameter, creating a separate load-bearing structure that reduces the force concentration on both the restriction pin and the cylinder body.
3Force
If the screw projection amount increases to move the piston forward, then the braking force is improved, but decentering of the screw tip increases causing piston inclination
Solution Approach 1:
A piston guide is installed in advance in the cylinder body to guide the piston during its forward movement. This preliminary guiding action prevents the piston from inclining as it moves forward, even when the screw has a large projection amount that generates strong braking force. The guide ensures stable piston movement throughout the braking process.
Data Source
AI summary
An electric brake device includes a first slave piston which is housed in a cylinder body and generates hydraulic pressure in a first hydraulic chamber by moving forward, a motor which transmits a driving force to the first slave piston, and a restriction pin which is inserted and secured to the cylinder body in a direction perpendicular to an axial direction of the cylinder body and restricts a backward position of the first slave piston when a hydraulic pressure is applied from an outside to the first hydraulic chamber, wherein the restriction pin is inserted and secured to the cylinder mechanism in the direction perpendicular to the axial direction of the cylinder main body. Further, a clearance is formed between an inner peripheral wall of the cylinder body and a first groove portion and second groove portion which are formed on an outer surface of the restriction pin.