Piston Seal Cutout Grooves for Brake Fluid Supply
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Solution Overview
Problem
The existing master cylinder design for vehicles faces issues with brake fluid supply due to the piston seal adhering to the side surface, causing obstruction and requiring multiple filling operations, which increases the overall size and complexity of the system.
Innovation Solution
The design incorporates a piston seal with an annular base, inner and outer circumferential lip portions, and an intermediate projecting portion with cutout grooves, allowing for efficient brake fluid supply through a gap between the outer circumferential lip and the bottom surface of the circumferential groove, minimizing the need for repeated filling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the communication groove is located inward of the bottom surface of the circumferential groove, then the piston seal can seal the pressure chamber, but the piston seal adheres to the side surface and obstructs brake fluid flow
Solution Approach 1:
The piston seal is segmented into multiple functional portions: a sealing portion for sealing the pressure chamber, an intermediate projecting portion with cutout grooves for guiding brake fluid flow, and an outer circumferential lip portion for preventing adhesion to the side surface. This segmentation allows each portion to perform its specific function independently, resolving the contradiction between sealing performance and fluid supply efficiency.
Solution Approach 2:
Different portions of the piston seal are given different local qualities and geometries. The sealing portion has a specific profile for sealing, the intermediate portion has cutout grooves for fluid passage, and the outer lip portion has a geometry that prevents adhesion. This local differentiation allows the seal to simultaneously achieve reliable sealing and maintain unobstructed brake fluid flow.
2Reliability
If a cylinder sleeve is incorporated into the cylinder body, then the sealing performance is improved, but the radial size and overall size of the master cylinder increases
Solution Approach 1:
The piston seal integrates multiple functions that were previously performed by separate components. The seal combines the sealing function, the fluid guidance function, and the adhesion prevention function into a single integrated component, eliminating the need for a separate cylinder sleeve and reducing the overall master cylinder size while maintaining sealing performance.
Solution Approach 2:
The piston seal is designed as a multi-functional component that simultaneously performs sealing, fluid guidance, and adhesion prevention. This universal design consolidates multiple functions into one component, reducing the number of parts and the overall size of the master cylinder while maintaining or improving sealing performance.
3Reliability
If the piston seal adheres to the side surface, then sealing is maintained, but the flow of brake fluid into the communication groove is obstructed
Solution Approach 1:
The intermediate projecting portion with cutout grooves extracts or creates a dedicated fluid passage pathway that is separate from the adhesion interface. This allows brake fluid to flow through the cutout grooves independently of whether the outer circumferential lip portion contacts the side surface, ensuring that sealing is maintained without obstructing fluid supply.
Solution Approach 2:
The cutout grooves in the intermediate projecting portion act as an intermediary fluid passage that mediates between the pressure chamber and the communication groove. This intermediary pathway ensures brake fluid can reach the communication groove even when the outer lip portion adheres to the side surface, maintaining both sealing and fluid supply.
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 ensures a sufficient brake fluid supply without obstruction, reducing the number of filling operations and maintaining a compact system size by facilitating smooth fluid flow through the cutout grooves, thus enhancing the efficiency and reliability of the brake fluid supply.
Implementation Method 1
a piston seal provided in a circumferential groove formed in the cylinder body, the piston seal having an inner circumferential surface thereof in slidable contact with the piston and being capable of sealing the pressure chamber from the supply passage
Implementation Method 2
brake fluid in the supply passage is supplied to the pressure chamber through a gap between the outer circumferential lip portion of the piston seal and the bottom surface of the circumferential groove
Implementation Method 3
cutout grooves are formed on a tip side of the intermediate projecting portion. Therefore, when the piston moves back, brake fluid in the supply passage is supplied to the pressure chamber through a gap between the outer circumferential lip portion of the piston seal and the bottom surface of the circumferential groove, and the cutout groove of the intermediate projecting portion
Data Source
AI summary
A piston seal is provided in a circumferential groove formed in a cylinder body. The piston seal is capable of sealing a pressure chamber, which supplies fluid pressure to a discharge passage, from a supply passage, which communicates with a reservoir. The piston seal comprises: an annular base portion; an inner circumferential lip portion projecting from an inner circumferential side of the base portion and being in slidable contact with an outer circumferential surface of a piston; an outer circumferential lip portion projecting from an outer circumferential side of the base portion and being in abutment with the circumferential groove of the cylinder body; and an intermediate projecting portion which is formed between the inner circumferential lip portion and the outer circumferential lip portion of the base portion and which is projected beyond the outer circumferential lip portion. Cutout grooves are formed on a tip side of the intermediate projecting portion. Therefore, when releasing air, a sufficient amount of brake fluid can be supplied through a gap between the piston seal and a bottom surface of the circumferential groove, and the cutout groove. As a result, the number of repetitions of an air releasing operation can be minimized.