Plastic Primary Piston for Tandem Master Cylinder
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Solution Overview
Problem
The existing tandem master-cylinder primary piston requires complex and costly machining, particularly for aluminum or aluminum alloy materials, leading to high manufacturing costs and potential issues with machining burrs.
Innovation Solution
A primary piston with a plastic material skirt and intermediate back wall, featuring a crown of ribs forming closed grooves that facilitate hydraulic fluid passage between the supply and pressure chambers, allowing for easy injection molding and assembly without finishing work, and providing sufficient mechanical resistance and damping effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aluminum or aluminum alloy material is used for the primary piston, then mechanical strength and resistance to mechanical forces are improved, but manufacturing complexity and cost increase significantly due to complex machining requirements
Solution Approach 1:
The patent changes the material parameter from metal (aluminum alloy) to plastic material, fundamentally altering the manufacturing approach. This parameter change allows the use of injection molding instead of complex machining operations, thereby reducing manufacturing complexity while maintaining the necessary mechanical strength through proper material selection and design
Solution Approach 2:
The patent replaces the mechanical machining system with an injection molding process. Instead of using cutting tools to remove material from aluminum blocks to create the piston and its features (such as the crown of holes and frustoconical groove), the design is directly formed through injection molding of plastic material, eliminating the need for complex mechanical machining operations
2Strength
If aluminum material is used for the primary piston, then mechanical resistance is improved, but manufacturing cost increases due to complex machining and finishing operations
Solution Approach 1:
The patent changes the material parameter from metal to plastic, which fundamentally alters the cost structure. Plastic material can be injection molded directly into the final shape without requiring expensive machining centers, tooling, or finishing operations, thereby significantly reducing manufacturing cost while maintaining adequate mechanical resistance for the application
Solution Approach 2:
The patent adopts a cost-effective material (plastic) and manufacturing approach (injection molding) that produces an affordable piston component. The design accepts that the piston may have a limited service life in exchange for dramatically reduced manufacturing costs, eliminating the need for expensive metal machining and post-processing operations
3Ease of manufacture
If crown of holes is machined in the primary piston, then hydraulic fluid passage is enabled, but machining burrs are generated requiring additional finishing work
Solution Approach 1:
The patent replaces the mechanical drilling and machining process with injection molding. The crown of holes (or ribs forming closed grooves) is formed as an integral part of the molded plastic piston, eliminating the generation of machining burrs and the need for additional finishing operations such as deburring or polishing
Solution Approach 2:
The patent changes the manufacturing process parameter from mechanical machining to injection molding, which fundamentally alters how the hydraulic passages are created. Instead of removing material through drilling (which creates burrs), the passages are formed by shaping the plastic material itself, resulting in clean, burr-free surfaces that require no additional finishing
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
The solution enables a cost-effective and easily manufactured primary piston that can withstand mechanical forces, disrupt hydraulic flow, and mitigate fluid hammer phenomena, while ensuring reliable operation in ESP mode and secondary piston support.
Implementation Method 1
spring 373 cooperating with the secondary piston
Implementation Method 2
pressure chamber 340 connected to the primary brake circuit
Data Source
AI summary
A primary piston composed of a skirt and an intermediate back wall having a rear face receiving the servobrake thrust rod and a forward face for the telescoping rod and the spring pushing the secondary piston. The front of the skirt has longitudinal grooves open in front and closed in the rear. The thickness of the skirt beneath the grooves and the part of the skirt between two successive grooves in the peripheral direction form a front face enabling the principal piston to push the secondary piston. The principal piston is made of a single piece of plastic material.