Plastic Master Cylinder Piston with Metal Insert for Noise Damping
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Solution Overview
Problem
Existing master cylinders experience noise issues due to rapid piston return, which causes brake fluid pressure to drop below atmospheric pressure, leading to 'water hammer' noise, and current solutions require complex and costly aluminum pistons for improved performance.
Innovation Solution
A primary brake master cylinder piston made of molded plastic with a metal insert, overmolded stamped sheet metal, and grooves on its surface, providing increased mechanical strength, compactness, and ease of production, while allowing for complex shape manufacturing and noise damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum pistons with special shapes are used to improve master cylinder performance, then the mechanical strength and performance are improved, but the production cost increases significantly due to complexity
Solution Approach 1:
The invention uses a composite structure combining plastic material with embedded metal reinforcement elements (such as metal inserts or mesh). This allows the piston to achieve the mechanical strength and durability of metal components while maintaining the ease of molding and cost-effectiveness of plastic manufacturing. The metal reinforcement is strategically placed in areas requiring high strength, such as the pushrod cavity and pressure chamber interfaces.
Solution Approach 2:
The invention changes the material parameters by transitioning from traditional aluminum to plastic with metal reinforcement. This parameter change enables the use of injection molding or similar plastic forming processes, which are more cost-effective and capable of producing complex shapes without additional machining operations, thereby reducing production costs while maintaining performance.
2Speed
If the pistons return rapidly to reduce braking time, then the response speed is improved, but noise is generated due to brake fluid pressure dropping below atmospheric pressure
Solution Approach 1:
The invention incorporates damping elements or cushioning structures within the piston design that are activated during rapid return. These elements may include viscoelastic materials, foam layers, or specially designed fluid passages that create backpressure, preventing the brake fluid pressure from dropping below atmospheric pressure and thus eliminating water hammer noise while allowing rapid piston return.
Solution Approach 2:
The invention converts the potentially harmful rapid piston return motion into a beneficial controlled movement by using the kinetic energy of the returning piston to drive fluid through damping passages or activate cushioning mechanisms. This converts the harmful noise-generating rapid motion into a controlled, quiet return while maintaining fast response time.
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 plastic piston with a metal insert enhances mechanical strength, reduces material thickness, simplifies production, and effectively mitigates noise issues, offering a cost-effective and reliable solution for master cylinder performance.
Implementation Method 1
The use of material(s) plastic(s) makes it possible to reduce costs by providing the shapes of the grooves in the mould. The use of plastic material(s) makes it necessary to increase the thicknesses and to use more material to compensate for the difference in mechanical strength of the materials.
Data Source
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AI summary
The invention relates to a primary piston (20) made of moulded plastic and fitted with a metal insert (22) and comprising grooves (24), which is mounted in a master cylinder comprising at least one primary piston and one secondary piston both of which are mounted in the bore of the master cylinder. These pistons make it possible to create a pressure in a primary pressure chamber and in a secondary pressure chamber respectively, under the action of a push rod on the primary piston.