Master Cylinder Floating Cover for Water Hammer Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing master cylinders experience noise issues due to 'water hammer' caused by rapid return of pistons, leading to brake fluid pressure dropping below atmospheric pressure, which is not adequately addressed by existing solutions like baffle caps that are prone to assembly errors and do not fully mitigate noise.
Innovation Solution
A floating cover or baffle is designed to be housed in the master cylinder chamber, with bearings on both faces to prevent sticking and ensure proper orientation, creating a chicane that slows down brake fluid flow and reduces noise without destandardizing the master cylinder, and can be adapted in dimensions to meet noise and operational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a baffle cap is used to limit brake fluid flow, then water hammer noise is reduced, but assembly errors occur when the seal is placed incorrectly
Solution Approach 1:
The sealing element is designed with asymmetric features including a protrusion that must align with a corresponding recess in the master cylinder body, and an inclined sealing surface that only contacts the body when properly oriented. This asymmetric design ensures the seal can only be assembled in the correct orientation, preventing assembly errors while maintaining its noise-reduction function.
Solution Approach 2:
The sealing element acts as an intermediary component between the brake fluid reservoir and the master cylinder chamber. It provides both the flow-limiting baffle function and the orientation-guiding alignment features, serving as a mediator that ensures proper assembly while reducing water hammer noise through its controlled flow restriction.
2Reliability
If the seal is made to stick by depression against the hole, then sealing is improved, but water hammer effect is amplified when the seal comes off
Solution Approach 1:
The sealing element has different functional zones: a protrusion for alignment, an inclined sealing surface for localized contact with the master cylinder body, and a main body that remains free-moving. The sealing surface is designed to contact only a small localized area of the body, providing adequate sealing without causing the entire seal to stick firmly, thus preventing water hammer when the seal detaches.
Solution Approach 2:
The sealing element transitions from a static, firmly stuck seal to a dynamic, partially free-moving seal. The design allows the seal to maintain contact through its inclined surface during normal operation, but permits it to move freely when pressure differential changes, preventing the sudden detachment that causes water hammer effect.
3Object-affected harmful factors
If the floating seal dimensions are increased to better block flow, then noise reduction is improved, but flow restriction for ABS and ESP systems is degraded
Solution Approach 1:
The sealing element's dimensions and geometry are optimized to provide the right balance between noise reduction and flow rate. The protrusion diameter, sealing surface angle, and body dimensions are carefully selected to create sufficient flow restriction to reduce water hammer noise while maintaining adequate brake fluid flow for ABS and ESP systems. These parameters can be adjusted based on specific application requirements.
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 floating cover effectively reduces or eliminates water hammer noise by slowing down brake fluid flow, ensuring proper assembly without orientation issues, and maintaining necessary flow rates for ABS and ESP systems, providing a noise/flow compromise.
Implementation Method 1
the brake fluid in the master cylinder pressure chambers drops below atmospheric pressure, due to the action of the springs which push the pistons back faster than the arrival of brake fluid in the master cylinder. When the pistons reach their rest position, the communication between the reservoir at atmospheric pressure and the chambers of the master cylinder opens directly, thus producing a passage or flow of rapid and brutal brake fluid which generates noise in the brake system, called 'water hammer'.
Implementation Method 2
a floating cover housed free to move in the chamber being held flat between the upper stop formed by the top of the chamber and its bottom
Data Source
Figure 1
Figure 2A~2C
Figure 2B~3B
AI summary
Master cylinder (200) equipped with a brake fluid reservoir (20) connected by its neck (201) which, with the body (29) of the master cylinder, forms a chamber (24) connected by drilling (23) to the (primary or secondary) pressure chamber of the master cylinder through the holes (220) in the piston (22). The chamber houses an orifice plate (30) limiting the flow/rate of flow of brake fluid drawn into the chamber (222) as the piston (22) returns to its rest position.