Brake Piston Guide Means for NVH Reduction
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Solution Overview
Problem
Current motor vehicle disc brake systems face challenges in reducing noise, vibration, and harshness (NVH) and roll-back properties, particularly in unpressurized states, due to limitations in existing sealing and guiding mechanisms that lead to unwanted vibrations and discomfort.
Innovation Solution
A guide system for the brake piston that incorporates a reversibly elastically clamped guide means, allowing for modal-acoustic detuning and lateral force modulation, enabling the brake piston to be asymmetrically clamped and oriented, thereby reducing hysteresis errors and unwanted vibrations through a dual function of sealing and lateral force modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a precision-machined cylindrical fit is used between the brake piston wall and brake piston bore wall for mechanical support, then linear guidance and mechanical stability are improved, but manufacturing complexity and cost increase due to high precision requirements
Solution Approach 1:
The invention changes the clearance parameter from a precision-machined tight fit to a deliberately enlarged clearance that accommodates a guide element. This parameter change transforms the guidance mechanism from direct contact between precision surfaces to contact through the guide element, reducing manufacturing precision requirements while maintaining mechanical stability.
Solution Approach 2:
The guide element acts as an intermediary component between the brake piston wall and brake piston bore wall. It provides the guidance function without requiring high precision between the piston and bore, as the guide element absorbs the misalignment and provides stable linear guidance through its own geometry and elastic clamping.
2Object-affected harmful factors
If the brake piston is firmly guided to reduce vibrations, then NVH performance improves, but roll-back function deteriorates due to increased friction
Solution Approach 1:
The guide element is designed with elastic properties, allowing it to deform flexibly during piston movement. This flexibility reduces the friction force between the guide element and brake piston wall compared to rigid guidance, while still providing sufficient constraint to reduce vibrations. The elastic deformation absorbs energy and reduces stick-slip phenomena.
Solution Approach 2:
The guide element transitions from a static rigid constraint to a dynamic elastic constraint that adapts to the piston movement. During normal operation, it provides firm guidance to reduce vibrations. During roll-back, its elastic properties allow controlled movement with reduced friction, enabling the piston to retract smoothly.
3Reliability
If a smooth surface is used between brake piston and ring seal, then sealing function improves, but stick-slip phenomenon increases leading to reduced roll-back behavior
Solution Approach 1:
The invention extracts the guidance function from the sealing interface by introducing a separate guide element. This separation allows the ring seal to maintain its smooth sealing surface for reliable sealing, while the guide element provides the necessary mechanical guidance and controlled friction for proper roll-back behavior, eliminating the conflict between sealing and roll-back requirements.
4Force
If carbon or graphite material is used for self-lubrication, then friction is reduced improving roll-back, but thermal and mechanical properties deteriorate and wear increases
Solution Approach 1:
Instead of using carbon or graphite materials with inherent self-lubrication properties, the invention creates a functional copy of the lubrication effect through the elastic guide element design. The guide element's geometry and elastic deformation provide controlled friction and lubrication-like behavior without requiring special materials, maintaining reliable thermal and mechanical properties while achieving satisfactory roll-back.
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 solution effectively decouples the brake piston, improving NVH and roll-back properties across all operating states, reducing assembly costs, and enhancing comfort by allowing variable orientations and angles of the brake piston axis, thus addressing the limitations of conventional systems.
Implementation Method 1
a guide means (15) that is reversibly elastically clamped in a gap (14) between the cylindrical brake piston wall (12) and the brake piston bore (13)
Implementation Method 2
An elastic ring seal (9), based on the plunger principle, is integrated into the housing and sits elastically and centrally on the brake piston wall (12) from the radial outside. This provides a hydraulic sealing function
Implementation Method 3
After brake application, the deforming ring seal (9) imparts the aforementioned restoring effect to the brake piston (3) and the housing (4) whereby its wall engages the brake piston wall (12) under frictional force
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
The invention relates to a guiding system for a brake piston of a motor-vehicle disk brake, comprising a brake piston, a cylindrical brake-piston bore (13) for accommodating the brake piston in a housing (4) in such a way that the brake piston can be axially displaced, and a ring seal supported in the housing (4) in an axially immovable manner, which ring seal is elastically clamped between a cylindrical brake-piston wall and a recess in the brake-piston bore (13). In order to improve the NVH behavior in the avoidance of disturbing noises of motor-vehicle disk brakes, a reversibly elastically preloaded guiding means (15) is clamped between the brake-piston bore (13) and the brake-piston wall, which guiding means is supported on the housing (4) and couples the brake piston to the brake-piston bore (13) in such a way that the brake piston is oriented in a specific manner.