Hydraulic Compression Stop Assembly for Damper NVH Relief
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Solution Overview
Problem
Existing hydraulic dampers require significant modifications to incorporate effective compression stops, and they often suffer from poor noise, vibration, and harshness (NVH) performance.
Innovation Solution
A hydraulic compression stop assembly with a sleeve, plunger, and biasing member that provides a gradual increase in damping force, combined with a pressure relief valve and a bumper cavity for improved NVH performance, allowing easy integration into existing passive damper designs without major structural changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hydraulic compression stop assembly is added to a passive damper, then the damping force increases gradually and end stop loads are reduced, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The compression stop assembly is nested within the existing damper structure, with the plunger fitting inside the pressure tube and the biasing member housed within the assembly. This nesting approach allows the compression stop functionality to be integrated into the existing damper without requiring separate external components, thereby reducing overall system complexity while still providing gradual damping force increase.
Solution Approach 2:
The invention uses hydraulic principles by incorporating a plunger that moves within a pressure tube, creating variable damping forces through fluid pressure changes. The biasing member (spring) provides mechanical force that combines with the hydraulic system to achieve gradual damping force increase during compression stroke, eliminating the need for complex electronic or mechanical control systems.
2Reliability
If conventional compression stops are used, then the piston and piston rod are cushioned at the end of compression stroke, but the NVH performance remains poor
Solution Approach 1:
The compression stop assembly provides dynamic damping force adjustment through the movement of the plunger and the compression of the biasing member. As the piston approaches the end of its stroke, the plunger restricts fluid flow, dynamically increasing damping force to cushion the impact. This dynamic response improves NVH performance by smoothly absorbing vibrations and shocks rather than providing rigid cushioning.
Solution Approach 2:
The invention changes the damping force parameter gradually during the compression stroke by varying the fluid flow restriction through the plunger's movement. This parameter change allows the system to transition from low damping during normal operation to high damping at end-of-stroke, providing effective cushioning while maintaining good NVH characteristics through smooth force transitions.
3Reliability
If existing passive damper designs are modified to include compression stops, then cushioning is provided, but significant structural changes and manufacturing modifications are required
Solution Approach 1:
The compression stop functionality is segmented into a separate, modular assembly that can be independently manufactured and then integrated into the existing damper. The plunger, biasing member, and associated components form a self-contained unit that fits within the existing pressure tube structure, allowing manufacturers to produce the compression stop assembly separately and assemble it into finished dampers without retooling entire manufacturing lines.
Solution Approach 2:
The compression stop assembly is designed to be universally applicable to existing passive damper designs by utilizing the existing pressure tube and piston rod structure. The assembly performs multiple functions: providing end-of-stroke cushioning, increasing damping force gradually, and improving NVH performance, all within a compact design that fits standard damper configurations, thereby eliminating the need for significant structural modifications.
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 enhances ride performance and quality by reducing end stop loads and improving NVH characteristics, while being economically viable and resistant to high rod speed events.
Implementation Method 1
The biasing member is arranged inside the hydraulic chamber and is configured to bias the plunger towards the extended position
Implementation Method 2
Together, the sleeve and the plunger of the damper cooperate to define a hydraulic chamber inside the hydraulic compression stop assembly
Implementation Method 3
The bumper is configured to cushion the piston and the piston rod when they reach the end of a compression stroke
Data Source
AI summary
A damper having a pressure tube, a piston, and a hydraulic compression stop assembly. The piston is arranged in sliding engagement inside the pressure tube. The piston divides the pressure tube into a first working chamber and a second working chamber and the piston is coupled to a piston rod that extends through the first working chamber. The hydraulic compression stop assembly is positioned in the second working chamber. The hydraulic compression stop assembly includes a sleeve, a plunger, a biasing member, and a pressure relief valve. The plunger is arranged in sliding engagement with the sleeve and can therefore move between an extended position and a retracted position. The biasing member biases the plunger towards the extended position and the pressure relief valve relieves excessive fluid pressure inside the hydraulic compression stop assembly.