Hydraulic Compression Stop Assembly for Low-NVH Dampers
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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 gradually increases 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 changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic compression stop is added to a passive damper, then the end stop loads are reduced and ride performance is improved, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The compression stop assembly is nested within the existing damper body, with the plunger moving inside a cylindrical bore that is part of the damper structure. This nesting approach allows the compression stop functionality to be integrated without adding external components or significantly increasing overall damper complexity.
Solution Approach 2:
The plunger serves multiple functions: it acts as both the compression stop mechanism and a flow restriction element that provides progressive damping. By combining these functions into a single component, the invention reduces the number of separate parts needed while achieving both end-stop protection and improved ride characteristics.
2Force
If a hydraulic compression stop with plunger is implemented, then the damping force is progressively increased at end of stroke, but the manufacturing precision and assembly difficulty increase
Solution Approach 1:
The invention uses changes in hydraulic flow parameters (flow area, fluid velocity) as the plunger moves to achieve progressive damping force increase. By controlling the geometry of the cylindrical bore and plunger to create varying flow restrictions, the system achieves the desired force progression through parameter variations rather than complex mechanical linkages.
Solution Approach 2:
The invention uses hydraulic principles to achieve the compression stop function, where fluid pressure and flow restriction through the plunger-cylinder interface create the progressive damping force. This hydraulic approach replaces what would otherwise require complex mechanical spring or lever systems, simplifying the overall mechanism while maintaining manufacturing feasibility.
3Ease of manufacture
If a simple bumper is used for compression stop, then the manufacturing is simple and cost-effective, but the NVH performance is poor and end stop loads are high
Solution Approach 1:
The invention replaces the simple mechanical bumper with a hydraulic compression stop that uses fluid pressure and flow restriction to gradually increase damping force. This hydraulic approach eliminates the abrupt impact characteristic of simple bumpers, significantly improving NVH performance while maintaining relative manufacturing simplicity through the use of basic cylindrical components and standard sealing elements.
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 provides enhanced ride performance and quality by reducing end stop loads and improving NVH characteristics, while being economically viable and structurally sound for high rod speed events.
Implementation Method 1
The biasing member biases the plunger towards the extended position
Implementation Method 2
a hydraulic compression stop assembly positioned in the second working chamber... cooperate to define a hydraulic chamber inside the hydraulic compression stop assembly
Data Source
AI summary
A damper includes a piston arranged in sliding engagement inside a pressure tube. The piston divides the pressure tube into a first working chamber and a second working chamber. A hydraulic compression stop assembly is positioned within the second working chamber and includes a plunger arranged in sliding engagement with a sleeve. The plunger includes a bumper cavity having a side wall. The bumper cavity extends a cavity depth from an end face of the plunger. The bumper cavity is in receipt of a compliant bumper. The bumper includes a bumper height greater than the cavity depth such that a portion of the bumper protrudes from the bumper cavity. The protruding bumper portion limits a maximum amount the bumper may be compressed before the sidewall is loaded by one of the piston and a piston rod.