Decoupled Hydraulic Mount Valve for Low-Frequency Stiffness Control
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Solution Overview
Problem
Decoupled hydraulic bearings face challenges in maintaining low dynamic stiffness at frequencies below 10 Hz, leading to potential stuttering behavior and idling issues due to sharp stiffness drops at specific frequencies.
Innovation Solution
A valve in the membrane between the nozzle discs opens at frequencies of 1 to 15 Hz and amplitudes of 0.05 to 10 mm, reducing dynamic stiffness and remaining closed above 50 Hz, designed as a non-return flap valve with a semicircular tongue shape, allowing fluid flow only under negative pressure in the working chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the diaphragm is clamped between the nozzle discs, then the structural stability is improved, but the dynamic stiffness drops sharply at 6 to 7 Hz causing deterioration in stuttering behavior
Solution Approach 1:
The patent introduces a switchable fluid passage that can be opened or closed depending on operating conditions. During idling, the passage is opened to create a damping channel that reduces dynamic stiffness in the problematic frequency range (6-7 Hz), while during normal operation it remains closed to maintain structural stability. This dynamic switching mechanism allows the system to adapt its stiffness characteristics based on operational requirements.
Solution Approach 2:
The patent changes the physical state and configuration of the fluid passage parameter - switching between open and closed states. By opening the passage during idling, the fluid can flow through the damping channel, fundamentally altering the stiffness parameter of the hydraulic mount in the critical frequency range without compromising overall structural integrity.
2Strength
If the clamp on the diaphragm is released to reduce stiffness reduction, then the stuttering behavior improves, but the stiffness during idling increases worsening the idling behavior
Solution Approach 1:
Rather than permanently releasing the clamp, the patent implements a dynamically switchable fluid passage. The passage remains closed during normal operation to maintain structural stability, but opens automatically during idling conditions to provide the necessary damping channel. This allows the system to have high stiffness during normal operation while providing low stiffness during idling, resolving the contradiction without compromising either state.
3Strength
If a damping channel is created during idling by opening a fluid passage, then the dynamic stiffness is reduced in the relevant frequency range, but the structural complexity increases
Solution Approach 1:
The partition wall serving as the diaphragm structure is given multiple functions: it maintains separation between chambers, provides structural support, and incorporates the switchable fluid passage that creates the damping channel during idling. By integrating these functions into a single component rather than adding separate elements, the patent reduces the increase in structural complexity while achieving the desired dynamic stiffness reduction.
Solution Approach 2:
The damping channel is nested within the existing partition wall structure. The fluid passage is integrated into the diaphragm assembly rather than being a separate external component. This nesting approach allows the damping function to be incorporated without significantly increasing overall structural complexity, as the damping channel utilizes the existing spatial configuration of the partition wall.
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 configuration significantly reduces dynamic stiffness below the resonant frequency, providing a flatter dynamic stiffness curve and improved idling behavior by reducing rigidity in the relevant frequency range.
Implementation Method 1
the valve which is closed when there is overpressure in the working chamber with respect to the compensation chamber and which opens automatically when there is underpressure in the working chamber with respect to the compensation chamber
Implementation Method 2
the elastomeric spring in the hydraulic mount's bearing, in conjunction with the hydraulic fluid in the working chamber, the compensation chamber, the damping channel, and the nozzle discs, determines the hydraulic mount's spring and damping characteristics
Implementation Method 3
low-frequency vibrations of large amplitudes originating from the engine are damped by fluid displacement within the damping channel
Implementation Method 4
High-frequency vibrations with small amplitudes are isolated by the diaphragm located within the partition
Implementation Method 5
The negative pressure occurs when the fluid in the damping channel reaches resonant vibrations
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Decoupled hydraulic mount (1) with a working chamber (7) and a compensation chamber (8) separated by a partition (6) with a damping channel (12) consisting of two nozzle discs (9, 10) and a diaphragm (11) arranged between them, wherein the diaphragm (11) has at least one valve (15) which is closed when there is overpressure in the working chamber (7) with respect to the compensation chamber (8) and which opens automatically when there is underpressure in the working chamber (7) with respect to the compensation chamber.