Hydraulic Circuit Pipe Variants for Noise Reduction
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Solution Overview
Problem
Hydraulic hybrid vehicles face noise emission issues due to high-frequency excitations from hydraulic machines, which are difficult to mitigate with existing soundproofing methods that increase weight and cost, especially in passenger vehicles requiring comfort, reduced weight, and cost efficiency.
Innovation Solution
A hydraulic circuit design that adjusts pipe lengths and uses solenoid valves to dynamically switch between different circuit variants based on the hydraulic machine's speed and excitation frequency, effectively shifting vibrational modes to avoid noise peaks without modifying the machine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If soundproofing elements are added to the hydraulic circuit to reduce noise from vibrations, then noise emission is reduced, but the size and mass of the installation increase and additional costs are incurred
Solution Approach 1:
The patent applies dynamics by making the hydraulic circuit configuration changeable through solenoid valves that can switch between different pipe variants (different lengths) based on operating conditions. This dynamic reconfiguration allows the system to adapt its vibration characteristics to different excitation frequencies, reducing noise without adding soundproofing mass.
Solution Approach 2:
The patent changes the physical parameter of pipe length to alter the natural frequencies of the hydraulic circuit. By selecting different pipe variants with different lengths, the system shifts its resonant frequencies away from the excitation frequencies generated by the hydraulic machine, thereby reducing vibration-induced noise without requiring soundproofing materials.
2Object-affected harmful factors
If a static eigenmode neutralization device with fixed pipe lengths is used, then noise is reduced at particular excitation frequencies, but it cannot attenuate eigenmodes in a wide frequency range generated by variable speed pumps
Solution Approach 1:
The patent transforms the static pipe configuration into a dynamic system by incorporating solenoid valves that can switch between multiple pipe variants of different lengths. This allows the system to adapt its natural frequencies to match different excitation frequencies caused by variable pump speeds, providing broad frequency range coverage rather than being limited to a single fixed frequency range.
Solution Approach 2:
The patent creates a multi-functional hydraulic circuit where the same circuit can operate in multiple configurations (different pipe lengths) to handle different operating conditions. The solenoid-controlled valve system enables a single circuit design to serve multiple frequency attenuation functions, making the system universally applicable across a wide frequency range rather than requiring separate solutions for different frequency bands.
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 approach allows for effective noise reduction without additional weight or cost, enabling the full utilization of the hydraulic pump's rotational speed range while maintaining vehicle comfort and efficiency.
Implementation Method 1
the controlled means comprise solenoid valves... the hydraulic circuit may include a solenoid valve at each end of the pipes of different lengths, which connects these pipes to the rest of the circuit
Implementation Method 2
by adjusting for example the particular lengths of pipes of each variant in order to obtain modes of these circuit variants which are shifted in frequency... to prevent a variant of this circuit from being used with the excitation frequency of one of its vibration patterns
Data Source
Figure 1~2
AI summary
The invention relates to an hydraulic circuit comprising an hydraulic machine (2) and receptors (4) connected by pipelines, said machine generating pressure oscillations in the circuit (1) according to a range of excitation frequencies, characterised in that said circuit comprises two variants (14, 16) of different lengths or volumes, providing different modal responses to the excitation frequencies, and controlled means (10, 12) which allow either one or the other (14, 16) of said variants to be implemented.