Variable Hydrostatic Damping Linkage for Multi-Frequency Vibration
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Solution Overview
Problem
Current hydrostatic drive systems face significant vibration challenges due to pressure and flow pulses, which existing damping devices struggle to address effectively across multiple resonating frequencies, especially in infinitely variable transmissions (IVTs), and these solutions often rely on costly and less robust electronic systems.
Innovation Solution
A hydrostatic drive system that employs a mechanical linkage to vary the attenuation frequency of a damping device, such as a Helmholtz resonator, allowing for robust and reliable vibration control by linking the displacement control of hydraulic drive units directly to the variable element of the damping device, eliminating the need for electronic sensors and controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fixed-tuned damping devices (Helmholtz resonators, side-branch resonators) are used to reduce vibration, then vibration amplitude is reduced at specific frequency bands, but the devices are ineffective across multiple resonating frequencies because they must be tuned for narrow frequency bands
Solution Approach 1:
The patent applies the dynamics principle by making the damping device tunable through a variable tuning mechanism that adjusts the resonant frequency of the Helmholtz resonator. This allows the damping device to adapt to different operating conditions and multiple resonating frequencies in hydrostatic drive systems, transforming a static fixed-tuned system into a dynamic adjustable one that can track and dampen vibrations across a broader frequency spectrum.
Solution Approach 2:
The patent implements parameter changes by varying the effective volume of the Helmholtz resonator chamber or the area of the neck opening through mechanical adjustment mechanisms. By changing these physical parameters, the resonant frequency of the damping device can be tuned to match different operating frequencies of the hydraulic pump and motor, enabling effective vibration reduction across multiple frequency bands rather than being limited to a single fixed frequency.
2Object-affected harmful factors
If electronic sensors and controllers are used to tune damping devices on the fly for varying operating conditions, then vibration control effectiveness is improved across varying speeds, but system cost increases and robustness decreases
Solution Approach 1:
The patent applies mechanics substitution by replacing electronic sensors and controllers with a purely mechanical tuning mechanism. The mechanical linkage directly couples the variable speed input from the hydraulic pump or motor to the tuning element of the Helmholtz resonator, eliminating the need for electronic components. This mechanical approach maintains vibration control effectiveness across varying operating conditions while significantly improving system robustness and reducing cost.
Solution Approach 2:
The patent implements self-service through a self-tuning mechanism where the varying operating conditions (speed changes) automatically adjust the damping device's resonant frequency through mechanical linkage. The system uses its own operational variations to drive the tuning action, requiring no external control system, sensors, or power source. This self-regulating mechanism ensures continuous effective vibration damping while simplifying the overall system architecture.
3Object-affected harmful factors
If physical isolation with special dampers in structural mounts and drive shafts is used to reduce vibration, then vibration transmitted to surrounding components is reduced, but integration and packaging problems arise
Solution Approach 1:
The patent applies the taking out principle by extracting the vibration damping function from separate structural mounts and drive shafts and concentrating it within the hydraulic circuit itself through the Helmholtz resonator. This integration of the damping function into the existing hydraulic system eliminates the need for additional external damping components, thereby reducing integration complexity and packaging issues while maintaining effective vibration reduction.
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 provides a simpler, more robust method for attenuating vibrations in hydrostatic drive systems, effectively reducing vibration levels across varying operating conditions without the added cost and fragility of electronic components, making it suitable for a wider range of transmission applications including IVTs and CVTs.
Implementation Method 1
a variable damping device connected to the first fluid line and fluidly connected to the first and second hydraulic drive units
Implementation Method 2
Typical damping devices include the Helmholtz or side-branch resonator
Data Source
AI summary
A hydrostatic drive system is disclosed which allows for simpler and more robust control of hydraulic vibration. The system comprises first and second hydraulic drive units and a variable damping device. At least the first hydraulic drive unit is a variable displacement type and comprises a displacement control. The variable damping device comprises at least one variable element. The system comprises a first linkage apparatus between the displacement control and the variable element and is operable to control the variable element in accordance with the displacement of the displacement control.