Frequency-Dependent Hydraulic Actuator for Force-Response Trade-Off
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Solution Overview
Problem
Hydraulic actuators face a trade-off between force capability and response time, limiting their adoption in applications requiring both high force and fast response, such as active suspension systems in vehicles.
Innovation Solution
A hydraulic actuator design with dynamically varying compliance, utilizing gas-charged accumulators and a restriction element to adjust the actuator's stiffness and compliance based on input frequency, allowing for increased force capability at low frequencies and faster response times at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If hydraulic actuators are designed for high force capability, then force output is improved, but response time deteriorates
Solution Approach 1:
The patent applies dynamics by making the compliance of the hydraulic actuator variable rather than fixed. The compliance is dynamically adjusted based on the frequency of the control signal: at low frequencies, higher compliance is maintained to enable high force capability, while at high frequencies, compliance is reduced to improve response time. This is achieved through a compliance control mechanism that modifies the effective compliance of the actuator in real-time according to operating conditions.
Solution Approach 2:
The patent changes the parameter of compliance based on frequency. The compliance control mechanism alters the compliance parameter dynamically: when the control signal frequency is below a threshold, high compliance is maintained for force capability; when the frequency exceeds the threshold, compliance is reduced to enhance response time. This parameter change allows the actuator to optimize performance across different operating regimes.
2Force
If compliance is increased to improve force capability, then force output is improved, but response time deteriorates
Solution Approach 1:
The compliance control mechanism dynamically adjusts compliance based on frequency conditions. At low frequencies where force capability is prioritized, high compliance is maintained. At high frequencies where response time is critical, the mechanism reduces compliance to minimize time loss. This dynamic adjustment resolves the contradiction between compliance and response time.
Solution Approach 2:
The compliance parameter is changed dynamically based on the frequency of operation. The compliance control mechanism modifies compliance from high to low depending on whether the control signal frequency is below or above a threshold, thereby optimizing the balance between force capability and response time under different operating conditions.
3Speed
If frequency response is optimized for high frequencies, then response time is improved, but force capability deteriorates
Solution Approach 1:
The compliance control mechanism dynamically adapts compliance to frequency conditions. When operating at high frequencies, the mechanism reduces compliance to improve response time. When operating at low frequencies, it increases compliance to restore force capability. This dynamic behavior allows the actuator to maintain optimal performance across the full frequency spectrum.
Solution Approach 2:
The compliance parameter is adjusted based on frequency: reduced at high frequencies to improve response time, and increased at low frequencies to maintain force capability. This frequency-dependent parameter change enables the actuator to overcome the trade-off between response time and force capability.
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 design enhances force capability for low-speed events while ensuring rapid response and reduced inertia effects at high-speed events, improving ride comfort and suspension performance in vehicles.
Implementation Method 1
a first gas charged accumulator; a second gas charged accumulator
Implementation Method 2
the restriction element is configured to vary an impedance or inertance of the first flow path
Implementation Method 3
the restriction element is configured to vary an impedance or inertance of the first flow path
Implementation Method 4
capable of generating, or configured to generate, a pressure differential between the compression chamber the extension chamber
Data Source
AI summary
Disclosed herein are hydraulic actuators and methods for the operation of actuators having variable relative pressure ratios. Further disclosed are methods for designing and/or operating a hydraulic actuator such that the actuator exhibits a variable relative pressure ratio. In certain embodiments, the relative pressure ratio of the hydraulic actuator may be dependent on one or more characteristics (such as, for example, frequency or rate of change) of an oscillating input to the hydraulic actuator.