Variable Displacement Pump Actuator with Dual Hydraulic Actuators
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Solution Overview
Problem
Conventional variable displacement pumps with single actuators exhibit nonlinear performance due to asymmetric areas, limited load capability, and directional control limitations, necessitating improved actuator systems for enhanced control and efficiency.
Innovation Solution
A variable positive displacement pump actuator system utilizing electro-hydraulic servo valves (EHSVs) with dual hydraulic actuators and a control module to regulate pressures and control the lever arm position, enabling balanced and accurate control in both directions, replacing traditional spring-based systems with a second actuator for balanced operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single actuator with asymmetric areas is used, then the pump can be controlled in one direction, but the performance becomes nonlinear and load capability is limited
Solution Approach 1:
The single actuator is segmented into two separate actuators with symmetric areas, allowing independent control of extension and retraction forces. This segmentation enables linear performance characteristics while maintaining control in both directions, resolving the contradiction between ease of operation and performance linearity.
2Device complexity
If a single actuator is used, then the system is simpler, but the load capability is limited by the reduced rod side area
Solution Approach 1:
The system is divided into two actuators with symmetric piston areas, eliminating the rod side area limitation of a single actuator. Each actuator can independently provide full force capability, doubling the overall load capability while maintaining manageable system complexity through modular design.
3Device complexity
If a single actuator with spring is used, then the system is simpler, but the force from the spring is a fixed constant limiting control flexibility
Solution Approach 1:
The fixed spring force is extracted and replaced with an active control system using two actuators. This allows dynamic adjustment of forces in both directions, providing adaptability and versatility in control while maintaining reasonable system complexity through the use of standard electro-hydraulic components.
4Ease of operation
If asymmetric actuator areas are used, then control in one direction is achieved, but the actuator extends faster in one direction and slower in the other
Solution Approach 1:
The patent deliberately uses symmetric actuator areas rather than asymmetric areas, and controls the hydraulic fluid flow to achieve balanced extension and retraction speeds. This symmetric design with active flow control resolves the contradiction by providing directional control capability while maintaining consistent slew rates in both directions.
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 system achieves identical load holding, slew rate, and response in both directions, providing improved performance and accuracy, with potential for reduced actuator size and weight while maintaining or exceeding the capabilities of larger single-actuator systems.
Implementation Method 1
at least one electro-hydraulic servo valve (EHSV) in fluid communication with the supply line and the main pump line to receive the supply pressure and the pump pressure. The at least one electro-hydraulic servo valve can be configured to output a first regulated pressure and a second regulated pressure
Implementation Method 2
a first hydraulic actuator configured to connect to and/or otherwise actuate a lever arm of the variable positive displacement pump, the first hydraulic actuator in fluid communication with the first control line and the supply line to receive the first control pressure and the supply pressure to control a position of the first hydraulic actuator
Data Source
AI summary
A variable positive displacement pump actuator system for a variable positive displacement pump can include a supply line configured to provide a supply pressure, a main pump line configured to provide a pump pressure greater than the supply pressure from the variable positive displacement pump, and at least one electro-hydraulic servo valve (EHSV) in fluid communication with the supply line and the main pump line to receive the supply pressure and the pump pressure. The at least one electro-hydraulic servo valve can be configured to output a first regulated pressure and a second regulated pressure. The system can include a first control line in fluid communication with at least one of the at least one EHSV to receive the first controlled pressure, a second control line in fluid communication with at least one of the at least one EHSV to receive the second controlled pressure, a first hydraulic actuator configured to connect to and/or otherwise actuate a lever arm of the variable positive displacement pump, the first hydraulic actuator in fluid communication with the first control line and the supply line to receive the first control pressure and the supply pressure to control a position of the first hydraulic actuator, and a second hydraulic actuator configured to connect to and/or otherwise actuate the lever arm of the variable positive displacement pump, the second hydraulic actuator in fluid communication with the second control line and the supply line to receive the second control pressure and the supply pressure to control a position of the second hydraulic actuator.