Hydraulic Actuator Pressure Feedback Control
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Solution Overview
Problem
Existing hydraulic system control methods, such as those described in U.S. Pat. No. 4,510,750, are complex due to their reliance on determining operating currents based on swashplate tilt angles, requiring additional hardware like swashplate tilt angle detectors and position sensors, which complicates the control of circuit pressure in variable displacement pumps.
Innovation Solution
A method and system that monitor pressure in a circuit supplying pressurized fluid to a motor, determining a difference between the monitored and desired circuit pressures to generate an actuator command independent of the actuator's position, allowing for the adjustment of pressurized fluid pressure without needing to measure the actuator's position or velocity, using a controller and pressure sensors to operate an actuator based on this command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control system determines operating current based on measured swashplate tilt angle, then the circuit pressure can be controlled, but the device complexity increases due to requiring swashplate tilt angle detectors and servo valves
Solution Approach 1:
The patent extracts and eliminates the position sensing function from the control system. Instead of using swashplate tilt angle detectors to measure position, the invention directly uses pressure feedback to determine actuator commands, removing the intermediate position measurement step and its associated hardware complexity
Solution Approach 2:
The patent implements direct pressure feedback control where the controller receives pressure feedback from the hydraulic circuit and directly determines actuator commands based on the pressure error, eliminating the need for position sensors and complex position-based control algorithms
2Manufacturing precision
If the control system determines operating current based on the difference between measured and commanded swashplate tilt angles, then the swashplate tilt angle can be controlled, but additional hardware like tilt angle detectors is required
Solution Approach 1:
The patent replaces the mechanical position sensing system (swashplate tilt angle detectors) with a pressure-based control system. The controller directly determines actuator commands from pressure feedback, substituting mechanical position measurement with hydraulic pressure measurement and control
3Ease of operation
If position or velocity sensors are used to control actuator position, then the actuator position can be determined, but the system complexity and cost increase
Solution Approach 1:
The patent enables the hydraulic circuit to self-regulate pressure through direct feedback control. The controller uses pressure feedback to automatically adjust actuator commands without requiring external position or velocity sensors, allowing the system to control itself based on its own operational state
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 simplifies the control of hydraulic systems by eliminating the need for position or velocity sensors, reducing system complexity and cost, while effectively adjusting the swashplate angle to match desired motor output torque and speed, thereby improving efficiency and stability.
Implementation Method 1
at least one pressure sensor configured to monitor a pressure of the pressurized fluid supplied to the motor
Implementation Method 2
a hydraulic actuator connected to the swashplate and capable of adjusting an angle of the swashplate
Implementation Method 3
A variable displacement pump generally includes a drive shaft, a rotatable cylinder barrel having multiple piston bores, and pistons held against a tiltable swashplate
Data Source
AI summary
A method of controlling a motor includes monitoring a pressure in a circuit supplying a pressurized fluid to the motor, determining a difference between the monitored circuit pressure and a desired circuit pressure, and determining an actuator command for an actuator that is capable of adjusting a pressure of the pressurized fluid supplied to the motor. The actuator command is determined based on the difference between the monitored circuit pressure and the desired circuit pressure, and is independent of a position of the actuator. The method also includes operating the actuator based on the actuator command.