Hydraulic Actuator Load Locking Without Continuous Motor Operation
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Solution Overview
Problem
Conventional freestanding hydraulic actuators rely on continuous operation of the prime mover and pump for load locking, leading to increased power consumption and reduced component life, and are limited by servo valve leakage and positioning accuracy issues.
Innovation Solution
A self-contained energy efficient hydraulic actuator system integrating a bi-directional hydraulic pump, servo motor, and solenoid valves, where solenoid valves perform load locking functions without motor operation, allowing the system to stop and restart from zero RPM, and control fluid flow and direction electronically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous motor operation is used for load locking, then positioning stability is maintained, but energy consumption increases and motor life decreases
Solution Approach 1:
The patent extracts the load locking function from the continuous motor operation by introducing solenoid valves that can independently lock the hydraulic fluid in position. The motor is taken out of the continuous operation requirement, allowing it to stop while the solenoid valves maintain positioning stability through one-way locking of hydraulic fluid.
Solution Approach 2:
The patent replaces the mechanical continuous motor operation system with an electro-magnetic solenoid valve system for load locking. The solenoid valves use electromagnetic fields to control fluid flow direction and locking, substituting the mechanical continuous rotation requirement with electronic control that can maintain position without continuous power consumption.
2Measurement precision
If servo valve is used for fluid direction control, then positioning accuracy is improved, but internal leakage increases requiring continuous pump operation
Solution Approach 1:
The patent uses solenoid valves instead of servo valves for fluid direction control. While solenoid valves have lower positioning precision than servo valves, they eliminate the continuous internal leakage problem that requires continuous pump operation. The system accepts a trade-off in precision to eliminate the energy waste from continuous leakage compensation.
3Reliability
If motor runs at minimum RPM to prevent stalling, then continuous operation is maintained, but energy is wasted and motor life is shortened
Solution Approach 1:
The patent implements periodic motor operation instead of continuous minimum RPM operation. The motor operates intermittently to move the actuator to desired positions, then stops completely while solenoid valves maintain positioning. This periodic action eliminates the continuous energy waste of running at minimum RPM while maintaining reliability through hydraulic locking.
4Speed
If VFD driven motor is used for pump control, then speed control is achieved, but torque availability at low RPM is limited
Solution Approach 1:
The patent replaces the VFD driven motor system with a solenoid valve controlled system for fluid direction and flow control. This substitution eliminates the torque limitation at low RPM by using electro-magnetic control instead of mechanical speed control, allowing the motor to operate efficiently at higher speeds while solenoid valves provide precise directional control regardless of motor speed.
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 solution enables energy savings, extended motor life, rapid RPM and direction changes, and improved positioning accuracy by eliminating continuous motor operation and reducing energy consumption.
Implementation Method 1
at least one solenoid valve configured to control the hydraulic fluid between the piston and the bi-directional pump
Implementation Method 2
a bi-directional hydraulic pump which is operationally coupled to a servo motor. A controller, in conjunction with the hydraulic pump/servo motor and solenoid valves, sequence flow operations
Implementation Method 3
The hydraulic cylinder consists of a hollow cylindrical tube along which a piston can slide. The term double acting is used when pressure is applied on each side of the piston
Data Source
AI summary
The self-contained energy efficient hydraulic actuator system of the present invention includes a hydraulic cylinder, a servo motor that is configured to produce rated torque from zero RPM to maximum rated RPM with rotor speed/position feedback to a servo motor, a pump, and a solenoid valve that enables the hydraulic cylinder to maintain its position without the motor running. The system has the ability to hold a load in place without motor operation via the use of the solenoid valve, and therefore saves energy and extends the motor lifetime by minimizing the motor running time.