Variable-Volume Pump Control for Low Current Hydraulic Actuation
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Solution Overview
Problem
Existing electric actuators face challenges in supplying high-pressure hydraulic fluid with low current consumption, leading to increased heat generation and power consumption, which affects reliability and efficiency, especially in applications like airplane rudder control where high forces are required.
Innovation Solution
A hydraulic fluid supply device with an adjustable-speed motor, variable-volume pump, and a pump control unit that adjusts ejection volume and pressure to reduce current demand, using a switch valve and elastic member to control the pump's operation, allowing high pressure output with low current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high pressure oil is supplied from the pump to the cylinder, then the actuator can output high force, but the electric motor requires high current which increases heat generation and power consumption
Solution Approach 1:
The pump uses a variable displacement mechanism where the swash plate angle can be dynamically adjusted during operation. This allows the pump to change its displacement volume based on system requirements, enabling high pressure output when needed while reducing displacement during normal operation to lower power consumption and heat generation.
Solution Approach 2:
The system changes the operating parameters of the pump by adjusting the swash plate angle, which directly controls the displacement volume. By varying this geometric parameter, the pump can operate at different displacement levels to match the actual force and flow requirements, avoiding constant high-power operation.
2Temperature
If the surficial area of the electric actuator is increased to ensure sufficient heat dissipation, then heat dissipation performance improves, but the volume and weight of the electric actuator increase
Solution Approach 1:
The invention converts the harmful effect of heat generation into a beneficial outcome by using the generated heat for hydraulic fluid heating. The hydraulic fluid passes through a heat exchange path that utilizes the heat from the motor and pump, converting waste heat into useful thermal energy for fluid temperature maintenance, thereby eliminating the need for additional heat dissipation structures.
3Stress or pressure
If high current is supplied to the electric motor to drive the pump at high pressure, then the pump can output high pressure hydraulic fluid, but the reliability of the electric actuator deteriorates due to heat generation
Solution Approach 1:
The variable displacement pump dynamically adjusts its operating characteristics based on system needs. During normal operation, it maintains lower displacement and pressure to reduce heat generation and improve reliability. When high force is required, it increases displacement and pressure output temporarily, then returns to lower power consumption mode afterward.
Solution Approach 2:
The system employs periodic high-pressure operation rather than continuous high-pressure operation. The pump alternates between high-displacement/high-pressure modes and low-displacement/low-pressure modes based on actuator demands, reducing cumulative heat generation and improving overall system reliability while maintaining the capability to deliver high pressure when needed.
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 solution enables efficient supply of high-pressure hydraulic fluid with low current consumption, reducing heat generation and power usage, while maintaining high actuation performance, particularly suitable for applications like airplane rudder control where high forces are needed with minimal stress.
Implementation Method 1
a variable-volume pump which is driven by the adjustable-speed motor and ejects hydraulic fluid
Implementation Method 2
an elastic member which biases the operation member in a direction against the pressure of hydraulic fluid acting on the operation member
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric actuator (1) of the present invention includes: a hydraulic fluid supply device (10), and an actuator (20) actuated in response to an input of hydraulic fluid from the variable-volume pump (12). The hydraulic fluid supply device (10) includes: an adjustable-speed motor (11); the variable-volume pump (12) which is driven by the adjustable-speed motor (11) and ejects hydraulic fluid; an electric motor control unit (13) which controls the adjustable-speed motor (11) so as to achieve an intended rotation speed; and a pump control unit (14) which controls the variable-volume pump (12) so that the ejection volume of the variable-volume pump (12) decreases with an increase in the ejection pressure of the variable-volume pump (12).