Variable Displacement Pump Flow Control Without Extra Electronics
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Solution Overview
Problem
Existing electric motor pump systems, particularly in aerospace applications, are burdened by additional electronics that add weight and complexity, making them difficult to service in inaccessible locations.
Innovation Solution
A simplified electric motor pump system using a variable frequency generator to control the electric motor's speed and a servo valve to maintain constant output flow, eliminating the need for complex electronics by employing a first and second control piston to adjust displacement based on pressure and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional electronics are added to control the pump system, then control precision is improved, but weight and device complexity increase
Solution Approach 1:
The patent extracts the electronic control components from the pump system and replaces them with a purely mechanical control mechanism. The mechanical governor directly couples the pump displacement control to the motor speed through mechanical linkages, eliminating the need for electronic sensors, processors, and actuators while maintaining precise speed-compensated flow control.
Solution Approach 2:
The patent replaces the electronic control system with a mechanical control system. The governor uses mechanical linkages, levers, and springs to sense motor speed and automatically adjust pump displacement, substituting electronic measurement and control with mechanical analog computation and feedback.
2Measurement precision
If additional electronics are added to control the pump system, then control precision is improved, but weight increases
Solution Approach 1:
The patent removes all electronic control components (microcontrollers, sensors, power electronics) from the system and replaces them with a compact mechanical governor assembly. This extraction of electronic subsystems dramatically reduces the overall weight while maintaining the required control precision through mechanical means.
3Adaptability or versatility
If additional electronics are added to control the pump system, then control functionality is improved, but ease of repair deteriorates
Solution Approach 1:
The mechanical governor system is inherently self-regulating and requires no external power source or electronic intervention to operate. The system automatically senses motor speed changes and adjusts pump displacement accordingly, making it self-sufficient and eliminating the need for complex electronic diagnostics or specialized servicing.
4Device complexity
If electronic components are reduced, then weight and complexity are reduced, but control precision may deteriorate
Solution Approach 1:
The mechanical governor incorporates direct feedback from the motor shaft through a speed-sensing mechanism that couples motor speed to the pump displacement control. This closed-loop mechanical feedback ensures that pump output flow remains precisely proportional to motor speed without requiring electronic measurement or computation.
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 reduced weight and complexity while maintaining consistent output flow across varying speeds, enhancing reliability and serviceability, especially in aerospace environments.
Implementation Method 1
a variable frequency generator configured to provide power to the electric motor, the variable frequency generator producing a constant voltage output with a variable frequency
Implementation Method 2
The second control piston is controlled via the servo valve according to an output speed of the electric motor, the second piston being configured to maintain a substantially constant output flow of the pump as the output speed of the electric motor changes
Implementation Method 3
The first control piston and the second control piston act on a yoke of the variable displacement pump to vary the displacement of the variable displacement pump
Data Source
Figure 1
Figure 2
AI summary
An electric motor pump system includes a variable displacement pump (100), an electric motor connected to drive the variable displacement pump, a first control piston (120) configured to limit an output pressure characteristic of the pump, and a second control piston (160) controlled via a servo valve (150) according to an output speed of the electric motor. The second piston (160) is configured to maintain a substantially constant output flow of the pump as the output speed of the electric motor changes. The first and second control pistons (120, 160) may act on a yoke (130) of the variable displacement pump.