Variable Displacement External Gear Machine
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Solution Overview
Problem
Existing external gear machines (EGMs) are fixed displacement units, making them unsuitable for energy-efficient systems, as they cannot adapt fluid displacement per revolution, and previous attempts to create variable displacement EGMs have faced technological challenges and commercialization issues.
Innovation Solution
The design incorporates asymmetrical teeth with specific angle ratios and sliders to vary fluid communication channels, allowing for adjustable flow rates by altering the operational volumes between the inlet and outlet, utilizing electromechanical actuators for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If EGMs are designed as fixed displacement units with simple structure, then manufacturing cost and structural simplicity are improved, but adaptability to different flow requirements deteriorates
Solution Approach 1:
The patent applies dynamics by making the EGM displacement variable through axial movement of the drive gear relative to the slave gear. The drive gear can be positioned at different axial locations to change the meshing length and tooth space volume, enabling continuous adjustment of flow rate from zero to maximum displacement. This dynamic adjustment mechanism resolves the contradiction by providing adaptability without requiring multiple fixed-displacement units.
Solution Approach 2:
The patent utilizes the axial dimension (third dimension) to control displacement variation. By moving the drive gear axially along its rotation axis, the meshing length between gears is changed, which directly affects the tooth space volume and thus the flow rate. This dimensional approach allows simple structural modification to achieve variable displacement, maintaining manufacturing simplicity while adding adaptability.
2Adaptability or versatility
If previous variable displacement EGM designs moved gears axially or changed inter-axis distance, then adaptability to flow requirements is improved, but device complexity and technological challenges increase
Solution Approach 1:
The patent makes the drive gear serve multiple functions: it acts as both the driving element and the displacement control element. The axial position of the drive gear simultaneously determines both the power transmission function and the displacement magnitude. This multi-functionality eliminates the need for separate displacement control mechanisms, reducing overall device complexity while achieving variable displacement capability.
Solution Approach 2:
The drive gear's axial position is controlled by the system's own operating conditions (pressure differential, flow requirements) rather than requiring external complex control systems. The design allows the EGM to self-regulate its displacement based on system needs, simplifying the control architecture while maintaining adaptability.
3Device complexity
If fixed displacement EGMs are used in energy efficient system configurations, then system simplicity is maintained, but energy consumption increases
Solution Approach 1:
The patent changes the displacement parameter dynamically to match system requirements. By adjusting the axial position of the drive gear, the tooth space volume and flow rate are optimized for different operating conditions. This prevents energy waste from delivering excess flow that would then require throttling or bypass, thereby reducing energy consumption while maintaining system simplicity.
Data Source
AI summary
An external gear machine (EGM) includes a housing, an inlet, a drive gear positioned in the housing and configured to be (i) driven by a mechanism when the EGM is operated as a pump, or (ii) drive an external mechanism when the EGM is operated as a motor, the drive gear having a plurality of teeth, a slave gear positioned in the housing having a plurality of teeth and configured to be driven by the drive gear, an outlet formed in the housing and configured to receive at least some of the volume of fluid via an outlet fluid communication channel, a first slider defining an inlet fluid communication channel and the outlet fluid communication channel, selective positioning of the first slider configured to vary net operational volumes of fluid communication between the inlet and the outlet, for a given rotational speed of the drive gear.