Non-Circular Low-Pressure Connection for Gear Machine Cavitation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gear machines, particularly pumps, experience cavitation issues at the low-pressure connection due to high flow velocities, which limits the diameter of this connection and affects sealing efficiency.
Innovation Solution
The low-pressure connection's cross-sectional shape is modified to have a larger area by introducing an imaginary boundary line that intersects the pressure equalization chamfer, ensuring a minimum distance of at least one gear pitch, allowing for a non-circular shape that increases the cross-sectional area, thereby reducing flow velocities and delaying cavitation to higher gear speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the diameter of the low-pressure connection is increased to reduce flow velocities and avoid cavitation, then cavitation resistance is improved, but the sealing distance between the high- and low-pressure connections at the tooth tips of the gear wheels is reduced
Solution Approach 1:
The low-pressure connection is designed with an asymmetric cross-sectional shape rather than a circular one. The shape is specifically contoured to maximize the cross-sectional area in regions that do not interfere with the sealing path of the gear tooth tips, thereby reducing flow velocity and cavitation risk while preserving adequate sealing distance where required.
Solution Approach 2:
The solution transitions from a one-dimensional parameter (circular diameter) to a two-dimensional cross-sectional shape optimization. By controlling the cross-sectional shape with specific geometric constraints (straight lines parallel to boundary lines at minimum distance), the design achieves larger area without compromising the critical sealing dimension.
2Speed
If the low-pressure connection has a larger cross-sectional area, then flow velocity is reduced and cavitation is delayed, but the geometric constraints for maintaining sealing become more complex
Solution Approach 1:
The low-pressure connection cross-section is designed with different geometric characteristics in different regions. Straight line segments are used in areas requiring maximum area expansion, while curved transitions are provided where sealing proximity is critical. This localized geometric optimization achieves high flow velocity reduction without excessive overall complexity.
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 design enhances the low-pressure connection's cross-sectional area, reducing flow velocities and minimizing cavitation, ensuring effective sealing and operation even at higher gear speeds.
Implementation Method 1
pressure fluid, in particular hydraulic oil, flowing from the low to the high-pressure connection
Implementation Method 2
the pressurized fluid flows from the high to the low pressure port, causing the gears to rotate
Implementation Method 3
The bearing bodies are arranged on both sides next to the gear wheels and are pressed by the pressure fluid to form a seal against the side surfaces of the gear wheels
Implementation Method 4
the gears are pressed with an easily predictable force against the inner peripheral surface of the housing in the area of the low-pressure connection in order to create a seal there
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The gear machine has housing having high and low pressure terminals (33). A notional boundary line (80) assigned to externally intermeshing gear wheels (50) on inner circumferential face of housing runs parallel to line (83) of contact between gear tooth tips of wheels and inner circumferential face. The cross sectional shape of low-pressure terminal deviates from circular shape such that cross sectional area overlapping wheels is greater than that of notional, circular low-pressure terminal overlapping wheels at minimum distance from boundary lines.