Gear Pump Bleed Mechanism Reducing Cavitation
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Solution Overview
Problem
Gear pump assemblies face challenges with cavitation in high-speed and high-pressure applications due to limited space for inlet and discharge ports, leading to gear and bearing damage from rapid volume changes, which worsens with larger gear sizes and faster rotation.
Innovation Solution
The introduction of additional bleed flow paths on gear teeth, both on the drive and driven gears, to direct carryover fluid from the discharge side to the inlet side, creating additional porting area and reducing cavitation by addressing gear intermesh starvation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gear pump size and rotation speed are increased to generate required flow, then productivity increases, but cavitation worsens due to limited filling time
Solution Approach 1:
The bleed path pre-fills the gear mesh region with fluid from the inlet side before the gears complete their rotation, ensuring the mesh is ready to accept fluid immediately when the teeth engage. This preliminary action occurs during the carryover volume phase, preparing the system for the next filling cycle and preventing cavitation even at high speeds
Solution Approach 2:
The bleed path acts as an intermediary fluid passage that connects the inlet side to the gear mesh region through the carryover volume. This intermediary path provides an additional route for fluid to reach the gear mesh, supplementing the traditional porting and ensuring adequate filling without increasing pump size or reducing speed
2Device complexity
If traditional porting methods are used with limited space, then device complexity is minimized, but filling efficiency deteriorates leading to gear intermesh starvation
Solution Approach 1:
The bleed path utilizes the radial dimension by drilling through the gear tooth, creating a three-dimensional fluid passage that traditional two-dimensional porting cannot achieve. This vertical path through the gear tooth provides additional porting area and creates a direct connection from the inlet side to the gear mesh region, improving filling efficiency without adding external components
3Manufacturing precision
If geometric variations and bearing face contours are used for porting, then manufacturing precision can be maintained, but additional porting area is insufficient to prevent cavitation
Solution Approach 1:
The bleed path segments the fluid delivery system by creating multiple independent pathways: the traditional porting paths and the new radial bleed paths through each gear tooth. This segmentation provides redundant fluid supply routes and increases total porting area while maintaining the precision of the original gear geometry and bearing face contours
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 effectively reduces cavitation and intermesh starvation, improving filling efficiency and minimizing gear and bearing damage by providing additional fluid to the gear intermesh region, thus enhancing the operational reliability of gear pump assemblies.
Implementation Method 1
The bleed mechanism includes a passage communicating with at least one of (i) a gear face of the drive gear, (ii) a gear face of the driven gear; and/or (iii) a bottom of a gear tooth profile adjacent a root region between adjacent gear teeth
Data Source
AI summary
A gear pump assembly includes a drive gear having a plurality of circumferentially spaced teeth, and a driven gear likewise having a plurality of circumferentially spaced teeth positioned for intermeshing engagement between the drive and driven gears via the teeth. A bleed mechanism directs carryover fluid from a discharge side of a bearing dam to an inlet side of the bearing dam in order to supply the carryover fluid to a carryover volume disposed between mating drive gear teeth and driven gear teeth. The bleed mechanism including a passage communicating with at least one of (i) a gear face of the drive gear, (ii) a gear face of the driven gear; or (iii) a bottom of a gear tooth profile adjacent a root region between adjacent gear teeth.