Gear Pump Suction Port Shallow Deep Portion Design
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Solution Overview
Problem
Conventional gear pumps face challenges in improving suction efficiency while effectively suppressing cavitation, especially at high rotational speeds of the inner rotor.
Innovation Solution
A gear pump design featuring an inner rotor with external teeth and an offset outer rotor, where the suction port has a shallow portion extending inward and a deep portion with a tilted section, ensuring fluid collection and smooth flow into inter-tooth chambers, thereby enhancing filling efficiency and suppressing cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suction port is closed by the inner peripheral portion immediately before inter-tooth chamber capacity is maximized, then cavitation on the internal tooth side is suppressed, but fluid may leak from the inter-tooth chamber into the outer peripheral-side region of the suction port, causing cavitation on the internal tooth side
Solution Approach 1:
The suction port is divided into different regions with different depths: a shallow portion that extends radially inward from the outer peripheral side and a deep portion that continues inward from the shallow portion. This local variation in depth allows the outer peripheral side to close earlier (suppressing cavitation) while the inner peripheral side remains open longer (maintaining suction efficiency)
Solution Approach 2:
The suction port design transitions from a conventional single-depth structure to a multi-depth structure by adding the deep portion that extends further radially inward than the shallow portion. This dimensional change creates distinct closing timings for different regions of the suction port, resolving the contradiction between cavitation suppression and suction efficiency
2Productivity
If the outer inner wall surface of the suction port is located inward of the bottom land between internal teeth, then fluid collection and flow into inter-tooth chambers is improved, but device complexity increases
Solution Approach 1:
The outer inner wall surface is positioned inward of the bottom land between internal teeth at the downstream side of the suction port, creating a localized fluid collection region. This local structural modification improves fluid guidance into inter-tooth chambers without requiring complex overall redesign
Solution Approach 2:
The suction port includes a curved surface that connects the shallow portion and deep portion, creating a smooth transition that guides fluid flow. This curved geometry simplifies the structure compared to sharp angular transitions while maintaining improved fluid collection and flow characteristics
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 design improves suction efficiency and effectively suppresses cavitation across a wide range of rotational speeds, maintaining high performance from low to high rotational speeds without significant cavitation issues.
Implementation Method 1
liquid that flows from the outer end of the suction port into the internal tooth side of an inter-tooth chamber whose communication with the suction port is about to cut off is limited by the shallow flat surface, and the liquid is made to flow from the inner end into the external tooth side of the inter-tooth chamber
Implementation Method 2
fluid that has flown into the inter-tooth chamber prevents stirring of fluid returning to the suction port by a centrifugal pressure
Data Source
AI summary
In a gear pump, an outer inner wall surface of a suction port which is located on a downstream side in a rotor rotation direction, that is, a first inner wall surface, is located inward of a bottom land between internal teeth of an outer rotor, and the suction port has a shallow portion extended inward from the first inner wall surface on the downstream side in the rotor rotation direction, and a deep portion that is formed so as to be continuous with the shallow portion and that is deeper than the shallow portion. Communication between an inter-tooth chamber and the suction port is cut off with the inter-tooth chamber facing only the shallow portion.