Internal Gear Pump Recess Reduces Wedge Effect
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Solution Overview
Problem
Internal gear pumps experience increased hydraulic oil leakage during high-speed operations due to the wedge effect between the ring gear and the housing, which is not effectively mitigated by existing configurations.
Innovation Solution
A recess is introduced in the housing's slide surface in the high-pressure region, partially increasing the distance between the ring gear and the housing, combined with a high-pressure oil supply that adjusts pressure through an introduction port and choke, reducing the wedge effect and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure hydraulic oil is supplied to the gap between the ring gear and housing to reduce leakage, then leakage reduction is achieved, but wedge effect increases causing seizure at high speeds
Solution Approach 1:
The patent applies local quality by creating a recess at the specific location where the ring gear contacts the housing in the high-pressure region. This localized structural modification allows the gap to be increased only where needed to prevent wedge effect, while maintaining the pressure-balancing function in other areas. The recess provides local space relief that prevents oil accumulation and wedge effect without compromising the overall leakage reduction mechanism.
Solution Approach 2:
The patent segments the housing structure by introducing a recess that divides the contact area between the ring gear and housing into distinct regions. This segmentation allows different functional zones: the recessed area prevents wedge effect by providing escape path for oil, while the surrounding areas maintain the pressure-balancing function. The segmentation enables simultaneous achievement of leakage reduction and seizure prevention.
2Reliability
If the gap between ring gear and housing is reduced to prevent leakage, then leakage decreases, but wedge effect increases pushing ring gear toward center at high speeds
Solution Approach 1:
The recess is strategically positioned at the high-pressure region where the ring gear contacts the housing, creating a localized quality change. This allows the gap to be effectively reduced for leakage prevention while the recessed area provides localized space relief that prevents wedge effect buildup. The local modification enables the system to maintain small overall gap for leakage prevention while having specific relief zones for high-speed stability.
3Reliability
If processing accuracy is increased to reduce gaps, then leakage reduces, but manufacturing complexity and cost increase
Solution Approach 1:
The recess is pre-formed in the housing structure during manufacturing, establishing a predetermined gap relief zone before the ring gear is assembled. This preliminary action of creating the recess allows for standard manufacturing tolerances while still achieving the desired gap control function. The recess serves as a built-in compensation feature that reduces reliance on extremely tight manufacturing precision.
Solution Approach 2:
Rather than requiring uniformly high precision across the entire housing surface, the recess creates a localized quality change at the critical contact point. This allows the majority of the housing to be manufactured with standard tolerances, while only the recessed area requires specific dimensional control. This significantly reduces overall manufacturing complexity and cost compared to requiring uniform high precision across the entire assembly.
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 solution significantly reduces hydraulic oil leakage and seizure between the ring gear and the housing, allowing for higher processing accuracy and efficient operation at both low and high speeds.
Implementation Method 1
high-pressure hydraulic oil is supplied through the introduction port into the gap between the outer circumferential surface of the ring gear and the inner circumferential surface of the housing
Implementation Method 2
a wedge effect occurs at the gap between the outer circumferential surface of the ring gear and the inner circumferential surface of the housing in accordance with the rotation of the ring gear
Implementation Method 3
the recess partially increases the distance between the ring gear and the housing, thereby reducing the wedge effect
Data Source
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AI summary
An internal gear pump (1) includes: a pinion gear (3); a ring gear (4); a housing (5) including a crescent (54) and a slide surface (51) on which an outer circumferential surface (41) of the ring gear slides; a high-pressure oil supply (8) having an introduction port (81) open to the slide surface to supply high-pressure hydraulic oil; and a recess (9) in the slide surface so as to increase the distance between the outer circumferential surface of the ring gear and the slide surface. The introduction port is located in the increasing pressure region, whereas the recess is located in the high-pressure region.