Gear Pump Bearings with Non-Concentric Inner Diameters
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Solution Overview
Problem
Traditional gear pumps face issues with gear journal bearings having insufficient clearance, leading to gear contact with bearings under varying operating conditions, causing leakage and potential damage.
Innovation Solution
The introduction of clearance and lubrication grooves with a lunate cross-sectional shape in the bearing inner diameter surface provides necessary clearance for gear motion and lubrication, preventing gear contact with the bearings and enhancing volumetric efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bearing inner diameter clearance is reduced to improve precision, then manufacturing precision is improved, but gear contact with bearings occurs under varying operating conditions, causing leakage and potential damage
Solution Approach 1:
The bearing inner diameter is pre-formed with an asymmetric groove pattern that anticipates gear motion variations. The groove is positioned and dimensioned in advance to accommodate the full range of gear journal motion, preventing contact before it occurs. This preliminary design ensures that even under varying operating conditions, the gear has predetermined clearance space and cannot contact the bearing outer surface.
Solution Approach 2:
The bearing inner diameter is not uniformly clearanced but has a localized asymmetric groove that provides clearance only in the specific region where gear contact would occur. The groove cross-section varies around the circumference, with greater clearance in directions where gear motion is greatest. This localized modification maintains precision where needed while providing necessary clearance where gear motion occurs.
2Adaptability or versatility
If bearing bore size is increased to accommodate gear motion, then adaptability to operating conditions is improved, but bearing clearance increases, leading to potential gear contact and leakage
Solution Approach 1:
The bearing inner diameter employs asymmetric groove geometry where the clearance distribution is non-uniform around the circumference. The groove cross-section varies angularly, providing maximum clearance in the direction of greatest gear motion while maintaining minimal clearance in other directions. This asymmetric design allows the bearing to adapt to gear motion variations without uniformly increasing clearance, thus preventing leakage while accommodating operational adaptability.
3Reliability
If asymmetric groove pattern is implemented in bearing inner diameter, then gear motion clearance is optimized, but device complexity increases
Solution Approach 1:
The asymmetric groove pattern is segmented into discrete angular zones around the bearing inner diameter. Each segment provides clearance for specific directions of gear motion, with the groove cross-section changing in predetermined steps rather than continuously. This segmentation simplifies manufacturing compared to a fully continuous asymmetric profile while still providing optimized clearance in all critical directions, reducing device complexity while maintaining reliability.
Data Source
Figure 1~2
Figure 3
AI summary
A bearing for a gear pump includes a bearing body (126) defining a bearing bore (128) defined therethrough along an axis for receiving a gear shaft (110). The bearing bore defines a cylindrical bearing inner diameter surface (130). The bearing body defines an outer mating surface (132) configured for mounting to another bearing body. A groove (134) is defined in the inner diameter surface along an axial direction relative to the axis to provide clearance for gear journal motion between the inner diameter surface and the gear shaft. The groove is defined in a portion of the inner diameter surface opposite the mating surface.