Hydraulic Machine Bearing Layout for Parasitic Force Isolation
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Solution Overview
Problem
Hydraulic machines face issues with shaft bending due to parasitic forces from the cylinder block and distributor, which compromise the robustness and efficiency of the rolling bearings, requiring either increased solidification of parts or reduced performance to avoid breakage.
Innovation Solution
Incorporating a third guide bearing that directly abuts the casing and cylinder block to take up parasitic forces, allowing the first and second bearings to remain dedicated to transmission, thereby enhancing robustness and reducing space requirements without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the machine comprises only two bearings directly in abutment against the casing and the sleeve, then the structure is simpler and space is reduced, but the parasitic forces from the cylinder block disturb the rolling bearings and compromise robustness
Solution Approach 1:
The bearing support function is segmented into two distinct systems: two guide bearings (first and second bearings) handle shaft guidance and torque transmission, while a separate third bearing handles parasitic forces from the cylinder block. This segmentation prevents force interference and allows each bearing to be optimized for its specific function, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The third bearing acts as an intermediary element that absorbs and isolates parasitic forces generated by the cylinder block before they can reach the main drive bearings. This intermediary bearing protects the first and second bearings from disturbing forces, enabling them to maintain robustness without requiring increased prestress or structural complexity.
2Reliability
If the first and second bearings are dimensioned to cope with parasitic forces, then bearing robustness is maintained, but the machine volume increases and performance is reduced
Solution Approach 1:
The bearing system is segmented into specialized components: small first and second bearings optimized for torque transmission and shaft guidance, and a dedicated third bearing optimized for absorbing parasitic forces. This segmentation allows each bearing to be minimized in size for its specific function, reducing overall machine volume while maintaining robustness.
Solution Approach 2:
The third bearing serves as an intermediary force-absorbing element that prevents parasitic forces from being transmitted to the drive bearings. By isolating these disturbing forces, the first and second bearings can be dimensioned smaller since they only need to handle torque and guidance, thereby reducing machine volume without compromising reliability.
3Reliability
If increased prestress is applied to the bearings to compensate for parasitic axial forces, then bearing robustness is maintained, but the machine complexity and space requirements increase
Solution Approach 1:
The third bearing acts as an intermediary that physically absorbs parasitic axial forces from the cylinder block, preventing them from reaching the first and second bearings. This eliminates the need for increased prestress mechanisms in the drive bearings, maintaining robustness while simplifying the overall structure and reducing space requirements.
Solution Approach 2:
The third bearing extracts and removes parasitic axial forces from the force transmission path before they can affect the main drive bearings. By taking out these disturbing forces separately, the system avoids the complexity of prestress mechanisms and maintains bearing robustness through a simpler structural solution.
Data Source
AI summary
The rotating hydraulic machine (102) comprises: —a housing (10), —a shaft (20) movably mounted relative to the housing about an axis, —an apron (24) rigidly connected to the shaft and extending around at least a portion of the housing, —a cam (12) rigidly connected to either the housing or the shaft, —a cylinder block (42) rotationally connected to the other of either the housing or the shaft, the cylinder block comprising pistons capable of engaging with the cam to produce a relative rotation between the shaft and the housing, —first and second guide bearings (28) each bearing directly on the housing and the apron, and —at least a third guide bearing (37) bearing directly on the housing and the cylinder block.