Bean-Shaped Dowels for Hydraulic Machine Interlocking
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Solution Overview
Problem
Conventional interlocking mechanisms in hydraulic machines, such as gear pumps, face challenges in maintaining minimal relative displacement between the body and flange at high operating pressures, leading to reduced volumetric efficiency and performance.
Innovation Solution
The use of bean-shaped dowels at both inlet and outlet sides, aligned with the resultant force direction, provides a more effective interlocking mechanism that minimizes deflection and stress, ensuring high volumetric efficiency even at pressures exceeding 275 bar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hollow dowels are used for interlocking body and flange, then the structure is simple and easy to manufacture, but relative displacement increases at high pressure leading to reduced volumetric efficiency
Solution Approach 1:
The patent applies asymmetry by using bean-shaped dowels with non-circular cross-sections instead of conventional circular hollow dowels. The asymmetric geometry creates directional interference fits that resist pressure-induced displacement more effectively, while the shape is optimized to maintain manufacturing feasibility through standard machining processes.
Solution Approach 2:
The patent changes the geometric parameters of the dowel cross-section from circular to bean-shaped, optimizing the distribution of contact areas and stress concentrations. This parameter change enables the dowel to maintain tighter tolerances and reduce relative displacement under high pressure, directly improving volumetric efficiency.
2Strength
If more hollow dowels are used to reduce relative displacement, then interlocking strength improves, but manufacturing complexity and cost increase
Solution Approach 1:
The bean-shaped dowel design concentrates interlocking strength in optimized directional contacts, allowing fewer dowels to achieve the same or better holding power compared to multiple conventional circular dowels. The asymmetric shape directs structural reinforcement where pressure loads are most severe.
3Productivity
If conventional dowel arrangement is used, then the design is simple, but deflection under pressure reduces volumetric efficiency
Solution Approach 1:
The bean-shaped cross-section modifies the structural parameters of the interlocking system, creating higher resistance to deflection through optimized stress distribution. The shape parameters are specifically tuned to maintain rigidity under pressure while accommodating the mechanical fastening requirements.
Data Source
AI summary
An interlocking device for rigidly holding together the body and flange of a hydraulic machine includes a body, flange, gears, sealing elements acting as a body seal and lobe seal adapted to effectively seal pressurized oil pockets within the hydraulic machine with a back-up ring that prevents squeezing of the lobe seal and to retain it in its original position, appropriately dimensioned bush bearings adapted to act as load bearing journals. The interlocking device includes a plurality of bean-shaped dowels located at both inlet and outlet sides that hold the body and flange together with minimum relative displacement to ensure high volumetric efficiency of the hydraulic machine even at high operating pressures in excess of 275 bar or higher.