Double-Helical Gear Pump Axial Force Balancing
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Solution Overview
Problem
Existing rotary positive displacement pumps face issues with mechanical and hydraulic noise, axial forces, low efficiency, and complex manufacturing due to straight tooth spur gears and double-helical designs, which are costly and difficult to assemble accurately.
Innovation Solution
A double-helical gear rotary positive displacement pump with continuous contact helical profiles and axial balancing, using separated helical wheels with one idle tooth and a constraining element to simplify assembly and reduce noise and manufacturing restraints, while maintaining high-pressure compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If double-helical toothings are used to balance axial forces, then axial force balance is improved, but manufacturing cost and complexity increase due to high accuracy requirements
Solution Approach 1:
The double-helical toothing is divided into two separate helical wheel portions that can be manufactured independently and then assembled together. This segmentation allows each portion to be produced using standard helical gear manufacturing processes without requiring complex double-helical gear cutting machinery, thereby reducing manufacturing cost and complexity while maintaining axial force balance
Solution Approach 2:
Two separate helical wheel portions are assembled together to form the complete double-helical toothing structure. This merging of independently manufactured components achieves the axial force balancing effect of a true double-helical gear while avoiding the high manufacturing costs and complexity associated with machining genuine double-helical gears
2Manufacturing precision
If high accuracy positioning of helical wheels is implemented to ensure proper phasing, then meshing quality is improved, but device complexity and assembly difficulty increase
Solution Approach 1:
The hub incorporates integrated positioning features (such as positioning pins, keys, or tapered surfaces) that automatically guide and constrain the helical wheel portions during assembly. This self-positioning mechanism ensures proper phasing and alignment without requiring complex external positioning devices or multiple assembly restraints, thereby reducing assembly difficulty while maintaining meshing quality
3Ease of manufacture
If traditional gear-cutting machines with fly cutters are used to manufacture double-helical gears, then manufacturing capability is improved, but ability to machine hardened materials is limited
Solution Approach 1:
The gear is divided into two separate helical wheel portions that can be manufactured using conventional gear-cutting machines before heat treatment. After machining, the portions are heat-treated to achieve the required hardness, then assembled together. This approach overcomes the limitation of traditional machines unable to machine hardened materials while maintaining manufacturing capability
Solution Approach 2:
The helical wheel portions are machined to near-final dimensions using conventional gear-cutting machines before heat treatment. This preliminary machining allows the use of standard equipment that cannot machine hardened materials, followed by heat treatment to achieve the required hardness, and then final assembly to complete the gear
Data Source
AI summary
The invention relates to a double-helical gear rotary positive displacement pump including a pump housing rotatably supporting at least a driving shaft and at least a driven shaft, at least a first toothing and a second toothing being associated to the driving shaft and at least a third toothing and a fourth toothing being associated to the driven shaft. The toothings have individually a helical profile that allows their mutual herringbone meshing. Three of toothings are rigidly connected to their respective shafts. The fourth toothing, or other suitable one, is idle on the shaft and axially constrained.