Gear Wheel Spline Profile for Hydraulic Pump Noise Reduction
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Solution Overview
Problem
Conventional gear wheels in hydraulic pumps experience noise issues due to fluid encapsulation and volume variations, leading to direct and indirect noise problems, especially at high pressures, and existing solutions are complex, inefficient, or compromise on displacement performance.
Innovation Solution
A gear wheel design with helical teeth featuring a spline-interpolated tooth profile within a tolerance band, allowing for semi-encapsulation and reduced noise, while maintaining efficient flow rates and ease of construction, utilizing a cubic natural spline function to define the nominal tooth profile and its top and bottom tolerance profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional involute gear profiles are used, then the gear pump can be manufactured with standard machining processes, but fluid is trapped and compressed in the meshing area causing direct operating noise and uncontrolled local stress peaks
Solution Approach 1:
The invention changes the fundamental geometric parameters of the gear tooth profile from conventional involute to a specifically designed profile with modified curvature characteristics. The new profile includes a transition curve that eliminates the closed fluid entrapment area formation during meshing, thereby preventing direct operating noise while maintaining manufacturability through standard gear manufacturing processes
Solution Approach 2:
Instead of accepting fluid entrapment as an inevitable consequence of gear meshing and trying to manage it through clearance design, the invention inverts the approach by designing a tooth profile that prevents entrapment from occurring in the first place. The profile geometry is specifically crafted to ensure continuous fluid communication between inlet and outlet sides during the meshing process
2Device complexity
If conventional gear profiles are used, then the gear pump structure remains simple, but fluid flow rate pulsation occurs causing indirect operating noise known as ripple noise
Solution Approach 1:
The modified tooth profile parameters create a more uniform volume displacement pattern during gear rotation. By changing the curvature and contact characteristics of the tooth flanks, the invention achieves continuous and steady fluid transfer from inlet to outlet, eliminating flow rate pulsation and the associated ripple noise while keeping the overall pump structure simple
3Object-generated harmful factors
If solutions with discharge pockets on lateral abutment means are implemented, then fluid entrapment is reduced, but the device complexity increases significantly
Solution Approach 1:
The invention extracts the noise-generating mechanism (fluid entrapment in closed areas) by redesigning the tooth profile geometry itself, rather than adding auxiliary structures like discharge pockets. The solution is embedded in the fundamental tooth shape, eliminating the need for additional components and keeping the overall device simple
Solution Approach 2:
Instead of adding discharge pockets to evacuate trapped fluid, the invention inverts the approach by designing a profile that prevents trapping from occurring. The tooth geometry ensures continuous fluid communication during meshing, making discharge pockets unnecessary
4Object-generated harmful factors
If helical gear wheels are used to reduce ripple noise, then fluid transfer smoothness improves, but the volume of each fluid entrapment area extends along a helical course creating potential bypass routes between intake and delivery
Solution Approach 1:
The invention changes the tooth profile parameters to achieve smooth fluid transfer similar to helical gears, but without the helical angle that creates bypass routes. The modified profile geometry provides gradual engagement and disengagement of teeth, ensuring continuous fluid displacement while maintaining effective sealing between intake and delivery sides
Data Source
AI summary
A gear wheel comprising a plurality of helical teeth, each helical tooth of the gear wheel having a tooth profile meshing with semi-encapsulation in a geared hydraulic apparatus. Each tooth having a profile which falls within a band of tolerance of +− 1/15 of the depth of a nominal tooth defined by a spline function interpolating a plurality of node points having pre-established coordinates {X,Y} with their origin on the gear wheel center.