Gear Wheel Cutting Edge for Hydraulic Pump Running-In
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Solution Overview
Problem
Geared rotary positive displacement pumps experience plastic deformation and material spreading during the running-in phase due to the interaction between gear wheels and the pump body, leading to unpredictable wear and potential damage, especially when the gear wheels are made of harder materials than the pump body.
Innovation Solution
The gear wheel design incorporates a cutting edge on the teeth, specifically a groove that decreases by 0.2% to 5% of the tooth height, which acts to remove material from the pump body during rotation, minimizing plastic deformation and material spreading by expelling chips with the pumped fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If gear wheels are made of harder material than the pump body, then the gear wheels can withstand higher loads and pressures, but plastic deformation and material spreading occur on the pump body during the running-in phase
Solution Approach 1:
The patent introduces a running-in phase with controlled light loads before full operation. During this preliminary phase, the gear wheels gently contact the pump body surfaces, allowing gradual material transfer and formation of a stable interface. This prevents sudden plastic deformation when full load is applied, as the harder gear wheel material has already adapted to the softer pump body geometry.
Solution Approach 2:
The patent modifies operational parameters during the running-in phase, specifically controlling load magnitude, rotation speed, and lubrication conditions. By gradually increasing these parameters from low to high values, the system allows the harder gear wheel material to adapt to the softer pump body without causing excessive plastic deformation, while still achieving the desired wear-in effect.
2Reliability
If gear wheels with rounded tooth tips are used, then continuous contact between meshing wheels is achieved and fluid encapsulation is prevented, but mechanical interference and excessive friction occur during the running-in phase
Solution Approach 1:
The patent implements a running-in phase where the rounded tooth tips gradually contact the mating surfaces under controlled light loads. This preliminary action allows the formation of optimal contact patterns and transfer of a thin layer of softer material from the pump body to the gear wheel surfaces, reducing friction for subsequent full-load operation while maintaining the continuous contact benefit of rounded tips.
Solution Approach 2:
The patent introduces lubrication as an intermediary substance during the running-in phase. The lubricant film mediates the contact between the harder gear wheel material and softer pump body, reducing direct mechanical interference and friction. This allows the rounded tooth tip geometry to maintain continuous contact while minimizing harmful friction and heat generation during the adaptation period.
3Adaptability or versatility
If the gear wheels are designed to create their own seat in the pump body, then adaptability is improved, but unpredictable wear and potential damage to the pump body occur
Solution Approach 1:
The patent designates a specific running-in phase as a preliminary action where controlled material transfer occurs. During this phase, the gear wheels gradually form their seating geometry in the pump body under light, controlled loads. This predictable preliminary deformation establishes stable contact surfaces before full operational loads are applied, preventing unpredictable wear and geometry deformation that would occur without such controlled preparation.
Solution Approach 2:
The patent controls the loading parameters during the running-in phase to manage the material transfer process. By maintaining light loads and gradually increasing them, the system ensures that the plastic deformation of the softer pump body material occurs in a controlled, predictable manner, creating the desired self-seating capability without excessive or unpredictable geometry changes that would compromise manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces material spreading and plastic deformation, ensuring a stable running-in phase, maintaining noiselessness and volumetric efficiency, and enhancing the reliability and durability of the hydraulic apparatus by preventing irreversible damage to the pump body.
Implementation Method 1
The cutting edge 12 is configured to remove material, in particular chip material, from an inner surface of a housing hole 120 of the casing 110, which is contacted by the cutting edge 12 during the rotation of the gear wheel 10
Data Source
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AI summary
A gear wheel (10) for a hydraulic apparatus is rotatable about an axis of rotation (H-H) and comprises a plurality of teeth (11) having a sectional profile (P) and being adapted to mesh with respective teeth of another gear wheel during a rotational motion about the axis of rotation (H-H), wherein at least one tooth (11) is shaped so as to have at least one cutting edge (12) configured to remove material, in particular chips, from a body which is contacted by said cutting edge during the rotation of the gear wheel (10). Suitably, the cutting edge (12) is defined by at least one groove (14) which is lowered by amount from 0.2% to 5% of the height (H') of the tooth (11), said groove (14) decreasing away from the cutting edge (12) along the profile (P).