Trochoidal Gear Pump Bearing Assembly for Leakage Control
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Solution Overview
Problem
Trochoidal gear devices experience efficiency losses and part wear due to friction between moving parts, particularly when used as engines or motors, with issues like unbalanced radial hydraulic forces and bypass leakage, leading to degradation in chamber sealing and increased fluid shear forces.
Innovation Solution
The implementation of a rotary, chambered fluid energy-transfer device with a coaxial hub and rolling element bearing assemblies to set precise rotational and axial positions of the rotors, maintaining fixed-gap clearances that minimize frictional losses and fluid shear forces, and incorporating a pressure regulating valve to control fluid pressure and reduce bypass leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rolling element bearings are used to control frictional losses between the drive shaft and housing, then frictional losses are reduced, but the internal mechanism of the device still experiences binding and friction due to unbalanced radial hydraulic forces
Solution Approach 1:
A balance hole is introduced as an intermediary feature in the outer rotor to equalize radial hydraulic forces. This balance hole acts as a mediator that allows pressure equalization between the inner and outer faces of the outer rotor, eliminating the binding force that causes friction and wear between the rotor and housing surfaces.
Solution Approach 2:
The invention changes the pressure distribution parameter by introducing a balance hole that equalizes radial hydraulic forces. This parameter change transforms the unbalanced pressure distribution into a balanced state, eliminating the net radial force that causes binding and friction in the rotor-housing interface.
2Loss of substance
If the inner and outer rotors are forced into close contact with the end plate to reduce bypass leakage, then bypass leakage is reduced, but frictional losses and wear increase
Solution Approach 1:
The invention employs dynamic sealing where the rotor surfaces maintain optimal clearance that adapts to operating conditions. The floating rotor design allows the rotors to dynamically adjust their position relative to the end plate, maintaining sufficient sealing clearance to prevent bypass leakage while avoiding excessive contact that would cause friction and wear.
Solution Approach 2:
The invention optimizes the clearance parameter between rotor surfaces and the end plate. By carefully selecting and maintaining an optimal clearance range, the system achieves effective sealing to prevent bypass leakage while ensuring that frictional forces remain minimal, thus resolving the contradiction between leakage prevention and friction reduction.
3Reliability
If close-fitting clearance is used between the outer rotor and housing to prevent bypass leakage, then sealing is improved, but frictional forces and fluid shear forces increase
Solution Approach 1:
The invention uses a floating rotor configuration where the outer rotor can dynamically adjust its radial position relative to the housing. This dynamic adjustment allows the system to maintain optimal clearance that prevents bypass leakage while minimizing frictional forces and fluid shear forces, as the rotor naturally finds the equilibrium position that balances sealing requirements with friction minimization.
Solution Approach 2:
The invention optimizes the radial clearance parameter between the outer rotor and housing. By carefully controlling this clearance parameter, the system achieves effective sealing to prevent bypass leakage while maintaining sufficient gap width to reduce frictional forces and fluid shear forces, thus resolving the contradiction between sealing performance and friction reduction.
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 significantly reduces frictional losses, maintains superior chamber sealing, and enhances the efficiency of the device as both an engine and a compressor, while eliminating wear on rotor gear profiles and reducing fluid shear forces, thus improving mechanical and fluidic efficiency.
Implementation Method 1
The inner rotor is mounted for rotation upon a hub which is mounted in the housing with a rolling element bearing assembly. The outer rotor is rotatably retained in the housing, eccentric to the inner rotor.
Implementation Method 2
The bearing assembly sets and maintains a fixed-gap clearance between at least one of the surfaces of the rotor and the housing or the other rotor. The fixed-gap clearance is a distance that is greater than a boundary layer of an operating fluid used in the device.
Implementation Method 3
At operating pressures, hydraulic forces urge the inner rotor to the minimum fixed-gap clearance position thereby also maintaining a fixed-gap clearance between the opposite face of the inner rotor and the inner face of the closed end of the outer rotor.
Data Source
AI summary
A trochoidal gear pump or engine uses a coaxial hub with an outer and/or inner rotor and an associated rolling element bearing assembly that uses pre-loaded bearings to precisely set the rotational axis and/or the axial position of the rotor with which it is associated. This allows the fixed-gap clearance between the rotor surfaces and the housing or other rotor surfaces to be set at a distance that minimizes operating fluid shear forces and/or by-pass leakage and eliminates gear tooth wear thus preserving effective chamber to chamber sealing. The device is useful in handling gaseous and two-phase fluids in expansion/contracting fluid engines/compressors and can incorporate an output shaft for an integrated condensate pump for use with Rankine cycles. A vent from the housing cavity to a lower pressure input or output port regulates built-up fluid pressure in the housing, thereby optimizing the efficiency of the device by controlling bypass leakage.