Eccentric Screw Pump Stator Interference Control
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Solution Overview
Problem
Uniaxial eccentric screw pumps face challenges in maintaining stable contact pressure between the stator and rotor, leading to increased torque requirements, stator wear, and potential damage due to temperature changes during CIP or SIP processes, where the stator expands, causing interference issues and frictional forces to rise.
Innovation Solution
A uniaxial eccentric screw pump design featuring a stator with a female threaded inner surface, a rotor with a male threaded shaft, and an exterior body that can move between compressing and alleviating compression states, guided by a circumferentially restricted guide member to set appropriate interference and prevent rotational movement, ensuring stable fastening and minimizing stator damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air pressure is increased to maintain stator contact pressure, then stator-to-rotor contact is improved, but cavity volume decreases and torque increases
Solution Approach 1:
A spring mechanism is introduced as an intermediary between the stator and rotor to maintain contact pressure. The spring continuously applies elastic force to keep the stator pressed against the rotor, eliminating the need for high air pressure while maintaining reliable contact and preventing fluid leakage.
Solution Approach 2:
Air pressure is utilized to actuate the exterior body, which indirectly compresses the spring and applies force to the stator. This pneumatic actuation allows for controlled, indirect pressure application that maintains contact without the harmful direct effects of high air pressure on the cavity volume.
2Reliability
If air pressure is increased to maintain stator contact pressure, then contact stability is improved, but stator wear accelerates
Solution Approach 1:
The spring acts as a cushioning intermediary that distributes contact pressure evenly between the stator and rotor. This elastic mediator prevents concentrated stress points that would accelerate wear, while still maintaining sufficient contact pressure for reliable operation.
Solution Approach 2:
The spring provides beforehand cushioning by continuously maintaining a controlled interference fit between the stator and rotor. This pre-established elastic contact prevents sudden impact loads and excessive friction that would otherwise accelerate stator wear during operation.
3Adaptability or versatility
If stator interference is increased for high temperature operation, then stator expansion is accommodated, but torque requirement increases
Solution Approach 1:
The spring mechanism provides dynamic adaptability, allowing the stator-to-rotor interference to automatically adjust based on operating conditions. When the stator expands due to temperature changes, the spring compresses accordingly, maintaining optimal contact pressure without requiring excessive pre-set interference that would increase torque requirements.
Solution Approach 2:
The system allows the interference parameter between stator and rotor to change dynamically with temperature. The spring mechanism enables the contact pressure to be maintained within an optimal range across varying temperatures, preventing both excessive interference (high torque) and insufficient interference (poor contact).
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 allows for stable fluid discharge pressure and minimizes stator wear by adjusting interference based on temperature changes, dispersing torque loads and preventing rotational damage, thus enhancing the pump's operational efficiency and longevity.
Implementation Method 1
a stator expands and contracts in response to a change of a liquid temperature or an atmospheric temperature
Implementation Method 2
an exterior body configured to be movable between a first position where the exterior body is capable of compressing the stator and a second position where the exterior body at least alleviates a compression state of the stator
Data Source
AI summary
A uniaxial eccentric screw pump includes: a stator 32 having a female threaded inner peripheral surface; a rotor 33 configured to be insertable into the stator 32, and formed of a male threaded shaft body; an exterior body 31 configured to be movable between a first position where the exterior body 31 is capable of compressing the stator 32 and a second position where the exterior body 31 at least alleviates a compression state of the stator 32; and guide members 55, 56 configured to restrict a movement of the exterior body 31 in a circumferential direction of the stator while allowing a movement of the exterior body 31 in a radial direction of the stator by guiding an end portion of the exterior body 31.