Fluid Pump Pressure Relief Path for Leakage and Crystallization
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Solution Overview
Problem
Liquid pumps used to inject chemicals like Sodium Hypochlorite into pressurized water streams face issues with crystallization and leakage due to abrasive crystals forming on the piston surface during idle periods, leading to seal wear and air aspiration, which complicates the design and increases costs.
Innovation Solution
A liquid pump design with a central longitudinal bore and transverse bore, featuring a piston that slides and rotates within a ceramic liner, includes a pressure relief passageway between the cavity and inlet port to manage fluid pressure and prevent leakage, using a thin-walled liner and minimal clearance to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a pressure relief slot is provided to maintain negative pressure at the inlet port, then leakage of liquid is prevented, but air is aspirated into the pump head causing evaporation of liquid and crystallization
Solution Approach 1:
The patent extracts the pressure relief function from the traditional scavenger slot design and relocates it to a dedicated pressure relief passage that opens directly to the inlet port. This separation allows the system to maintain negative pressure for leakage prevention while eliminating the air aspiration pathway that causes crystallization, thus resolving the contradiction between preventing liquid loss and avoiding harmful air ingress.
Solution Approach 2:
The patent introduces an intermediary pressure relief passage structure that mediates between the cavity and inlet port, providing a controlled pathway for pressure equalization without creating direct communication with the external environment. This intermediary structure enables pressure management while preventing air aspiration into the pump head, thereby eliminating crystallization while maintaining leakage prevention.
2Use of energy by moving object
If the pump is allowed to sit idle with the piston withdrawn, then energy consumption is reduced, but abrasive crystals form on the piston surface causing seal wear
Solution Approach 1:
The patent applies preliminary action by maintaining a film of liquid on the piston surface through the pressure relief passage during idle periods. This preliminary liquid film prevents crystallization from forming on the piston surface, thereby protecting the seal elements from wear when the pump is later activated, while still allowing the piston to be withdrawn for energy savings.
Solution Approach 2:
The patent changes the pressure parameter by maintaining negative pressure in the cavity during idle periods through the pressure relief passage. This parameter change prevents liquid evaporation and crystallization on the piston surface, thereby protecting seal elements from abrasive damage while allowing the pump to remain energy-efficient during idle time.
3Reliability
If a ceramic piston and liner are used to resist crystallization, then pump reliability is improved, but the abrasive nature of crystals still causes seal wear and eventual failure
Solution Approach 1:
The patent converts the harmful effect of negative pressure (which causes air aspiration and crystallization) into a beneficial effect by using the same negative pressure to maintain a protective liquid film on the piston surface. This liquid film prevents crystal formation and protects seals from abrasive damage, thus transforming the potential harm into a protective mechanism that enhances seal durability.
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
The solution effectively reduces leakage and prevents crystallization by managing fluid pressure, maintaining seal integrity, and simplifies the pump design without increasing size or complexity, ensuring reliable operation.
Implementation Method 1
a pressure relief passageway between the cavity and inlet port to manage fluid pressure and prevent leakage
Implementation Method 2
typically utilize a slight negative pressure of approximately 1-2 psig on the inlet port to preclude leakage of NaOCl out of the pump head during idle times
Implementation Method 3
Upon outward movement of the piston, suitably designed sealing elements will wipe the piston surface to minimize dragging of any pumped liquid out of the pump head. This squeegee action of the seals
Implementation Method 4
This air flow will gradually lead to evaporation of NaOCl liquid within the pump head such that crystallization will cause the piston to lock and be unmovable when the pump is later energized.
Data Source
Figure 1~3
Figure 1A
Figure 4
AI summary
A liquid pump including a pump housing having an interior sidewall forming an interior. The housing has an inlet port and an outlet port. A liner is disposed in the interior and has opposed transverse openings in line with the inlet and outlet ports. The liner has a central longitudinally extending bore. A pump piston is axially and rotatably slidable within the liner longitudinal bore for pumping the liquid from the inlet port to the outlet port. A seal assembly is secured to the pump housing adjacent to an upper end of the liner. The seal assembly including a seal body, an upper end of the piston extending though the cap and in sealing engagement with the seal body, the seal assembly and liner upper end forming a cavity there between. An upper end of the piston extending though the seal assembly and in sealing engagement with the seal body, the seal body and liner upper end forming a cavity there between. The housing having a passageway providing a fluid communication between the cavity and the inlet port.