Pump Wash Flow Path for Piston and Seal Cleaning
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Solution Overview
Problem
Existing displacement pumps with tight fits between ceramic pistons and cylinders fail to adequately wash and clean the piston and seals, leading to contamination and potential seizing issues when dispensing liquids that precipitate solids, such as EDTA/salt solutions in medical applications.
Innovation Solution
A pump design incorporating a wash flow path with axial wash channels and a counterbore to allow a wash liquid to pass through and clean the displacement piston and lip seal, ensuring thorough washing and removal of solid particulates during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tight fit is used between the displacement piston and cylinder to seal the pump chamber, then pumping precision is improved, but the piston and seals cannot be adequately washed and cleaned
Solution Approach 1:
The pump chamber is segmented into a pumping section and a washing section. The washing section includes wash inlet and outlet openings, axial wash channels, and a counterbore that create a dedicated wash flow path separate from the pumping chamber, allowing independent optimization of washing function without compromising pumping precision.
Solution Approach 2:
A lip seal is introduced as an intermediary element between the displacement piston and the pump chamber wall. The lip seal creates a secondary sealing mechanism that allows wash liquid to penetrate and reach the piston surface, enabling effective washing while maintaining the tight fit required for pumping precision.
2Reliability
If a tight fit is used between the displacement piston and cylinder to seal the pump chamber, then pump reliability is improved, but solid particulates cause contamination and seizing
Solution Approach 1:
The washing section is designed to perform preliminary cleaning of the displacement piston and seals before the pump operates with precipitating solutions. The wash flow path continuously removes solid particulates and prevents their accumulation, addressing contamination issues before they can cause pump seizing and maintain reliability.
Solution Approach 2:
The wash flow path enables continuous washing action during pump operation. Wash liquid flows continuously through the axial wash channels and around the displacement piston, providing ongoing protection against solid particulate contamination and preventing seizing, thereby maintaining pump reliability throughout operation.
3Ease of manufacture
If existing washing features are added to the pump, then some cleaning is achieved, but the piston and seals are not adequately washed particularly where a tight fit is used
Solution Approach 1:
The washing section introduces a new spatial dimension for washing by creating axial wash channels that extend along the piston axis and a counterbore that provides radial washing coverage. This multi-dimensional wash flow path ensures comprehensive contact between wash liquid and all critical surfaces of the piston and seals, achieving adequate washing that existing features cannot provide.
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 wash flow path effectively removes solid particulates and prevents contamination by ensuring continuous washing and cleaning of the piston and seals, maintaining pump functionality and precision in liquid dispensing systems.
Implementation Method 1
The pump cylinder includes a wash inlet and a wash outlet in communication with the piston wash section proximate a second end of the pump cylinder. The pump cylinder further defines a counterbore at the second end of the pump cylinder and first and second axial wash channels extending from the wash inlet and the wash outlet, respectively, along the piston wash section to the counterbore.
Data Source
AI summary
In general, a piston-type pump includes a wash flow path that allows a wash liquid such as water to pass through to provide washing and cleaning as the pump operates. The pump may be used in precision liquid dispensing systems and particularly with liquid solutions that have a tendency to precipitate solid particulate. By washing a portion of the pump piston, the liquid solution being dispensed and any solid particulates may be carried away and removed from the pump.