Metering Pump Eccentric Piston Viscosity Dosing Accuracy
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Solution Overview
Problem
Dosing pumps for household appliances, such as washing machines and dishwashers, face inaccuracies in dosing liquid detergents due to viscosity dependency, leading to inconsistent dispensing of detergents with varying viscosities.
Innovation Solution
A piston pump design with an eccentric mechanism that engages in a groove on the reciprocating piston, utilizing a synchronous motor and umbrella valves with preload, ensuring accurate dosing across a wide viscosity range while maintaining compact dimensions and low noise levels, and allowing self-priming up to 1 meter delivery height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional piston pump with electric motor is used, then the pump can deliver liquid detergent, but the dosing accuracy deteriorates due to viscosity dependency
Solution Approach 1:
The invention changes the key parameter from rotational speed control to direct reciprocating motion control. By using an eccentric mechanism that directly converts motor rotation into piston reciprocation, the pump delivers a fixed volume per stroke regardless of viscosity variations, eliminating the dosing accuracy deterioration that occurs with conventional speed-controlled pumps when handling detergents of different viscosities.
2Measurement precision
If the pump design is made more complex to improve dosing accuracy, then dosing precision improves, but device complexity increases
Solution Approach 1:
The invention replaces complex flow control mechanisms with a simple eccentric-mechanism-driven reciprocating piston system. Instead of using sophisticated valves, flow meters, or electronic control systems to achieve precise dosing, the patent uses the inherent mechanical property of the eccentric mechanism to provide fixed displacement per stroke, achieving high dosing precision with minimal structural complexity.
Solution Approach 2:
The eccentric mechanism automatically compensates for viscosity variations without requiring external control systems. The fixed geometric relationship between the eccentric, crankshaft, and piston ensures that each reciprocating stroke delivers a consistent volume regardless of the detergent's viscosity, making the system self-regulating and eliminating the need for complex control mechanisms.
3Reliability
If the pump is designed for high delivery height, then self-priming capability improves, but noise level increases
Solution Approach 1:
The invention uses periodic reciprocating motion driven by the eccentric mechanism to create controlled suction and delivery phases. This periodic action allows the pump to self-prime by creating negative pressure during the suction stroke, enabling delivery heights up to 1 meter. The controlled, rhythmic motion reduces turbulence and cavitation noise compared to continuous high-speed rotational pumps, achieving both high self-priming capability and low noise operation.
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 achieves high dosing accuracy within ±10% with minimal viscosity dependency from 1 mPas to 5000 mPas, low noise operation, and easy control via a timer relay, while being cost-effective and suitable for both thick and thin detergents, with adaptable inlet and outlet cross-sections.
Implementation Method 1
the electric motor can be a synchronous motor
Implementation Method 2
an eccentric being arranged on the output shaft. The eccentric engages in a groove, a long groove, a recess or the like on the reciprocating piston in such a way that the rotational movement of the output shaft of the electric motor causes a translational, in particular oscillating translational, reciprocating movement of the reciprocating piston
Implementation Method 3
the piston pump can have an umbrella valve on its suction and/or pressure connection. In order to allow a particularly sensitive dosing, the umbrella valve can be provided with a valve preload
Data Source
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AI summary
The invention relates to a metering pump (1), in particular for liquid detergent in a washing machine, a dishwasher or similar, said pump comprising a pump designed as a piston pump with a reciprocating piston (7), and comprising an electric motor (6) that has an output shaft (8). An eccentric (9) which interacts with the reciprocating piston (7) is arranged on the output shaft (8) in such a way that the rotational motion of the electric motor (6) is converted into a translatory reciprocating motion of the reciprocating piston (7).