Nutating Pump Flow Pulsation Reduction via Dual Chambers
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Solution Overview
Problem
Conventional nutating pumps experience pulsation and splashing issues during fluid dispensing, particularly at higher flow rates, leading to inaccurate dispensing and increased maintenance due to the sinusoidal dispense profile and constant motor speed operation.
Innovation Solution
The design introduces two pump chambers within the nutating pump, with output from the secondary chamber occurring during a different part of the piston cycle than the primary chamber, distributing the output flow over the entire cycle and using a controller to vary motor speed for reduced peak flow rates and extended cycle duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional nutating pumps operate at constant motor speed, then the pump structure is simple and easy to control, but the output flow exhibits pulsation and splashing leading to inaccurate dispensing
Solution Approach 1:
The patent applies dynamics by transitioning from constant motor speed to variable motor speed operation. The motor speed is dynamically adjusted throughout the piston cycle, being reduced during the dispense portion and increased during the intake portion, thereby eliminating flow pulsation and splashing while maintaining dispensing accuracy
Solution Approach 2:
The patent changes the operational parameters by varying motor speed as a function of piston position and cycle phase. This parameter modulation transforms the fixed-speed operation into a variable-speed regime that optimizes flow characteristics and eliminates harmful pulsations
2Productivity
If the motor speed is increased to achieve higher dispensing speed, then productivity improves, but flow pulsation and splashing increase causing inaccurate dispensing
Solution Approach 1:
The system dynamically adjusts motor speed based on the instantaneous requirements of the pump cycle. During the dispense portion, speed is reduced to eliminate splashing, while during the intake portion, speed is increased to maintain high productivity. This dynamic adjustment allows the system to achieve high average speeds without the harmful effects of constant high-speed operation
3Device complexity
If conventional nutating pumps use single chamber design, then the device structure is simple, but the output flow rate varies significantly during the cycle causing pulsation
Solution Approach 1:
The pump chamber is segmented into a dispense chamber and an intake chamber that operate on opposite sides of the piston. This segmentation allows the two chambers to produce complementary flow patterns, with one chamber dispensing while the other is being filled, thereby smoothing the overall output flow and reducing pulsation
4Quantity of substance
If partial revolution dispense is used to achieve small dispense volumes, then the pump capacity is optimized, but the non-linear output profile makes accurate dispensing difficult
Solution Approach 1:
By varying the motor speed parameter throughout the cycle, the patent linearizes the relationship between piston rotation angle and dispensed volume. This parameter modulation compensates for the inherent non-linearity of the nutating pump mechanism, enabling accurate partial-revolution dispenses of small volumes
Data Source
Figure 1A
Figure 1B~1C
Figure 1D~6D
AI summary
A nutating pump is disclosed which has a modified piston and housing or casing that provides two distinct pump chambers or areas. Output from the first pump chamber is delivered during a first half of the dispense cycle or the piston movement cycle. A substantial portion of this output is held for delivery by the second chamber during a second part or half of the dispense cycle. Thus, the output generated by the pump is not altered or reduced, it is delivered over the entire piston movement cycle as opposed to prior art pumps which deliver all of the fluid during a first half or first portion of the piston movement cycle. In this way, superior pulse modification is achieved as fluid is delivered across the entire piston movement cycle as opposed to a first half or first portion of the piston movement cycle. In additional embodiments disclosed, two distinct chambers are also provided but each chamber generates its own output as the piston includes two machined or flat sections for active pumping. Thus, each chamber generates its own positive output flow but the flow from each chamber is delivered during a different half of the piston movement cycle. Thus, the flow is still distributed throughout the entire piston movement cycle. In the first embodiment with a first and second chamber, the second chamber essentially acts as a holding station for fluid to be delivered during a second half of the piston movement cycle.