Espresso Machine Flow Rate Control for Puck Permeability Variation
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Solution Overview
Problem
Existing espresso machines lack the ability to consistently accommodate variations in coffee puck permeability, leading to inconsistent espresso shots due to factors like grinder performance, bean selection, and humidity, resulting in wasted coffee and time as baristas adjust settings to achieve desired shot characteristics.
Innovation Solution
A system dynamically controls water flow rate in real-time during pre-infusion and extraction, using pre-infusion and extraction tables to adjust flow rates based on puck pressure and permeability, ensuring consistent shot quality by maintaining target flow rates and pressures despite variations in puck preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If pressure control and pressure profiles are used to extract coffee, then the extraction process can be automated, but the system cannot accommodate variations in puck permeability leading to inconsistent shots
Solution Approach 1:
The system incorporates a flow meter that continuously measures the actual flow rate of water through the puck during extraction. This real-time feedback is fed to a controller that dynamically adjusts the pump pressure to maintain the target flow rate, automatically compensating for variations in puck permeability caused by grinding inconsistencies, tamping variations, or bean characteristics.
Solution Approach 2:
The system transitions from static pressure control to dynamic flow rate control. The pump pressure is continuously adjusted during the extraction process based on actual flow rate measurements, allowing the system to adapt to changing puck conditions in real-time and maintain consistent extraction parameters despite variations in coffee preparation.
2Reliability
If baristas manually adjust grinder settings to achieve desired shot characteristics, then shot quality can be optimized, but time and coffee are wasted during the dial-in process
Solution Approach 1:
The system enables self-adjustment by automatically compensating for puck permeability variations through real-time flow rate measurement and dynamic pressure control. This eliminates the need for manual grinder adjustments during the dial-in process, as the system adapts to different coffee batches, grinding settings, and barista techniques automatically, significantly reducing the time and coffee wasted during optimization.
3Reliability
If baristas monitor shot parameters to determine when to stop extraction, then shot quality can be controlled, but the barista's attention is occupied during the shot
Solution Approach 1:
The system uses a flow meter to continuously monitor the actual flow rate during extraction and provides real-time feedback to the controller. This automatic monitoring and adjustment system eliminates the need for baristas to visually inspect the shot or manually time it, freeing them to attend to other tasks while maintaining consistent shot quality through automated flow rate control.
4Extent of automation
If volumetric dosing is used to control water volume, then the end point can be automated, but the flow rate progression through the puck is not controlled
Solution Approach 1:
The system replaces static volumetric dosing with dynamic flow rate control. Instead of simply controlling the total water volume delivered, the system continuously measures and adjusts the instantaneous flow rate throughout the extraction process, ensuring consistent water movement through the puck regardless of variations in puck permeability, thereby achieving both automated endpoint control and extraction consistency.
Data Source
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AI summary
An espresso brewing system to dynamically control the flow rate of water during pre-infusion and extraction to improvement shot consistency. Simple user controls create a programmatic "brewing environment" which allows shots to be very repeatable and shared, allowing shots to be reproduced on other machines with this system.