Method and apparatus for improving the consistency of espresso shots
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Solution Overview
Problem
Existing espresso machines lack the ability to accommodate variations in coffee puck characteristics, leading to inconsistencies in espresso shots due to factors like grinder performance, coffee bean selection, and humidity, resulting in inconsistent shot volume, crema quality, and flavor.
Innovation Solution
A method and system that dynamically control the flow rate of water during pre-infusion and extraction, using a Pre-Infusion Table and Extraction Table to adjust flow rates based on puck permeability, pressure, and user inputs, ensuring consistent water contact time and reducing channeling, with a closed-loop control system to adapt to varying puck conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure control and pressure profiles are used to indirectly control water flow into the coffee puck, then the espresso machine can extract coffee, but the system cannot accommodate variations in puck permeability, leading to inconsistent shot volume and flow rate
Solution Approach 1:
The system uses a flow meter to continuously measure the actual flow rate of water through the puck and feeds this information back to the control system. The controller compares the measured flow rate with the target flow rate and dynamically adjusts the pump pressure to maintain consistent flow despite variations in puck permeability caused by different grind sizes, doses, or tamping forces.
Solution Approach 2:
The system transitions from static pressure control to dynamic flow control. The pump pressure is continuously adjusted during the extraction process based on real-time flow measurements, allowing the system to adapt to changing puck conditions and maintain the desired flow rate throughout the shot.
2Manufacturing precision
If the barista manually monitors shot color, time, and volume to determine when to stop the shot, then shot quality can be controlled, but the barista's time and attention are occupied, reducing productivity
Solution Approach 1:
The system automatically determines the optimal shot termination point by monitoring the extraction process and detecting when the desired extraction is achieved. The controller stops the shot automatically based on pre-programmed parameters such as target flow rate, time, or volume, eliminating the need for continuous barista monitoring and allowing the barista to focus on other tasks.
Solution Approach 2:
The manual visual monitoring and decision-making process is replaced with an automated electronic control system that uses flow meters, pressure sensors, and controllers to monitor and terminate the shot based on objective measurements rather than subjective barista assessment.
3Loss of time
If volumetric dosing is used to stop the machine after a programmed water volume, then the endpoint can be controlled, but the system cannot account for variations in water movement through the puck, resulting in inconsistent extraction
Solution Approach 1:
The system replaces simple volumetric control with flow rate control based on actual water movement through the puck. The flow meter measures the real-time flow rate, and the controller adjusts pressure to maintain the target flow rate, ensuring consistent extraction regardless of puck variations. This substitutes volume-based control with flow-rate-based control that accounts for actual water-puck interaction.
4Manufacturing precision
If the grinder is adjusted multiple times throughout the day to accommodate bean and humidity changes, then shot weight can be maintained, but coffee and time are wasted during dialing in
Solution Approach 1:
The system compensates for grinder variations and puck permeability changes by dynamically adjusting the water flow rate parameter. Instead of requiring manual grinder adjustments, the electronic control system adapts to different coffee characteristics by modifying the flow rate to achieve consistent extraction, reducing the need for physical grinder dialing-in and associated waste.
Data Source
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.