Improved espresso machine method and apparatus
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Solution Overview
Problem
Existing espresso machines lack efficient methods for regulating pressure and volume during the brewing process, particularly in the pre-infusion stage, which affects the quality and consistency of espresso production.
Innovation Solution
The integration of a flow measurement apparatus and a pump power modification module that allows for real-time measurement of resultant flow and adjustable pressure profiling, enabling controlled low-pressure pre-infusion and precise dose delivery by subtracting return flow from feed flow, and modifying electrical power to the pump for pressure profiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a pump is used to deliver water at high pressure (9-10 bar) for espresso extraction, then the extraction pressure is sufficient, but the pre-infusion stage cannot effectively wet the coffee grounds without forcing water through them
Solution Approach 1:
The system dynamically adjusts pump pressure by controlling electrical power delivery to the pump motor. During pre-infusion, the controller reduces power to achieve low pressure (1-5 bar) for effective coffee wetting, then increases power for high pressure (9-10 bar) extraction, making the pressure adaptable to different brewing stages
Solution Approach 2:
The system changes the operational parameters of the pump by modifying electrical power input. The power modification module varies voltage or current to the pump motor, enabling transition from low-power pre-infusion mode to high-power extraction mode, thereby achieving both effective wetting and proper extraction pressure
2Measurement precision
If flow meters are installed to measure feed flow and return flow, then precise dose measurement is achieved, but the device complexity increases
Solution Approach 1:
The flow measurement function is segmented into two independent measurements: feed flow (total water pumped) and return flow (water diverted by over-pressure valve). By measuring these separately and calculating resultant flow as their difference, the system achieves precise dose measurement while using simple, reliable flow meter components
Solution Approach 2:
The over-pressure valve acts as an intermediary that creates a measurable return flow. By diverting excess water through a controlled path with a flow meter, the system indirectly measures the actual dose (feed flow minus return flow) without requiring direct measurement at the complex extraction point
3Power
If the pump operates at constant high power, then water delivery speed is sufficient, but pressure control during pre-infusion and extraction stages cannot be achieved
Solution Approach 1:
The controller receives feedback from flow meters measuring feed flow and return flow, calculates resultant flow, and uses this information to adjust pump power delivery. This closed-loop control enables precise pressure regulation during pre-infusion and extraction by dynamically matching power output to brewing stage requirements
Solution Approach 2:
The system applies periodic control actions by switching between distinct power delivery phases: low-power pre-infusion phase, high-power extraction phase, and power-off intervals. This periodic modulation of pump power enables precise pressure control throughout the brewing cycle
Data Source
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AI summary
An improved espresso machine includes a pump for delivering water to coffee grinds. Fluid pressure delivered by the pump is controllable by adjustment of electrical input power. In the method and apparatus of this invention, pump output is controlled during the brewing cycle to deliver a pre-infusion fluid dose at a pressure that is less than maximum pump pressure and, more specifically, less than the output pressure normally provided by the pump.