Coffee machine with pre-infusion system
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Solution Overview
Problem
Existing coffee machines with high-pressure hot water systems face inefficiencies due to excessive compression of coffee grounds, leading to reduced water flow and suboptimal beverage extraction, and prior pre-infusion methods are slow and imperfect.
Innovation Solution
A coffee machine equipped with a pulsing electrovalve that supplies intermittent hot water pulses of less than 1 second for pre-infusion, allowing coffee grounds to relax and settle, thereby increasing water flow during extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high-pressure hot water (9-11 bars) is supplied to the coffee dose, then extraction pressure is sufficient, but the coffee dose becomes excessively compressed reducing water flow
Solution Approach 1:
The system performs pre-infusion by supplying water at reduced pressure (closing the main pump and using only the booster pump) before the main extraction phase. This preliminary wetting of the coffee grounds prevents excessive compression when high-pressure water is later applied, maintaining both adequate flow and extraction pressure.
Solution Approach 2:
The system uses periodic pumping cycles with distinct phases: a pre-infusion phase with low pressure followed by a main extraction phase with high pressure. The pump operates intermittently rather than continuously, switching between different pressure levels to achieve both goals sequentially.
2Reliability
If continuous pre-infusion is performed to wet the coffee dose, then the coffee is thoroughly wetted, but the process is slow and efficiency is reduced
Solution Approach 1:
The system performs pre-infusion by supplying water at reduced pressure (closing the main pump and using only the booster pump) before the main extraction phase. This preliminary wetting of the coffee grounds prevents excessive compression when high-pressure water is later applied, maintaining both adequate flow and extraction pressure.
Solution Approach 2:
The system uses periodic pumping cycles with distinct phases: a pre-infusion phase with low pressure followed by a main extraction phase with high pressure. The pump operates intermittently rather than continuously, switching between different pressure levels to achieve both goals sequentially.
3Stress or pressure
If the additional valve is closed during pre-infusion to maintain pressure, then pressure is sufficient, but water flow to the coffee dose is limited
Solution Approach 1:
The water supply system is divided into two separate pumps: a main pump for high-pressure extraction and a booster pump for low-pressure pre-infusion. This segmentation allows each pump to operate independently at its optimal pressure level, with the booster pump feeding into the main pump's inlet during pre-infusion phase.
Solution Approach 2:
The system performs pre-infusion by supplying water at reduced pressure (closing the main pump and using only the booster pump) before the main extraction phase. This preliminary wetting of the coffee grounds prevents excessive compression when high-pressure water is later applied, maintaining both adequate flow and extraction pressure.
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
This approach results in a rapid, efficient, and reliable pre-infusion process that enhances beverage extraction efficiency by maintaining counterpressure and preventing excessive compression, ensuring a perfect pre-infusion and continuous flow during extraction.
Implementation Method 1
a pulsing electrovalve provided with a shutter intended to open and close the communication in the water system with opening and closing time that is equal to or lower than 1 second
Implementation Method 2
a source of pressurized water; a heater connected to the source of pressurized water and to the dispensing nozzles
Implementation Method 3
a heater connected to the source of pressurized water and to the dispensing nozzles
Implementation Method 4
the wet coffee is less compressed by the pressure of the hot water and the flow of hot water is increased, obtaining a more efficient extraction
Data Source
Figure 1
Figure 2
AI summary
A coffee machine (1) comprises: a filter holder (2) intended to contain at least one coffee dose (3), a dispensing unit (4) with dispensing nozzles (40) intended to send a flow of hot water on the coffee dose (3), a water system (5) provided with a pump (50) to supply pressurized water towards the dispensing nozzles (40), a heater (6) to heat the water to be supplied to the dispensing nozzles (40), a dispensing valve (7) to enable/disable the supply of hot water towards the dispensing nozzles, and a pre-infusion valve (9) disposed upstream the dispensing valve (7); the pre-infusion valve (9) being set in such a way as to operate in pulsed mode for a pre-infusion time of at least 4 seconds, with opening and closing time equal to or lower than 1 second.