Espresso Machine Pump Priming for Accurate Beverage Dose Metering
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Solution Overview
Problem
Existing beverage preparation machines, such as espresso coffee machines, face issues with inaccurate measurement of the beverage dose due to the presence of a self-priming valve that continuously draws variable amounts of water, affecting the flow-rate meter's ability to determine the actual amount of water sent to the brewing assembly.
Innovation Solution
The machine employs a two-position three-way solenoid valve, normally closed and controlled by an electronic control unit, to prime the pump by drawing a small amount of water, allowing precise measurement of the beverage dose without a self-priming valve, and uses an additional unidirectional valve configuration to manage pressure and flow during brewing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-priming valve is used to continuously draw water from the pump outlet, then the pump is kept primed and operational, but the flow-rate meter cannot accurately determine the actual amount of water sent to the brewing assembly
Solution Approach 1:
The invention extracts the priming function from the main water flow path by introducing a separate priming circuit with its own control valve. This allows the self-priming valve to operate independently without interfering with the measurement of water intended for the brewing assembly, thereby resolving the contradiction between maintaining pump priming reliability and achieving accurate beverage dose measurement.
Solution Approach 2:
The water flow is segmented into two distinct paths: one for priming the pump (controlled by the first solenoid valve) and another for delivering water to the brewing assembly (monitored by the flow-rate meter). This segmentation allows independent control and measurement of each function, eliminating the measurement error caused by the self-priming valve drawing water from the main flow.
2Stability of the object's composition
If a self-priming valve continuously draws variable amounts of water from the pump outlet, then the pump remains primed, but the flow-rate meter detects inaccurate water quantities
Solution Approach 1:
The invention introduces a second solenoid valve as an intermediary between the pump outlet and the brewing assembly. This valve acts as a gatekeeper that controls when water flows to the brewing assembly, ensuring that only water intended for brewing (and not priming) is measured by the flow-rate meter, thus maintaining both pump water content stability and measurement precision.
3Reliability
If the self-priming valve draws variable water amounts based on back pressure, then the pump is maintained in operational state, but the beverage dose cannot be accurately metered
Solution Approach 1:
The invention performs the priming action preliminarily and separately from the brewing process. The first solenoid valve is activated before water flow to the brewing assembly begins, ensuring the pump is primed and ready. This preliminary priming action is decoupled from the main brewing flow, allowing accurate metering of the beverage dose without compromising pump operational readiness.
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 solution enables accurate metering of the beverage quantity dispensed, eliminating the need for a self-priming valve and improving the precision of the dose measurement, while maintaining the machine's operational efficiency and functionality.
Implementation Method 1
a flow-rate meter 6, for example of the turbine type, for providing electrical signals (pulses) indicative of the amount of water sucked by the pump
Implementation Method 2
a self-priming valve 7, of a type known per se, which in use continuously draws a quantity of water from the outlet of the pump 3 and discharges the water drawn into a drip recipient 8
Implementation Method 3
a unidirectional hydraulic valve 10 adapted to allow a flow of water towards said brewing assembly when the pressure of the water supplied by the pump 3 exceeds a predetermined threshold value
Implementation Method 4
a solenoid valve 12, having its inlet coupled between the outlet of the unidirectional valve 10 and the inlet of the brewing assembly 1 and its outlet connected to the drip recipient 8. Said solenoid valve 12 is capable of assuming an open condition and a closed condition
Implementation Method 5
The water that comes from the pump 3 and passes through the self-priming valve 7 therefore arrives at an electric heater device or boiler 9
Implementation Method 6
An electronic temperature sensor 11 is associated with the heating device 9
Implementation Method 7
The pump 3 is a vibration pump and, in a manner known per se, comprises a control solenoid valve connected in series with a diode
Data Source
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AI summary
The machine (M) comprises a brewing assembly (1), a water tank (4), an electric vibration pump (3) having its inlet connected to the tank (4) and its outlet or discharge connected to the brewing assembly (1), a unidirectional valve (10) between the pump (3) and the brewing assembly (1) to allow a flow of water towards the brewing assembly (1) when the pressure of the water supplied by the pump (3) exceeds a predetermined threshold, a heating device (9) for heating the water supplied by the pump (3), at least one solenoid valve (12, 13) having its inlet coupled between the outlet of the pump (3) and the brewing assembly (1) and adapted to assume an open condition and a closed condition in which it allows and prevents, respectively, a flow of fluid from its inlet towards a discharge environment, for controlling an auxiliary function of the machine (M) which is not utilized for the preparation of the beverage; and an electronic control unit (ECU) predisposed to control the solenoid valve (12, 13) such that upon starting a cycle for the preparation of a beverage the solenoid valve (12, 13) is opened for a predetermined period of time and allows a flow of water from the outlet or discharge of the pump (3) towards the discharge environment (8) so as to prime the pump (3), and is subsequently closed.