Beverage Machine Pump Control Using Virtual Pressure Sensing
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Solution Overview
Problem
Existing beverage preparation machines require complex and costly pressure sensors to achieve precise control over extraction parameters, which is cumbersome and inaccurate for complex parameter profiles and various beverages.
Innovation Solution
A beverage preparation system using a pressure adjustable pump with pre-established pressure interpolation data to determine extraction pressure without a physical pressure sensor, based on measured pump and liquid flow parameters, allowing for accurate control of extraction pressure across different cartridges with varying flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is provided in the fluid circuit to measure extraction pressure, then measurement precision of extraction pressure is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual copy of the pressure sensor by using a mathematical model that calculates extraction pressure from pump motor current and flow rate measurements. This virtual pressure sensor replicates the function of a physical pressure sensor without requiring actual pressure sensing hardware in the fluid circuit, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent replaces the mechanical pressure sensor system with an electrical calculation system. Instead of using a physical sensor to detect pressure mechanically, the system uses electrical measurements (pump motor current) combined with flow rate data and a mathematical model to compute pressure, substituting a mechanical detection system with an electrical computation system
2Device complexity
If a virtual model based calculation method is used to determine pressure from pump parameters, then device complexity is reduced, but measurement precision and accuracy deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the calculated pressure from the virtual model is continuously compared with target pressure values, and the pump motor control is adjusted based on the difference. This closed-loop feedback ensures that the simplified calculation method maintains accurate pressure control by constantly correcting deviations, thereby preserving measurement precision despite using a less complex system
Solution Approach 2:
The patent changes the parameters used for pressure determination from direct physical pressure measurement to electrical parameters (pump motor current) combined with flow rate. By transforming the measurement approach to use electrical and flow parameters that are easier to measure with high precision, the system maintains accuracy while reducing complexity
3Reliability
If complex sensor means are provided for feedback control, then beverage quality consistency is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the pump motor serve multiple functions: it not only delivers liquid at the required flow rate but also acts as an indirect pressure sensor through its current measurements. This multi-functional approach eliminates the need for separate dedicated pressure sensing hardware while maintaining the feedback control necessary for consistent beverage quality
Solution Approach 2:
The system uses the pump motor's own electrical characteristics (current draw) to provide pressure information needed for control. The pump motor essentially monitors itself, using its inherent electrical properties to generate the pressure data required for feedback control, thereby eliminating the need for external sensing components
Data Source
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AI summary
The present invention relates to a beverage preparation system (10) for controlling a beverage preparation process by injection of liquid into a cartridge (20), the system comprising - a pressure adjustable pump (2) for delivering different pressures upon varying at least one of its drive characteristics such as the speed of the pump, - a sensor (3) for measuring an operating parameter of the pump (2) such as a current absorbed by the pump, - a flow sensor (1) for measuring a liquid flow parameter of liquid injected into the cartridge (20), - a control unit (6) designed to control an extraction pressure of the cartridge (20) by adjusting the drive characteristics of the pump (2) based on pre- established pressure interpolation data (12) depending on the measured liquid flow parameter and the measured operating parameter of the pump.