Variable-Volume Coffee Infusion Chamber With Adjustable Piston Sealing
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Solution Overview
Problem
Existing coffee machines face challenges in reliably sealing the infusion chamber under varying coffee doses, requiring adaptation of chamber dimensions and motor torque to maintain consistent extraction pressure and quality, which is inefficient and costly, especially when producing different types of coffee with different powder quantities.
Innovation Solution
The apparatus uses a connecting-rod-and-crank mechanism with a reversible electric motor and a control unit to adjust the piston's position within a cylindrical infusion chamber of fixed diameter, allowing for varying chamber volumes and overcoming torque issues by using a toothed sector to lock the connecting rod, enabling efficient closure and expansion of the chamber for different coffee doses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the infusion chamber diameter is increased to accommodate larger coffee doses, then the chamber can hold more coffee powder, but the sealing forces on the closure members increase significantly
Solution Approach 1:
The piston position is made variable and adjustable along the infusion chamber axis, allowing the effective chamber volume to be dynamically changed. This enables the system to accommodate different coffee doses (from ristretto to American coffee) without requiring different chamber diameters, thus avoiding the exponential increase in sealing forces that would result from increasing diameter.
2Quantity of substance
If the infusion chamber volume is increased to prepare larger doses, then more coffee powder can be used, but the extraction pressure consistency becomes difficult to maintain
Solution Approach 1:
The system changes the parameter of chamber volume by adjusting the piston position rather than changing chamber diameter. This allows volume to be scaled linearly (by piston displacement) while maintaining the same chamber cross-section and sealing characteristics, thereby preserving extraction pressure consistency across different dose sizes.
3Reliability
If the motor torque is increased to maintain sealing under larger doses, then the chamber can be reliably sealed, but the device complexity and cost increase
Solution Approach 1:
By making the piston position adjustable, the system dynamically adapts the chamber volume to match the coffee dose being prepared. This prevents the need for oversized motors that would be required to seal large-volume chambers, as the motor only needs to seal the actual volume being used, maintaining reliability without increasing complexity.
4Reliability
If the chamber dimensions are adapted for each coffee type, then extraction quality is optimized, but the device versatility and efficiency decrease
Solution Approach 1:
A single infusion chamber with adjustable piston position serves multiple functions by accommodating different coffee doses (ristretto, espresso, American coffee) within its volume range. This universal design eliminates the need for multiple fixed-dimension chambers, thereby improving device versatility while maintaining extraction quality through precise volume control.
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 allows for the production of various coffee types with consistent extraction quality by adjusting the piston's position within the infusion chamber, reducing the need for motor torque and enabling efficient expulsion of exhausted coffee grounds, thus improving operational efficiency and versatility.
Implementation Method 1
resilient means for compressing said quantity of powdered product to a defined compression value
Implementation Method 2
a connecting-rod-and-crank mechanism in which mechanism the crank is connected to the rotation shaft of the motor and the connecting rod is connected between the end of the crank and the end of the piston
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Apparatus for the preparation and dispensing of doses, in selectable variable volumes, of infusions, particularly of coffee, by means of pressurised water, comprising a cylindrical infusion chamber (3), a piston (8) with an end (10) axially insertable into said infusion chamber (3), means (15,16,17,18) for feeding into said infusion chamber (3) a predetermined quantity of powdered product, and means (7,52,54,55) for expelling from said infusion chamber (3) the quantity of exhausted product used for the infusion at the end of preparation thereof. The apparatus includes drive means for actuating said piston (8), which means comprise an electric motor with reversible direction of rotation and a connecting-rod-and- crank mechanism in which the connecting rod (12) comprises two members (24, 25) partly superposed on each other and able to slide for a defined distance in opposition to resilient means (44) interposed between them. The apparatus further comprises locking devices (49,50) for detachably connecting said first member (24) of the connecting rod (12) to a point (51) outside the apparatus when said members (24,25) are in angular positions not aligned axially with said crank (21).