Coffee Machine Return-Line Heating for First-Cup Temperature
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Solution Overview
Problem
Existing coffee machines struggle to consistently achieve the desired beverage temperature in the first cup, often requiring excessive time to heat water to brewing temperature, especially when starting from a cold state, and may result in uneven coffee temperatures due to inadequate preheating.
Innovation Solution
The device incorporates a return line that connects behind the heating device to the liquid line, allowing preheated water to recirculate and be re-heated until the desired temperature is reached, using a control valve and pump to manage the recirculation, and optionally routing the return line through the brewing chamber for additional preheating, ensuring consistent temperature delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is heated directly to brewing temperature without recirculation, then heating time is short, but the first cup temperature is insufficient
Solution Approach 1:
The system performs preliminary heating action by recirculating water through the heating device multiple times before brewing. The recirculation valve directs water back to the inlet of the heating device, allowing it to be preheated in advance. This preliminary action ensures that when brewing starts, the water is already at or near the desired temperature, eliminating the need for additional heating time during the brewing process.
2Productivity
If a pump is added to control water flow in the recirculation system, then flow rate and pressure are controllable, but device complexity increases
Solution Approach 1:
The system employs a self-service approach where the pump is integrated into the existing water circulation pathway. The pump automatically draws water from the water tank and delivers it to the heating device when the recirculation valve is open, eliminating the need for separate complex flow control mechanisms. The pump's inherent capabilities provide sufficient flow rate and pressure control without requiring additional regulatory components.
3Temperature
If the return line is routed through the brewing chamber, then preheating efficiency is improved, but heat loss and noise increase
Solution Approach 1:
The return line is nested within or alongside the brewing chamber structure, allowing the heated water in the return line to transfer heat directly to the brewing chamber walls and components. This nested arrangement maximizes thermal contact area and efficiency, preheating the brewing chamber effectively. The close proximity enables direct heat transfer without requiring additional insulation or thermal management components.
Solution Approach 2:
The system converts the potential harm of heat loss from the heated water in the return line into a beneficial effect. Instead of insulating the return line to prevent heat loss, the design intentionally allows heat to transfer from the water to the brewing chamber, preheating it in preparation for brewing. This transforms what would normally be energy waste into a useful preheating function.
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 faster achievement of brewing temperature, reduces energy consumption by using preheated water, and ensures the first cup is served at the desired temperature, while minimizing noise and heat loss through sound-damping and thermal management.
Implementation Method 1
a heating device (14), which heats water to a brewing temperature
Implementation Method 2
a pump (20) is arranged in the first section of the liquid line between the junction of the return line in the first section and the heating device
Implementation Method 3
a control valve (38) is arranged in the first section of the liquid line and is connected to an outlet of the return line (24)
Implementation Method 4
the return line (24) in the device mentioned at the beginning behind the heating device connects the second section to the first section of the liquid line
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
The present invention relates to an apparatus (10) for preparing hot beverages, in particular a pad coffee machine, comprising a water container (12), a heating device (14) and a brewing chamber (16). These components are connected to one another by a liquid line (18, 22), with the first section (22) of said liquid line being situated between the water container (12) and the heating device (14), and the second section (22) of said liquid line being situated between the heating device (14) and the brewing chamber (16). In addition, a return line (24) is provided, in which or at whose inlet a return valve (28, 36) is arranged. The return line (24) connects the first section (18) to the second section (22) of the liquid line, with the result that water which is heated by the heating device (14) can be returned from the second section (22) to the first section (18) of the liquid line.