Meal Tray Trolley Coupling for Centralized Temperature Control

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Solution Overview

Problem

Existing meal tray transport and distribution systems are bulky, heavy, and expensive due to the integration of refrigeration units, and lack automatic temperature regulation and the ability to handle superimposed trays with both hot and cold dishes.

Innovation Solution

The system consists of isothermal trolleys with insulating envelopes and a fixed terminal equipped with a refrigeration unit and control unit, featuring air inlet and outlet vents connected via pipes for efficient temperature control, allowing for automatic regulation and the use of both single and double refrigeration modes, and includes means for reheating meal trays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If refrigeration units are integrated inside each trolley, then temperature control capability is improved, but the trolley becomes bulky, heavy, and expensive

Engineering Contradiction:
Improvetemperature control capabilityVSAvoidtrolley weight
Core Design Contradiction:
TemperatureVSWeight of stationary object

Solution Approach 1:

The refrigeration unit is extracted from the trolley and relocated to a fixed terminal. The trolley now only contains an evaporator and insulating envelope, while the compressor, condenser, and expansion device remain at the fixed terminal, connected via refrigerant pipes. This extraction eliminates the heavy components from the moving trolley while maintaining temperature control capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The refrigeration system is segmented into mobile and stationary parts. The evaporator and insulating envelope form the mobile portion in the trolley, while the compressor, condenser, and control systems form the stationary portion at the fixed terminal, connected through refrigerant piping.

Inventive Principle:
Principle #1Segmentation

2Temperature

If refrigeration units are integrated inside each trolley, then temperature control capability is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature control capabilityVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The complex components (compressor, condenser, expansion device) are extracted from the trolley and centralized at the fixed terminal, reducing the complexity of the mobile unit while maintaining full refrigeration functionality through the distributed evaporator system.

Inventive Principle:
Principle #2Taking out (Extraction)

3Weight of stationary object

If a fixed terminal with centralized refrigeration is used, then trolley weight and complexity are reduced, but automatic temperature regulation capability is lost

Engineering Contradiction:
Improvetrolley weightVSAvoidautomatic temperature regulation
Core Design Contradiction:
Weight of stationary objectVSExtent of automation

Solution Approach 1:

Temperature sensors are installed in the trolley compartments to detect actual temperature conditions. This feedback is transmitted to the control unit at the fixed terminal, which automatically adjusts the refrigeration cycle parameters (compressor speed, expansion valve opening) to maintain the desired temperature setpoints without manual intervention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-regulation through automatic control. The control unit continuously monitors temperature via sensors and autonomously adjusts refrigeration parameters to maintain optimal conditions, eliminating the need for manual operation while the trolley is in transit or at the terminal.

Inventive Principle:
Principle #25Self-service

4Ease of manufacture

If the fixed terminal design is simplified, then ease of manufacture is improved, but the ability to handle multiple trolley formats is reduced

Engineering Contradiction:
Improveease of manufactureVSAvoidtrolley format compatibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The fixed terminal is designed with universal connection interfaces that can accommodate different trolley formats and sizes. The refrigerant piping system includes multiple connection points and adjustable components that can serve various evaporator configurations, allowing a single terminal design to support multiple trolley types without requiring complex customization.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The solution provides an efficient, cost-effective, and automatically regulated temperature control system for meal trays, enabling the transportation of both hot and cold dishes without the need for manual handling and accommodating multiple tray formats, while reducing the system's size and complexity.

Implementation Method 1

a fixed terminal comprising a refrigeration unit and a control unit

Methodology Applied
Scientific EffectHeat removal (refrigeration): Cooling

Implementation Method 2

isothermal trolleys with insulating envelopes

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

at least one air inlet vent and at least one air outlet vent connected via ducts with the cold compartment

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP1902647B1Installation allowing the connection to a fixed terminal of two carts for transporting meal trays
Publication Date: 2016.11.09 ELECTRO CALORIQUE
  • EP1902647B1 patent drawingFigure 1~2
  • EP1902647B1 patent drawingFigure 3~4
  • EP1902647B1 patent drawingFigure 5~8

AI summary

The installation has a fixed terminal (16) comprising two parallel walls (19) each with cold air blowing socket pieces (27) complimentary to air inlet socket pieces (12) of a carriage. Air suction socket pieces (28) and the pieces (27) communicate with a refrigeration unit via channels. A temporary coupling unit (31) allows carriage maintenance in a fixed coupling position for which the pieces (27, 28) cooperate with the pieces (12) and air outlet socket pieces (13). The terminal has a coldness regulation and control unit controlling the carriages.