Hydropneumatic Door Closing for Quiet Refrigerated Cabinets
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Solution Overview
Problem
Existing refrigerated cabinet door closing systems generate noise, vibrations, and reduce the useful life of components due to impacts between the door and frame, and require additional devices for door stop positions, while also potentially increasing energy consumption and heat exchange with the environment.
Innovation Solution
A refrigerated cabinet with an automatic closing system using a hydropneumatic piston that generates a substantially constant force, allowing the door to stop in a predefined open position without additional devices, and minimizing closing time and impact by varying the closing speed through a differentiated closing phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If torsion springs are used for automatic door closing, then the door closes automatically, but the door generates noise and vibrations due to impact with the frame
Solution Approach 1:
The patent uses a hydropneumatic mechanism (damper with compressible gas and viscous fluid) to control door closing. The hydraulic damping dissipates kinetic energy through fluid resistance, preventing impact with the frame while maintaining automatic closing functionality. This eliminates noise and vibrations caused by traditional spring-based systems.
Solution Approach 2:
The patent changes the closing speed parameter dynamically during the closing process. The door closes faster during the initial phase and slows down near the closed position, optimizing both energy efficiency and impact prevention. This variable speed control is achieved through the hydropneumatic damper's resistance characteristics.
2Extent of automation
If torsion springs are used for automatic door closing, then the door closes automatically, but additional devices are required for door stop positions
Solution Approach 1:
The hydropneumatic damper serves multiple functions: it provides automatic closing force, controls closing speed, prevents impact, and enables door stop positions. By integrating these functions into a single device, the patent eliminates the need for separate spring mechanisms and stop devices, reducing overall system complexity.
Solution Approach 2:
The patent combines the closing force generation and speed control functions into a single hydropneumatic mechanism. The compressible gas provides the closing force while the viscous fluid controls the speed, merging what would traditionally require separate components into one integrated system.
3Loss of energy
If the door closes quickly to improve energy efficiency, then heat exchange is reduced, but impact with the frame increases
Solution Approach 1:
The patent implements a two-phase closing action: a first phase with faster closing speed to minimize heat exchange duration, and a second phase with slowed closing speed to prevent impact. The hydropneumatic damper naturally provides this periodic variation in closing speed through its resistance characteristics throughout the closing stroke.
4Object-generated harmful factors
If hydraulic mechanisms are used to slow down door closing, then impact is reduced, but closing time increases and energy efficiency decreases
Solution Approach 1:
The patent uses a dynamic closing speed control system that adapts the closing rate throughout the closing stroke. The door closes faster when far from the frame and slows down as it approaches, optimizing the balance between energy efficiency and impact prevention. This is achieved through the hydropneumatic damper's velocity-dependent resistance.
Solution Approach 2:
The patent changes the closing speed parameter dynamically during the closing process. The door closes faster during the initial phase to minimize heat exchange and slows down near the closed position to prevent impact. This variable speed control is achieved through the hydropneumatic damper's resistance characteristics.
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 system eliminates noise and vibration, extends the life of components, reduces energy consumption, and maintains efficient temperature control by ensuring a complete and effective door closure without additional stop devices, while minimizing closing time and heat exchange.
Implementation Method 1
an automatic closing system of said door comprising a hydropneumatic piston which is hinged at its opposite two ends along its own dynamic action axis respectively to said frame and to said door
Implementation Method 2
The cylinder has at least two longitudinal portions with different internal cross-sections so that the ratio between the force (F of extension) generated in an initial compression phase and the force (F of extension) generated in a final compression phase is between 1.2 and 1.4
Implementation Method 3
The cylinder has at least two longitudinal portions with different internal cross-sections so that the ratio between the force (F of extension) generated in an initial compression phase and the force (F of extension) generated in a final compression phase is between 1.2 and 1.4
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A refrigerated cabinet with one or more self-closing doors, comprising a support frame (2), which defines a load compartment 3, and at least one door (10) for closing the load compartment. The door is hinged to the frame with a vertical rotation axis (X) and may rotate to move between a closed position and a predefined position of maximum opening. The cabinet comprises an automatic door closing system, which comprises a hydropneumatic piston (40). The piston is hinged to the door in an offset position with respect to the rotation axis by means of a lever extension (43) integral with the door. The two hinging points of the piston are positioned with respect to the rotation axis so that: the hydropneumatic piston exerts a force (F) which always develops an angular momentum (M) for closing the door about the rotation axis, and the perpendicular distance (B) between the dynamic action axis (Y) of the piston and the rotation axis (X) decreases as the degree of angular opening of the door increases.