Refrigerator Quiet Mode Control With Pre-Cooling Safeguards
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Solution Overview
Problem
Conventional refrigeration appliances generate loud noise during operation, disrupting users, and existing solutions either require users to turn off the device, risking spoilage, or offer limited quiet modes that are not sustainable due to temperature constraints.
Innovation Solution
A refrigeration device with a control unit that allows users to switch to a low-noise operating mode, which temporarily inhibits the chiller's operation, using pre-cooling to maintain temperature and automatically switching back to thermostat mode when necessary to prevent spoilage, with user interface options for immediate or timed quiet mode activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigeration generator operates continuously to maintain temperature, then temperature stability is improved, but noise emission increases
Solution Approach 1:
The system performs pre-cooling of the storage chamber before the user arrives or before noise-sensitive periods begin. This preliminary action lowers the temperature in advance, creating a buffer that allows the refrigeration generator to remain off during noisy operation periods while still maintaining acceptable temperature levels.
Solution Approach 2:
The control unit dynamically adjusts the temperature setpoint and hysteresis parameters based on the operational mode (thermostat mode vs. low-noise mode). In low-noise mode, the system accepts a wider temperature range and delays activation of the refrigeration generator, adapting the temperature control strategy to prioritize noise reduction while maintaining food safety.
2Object-generated harmful factors
If the refrigeration generator is blocked to reduce noise, then noise emission is reduced, but temperature control reliability deteriorates
Solution Approach 1:
The control unit continuously monitors the temperature in the storage chamber and uses this feedback to determine when to activate the refrigeration generator, even in low-noise mode. The system compares the current temperature against dynamically adjusted thresholds and automatically restarts cooling when necessary, ensuring temperature reliability while maintaining noise reduction benefits.
Solution Approach 2:
The system changes the temperature control parameters (setpoint and hysteresis width) depending on the operational mode. In low-noise mode, the temperature setpoint is relaxed and the hysteresis window is widened, allowing the generator to remain off longer. The control unit monitors temperature closely and adjusts parameters dynamically to balance noise reduction with temperature safety.
3Object-generated harmful factors
If the allowable temperature interval is widened for low-noise operation, then noise emission is reduced, but food safety risk increases
Solution Approach 1:
The control unit continuously monitors temperature and uses feedback control to ensure that even with a widened temperature interval, the temperature does not exceed safe limits for food preservation. The system automatically activates the refrigeration generator when temperature approaches critical thresholds, preventing food safety issues while allowing broader temperature ranges during normal low-noise operation.
Solution Approach 2:
The system performs pre-cooling to lower the temperature before low-noise mode begins, creating a temperature buffer. This preliminary action ensures that even when the temperature interval is widened and the generator is delayed, the temperature has sufficient headroom to remain within safe food preservation limits throughout the low-noise operation period.
Data Source
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AI summary
A refrigeration device, in particular a domestic refrigeration device, has a storage chamber, a cold generator which refrigerates the storage chamber, a temperature sensor for recording the temperature of the storage chamber, and a control unit which, in a thermostat operating mode (S1-S5), is designed to start the cold generator running (S2) when a first upper limit temperature (T+1) in the storage chamber is exceeded. The control unit can be temporarily switched into a low-noise operating mode (S7, S8) in which the operation of the cold generator is suspended even when the first upper limit temperature (T+1) has been exceeded.