Refrigerator Compressor Two-Stage Motor Start-Up to Reduce Leakage
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Solution Overview
Problem
Household refrigeration appliances face challenges in efficiently starting the compressor during cooling phases, leading to inefficient refrigerant compression and potential refrigerant leakage due to dynamic forces not being effective during initial rotor rotation.
Innovation Solution
The method involves operating the electric motor at a slow start-up speed, up to 5% of the target speed, to move the piston past the top dead center and then increasing to at least 800 revolutions per minute to compress refrigerant effectively, while ensuring the rotor rotates in a predetermined direction to manage refrigerant flow and compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric motor is started at full target speed (at least 800 rpm) during cooling phases, then refrigerant compression efficiency is improved, but starting torque requirements increase causing potential refrigerant leakage and reduced reliability
Solution Approach 1:
The patent applies dynamic speed control by transitioning the electric motor through different operational phases: initially rotating at a reduced speed (maximum 5% of target speed) to move the piston past top dead center, then progressively increasing to the full target speed of at least 800 rpm for effective refrigerant compression. This dynamic adjustment of motor speed resolves the contradiction by adapting the starting characteristics to reduce torque demands while maintaining compression efficiency.
Solution Approach 2:
The patent implements preliminary action by first rotating the piston to a predetermined position (past top dead center) before initiating full-speed refrigerant compression. This preliminary movement prepares the compressor chamber for efficient compression operation, ensuring that when full speed is reached, the piston is positioned optimally to prevent refrigerant leakage and maximize compression effectiveness.
2Object-generated harmful factors
If the electric motor is operated at reduced starting speed (maximum 5% of target speed), then starting torque is reduced preventing refrigerant leakage, but time to reach effective compression speed increases
Solution Approach 1:
The patent employs periodic action through a two-stage starting sequence: first a low-speed phase (maximum 5% of target speed) to position the piston and prevent leakage, then a transition to full-speed operation (at least 800 rpm) for effective compression. This periodic progression through different speed phases minimizes harmful refrigerant leakage during the critical start-up period while rapidly achieving productive compression speed, thereby reducing overall start-up time losses.
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 approach improves compressor start-up efficiency by initially reducing the starting torque and preventing refrigerant leakage, allowing for effective refrigerant compression and maintaining the coolable interior space, enhancing the appliance's operational reliability and energy efficiency.
Implementation Method 1
The electric motor comprises a stator and a rotor rotatably mounted with respect to the stator and coupled to the piston via the crankshaft
Data Source
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Figure 3~4b
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AI summary
The invention relates to a household refrigeration appliance (1) and a method for operating a household refrigeration appliance (1). The household refrigeration appliance (1) comprises a thermally insulated body (10) with an inner container (2) that defines a coolable interior space (3) intended for storing food, a refrigerant circuit (20) for cooling the coolable interior space (3) with a refrigerant and with a compressor (21), an electric drive (40) with an electric motor (36), and an electronic control device (8). The compressor (21) comprises a compressor chamber (31) with an inlet (32) and with an outlet (33), a piston (34) slidably mounted within the compressor chamber (31), a crankshaft (35), and the electric motor (36) of the electric drive (40).The electric motor (36) comprises a stator (37) and a rotor (38) rotatably mounted relative to the stator (37) and coupled to the piston (34) via the crankshaft (35). The domestic refrigeration appliance (1), in particular its electronic control device (8), is configured to operate the electric motor (36) at a set speed of at least 800 revolutions per minute during cooling phases of the domestic refrigeration appliance (1) in order to move the piston (34) back and forth via the crankshaft (35) between a top dead center, at which the volume (39) enclosed by the compressor chamber (31) and the piston (34) for compressing the refrigerant is minimal, and a bottom dead center, at which the volume (39) is maximal. Between cooling phases, the rotor (38) of the electric motor (36) is stationary during the compressor's (31) idle phases.