Refrigerant Valve Timing Control to Reduce Compressor Start Torque

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Solution Overview

Problem

Existing compressor cooling systems in refrigerators suffer from efficiency losses due to non-optimal refrigerant flow rates through capillary tubes, which are influenced by varying evaporator and condenser pressures, leading to energy inefficiencies and increased start torque requirements.

Innovation Solution

Implementing a valve in the refrigerant path between the condenser and evaporator, controlled by a controller to optimize the opening and closing times based on external parameters such as ambient temperature and compressor speed, to match refrigerant flow with optimal system conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a valve is installed to stop refrigerant flow during compressor off-phase, then energy loss from refrigerant migration is reduced, but the compressor must start against a pressure difference between condenser and evaporator

Engineering Contradiction:

Improveenergy loss from refrigerant migrationVSAvoidstart torque requirement

Core Design Contradiction:

Loss of energyVSForce

Solution Approach 1:

The valve is opened a predetermined period before the compressor starts to equalize the pressure difference between condenser and evaporator, thereby reducing the required start torque. This preliminary action prevents the compressor from starting against a large pressure differential while still maintaining energy efficiency by closing the valve before the compressor off-phase begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The valve timing is made dynamic and adjustable based on system conditions. The controller can adjust the pre-opening duration and closing timing according to ambient temperature, compressor type, and system state, optimizing both energy efficiency and start torque requirements for different operating conditions.

Inventive Principle:

Principle #15Dynamics

2Force

If the valve is opened early to equalize pressure, then start torque is reduced, but refrigerant flow rate may not match optimal conditions during compressor on-phase

Engineering Contradiction:

Improvestart torqueVSAvoidrefrigerant flow rate optimization

Core Design Contradiction:

ForceVSProductivity

Solution Approach 1:

The valve is opened before compressor start to equalize pressure and reduce start torque, but closed before compressor off-phase begins to optimize refrigerant flow rates. This timing strategy ensures both easy compressor startup and optimal refrigerant flow during the compression cycle.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller uses feedback from pressure sensors and system state monitoring to dynamically adjust valve timing. By monitoring the actual pressure differential and system conditions, the controller optimizes the pre-opening duration and closing timing to simultaneously achieve low start torque and optimal refrigerant flow rates.

Inventive Principle:

Principle #23Feedback

3Device complexity

If valve timing is fixed, then control is simple, but energy efficiency cannot be optimized for varying ambient conditions

Engineering Contradiction:

Improvecontrol system complexityVSAvoidenergy efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system adjusts key parameters such as pre-opening duration, closing timing, and valve position based on varying ambient conditions and system state. This allows the system to optimize energy efficiency across different operating scenarios while maintaining manageable control complexity through parameter adjustment rather than structural complexity.

Inventive Principle:

Principle #35Parameter changes

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

Improves energy efficiency by aligning refrigerant flow with optimal conditions, reducing energy losses and minimizing start torque requirements, especially in systems with multiple evaporators.

Implementation Method 1

use a capillary tube to reduce the pressure of the refrigerant flowing from condenser to evaporator

Methodology Applied

Scientific EffectPressure drop: Pressure Drop

Implementation Method 2

Since nothing stops the vapor from flowing through the capillary tube during compressor off time, this will happen until the pressures are equalized

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentUS12578133B2Cooling system control

Publication Date: 2026.03.17 ELECTROLUX APPLIANCES

AI summary

A cooling system includes a compressor, a condenser, and an evaporator where a refrigerant is circulated, and a valve interconnected in the flow of the refrigerant from the condenser to the evaporator. The valve is configured to enter a first, open, state when the compressor is in an on-phase and to enter a second, closed, state when the compressor is in an off state by a controller. The controller controls the valve to operate in accordance with opening the valve at a first variable time period before the compressor is switched to an on-phase; where the first variable time period is set in response to an external parameter obtained by the controller, and/or closing the valve at a second variable time period before the compressor is switched to an off-phase, where the second variable time period is set in response to an external parameter obtained by the controller.