EVDC Cold-Start Delay Reduction via Iterative Valve Control

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Solution Overview

Problem

Variable displacement compressors in vehicle HVAC systems experience a significant delay in cooling performance after an extended period of shut-off due to refrigerant and oil mixture accumulation in the control chamber, leading to a perceptible delay in cooling airflow to the passenger cabin.

Innovation Solution

A method involving iterative alternation of the control current supplied to the electronic control valve between no control current and full control current during the cold-start procedure, with the controller determining the HVAC airflow temperature gradient from sensors to terminate the procedure when a predetermined temperature decrease is achieved, thereby reducing start-up delay.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the compressor is shut off for an extended period, then energy consumption is reduced, but refrigerant and oil mixture accumulates in the control chamber causing start-up delay

Engineering Contradiction:

Improveenergy consumptionVSAvoidstart-up delay

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The control method activates the electronic control valve before the compressor actually needs to cool, performing preliminary evacuation of refrigerant and oil mixture from the control chamber. This preliminary action prevents the accumulation problem before it occurs, allowing the compressor to start up immediately when needed without delay.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control method uses periodic activation of the electronic control valve during the shutdown period to intermittently evacuate the control chamber. This periodic action maintains the chamber in a ready state without requiring continuous operation, balancing energy savings with start-up readiness.

Inventive Principle:

Principle #19Periodic action

2Loss of time

If the electronic control valve operates continuously to evacuate the control chamber, then start-up delay is reduced, but energy consumption increases

Engineering Contradiction:

Improvestart-up delayVSAvoidenergy consumption

Core Design Contradiction:

Loss of timeVSLoss of energy

Solution Approach 1:

The electronic control valve is activated periodically rather than continuously during shutdown periods. This intermittent operation maintains the control chamber in a ready state for quick start-up while minimizing energy consumption during the off-period.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control valve performs preliminary evacuation actions before the compressor actually needs to operate, preparing the system in advance. This allows the system to be ready for immediate start-up without requiring continuous valve operation, thus reducing both start-up delay and energy consumption.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the compressor starts immediately after shut-off, then cooling performance is maintained, but refrigerant and oil mixture causes operational issues

Engineering Contradiction:

Improvecooling performanceVSAvoidoperational reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The electronic control valve performs preliminary evacuation of the control chamber before the compressor starts operating. This preliminary action removes the harmful refrigerant and oil mixture accumulation, ensuring that when the compressor starts immediately for optimal cooling performance, it does so without operational issues or reliability problems.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control method converts the potentially harmful effect of refrigerant and oil mixture accumulation into a manageable condition by using the electronic control valve to periodically evacuate the chamber. This transforms what would be a harmful accumulation into a controlled process that enables both immediate start-up and reliable operation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 method reduces the compressor start-up delay, enabling quicker provision of cooling airflow to the vehicle passenger cabin, enhancing user satisfaction by minimizing the time taken to achieve cooling performance.

Implementation Method 1

the control chamber 216 accumulates fluid (typically a liquid refrigerant and oil mixture) due to refrigerant migration into the relatively cooler compressor from the relatively warmer refrigerant subcomponents

Methodology Applied

Scientific EffectRefrigerant migration: Diffusion

Data Source

PatentUS10538146B2Reducing externally variable displacement compressor (EVDC) start-up delay

Publication Date: 2020.01.21 FORD GLOBAL TECH LLC

AI summary

An externally-controlled variable displacement compressor (EVDC) cold-start method is described including, during an EVDC cold-start procedure, iteratively alternating an amount of a control current supplied to an electronic control valve (ECV) associated with the EVDC between no control current and a full control current. Systems for implementing the described method are provided.