Vehicle A/C Compressor Control During Deceleration Fuel Cutoff
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Solution Overview
Problem
Existing vehicle air-conditioner control systems face issues with inconsistent evaporator cooling power during deceleration fuel cutoff, leading to either insufficient or excessive cooling when the air conditioner is ON or OFF, due to the predetermined time Tup affecting the compressor running rate.
Innovation Solution
A vehicle air-conditioner control system that adjusts the compressor running rate during deceleration fuel cutoff, increasing the rate before fuel supply recovery when the air-conditioner is ON and decreasing it when the air-conditioner is ON, to maintain adequate evaporator cooling power and prevent freezing, by setting a predetermined period based on evaporator temperature limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor running rate is increased during deceleration fuel cutoff period with air-conditioner ON, then the evaporator cooling power is improved, but the risk of evaporator freezing increases
Solution Approach 1:
The control device increases the compressor running rate in advance during the deceleration fuel cutoff period with air-conditioner ON, before fuel supply recovery occurs. This preliminary action ensures that the evaporator maintains adequate cooling power and prevents freezing when fuel supply recovers and engine output increases
Solution Approach 2:
The compressor running rate is dynamically adjusted based on the fuel cutoff execution state and vehicle deceleration conditions. The control device increases the running rate during fuel cutoff period with air-conditioner ON, and decreases it at fuel supply recovery time, adapting to changing engine output conditions to maintain optimal evaporator temperature
2Loss of energy
If the compressor running rate is decreased at fuel supply recovery time, then fuel consumption is improved, but the evaporator cooling power becomes insufficient
Solution Approach 1:
The control device increases the compressor running rate in advance during the deceleration fuel cutoff period, building up sufficient cooling capacity before fuel supply recovery. This ensures that when the running rate is subsequently decreased to save fuel, the evaporator cooling power remains adequate due to the preliminary cooling action
Solution Approach 2:
The control device monitors the fuel cutoff execution state, vehicle speed, and air-conditioner operation status to dynamically adjust the compressor running rate. This feedback mechanism ensures optimal balance between fuel consumption and evaporator cooling power by adjusting the running rate based on actual operating conditions
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 solution ensures consistent evaporator cooling power and prevents freezing, maintaining effective air conditioning performance during deceleration fuel cutoff by optimizing compressor running rate adjustments based on evaporator temperature, thereby enhancing fuel efficiency and air conditioning capability.
Implementation Method 1
a compressor that intakes, compresses, and discharges a refrigerant
Implementation Method 2
a condenser that condenses the refrigerant discharged from the compressor
Implementation Method 3
an expansion valve that depressurizes the refrigerant condensed by the condenser
Implementation Method 4
an evaporator that performs heat exchange between open air and the refrigerant to vaporize the refrigerant
Implementation Method 5
an evaporator that performs heat exchange between open air and the refrigerant
Data Source
AI summary
A vehicle air conditioner control system has an air conditioning device has a compressor, a condenser, an expansion valve, and an evaporator, a compressor running rate control device, a deceleration fuel cutoff executing device, and a fuel supply recovery executing device that cancels cutoff of fuel supply and recovers fuel supply at a higher vehicle speed during vehicle deceleration fuel cutoff period with air-conditioner ON than during vehicle deceleration fuel cutoff period with air-conditioner OFF. The compressor running rate control device increases the compressor running rate for a predetermined period just before a fuel supply recovery time with air-condition ON during the deceleration fuel cutoff period more than during non-execution of the deceleration fuel cutoff, and subsequently decreases the compressor running rate at or just before the fuel supply recovery time with air-condition ON equal to or less than during non-practice of the deceleration fuel cutoff.