Variable Compressor Cooling for Start-Stop Vehicle Stops
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Solution Overview
Problem
In vehicles equipped with Start-Stop technology and variable displacement compressors, the existing systems maximize cooling during coasting, leading to increased engine load and fuel consumption when the vehicle stops, causing discomfort and reducing fuel economy improvements.
Innovation Solution
A vehicular air conditioning system that uses a controller to monitor vehicle speed and deceleration, adjusting the compressor stroke to optimize cooling during stops, maintaining a comfortable cabin temperature while minimizing engine restart time and reducing compressor power consumption by setting a target evaporator temperature based on Climate Thermal Load and deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor stroke is maximized during coasting to provide maximum cooling, then cooling effect is improved, but engine load and fuel consumption increase
Solution Approach 1:
The patent dynamically adjusts the compressor stroke parameter based on vehicle operating conditions. During coasting, instead of maintaining maximum stroke, the system optimizes the stroke to provide sufficient cooling while minimizing engine load. The controller modifies compressor operation parameters (stroke, duty cycle) according to thermal load, vehicle speed, and deceleration rate, thereby resolving the contradiction between cooling effect and fuel consumption.
2Temperature
If the compressor runs at high capacity during stops to maintain cabin temperature, then passenger comfort is improved, but engine restart time increases and fuel economy benefits are reduced
Solution Approach 1:
The system performs preliminary cooling action during the coasting phase before the vehicle comes to a complete stop. By anticipating the upcoming stop and providing enhanced cooling during deceleration, the evaporator and cabin are pre-cooled, allowing the engine to be shut off longer without compromising passenger comfort. This extends engine shutdown duration and preserves fuel economy benefits.
Solution Approach 2:
The controller continuously monitors thermal load, vehicle speed, and deceleration rate to dynamically adjust compressor operation. This feedback mechanism ensures optimal cooling is provided during coasting and stop phases, balancing cabin temperature maintenance with engine restart timing to maximize fuel efficiency.
3Quantity of substance
If the compressor stroke is increased during coasting to store cold in the evaporator, then cold storage capacity is improved, but engine load increases during deceleration
Solution Approach 1:
The system applies partial excessive cooling action during coasting by increasing compressor stroke beyond normal operating levels. This temporary excessive cooling builds up cold storage capacity in the evaporator, which then sustains cabin cooling during the stop period. The additional engine load during coasting is justified by the extended engine shutdown time achieved later.
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 optimizes cooling during vehicle stops, extending engine shutdown time, reducing fuel consumption, and preventing cabin temperature increases, thus enhancing passenger comfort and fuel efficiency.
Implementation Method 1
a variable displacement compressor having a variable stroke for generating a variable amount of cooling of the evaporator
Implementation Method 2
generating a variable amount of cooling of the evaporator
Data Source
AI summary
An air conditioning system for a start-stop vehicle employs a compressor with a variable displacement. A controller determines a normal Climate Thermal Load (CTL) value for controlling a variable stroke of the variable displacement compressor. A stop event is detected in response to a speed of the vehicle and the occurrence of a predetermined deceleration. During the stop event, the variable stroke is increased by an amount determined in response to the normal CTL value, the speed of the vehicle, and a measure of the deceleration of the vehicle so that an evaporator temperature within the air conditioning system is allowed to decrease while the vehicle is stopping so that climate comfort can be maintained even while the engine is shut off during the subsequent time that the vehicle is stopped.