Vehicle HVAC Compressor Switching for Engine-Off Cabin Cooling
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Solution Overview
Problem
Existing vehicle HVAC systems face challenges in maintaining a comfortable environment for drivers and passengers, especially when the engine is off, and there is a need for more efficient methods to manage engine-driven and electrically-driven compressors to optimize thermal load and fuel consumption.
Innovation Solution
A climate system with a primary air conditioning system and an auxiliary unit, including a second compressor powered by an electric motor, is controlled by a controller that automatically activates or deactivates the compressors based on thermal load thresholds, using engine power efficiently to maintain desired compartment temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine-driven compressor is used to cool the vehicle compartment, then the cooling capability is sufficient, but the fuel consumption increases
Solution Approach 1:
The air conditioning system is segmented into two independent compressors: an engine-driven compressor and an electrically-driven compressor. This segmentation allows the system to select the most appropriate compressor based on thermal load requirements, enabling the electrically-driven compressor to handle smaller loads without engaging the engine, thereby reducing fuel consumption while maintaining sufficient cooling capability when needed
Solution Approach 2:
The system dynamically switches between different compressor configurations based on real-time thermal load conditions. The controller monitors the thermal load and automatically activates or deactivates compressors to optimize performance. This dynamic adaptation allows the system to use the electrically-driven compressor for low-to-moderate loads and engage the engine-driven compressor only when high cooling power is required, thus resolving the contradiction between cooling capability and fuel consumption
2Use of energy by moving object
If the engine is turned off to reduce fuel consumption, then fuel efficiency improves, but the climate system cannot maintain comfortable temperatures
Solution Approach 1:
The system replaces the traditional mechanical coupling where the engine must run to power the air conditioning compressor with an electrically-driven compressor that operates independently. This substitution allows the climate system to function without the engine being running, enabling the engine to be turned off for fuel savings while the electrically-driven compressor maintains comfortable temperatures through electrical power
3Power
If both compressors are activated to handle high thermal load, then the cooling performance is maximized, but the system complexity increases
Solution Approach 1:
The controller implements a feedback mechanism that continuously monitors the thermal load of the vehicle compartment and automatically adjusts compressor operation accordingly. This feedback control simplifies the user interface while managing the complexity of dual-compressor coordination internally, allowing both compressors to operate simultaneously when high cooling performance is needed without requiring complex user intervention
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
The system effectively maintains comfortable vehicle compartment temperatures by optimizing compressor usage, reducing fuel consumption, and allowing pre-conditioning before entry, enhancing user satisfaction and system efficiency.
Implementation Method 1
a first compressor driven by an engine of the vehicle to compress a refrigerant
Implementation Method 2
the first compressor... to compress the refrigerant for cooling the compartment
Implementation Method 3
a second compressor fluidly coupled to the first compressor and disposed in series with the condenser and the evaporator, the second compressor being powered by an electric motor to compress the refrigerant
Implementation Method 4
the second compressor... to compress the refrigerant for cooling the compartment
Implementation Method 5
fluidly coupled in series with a condenser and an evaporator
Implementation Method 6
an evaporator thermally coupled to the compartment to cool the compartment
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Disclosed are climate systems for vehicles and methods for controlling the climate systems. In some implementations, a climate system (101) includes: a temperature sensor (106) configured to measure a temperature within a compartment of a vehicle; a user interface (108) configured to receive a desired temperature from a user; a first compressor (102) powered by an engine (110) of the vehicle to compress a refrigerant; a second compressor (104) driven by an electric motor (112) to compress the refrigerant; and a controller (124) electrically coupled to the first compressor and the second compressor. The controller configured to: calculate a thermal load of the compartment based on a difference between a desired temperature and a measured temperature; and, based on the calculated load, selectively activate: the engine (110), the first compressor (102), and/or the second compressor (104).