Partial Air Inlet Control for HVAC Systems
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Solution Overview
Problem
Current vehicle HVAC systems face a trade-off between heating/cooling performance, fuel economy, and high voltage battery power consumption, as the selection between fresh air and recirculated air modes is often made without consideration for optimization, leading to compromised fuel efficiency and increased battery power usage, particularly in hybrid and electric vehicles.
Innovation Solution
A partial recirculation control strategy that progressively adjusts the air inlet door position based on cooling/heating loads and cabin fogging probability, allowing for selective selection between 100% recirculation and 100% fresh air modes to optimize fuel economy and battery power consumption while preventing cabin fogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If 100% fresh air mode is selected for HVAC system, then cabin air quality is improved, but cooling load increases and fuel economy deteriorates
Solution Approach 1:
The patent applies partial recirculation by allowing a portion (e.g., 20-80%) of fresh air to mix with recirculated air, rather than using 100% fresh air or 100% recirculated air. This partial action optimizes the balance between cabin air quality and cooling load, reducing fuel consumption while maintaining acceptable air quality standards.
Solution Approach 2:
The system dynamically changes the recirculation ratio parameter based on ambient temperature, humidity, and cabin conditions. By adjusting this parameter in real-time, the system optimizes the trade-off between fresh air intake (for air quality) and recirculation (for reduced cooling load and improved fuel economy).
2Ease of operation
If 100% fresh air mode is selected in hot weather, then cabin ventilation is improved, but cooling load and compressor power consumption increase
Solution Approach 1:
The patent implements partial recirculation where only a portion of the incoming air is fresh air, while the remainder is recirculated conditioned air. This reduces the cooling load on the compressor while still providing adequate ventilation, thereby reducing compressor power consumption during hot weather operation.
Solution Approach 2:
The system uses feedback from temperature sensors, humidity sensors, and occupancy detectors to dynamically adjust the recirculation ratio. This feedback mechanism ensures that ventilation requirements are met while minimizing unnecessary cooling load and compressor power consumption.
3Use of energy by moving object
If 100% recirculated air mode is selected, then fuel economy is improved, but cabin fogging risk increases
Solution Approach 1:
The patent prevents complete recirculation by maintaining a minimum proportion of fresh air (e.g., 20-80% fresh air ratio). This partial fresh air intake reduces moisture accumulation and condensation risk on interior surfaces, thereby preventing cabin fogging while still achieving fuel economy benefits through reduced cooling load.
Solution Approach 2:
The system proactively introduces fresh air in partial recirculation mode to prevent fogging conditions before they occur. By maintaining adequate fresh air intake, the system counteracts moisture buildup that would lead to condensation and fogging on windows and interior surfaces.
Data Source
AI summary
A system and method of selecting air intake between 100% fresh air mode and 100% recirculated air mode for optimum heating/cooling performance, fuel economy and/or high voltage (HV) battery power consumption is disclosed. The system and method includes a partial recirculation control strategy in which the air inlet door is moved progressively to any position by taking into account cooling/heating loads and cabin fogging probability. As cooling/heating loads increase the air inlet door moves toward 100% recirculation mode. As fogging probability increases the air inlet door moves toward 100% fresh air mode. By selectively choosing a position between 100% recirculation and 100% fresh air, fuel economy and/or HV battery power consumption is optimized without compromising passenger comfort or causing fogging on interior glass surfaces. In cooling applications the compressor load is minimized and air conditioning performance is improved due to the reduced evaporator cooling load. The direct result of this improvement is increased fuel economy in the case of the internal combustion vehicle, reduced engine on time in the case of the hybrid electric vehicle (due to reduced HV battery power consumption), and reduced HV battery power consumption in the case of the hybrid electric vehicle (HEV) and the electric vehicle (EV). In heating applications, as the heating load is reduced the fuel economy of the internal combustion (IC) engine will be improved, the engine on time is reduced in the case of the HEV, and HV battery power consumption is reduced in the case of the EV.