Vehicle HVAC Solar Load Control for Smooth Cabin Temperature

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Solution Overview

Problem

Existing HVAC systems in vehicles fail to effectively account for solar load, leading to unexpected temperature adjustments that can be unpleasant for occupants, particularly when the cabin temperature is close to the user-set temperature.

Innovation Solution

A vehicle HVAC system that incorporates solar sensors and temperature sensors to determine a radiation temperature, adjusting the target discharge temperature and airflow using a solar aggressiveness factor that scales down solar offsets based on cabin conditions, including ambient temperature, windshield temperature, and solar heat load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the HVAC system adjusts discharge temperature to compensate for solar load, then the cabin temperature control responds to solar heating, but abrupt temperature adjustments occur that are unpleasant for occupants

Engineering Contradiction:

Improveresponse to solar loadVSAvoidoccupant comfort

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The solar aggressiveness factor dynamically adjusts the solar offset based on real-time cabin conditions (cabin temperature, user-set temperature, solar heat load). When cabin temperature is close to user-set temperature, the factor reduces the solar offset to prevent abrupt adjustments. When cabin temperature deviates significantly, the factor increases the solar offset to provide stronger compensation. This dynamic adjustment resolves the contradiction by making the system adaptable to solar load while maintaining occupant comfort.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of solar offset magnitude based on the calculated solar aggressiveness factor. The factor is determined by comparing cabin temperature to user-set temperature and scaling the solar offset accordingly. This parameter change allows the system to respond effectively to solar load while avoiding unpleasant abrupt temperature adjustments when the cabin is already close to the desired temperature.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the HVAC system uses fixed solar offset for temperature adjustment, then the system structure is simple, but the system cannot adapt to varying cabin conditions and solar intensity

Engineering Contradiction:

Improvecontrol algorithmVSAvoidresponse to solar conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The solar aggressiveness factor changes the solar offset parameter based on multiple inputs including cabin temperature, user-set temperature, and solar heat load. This parameter adaptation enables the system to respond to varying solar conditions and cabin states without requiring a completely complex control architecture. The factor serves as a simple yet effective adaptation mechanism.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system uses feedback from temperature sensors and solar sensors to calculate the solar aggressiveness factor. The cabin temperature and user-set temperature difference feeds into the factor calculation, which then adjusts the solar offset. This feedback loop provides adaptability to varying conditions while maintaining a relatively simple control structure based on sensor inputs and calculated adjustments.

Inventive Principle:

Principle #23Feedback

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 provides smoother temperature adjustments by reducing abrupt changes in response to solar heat, enhancing occupant comfort by aligning cabin temperature with user-set temperature more effectively.

Implementation Method 1

one or more solar sensors configured to sense solar radiation on the cabin

Methodology Applied

Scientific EffectSolar radiation detection: Absorption (EM radiation)

Implementation Method 2

one or more temperature sensors configured to sense air within the cabin

Methodology Applied

Scientific EffectThermal detection: Temperature Gradient

Implementation Method 3

determine a radiation temperature corresponding to radiative heat transfer into the cabin

Methodology Applied

Scientific EffectRadiative heat transfer: Thermal Radiation

Data Source

PatentUS20250340098A1Solar aggressiveness factor for determining airflow and discharge temperature of a vehicle HVAC system

Publication Date: 2025.11.06 RIVIAN HOLDINGS LLC

AI summary

A vehicle includes a system configured to supply air to a cabin of a vehicle at a target discharge temperature. One or more solar sensors configured to sense a solar radiation on the cabin and one or more temperature sensors configured to sense air within the cabin. A controller is configured to receive a user set temperature, obtain a solar heat load from one or more outputs of the one or more solar sensors, and obtain a feedback temperature from one or more outputs of the one or more temperature sensors. The controller is further configured to determine a radiation temperature corresponding to radiative heat transfer into the cabin, the radiation temperature being a function of the feedback temperature and the solar heat load. The controller may then set the target discharge temperature according to the user set temperature, the feedback temperature, and the radiation temperature.