Vehicle HVAC Heater Valve Feedback Using Downstream Air Sensing
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Solution Overview
Problem
Existing HVAC systems for motor vehicles face challenges in easily controlling the temperature of air flowing into the vehicle interior due to mechanical hysteresis in interface devices and poor linearity in actuator commands.
Innovation Solution
The HVAC system incorporates a temperature sensor to detect the actual temperature of air flowing into the air treatment cavity, allowing the control unit to adjust the actuator's operation based on both the user's temperature command and the detected temperature data, thereby reducing mechanical hysteresis and improving linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical interface device (knob) with electrical potentiometer is used to control the actuator, then the system structure is simple, but mechanical hysteresis occurs and linearity in actuator command is poor
Solution Approach 1:
The patent replaces the electrical potentiometer (electrical system) with a temperature sensor that directly measures the actual air temperature. This substitution eliminates the mechanical hysteresis and linearity issues associated with potentiometers, as the temperature sensor provides direct feedback on the thermal state without mechanical intermediate components.
Solution Approach 2:
The patent implements a feedback control system where the temperature sensor continuously measures the actual air temperature and feeds this information back to the control unit. The control unit compares the actual temperature with the desired temperature and adjusts the actuator accordingly, creating a closed-loop system that improves temperature control accuracy and eliminates the open-loop limitations of potentiometer-based systems.
2Ease of manufacture
If a potentiometer is used to detect interface device position, then the system is simple to manufacture, but linearity in actuator command is poor
Solution Approach 1:
The patent substitutes the potentiometer-based electrical measurement system with a temperature sensor that directly measures the physical quantity of interest (air temperature). This replacement improves measurement precision by directly sensing temperature rather than inferring it from mechanical position, while the overall system remains manufacturable using standard automotive temperature sensing components.
Solution Approach 2:
The temperature sensor performs self-measurement of the air temperature, eliminating the need for mechanical position detection and subsequent calculation. The sensor directly provides accurate temperature data to the control unit, improving measurement precision without significantly increasing manufacturing complexity.
3Device complexity
If open-loop control based on interface device position is used, then the control system is simple, but temperature regulation precision is poor
Solution Approach 1:
The patent implements feedback control by continuously measuring the actual air temperature with a temperature sensor and using this information to adjust the actuator position. The control unit compares the measured temperature with the desired temperature and modifies the water flow control valve opening accordingly, creating a closed-loop system that significantly improves temperature regulation accuracy while maintaining reasonable system complexity.
Solution Approach 2:
The patent replaces the open-loop mechanical position-based control system with a closed-loop temperature-based control system. By substituting position detection with direct temperature measurement and using feedback control, the system achieves superior temperature regulation accuracy without excessive complexity.
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 enhances the ability to precisely control the temperature of air flowing into the vehicle interior, improving user satisfaction by reducing temperature regulation issues associated with mechanical hysteresis and poor linearity.
Implementation Method 1
a temperature sensor configured to detect temperature data representative of the temperature reached by the air flowing into said air treatment cavity downstream of said heater core
Implementation Method 2
The air treatment cavity contains a heater core which is part of the engine cooling circuit
Data Source
Figure 1
Figure 2
AI summary
The system (10) comprises a casing (12) configured to allow air to flow towards the vehicle (V) interior or cabin. An air treatment cavity (18) contains a heater core (208) of a cooling circuit (200). A control unit (22) is provided which is configured to control the temperature of the air. An interface device (24) provides the control unit (22) with a required temperature command (TR). An actuator (26) is configured to adjust, in a controlled way by the control unit (22), the opening of a flow control valve (210) situated upstream of the heater core (208). The system (10) further comprises a temperature sensor (28) configured to detect temperature data (TA) representative of the temperature reached by the air flowing into the air treatment cavity (18) downstream of the heater core (208). Besides as a function of the temperature command (TR), the control unit (22) is also configured to control the actuator (26) also as a function of the temperature data (TA).