Motor Vehicle Air Conditioning With Dynamic PTC Airflow Control
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Solution Overview
Problem
Conventional air conditioning systems for hybrid and electric vehicles face overheating issues with positive temperature coefficient (PTC) heaters due to inadequate control of the hot air path opening, leading to unnecessary air resistance and reduced cooling/heating efficiency when the PTC heater is turned off.
Innovation Solution
An air conditioning system with a control unit that actively adjusts the minimum opening degree of the hot air path based on the on/off condition of the PTC heater, preventing unnecessary opening and air introduction when the heater is off, and increasing the opening degree when overheating is likely to prevent thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the opening degree of the hot air path is sharply reduced to minimize cooling, then the cooling effect is improved, but the PTC heater overheats due to reduced air flow
Solution Approach 1:
The patent applies dynamics by making the minimum opening degree of the hot air path variable rather than fixed. The control unit dynamically adjusts the minimum opening degree based on the PTC heater's operating status - when the PTC heater is on, a larger minimum opening degree is maintained to prevent overheating, while when it is off, a smaller minimum opening degree is used to optimize cooling efficiency.
2Reliability
If a fixed minimum opening degree is maintained to prevent PTC heater overheating, then heater reliability is improved, but unnecessary air resistance occurs when the heater is turned off
Solution Approach 1:
The patent makes the minimum opening degree dynamic by linking it to the PTC heater's on/off status. When the heater is off, the minimum opening degree is reduced to minimize unnecessary air resistance and energy loss, while when the heater is on, the opening degree is increased to ensure adequate air flow and prevent overheating.
Solution Approach 2:
The patent changes the parameter of minimum opening degree based on the operational state of the PTC heater. By adjusting this parameter dynamically - larger opening when heater is on, smaller opening when heater is off - the system optimizes both heater protection and energy efficiency under different operating conditions.
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
Effectively prevents overheating of the PTC heater, reduces air resistance, and maintains efficient cooling and heating by dynamically controlling the hot air path opening in response to the PTC heater's on/off state and temperature conditions.
Implementation Method 1
The PTC heater 5 is a high-voltage heater, the heat generation amount of which is adjusted by the control of a pulse width modulation (PWM) duty ratio
Implementation Method 2
the heat exchange amount of the PTC heater 5 is reduced
Data Source
AI summary
An air conditioning system for motor vehicles includes a temperature door configured to adjust an opening degree of a hot air path, a PTC heater configured to heat an air introduced into the hot air path, and a control unit configured to control an opening position of the temperature door with respect to the hot air path and to secure a minimum opening degree of the hot air path, so that a minimum amount of air is blown toward the PTC heater regardless of the opening position of the temperature door. The control unit is configured to actively adjust the minimum opening degree of the hot air path depending on an on/off condition of the PTC heater.