Seat Heater Control Unit Voltage Detection Circuit
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Solution Overview
Problem
Conventional seat heater devices are prone to abnormal heat generation due to liquid ingress into the manually-operated switch, which can cause insulation failure and reduce the drive voltage, leading to increased internal resistance and potential overheating of the switching element.
Innovation Solution
Incorporation of a low-voltage detecting means within the seat heater device that compares the detected drive voltage with a predetermined value, using a comparator and zener diode for enhanced accuracy, to determine if a liquid has entered the switch and prevent energization of the switching element, thereby avoiding abnormal heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manually-operated switch is used to control the heater, then the seat heater device is simple to operate, but liquid may enter the switch causing insulation failure and abnormal heat generation
Solution Approach 1:
The patent introduces a control unit as an intermediary between the manual switch and the heater. The control unit monitors voltage to detect liquid ingress and prevents direct activation of the heater, thereby protecting the electronic circuit while maintaining manual operation capability.
Solution Approach 2:
The control unit continuously monitors the voltage across the manual switch and provides feedback to determine whether the switch is properly activated. When voltage indicates liquid ingress (insulation failure), the system feedback prevents heater activation, avoiding abnormal heat generation.
2Productivity
If the switching element is activated despite low voltage detection, then the heater can still function, but the internal resistance increases causing abnormal heat generation
Solution Approach 1:
The control unit performs preliminary detection of voltage levels before activating the heater. When low voltage (indicating liquid ingress) is detected, the system takes preliminary protective action by preventing switching element activation, thereby avoiding the harmful effect of abnormal heat generation before it can occur.
Solution Approach 2:
The patent converts the harmful effect of liquid ingress (which causes low voltage) into a beneficial detection mechanism. The voltage drop, normally a harmful symptom, becomes a useful signal that triggers protective action, preventing abnormal heat generation while maintaining system functionality under normal 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
The solution effectively prevents abnormal heat generation by turning off the switching element when a liquid is detected, maintaining safe operating conditions and ensuring the seat heater functions correctly without overheating.
Implementation Method 1
a low-voltage detecting means for detecting the drive voltage
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A seat heater device initiates power supply upon operation of a switch by a seat occupant within a vehicle interior and includes a heater for warming installed in a seat within the vehicle interior and a control unit for controlling energization of the heater for warming. The control unit includes a low-voltage detecting means for detecting whether an input voltage is a regular drive voltage value of the control unit or a voltage value lower than a predetermined voltage value and a switching element that is turned on when the low-voltage detecting means detects the regular drive voltage value of the control unit and turned off when the low-voltage detecting means detects a voltage value lower than the predetermined voltage value. This configuration can avoid heat generation of the switching element even if a leakage occurs in an electronic circuit within the switch due to, for example, insulation failure.