Heating device
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Solution Overview
Problem
Heating devices for vehicles with high on-board power supplies (48 V or above 100 V) face challenges in managing inrush currents when using plate-shaped PTC resistors, as they require costly voltage transformation to prevent excessive currents, and series connections increase manufacturing costs.
Innovation Solution
Electrical contact of PTC resistors at their narrow sides instead of the conventional front and back sides, with contact elements embedded in an isolating frame and using resilient contact elements like leaf springs or metal strips to maintain lower currents, allowing for parallel connection and efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If PTC resistors are connected in parallel to increase heating power, then heating performance is improved, but inrush currents become excessively high
Solution Approach 1:
Instead of connecting PTC resistors in parallel with conventional front-to-back contact, the patent inverts the contact configuration to side contacts. This geometric inversion fundamentally changes the current path and effective resistance characteristics, allowing parallel connection without excessive inrush current while maintaining heating power.
Solution Approach 2:
The patent changes the contact geometry parameter from face-to-face contact to side contact. This parameter change increases the effective path length and reduces the effective contact area, thereby increasing the effective resistance and limiting inrush current while maintaining the heating function.
2Object-generated harmful factors
If voltage transformation is used to reduce currents at high voltages, then current levels are acceptable, but manufacturing costs increase significantly
Solution Approach 1:
The patent extracts the voltage transformation function entirely from the system by using side-contact configuration. This extraction eliminates the need for expensive DC-DC converters or voltage transformation components, allowing direct connection to high-voltage power supplies (48V, 100V, or higher) without additional cost.
Solution Approach 2:
The patent replaces expensive voltage transformation components with a simple geometric configuration change. The side-contact PTC resistor structure itself becomes the current-limiting mechanism, eliminating the need for additional expensive components.
3Object-generated harmful factors
If NTC resistors are connected in series with PTC resistors to reduce currents, then inrush currents are limited, but manufacturing costs increase significantly
Solution Approach 1:
The patent extracts the current-limiting function from a separate NTC resistor component and integrates it into the PTC resistor's geometric configuration. The side-contact arrangement itself provides the current-limiting effect, eliminating the need for additional NTC resistor components and their associated assembly complexity.
4Device complexity
If PTC resistors are contacted on front and back sides conventionally, then electrical contact is simple, but electrical resistance is too low causing high currents
Solution Approach 1:
The patent inverts the conventional contact configuration from front-to-back contact to side contact. This inversion increases the current path length and reduces the effective contact area, thereby increasing the electrical resistance to acceptable levels while maintaining manufacturing simplicity.
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 configuration maintains acceptable currents at high voltages while reducing manufacturing costs and enabling an economical solution for heating devices with PTC resistors, allowing for efficient heating performance in vehicles with higher voltage power supplies.
Implementation Method 1
plate-shaped ceramic PTC resistors for generating heat because PTC resistors are inherently protected from overheating as they show a marked increase of electrical resistance at a critical temperature
Implementation Method 2
the contact elements press resiliently against the PTC resistor(s). For example, the contact elements may form springs that press against the PTC resistors. The contact elements may be provided as leaf springs, especially as bent leaf springs
Implementation Method 3
The bent off rim section acts like a bent leaf spring. Spring forces can be used to clamp the PTC resistor(s) in the frame
Data Source
AI summary
Disclosed is a heating device comprising a plate-shaped ceramic PTC resistor having a thickness, a front side, a back side and narrow sides, wherein the distance from the front side to the back side equals the thickness, and a first contact element and a second contact element, which are electrically contacting the PTC resistor. The PTC resistor is electrically contacted by the contact elements on opposite narrow sides.