Graphite Ring Seal for Cooking Appliance Light Guide Vapor Containment
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Solution Overview
Problem
Existing sealing arrangements in cooking appliances, such as ovens and microwave ovens, fail to effectively prevent vapor passage through lighting openings, particularly with the increasing use of temperature-sensitive LED light sources and light guides that require sealing against vapors while maintaining thermal compatibility.
Innovation Solution
A sealing arrangement featuring a housing part with a circular-cylindrical base body, an annular groove, and a graphite sealing ring that matches the thermal expansion coefficient of the light-conducting rod, ensuring a tight seal by expanding to maintain contact and prevent vapor leakage, with a retaining clip for secure mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a sealing arrangement is provided for a lighting opening in the cooking chamber wall, then the cooking chamber can be illuminated, but cooking fumes can escape through the lighting opening into the appliance compartment
Solution Approach 1:
The sealing arrangement is divided into multiple functional components: a housing part with collar, a first seal (ring seal) for sealing against the cooking chamber wall, a second seal (graphite seal) for sealing against the light guide rod, and retaining elements. This segmentation allows each component to address specific sealing requirements - the first seal prevents vapor escape at the wall interface while the second seal maintains the light guide rod sealing, thus preventing fume leakage while preserving illumination functionality.
Solution Approach 2:
The housing part with collar acts as an intermediary structure between the cooking chamber wall and the light guide rod. It provides mounting recesses that receive the light guide rod and positions the seals at appropriate locations. The collar specifically serves as an intermediary element that the first seal seals against, creating a vapor-tight barrier while allowing the light guide rod to pass through for illumination purposes.
2Temperature
If LED light sources are positioned far away from the heated cooking chamber using light guides, then the temperature-sensitive LED light sources are protected, but the sealing arrangement must maintain thermal compatibility with the light guide material
Solution Approach 1:
The second seal is specifically designed as a graphite ring whose coefficient of thermal expansion is matched to that of the light guide rod (glass or plastic). This parameter matching ensures that both materials expand and contract at similar rates during heating and cooling cycles, maintaining consistent sealing contact. This resolves the thermal compatibility requirement while allowing the light guide to effectively transmit illumination from temperature-sensitive LEDs positioned in the appliance compartment away from the heated cooking chamber.
3Adaptability or versatility
If a sealing ring is made to match the thermal expansion coefficient of the light guide rod, then thermal compatibility is maintained, but the sealing ring must expand to maintain contact under temperature variations
Solution Approach 1:
The graphite ring seal is specifically selected and dimensioned to match the thermal expansion characteristics of the light guide rod material. As the assembly undergoes temperature variations during cooking operations, both the graphite seal and the light guide rod expand and contract at matched rates, maintaining consistent sealing contact. This thermal expansion matching ensures reliable sealing performance across the operating temperature range while preserving thermal compatibility between dissimilar materials.
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 provides a reliable vapor-tight seal that maintains thermal compatibility with LED light sources, ensuring effective prevention of vapor passage and maintaining the integrity of the cooking environment.
Implementation Method 1
A particularly preferred embodiment of the invention is characterized in that the sealing ring (16) is made of graphite and that the sealing ring (16) and the light guide rod have a nearly identical coefficient of thermal expansion
Implementation Method 2
The collar (13) is positioned against the cooking chamber wall (21) on the cooking chamber side, so that the ring seal (15) seals against the collar (13) on one side and against the cooking chamber wall (21) on the other
Implementation Method 3
If the frictional connection between graphite and a light guide rod, especially one made of glass, proves to be extremely low, the sealing ring's tightness against the light guide rod can also be achieved
Data Source
Figure 1
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AI summary
Described and illustrated is a sealing arrangement for a cooking appliance such as an oven, steam cooker or microwave for sealing an opening in the cooking chamber wall, which serves as a passage for a lighting element for the cooking chamber, in particular a glass rod with a substantially circular cylindrical shape, with a housing part which is sealed against the cooking chamber wall with a first seal and has a receptacle for a second seal which seals the housing part against the lighting element, with retaining parts which arrange the housing part on the cooking chamber wall, wherein the second seal is a graphite ring, within whose annular space the lighting element can be arranged.