Valve Sealing Body Thermal Coating for Heat Dissipation
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Solution Overview
Problem
Sealing bodies of gas-exchange valves in internal combustion engines face challenges in achieving uniform heat distribution and are prone to high temperature gradients, which can lead to stress and wear due to conventional heat management methods.
Innovation Solution
A metallic covering with high heat conductivity is applied using thermal spraying methods, such as cold gas spraying, directly onto the base material without an intermediate insulation layer, allowing for efficient heat dissipation from the valve disc edge to the valve seat and body, ensuring uniform heating and minimizing wear at contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an insulation material is applied on the exterior of the base material in conventional sealing bodies, then thermal insulation is provided, but high temperature gradients and stress arise due to poor heat dissipation
Solution Approach 1:
The patent changes the thermal conductivity parameter of the sealing body surface by applying a metallic coating with high heat conductivity (such as copper, aluminum, or their alloys) onto the base material. This parameter change enables efficient heat dissipation from the hot gas-exposed regions through the coating and into the valve seat and cooling channels, creating uniform heat distribution and reducing temperature gradient stress.
Solution Approach 2:
The patent employs a composite structure consisting of a base material (such as cast iron or steel) combined with a metallic heat-conducting coating layer. This composite material approach combines the advantages of both materials: the base material provides structural strength and wear resistance, while the metallic coating provides high thermal conductivity for uniform heat distribution and stress reduction.
2Temperature
If a metallic covering with high heat conductivity is applied directly onto the base material without insulation layer, then uniform heat distribution is achieved, but wear resistance at contact points may be reduced
Solution Approach 1:
The patent applies the metallic heat-conducting coating selectively to specific regions of the sealing body, particularly to the valve disc surface exposed to hot gases and the regions adjacent to cooling channels. The coating thickness and material composition can vary locally to optimize both heat dissipation in hot zones and wear resistance at contact points with the valve seat.
Solution Approach 2:
The sealing body is divided into functional zones: the base material provides structural support and wear resistance at contact points, while the metallic coating is applied to heat-exposed regions for thermal management. This segmentation allows each zone to perform its primary function optimally without compromising the other.
3Ease of manufacture
If conventional surface coating methods are used, then coating application is simple, but the coating may have high porosity, cracks, and poor adhesion to the base material
Solution Approach 1:
The patent replaces conventional mechanical surface coating methods with thermal spraying technology. This substitution uses thermal energy to melt or partially melt the coating material and propel it onto the base material at high velocity, creating a dense, well-adhered coating with minimal porosity and no cracks, thereby achieving superior coating quality.
Solution Approach 2:
The thermal spraying process utilizes controlled parameter changes including spray particle temperature, velocity, and impact conditions to optimize coating formation. By adjusting these parameters, the process achieves low porosity, strong adhesion to the base material, and a homogeneous microstructure without the defects associated with conventional coating methods.
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 approach provides uniform heat distribution and reduces stress on the sealing body, enhancing its operational performance and longevity by effectively managing high component temperatures without excessive wear at critical contact areas.
Implementation Method 1
the second material, which conducts heat well, can dissipate the heat both in the edge region of a valve disc of the sealing body as well as from this edge region into a valve seat and into a valve body itself
Implementation Method 2
Conventional surface coating methods are subsumed under a thermal spraying method in which filler materials, the so-called spray adjunct, that are fused, vitrified, or melted in a gas flow within or outside a spray burner are accelerated in the form of spray particles and are thrown onto the surface of the material to be coated
Implementation Method 3
In cold gas spraying, a coating material in powder form is applied onto the carrier material (substrate) with a very high velocity for which a process gas, which is heated to a few hundred degrees ° C., is accelerated to supersonic velocity by expansion in a Laval nozzle
Data Source
AI summary
A moveable valve sealing body, especially a valve sealing body of a gas exchange valve of an internal combustion engine, exposed to hot gases and comprising a sealing area that can be applied to a valve seat ring, enabling good heat dissipation outside an oil-lubricated guiding means connected to the sealing body. For this purpose, such a sealing body is characterized in that at least one surface region of the sealing body, which region being exposed to the hot gases, up to maximally directly on the sealing region of this sealing body, is composed respectively of at least one first and one second material (1, 2), wherein the second material (2) overlaps the first material (1) in an externally heat-conducting manner and furthermore has a greater heat conductivity than the first material (1). The second material (2) is applied by means of a thermal spraying method.