Heated Valve Guide Structure to Prevent Valve Rod Seizing
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Solution Overview
Problem
In internal combustion engines, high exhaust gas recirculation rates reduce NOx emissions but increase soot particle and water content, leading to contamination deposits between the valve rod and guide, causing sticking issues, especially at temperature changes, which requires heating to prevent jamming and maintain valve functionality.
Innovation Solution
The valve guide is partially reduced in outer diameter with a heating element arranged on the reduced area, allowing for press or transition fits with the housing, reducing friction and assembly complexity, and using thick-film heating for precise and efficient heat distribution, eliminating the need for additional electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve guide is heated to prevent contamination deposits, then the valve rod sticking is prevented, but the assembly complexity increases due to additional electrical connections required
Solution Approach 1:
The heating element is integrated directly into the valve guide structure, merging the heating function with the guiding function. This eliminates the need for separate heating components and their associated electrical connections, thereby maintaining reliability while reducing assembly complexity
Solution Approach 2:
The valve guide serves dual purposes: it guides the valve rod and simultaneously provides heating functionality through the integrated heating element. The valve guide essentially serves itself by incorporating the heating capability needed to prevent its own contamination, eliminating the need for external heating systems
2Reliability
If a heater is mounted between the housing bore and valve stem, then the valve stem is heated to prevent deposits, but the assembly becomes more complicated and damage risk increases
Solution Approach 1:
The heating element is extracted from the space between the housing bore and valve stem, and instead is integrated directly into the valve guide. This removes the problematic mounting location that caused assembly complications and damage risk, while preserving the heating function where it is most needed
3Ease of manufacture
If the valve guide outer diameter is reduced for heating element integration, then assembly is easier with less friction, but the structural strength may be compromised
Solution Approach 1:
The valve guide maintains its full outer diameter in the critical load-bearing regions where it contacts the housing bore, ensuring structural strength. The outer diameter is selectively reduced only in the specific area where the heating element needs to be integrated, providing local optimization without compromising overall strength
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 design prevents valve rod seizing due to contamination, ensures easier assembly, maintains standard production costs, and extends the service life of the valve device by effectively heating and evaporating deposits, thus preventing functional failures.
Implementation Method 1
a heating element (60) having at least one conductor track (62) which can be heated by the heating element
Implementation Method 2
The evaporated contaminants can then be flushed away with the exhaust gas flow, ultimately ensuring that the functionality of the EGR valve is not impaired
Implementation Method 3
the heating element is preferably formed by an electrical thick-film heater, which is applied to the outer surface and the reduced-diameter areas of the valve guide
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Valve devices, comprising: - a housing (15), which has an inlet (16) and an outlet (18); - a flow channel (19), which is formed between the inlet (16) and the outlet (18); - a valve element (38), by means of which a free cross section of the flow channel can be controlled; - a valve rod (30), which is connected to the valve element (38) and can be moved by means of an actuator (22); - a bore in the housing (15); and - a valve guide (40), which is fastened in the bore (50) and can be heated by means of a heating element (60, 61) having at least one conducting track (62), are known. In order to achieve simplified, quick and damage-free mounting of the valve guide (40) and to ensure good heating performance of the valve guide (40) to prevent locking of the valve rod (30) as a result of contaminants and freezing as a result of low temperatures, the valve guide (40) is reduced in its outer diameter at least in parts and the heating element (60, 61) is arranged in the region (46) of the valve guide (40) that is reduced in its outer diameter.