Slide Valve With Steel-Graphite Sliding Pair
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Solution Overview
Problem
Existing slide valves in waste heat recovery systems of combustion engines face challenges with chemical resistance, temperature stability, and wear resistance, especially when operating with aggressive working media at high temperatures.
Innovation Solution
The slide valve employs a material combination of steel-graphite or ceramic-graphite for the sliding pairs, with optional coatings like Ti(C,N)+MoS2, and uses a graphite bushing for the valve tube to enhance chemical resistance, temperature stability, and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used for the sliding pair, then the slide valve can be manufactured with standard materials, but the chemical resistance, temperature stability, and wear resistance are insufficient for aggressive working media at high temperatures
Solution Approach 1:
The patent applies composite materials by combining graphite with metal coatings (such as titanium carbide, nickel, or chromium) to create a sliding pair material that exhibits superior chemical resistance, temperature stability, and wear resistance. The graphite provides self-lubrication and chemical inertness, while the metal coating enhances mechanical strength and resistance to aggressive working media, resolving the contradiction between reliability and ease of manufacture.
Solution Approach 2:
The patent changes the material parameters of the sliding pair by selecting graphite-based materials with specific physical and chemical properties. The graphite material is chosen for its high temperature stability, chemical resistance to aggressive working media like ethanol or cyclopentane, and low friction coefficient. This parameter change enables the slide valve to operate reliably in harsh conditions without requiring complex manufacturing processes.
2Reliability
If the sliding pair uses high-performance material combinations like steel-graphite or ceramic-graphite, then chemical resistance and temperature stability improve, but friction and wear characteristics may worsen without proper surface treatment
Solution Approach 1:
The patent applies local quality by providing different surface treatments to different regions or aspects of the sliding pair. The graphite material is coated with specific metal layers (such as titanium carbide for hardness and nickel or chromium for corrosion resistance) to create localized zones with optimized properties. This ensures that the surface in contact with the working medium has low friction and high resistance, while maintaining the overall temperature stability of the graphite substrate.
3Ease of manufacture
If the valve tube is produced as an integrated component, then manufacturing is simpler, but complex flow geometries and optimized tribological conditions cannot be achieved
Solution Approach 1:
The patent applies segmentation by dividing the valve into separate components: the valve body and the valve tube. The valve tube can be produced separately with optimized flow geometries and internal passages, then assembled into the valve body. This segmentation allows for complex flow patterns and optimized tribological conditions at the slide seat without compromising the overall manufacturing simplicity, as each component can be manufactured using standard processes.
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 slide valve that is highly resistant to chemicals and wear, capable of operating at high temperatures, and effectively manages mass flow in waste heat recovery systems, particularly with aggressive working media like ethanol or cyclopentane, ensuring reliable performance.
Implementation Method 1
the steel is coated with a Ti(C,N)+MoS2 coating, preferably with Tribobond 62. By virtue of this coating, the sliding pair has particularly low friction
Implementation Method 2
the sliding pair has the material combination steel-graphite or the material combination ceramic-graphite
Data Source
AI summary
Slide valve (1), in particular for a waste heat recovery system of a combustion engine, having a valve housing (4), wherein an inlet passage (5) and an outlet passage (6) are formed in the valve housing (4). A substantially cylindrical slide (3) is guided in a longitudinally movable manner in a guide bore (20) in the valve housing (4), wherein the guide bore (20) can be connected hydraulically to the inlet passage (5) and to the outlet passage (6). A closing body (35, 35a) is arranged on the slide (3), wherein a slide seat (75, 75a) is formed between the guide bore (20) and the closing body (35, 35a). The guide bore (20) and the sliding body (35, 35a) form a sliding pair, wherein the sliding pair has the material combination steel-graphite or the material combination ceramic-graphite.