Threaded Side Plate Retention for Rotary Engine Thermal Sealing
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Solution Overview
Problem
The end walls of rotary engines, such as Wankel engines, face high pressure and thermal loads while also serving as the running surface for rotor seals, leading to issues like wear, thermal stress, and potential sealing failures due to differential thermal expansion and complex assembly that complicates design and increases oil consumption.
Innovation Solution
A side housing design for rotary engines featuring a side plate secured to the side wall via a threaded engagement between protrusions and nuts, allowing for uniform retention and minimizing thermal stress through axial locking and radial gaps, while using hard coatings on the side plates to enhance wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the end walls are made robust to withstand high pressure and thermal loads, then strength and durability are improved, but the complexity of assembly increases and oil consumption rises
Solution Approach 1:
The end wall assembly is segmented into multiple components: the side plate (16), nut (117), and retaining member (119). This allows the robust structure to be achieved through coordinated assembly of simpler parts rather than a single complex component, resolving the contradiction between strength and assembly complexity.
Solution Approach 2:
The retaining member (119) is pre-installed in the annular recess (14M) of the side wall (14) before the nut (117) is secured. This preliminary action simplifies the overall assembly process by preparing the retention mechanism in advance, reducing the complexity of the final assembly step while maintaining structural integrity.
2Reliability
If hard coatings are applied to the side plates to reduce wear, then wear resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
Hard coatings (50) are applied selectively to specific surfaces of the side plate (16) that require enhanced wear resistance, such as the rotor-engaging face (16A). This localized coating approach provides wear protection where needed while minimizing the overall manufacturing complexity and cost compared to coating the entire component.
3Stability of the object's composition
If the side plate is tightly secured to the side wall to minimize thermal stress, then thermal stability is improved, but differential thermal expansion is restricted leading to potential sealing failures
Solution Approach 1:
The threaded engagement between the nut (117) and side plate (16) allows for controlled adjustment of the clamping force and axial position. This parameter adjustment capability enables the system to accommodate differential thermal expansion between components while maintaining sufficient retention to minimize thermal stress, thus preserving both thermal stability and sealing reliability.
Solution Approach 2:
The retaining mechanism using nut and threaded protrusion provides a dynamic retention system that can adapt to thermal expansion and contraction during engine operation. Unlike rigid fixed connections, this threaded system allows for controlled movement and stress distribution, maintaining sealing effectiveness under varying thermal conditions.
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 design improves wear resistance, reduces oil consumption, and minimizes thermal stress by allowing for uniform retention and controlled thermal expansion, enhancing the durability and efficiency of the rotary engine's sealing mechanism.
Implementation Method 1
the side plate secured to the side wall via a threaded engagement between the first threads of the side plate and second threads defined by the nut
Implementation Method 2
the side plate is made of aluminum, the rotor-engaging side being coated with a coating, such as a hard coating (i.e. harder than aluminium), such as silicon carbide, aluminum nitride, chromium carbide, tungsten carbide
Data Source
Figure 1
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Figure 4~5
AI summary
A side housing (111) for a rotary internal combustion engine, has: a side wall (14); a side plate (116) having a rotor-engaging side facing away from the side wall (14) and a back side (116B) opposite the rotor-engaging side and facing the side wall (14), the side plate (116) defining first threads (1160) located on the back side (116B), the first threads (116D) extending circumferentially around a central axis of the side plate (116); and a nut (117) rotatable relative to the side wall (14) about the central axis of the side plate (116) and axially locked to the side wall (14) relative to the central axis, the side plate (116) secured to the side wall (14) via a threaded engagement between the first threads (116D) of the side plate and second threads (117B) defined by the nut (117).