Decoupling Nut Integrates Washer for Exhaust Manifold Thermal Management

The patent combines the sliding disc and nut into a single integrated component called a 'decoupling nut'. The nut body incorporates an integrated sliding surface that provides the thermal decoupling function previously requiring a separate sliding disc. This merging eliminates the need for separate components and assembly steps, reducing assembly costs while maintaining the thermal decoupling effectiveness between the exhaust manifold and engine block.

The patent applies a self-locking thread profile specifically to the internal thread of the decoupling nut. This special thread geometry features asymmetric flank angles where the bearing surface has a larger angle than the driving surface, creating a mechanical locking effect that prevents loosening under vibration. The self-locking property is localized to the thread structure itself, providing vibration resistance without requiring additional external locking mechanisms or complex assembly procedures.

The patent modifies the surface properties of the decoupling nut by applying a dry lubricating film to the integrated sliding surface. This surface treatment changes the coefficient of friction parameter, creating a low-friction interface between the exhaust manifold and the decoupling nut. The dry lubricating film maintains effective thermal decoupling by reducing friction and allowing for thermal expansion movements while preventing galling and seizing during assembly and operation.