Heat insulation structure

A heat insulation structure for a component of an exhaust system of a piston engine, the heat insulation structure being configured to be arrangeable around the component of the exhaust system in such a manner that an air space will be formed between the component and the heat insulation structure during use, the heat insulation structure comprising:

• an outer shell layer;
• a middle shell layer that is arranged inside the outer shell layer;
• and
• a first inner shell layer that is arranged inside the middle shell layer;
• wherein a first air gap is arranged between the outer shell layer and the middle shell layer;
• a first insulation layer of insulation material is arranged between the middle shell layer and the first inner shell layer;
• the outer shell layer is provided with venting apertures for natural ventilation of the first air gap, the venting apertures having air outlets, which are arranged in an upper part of the outer shell layer for releasing venting air from the first air gap;
• and
• a cover structure that is provided with venting apertures arranged above the outer shell layer to cover the air outlets of the outer shell layer, the venting apertures of the cover structure having air outlets, which are arranged in a vertical direction above the air outlets of the outer shell layer, and the venting apertures of the cover structure having air inlets, which are arranged in a vertical direction below the air outlets of the cover structure.