| 摘要 |
The crankcase (10) consists of a rigid frame (1) with an over-moulded covering of a thermoplastic, e.g. cellular, sound insulating material. The frame has apertures (11) and reinforcing ribs (3), e.g. in a honeycomb configuration, and the covering has areas of increased thickness for fixings. The crankcase is fitted with a peripheral seal (4) between the upper edge of the frame and its support (5), and the seal can be made during the over moulding procedure. The frame can also be made from a moulded thermoplastic material, e.g. of polyamide or polypropylene. The insulating material can be, for example, of polypropylene or polydiene ethylene monomer with a foaming agent such as azocarbon amide.
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