GB1346349A - Heat insulative gasket - Google Patents

Abstract

1346349 Joint-making packing F D FARNAM CO 22 July 1971 [26 Aug 1970 29 Sept 1970] 34444/71 Heading F2B In a gasket 16, particularly for use between an engine intake manifold and a carburetter, having therein a fluid passageway 20 and bolt holes 36 and comprising a body portion including a core of heat insulating material 24 having a layer of sealing material 28, 30 bonded to at least one face of the core, each bolt hole is surrounded by a portion 34 having a density greater than that of the core and a thermal conductivity factor k of not more than 3 BTU's/hr/ft/oF and the passageway 20 is completely surrounded by a part of the sealing material which extends laterally beyond the bolt hole portions. In the embodiment shown in Figs. 2 and 3, the core 24 is formed by two laminates 24a, 24b bonded together as at 26 and the top sealing layer 28 is integrally formed with a sealing head 22 surrounding the passage 20 and of lower density than the rest of the layer material. The laminates 24a, 24b may be of phenolic-resin-impregnated vegetable fire board and the sealing material may be nitrile rubber or other elastomeric material, the layers 28, 30 being secured to the core 24 by an adhesive layer (not shown). Each bolt hole 36 is formed in a bush 34 of synthetic, non-metallic material. In a modification, Fig. 4A, (not shown), the core (40) is formed by a single fibreboard the density of which is increased at the bolt hole portions (18<SP>1</SP>), e.g. by coining or pressing. In a further modification, Fig. 4B, a washer 50 of asbestos fibre or plastics is located in a recess 48 in each position 18<SP>1</SP> below the sealing layer 42<SP>1</SP>. The bush 34 or washer 50 may be made as an insert (60, Fig. 5A) from a stack of laminations of thermosetting resin impregnated asbestos paper having long fibres (64) perpendicular to the bolt holes (66), the stack after impregnation being compressed and densified. In a further modification; Figs. 6 and 9, the asbestos millboard core 85 has projections 93, 94 surrounding the bolt holes and extending through the gasket layers 88, 89, whereby, in use, an air gap 98 is formed between each of the sealed flanges 3, 7 and the gasket. In addition to the sealing heads 95, buttons 96 or a continuous head may be provided in the layers 88, 89 adjacent the outer margin of the gasket. As shown in Fig. 8, the gasket is made by placing on a hot pin mould two pieces of asbestos millboard 86 with a washer 87 therebetween at each bolt: hole position and a gasket layer 88, 89 on their outer faces. The pieces 86 and washer 87 have bolt holes 90 and 91 therein and the layers have openings 92 corresponding to the outer diameter of washers 87. The components are then hot pressed in the pin mould to form the gasket as shown in Fig. 9, the material in the bolt hole portions forming protuberances 93, 94 and having a density exceeding that of the rest of the core.