| 摘要 |
A head gasket 112 is arranged between a cylinder block 116 and a cylinder head 110 of an engine. The gasket includes at least one passageway arranged to fluidly communicate a cylinder block opening 145 with a cylinder head opening 130. The gasket is sized and arranged so that coolant passing through the passageway is selectively restricted by viscous drag whereas gas is able to pass freely through the passageway. Preferably, the passageway includes a control gap 120 that has a maximum height of 0.3mm so that coolant is restricted from passing by viscous drag when the coolant is cold, i.e. during a cold engine start, thereby allowing coolant to be quickly heated up to an operating temperature by the engine. Once heated to the operating temperature, the viscosity of the coolant is decreased and coolant can pass through the control gap. The gasket reduces the warm-up time of the engine. The gasket may comprise three or more layers 112a-c and may define more than one control gap. The control gap is defined, at least in part, by the cylinder head and/or cylinder block and can include perturbations (405, figure 5D) to increase viscous drag. |
