| 摘要 |
An expansion tank 21 for an engine cooling system comprises a housing 20 formed by a lower moulding 24 and an upper moulding 25 joined at a joint plane 31. The external walls of lower moulding 24 include a deep side wall 43, a small bottom wall 46, an inclined wall 36 and a short near-vertical wall 37 which form a relatively deep tank portion. Parallel webs 44, 45 form a passageway 47 which is intersected by an array of intersecting webs 48 arranged in a parallel formation, the intersecting webs 48 being formed alternately on one side and the other of the passageway 47 and extending alternately from the deep side wall 43 and a transverse web 38. Each of the intersecting webs 48 has a side edge which extends substantially perpendicularly from the joint plane 31 towards the external wall and intersects the external wall at an obtuse angle which is achieved by giving each side edge a curved portion 49 where it intersects the external wall, the curved portion having a radius of at least 10mm and more preferably 20mm. Similar webs have similar curved portions, these allowing the stresses induced by the internal pressure of the cooling system (approximately 1 bar) to be spread over an area of the adjoining external wall which is considerably greater than the normal cross-section of the web where it meets the joint plane 31. |
