IMPROVEMENTS IN OR RELATING TO CRANKCASE BREATHERS FOR INTERNAL COMBUSTION ENGINES

摘要

1,255,642. Separating oil from air; centrifugal separators. PERKINS ENGINES Ltd. 6 Jan., 1969 [23 Jan., 1968], No. 3478/68. Headings BIT and B2P. [Also in Division F1] ; An I.C. engine crankcase breather includes means for separating oil from a gas in which it is suspended, means for venting the gas after the separation and a duct adapted to contain a pressure head of separated oil so that, in use, the duct allows the separated oil to return to the crankcase while preventing back flow from the duct, the means for separating the oil comprising a primary and a secondary oil separator. Oil suspended in gas rises from the crankcase through rocker box 2 and tube 4 into cap 7 in which a primary separation takes place in a first wire mesh filter 10. The initially separated oil drops through portion 8 into chamber 9. The pressure in chamber 9 remains greater than atmospheric pressure and the gas rises through a second wire mesh filter 12 where the remaining oil is separated out and falls to the bottom of chamber 9 whilst the gas is vented to atmosphere. The separated oil is returned to the crankcase through duct 13 in which a pressure head A is maintained to prevent back flow. In modifications the duct either extends into a reservoir 18 or the duct 13 is twisted to form a vertical loop. In another embodiment the crankcase gas flows through an inlet tube 28, Fig. 2, tangentially into a casing 20 so that a primary separation takes place centrifugally and the separated oil flows into a duct 22. The gas rises through a filter 27 and further separated oil is returned to duct 22 whilst the gas is vented into the inlet manifold 32 through a spring loaded valve 31. In another embodiment the breather casing has an inlet aperture and an annular flange (39), Fig. 4 (not shown) in which a closed permeable walled tube (40) forms an upwardly directed extension. Crankcase gases flow up a helical ramp (49) between the casing and the tube and are vented from the open end of the casing. Oil separated by centrifugal forces runs to the centre of the ramp and through the permeable wall into a cylindrical duct which extends within a cup reservoir (43). A hole (46) in the reservoir above its lower end allows overflow of the separated oil into the rocker box. In modifications of this embodiment the helical ramp is formed from metal, or plastics or resin-based paper or wire or glass mesh or moulded integrally with the tube. The casing may include a wire mesh filter.