Oct. 6, H, F, BARR ET AL . '

v CRANKCASE VENTILATION Filed Jan. 6, 1936 2 Sheets-Sheet l

COMB‘NED MANIFOLD AND

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ENGINE SPEED i oct». 6, 1936. H_ F, Bmg ET AL i 2,056,762 CRANKCASE VENTILATION Patented Oct. 6, 1936 2,056,762

UNITED STATES' PATENT OFFICE

cnANxcAsE vEnmA'rroN Harry F. Barr, Charles F. Arnold, and Johnr F. Gordon, Detroit, Mich., assignors to General 'Motors Corporation, Detroit, Mich., a corpo ration of Delaware Application January 6, 1986, Serial No. 57,722 4 Claims. (Cl. 12S-196) This invention has to do with a crankcase quate ventilation, while the flow of air through Ventilating system for _internal combustion en the air is so slight as to pro gines. ,Most modern internal combustion en duce little or no suction.. As the speedof the gines are provided with means for passing air engine increases the `intake manifold suction de through the engine crankcase to remove from the creases while the suction through the air intake 5 engine oil diluents, such as water and unburnt connection'increases since a considerable stream­ . fuel, «entering­ by leakage past the . of air is now flowing to the-carburetor.A TheY Usually the necessary ñow of air is obtained by connections may be so designed as to secure a applying to the crankcase either the suction uniform flow ­of air through the engine at all existing-in­ the engine manifold or in the carbu speeds, and thus the crankcase is at all times 10 retor air intake or the suction, sometimes called ladequately ventilated maintaining the engine oil “roadsuction”, produced by extending an outlet substantially free of undesirable dilution. from the crankcase below the automobile so as to In the drawings: be exposed to the aspirating effect producedY by Figure l is an end view of a vconventional V the motion of the . - type automobile engine having parts broken 5 With prior arrangements it has not been pos away to show parts of the Ventilating system. sible to secure under all conditions the desired Figure 2 is a view, partly in section, taken sub flow of air through the crankcase for in each stantially along the line 2­­2 of Figure l. ' case the suction employedvaries withv the speed Figure 3 is an enlarged section taken on line or load of the engine or both.l Where engine 3_3 of Figure 2. p 20 manifold suction is used it is possible to secure Figure 4 is a graph showing the speed-110W the proper amount of ventilation at low speeds, characteristics of two suction connections com but the ventilation at high speeds is insuii‘lcient bined to provide constant iiow throughout the owing to lowering of the when speed range. ì A the carburetor valve is opened. Fur I0 indicates a conventional V-type automobile thermore,._the introduction of any great amount engine having banks of cylinders I2, of air into the manifold is objectionable in that I3, crankcase I4, carburetor I 6, throttle valve it makes the mixture too lean, interfering with Il and intake manifold I8. The intake manifold engine performance, and this factor makes it is preferably of a twin construction used on V necessary to restrict the air flow in su'ch a system type engines. The engine is of course provided to an extent to make it inadequate for proper with‘the usual cooling jacket, exhaust'manifold ventilation. Road suction is objectionable in that and Aother appurtenances. it is not operative at low speeds, and further 20 indicates the air intake to the crankcase more in some engine designs it is diiiicult to in preferably provided with a suitable or stall. It also presentsthe possibility of drawing air'cleaner indicated at 22. The air intake 20 35 dust into the engine when the car is moving is preferably arranged so as to be subject to the slowly through dusty regions. pumping action of the engine crankshaft as de According to our invention the ñow of air scribed and claimed in the prior patent to Ellis through the crankcase may be controlled so as No. 1,849,000, granted March 8, 1932. The air to give any desired characteristics without the from the crankcase, laden with diluents, passes 40 employment of moving parts by simultaneously into the valve chamber 24 through suitable open making use of severalv sources of suction having ings, one of which is indicated at 26 in Figure 1. different speed-flow characteristics so that one The valve chamber is provided with covers indi offsets or supplements the other. These may be cated at 28 and 30. so designed that a uniform ñow is produced, or, Conduit 32 leads from the valve cover 28 to if desired, the flow may be reduced slightly as the carburetorair intake 34, which is preferably the speed increases, or increased with increase equipped with a suitable air filter or cleaner 35. in speed. The new Ventilating system thus pro The' end of the conduit 32 is bent in the direc vides a simple but effective means of obtaining tion of flow of air to the f rburetor so as to be the desired speed-flow characteristics. _ subject to aspiration. . 50 In the preferred form of the invention the Conduit 36 leads from the valve cover 30 to a -case is provided with two suction connec T-fitting 38 communicating with ports 4D lead tions, one leading to the intake manifold and the ing into the central portions of the twin intake other to the carburetor air intake. When idling manifoldl I8 supplying combustible mixture to the strong intake manifold suction insures ade the cylinders. T-ñtting 38 also affords com- 55 2 , 4 2,056,762 munication between conduit 36 and conduit 42 ant of the two. n win be named that the re leading to a point beneath the engine. Conduit sultant is a substantially ilat curve indicating 'a 42 is normally closed by a suitable valve 44 held constant volume of air passing through the in upper position against its seat 45 by the suc crankcase at all speeds. However, by modiflca- ‘ ' tion in the manifold. When the engine­ is not' tion of the size of the passages a resultant flow running or-when the manifold suction is insuf of almost any desired characteristics can be ob flci'ent the valve drops away from its seat per tained. »Y _ mitting the escape of any fuel which may have It will, be obvious that instead ofV extending 'found its way out of the manifold. To prevent the conduit> 34 to the carburetor air intake it the passage of fuel into the crankcase through could, if desired, have been extended below the 10 the conduit 36,- the latter is provided withl an _engine so as to be subject to road suction, and upwardly bent portion 46. , ` ' the character of the resultant ñow would have To prevent the passage of oil out of the crank been substantially- the same, since road suction case through conduits 32 and 36, the entrances Aincreases with increased car speed. 15 to the conduits are provided with bailles as We claim: - 15 shown at 48 and 50, providing a labyrinth to l. In a Ventilating system for crankcases of catch oil. internal combustion engines and the like the 'I'he system operates as follows: At low engine combination of a chamber to be ventilated, a speed the throttle I1 is closed, the manifold de conduit leading from said chamber to a source 20 pression will be great and there will be a pro of >suction increasing with th_e engine'speed, and nounced suction on conduit 36. As the throttle a second conduit leading from said chamber to is opened and the speed increases the manifold a source of suction decreasing y.with increase in ' suction decreases ­and the air passing through engine speed. ' ­conduit 36 will correspondingly decrease but the 2. In aventilating system for internal com 25 velocity of air passing through the carburetor bustion engines and the like the combination of air intake 34 will increase so that the aspirating an engine having a crankcase and a combus effect on conduit 32 will increase drawing air in tible mixture supply system having a throttle increasing volume through this conduit into the 'valve therein, means for drawing gases from crankcase. the crankcase connected to said system ori one 30 At low speeds lsome air will enter the system side of the throttle valve and means for draw 30 through conduit 32 rather than through the ing gases from the crankcase connected to said crankcase inlet. However, owing to the pro system on the other side oi’ the throttle valve. vision of the vertical bulkhead 52 dividing _the 3. In a Ventilating system for the crankcases, engine in the center air thus entering must pass of internal combustion engines and the like, the ' 35 through the 'crankcase in` order to reach the combination of _ an engine crankcase,' means for ' conduit 36 so that even this air contributes to drawing gases from said crankcase including a the ventilation of the crankcase. However, since source of suction increasing with engine speed, the amount so _entering is small and'since this and means for simultaneously drawing gases action only occurs under idling or low speed > from saidcrankcase including a source of suc- ­ 40 throttled conditions it would not prove seriously tion decreasing with increase in~engine speed. ' objectionable to have this air pass directly 4. In. the combination as deñned in claim 3, through thevalve chamber into conduit 36. the increase in‘suction of the first named means With this arrangement it is possible by mak being substantially equal to the decrease in suc ing the ports 40 and the conduit 34 of proper tion of the second named means throughout 45 diameter vto secure almost any desired speed the range of engine speed so as to maintain 45 ñow characteristics in the Ventilating system. substantially constant suction on the crankcase. In the graph, Figure 4, are shown the separate HARRY F. BARR. ' speed-flow characteristics of ventilation through conduits 32 and 36, respectively, and the result