US3533384A - Crankcase ventilation system - Google Patents

Description

' Elni'ted States Patent [72] lnventors John D. Bennett 60] Thompson; Preston E. Chaney, 6114 Waggoner Drive. Richardson, Texas 75080 [21] Appl. No. 718,785 [22) Filed April -l. l968 [4S] Patented I Oct. 13, 1970 [54] CRANK-CASE VENTILATION SYSTEM 3 Claims. 3 Drawing Figs.

[52] U.S.Cl, .1 123/119 511 1m. (:1 Fozr 9/00 [50] Field ofSearch 123/] 19(8) 56] References Cited UNITED STATES PATENTS 1.521187 2/1925 lndlekofer. .l23/ll9(B)L'X 4/1960 Geffroy l 23/1 l9tB )UX 1130.080 6/1964 McMahon ..l23/ll9(B)UX 3.246.639 4/1966 Oliver, ..l23/ll9(B)UX FORElGN PATENTS 1 1030.500 5/1966 GreatBritain .;.....123/1191B1ux 375.975 8/1939 1:61 ..123/1191B ux Primar Erwniner-JNendell E. Burns Attorneys-George L. Church. Donald R. Johnson. and

Wilmer E. McCorquodaleJr. andJohn E. H older v ABSTRACT: The particular embodiments described herein as illustrative ot'one form of the invention utilize a condenser in the air cleaner of an internal combustion engine to condense crankcase vapors and return the'condensate to the crankcase. Water condensate is trapped and separated from condensibles in the return line to the crankcase to prevent an excessive accummulation of moisture in the crankcase. Noncondensibles are passed into the engine air-fuel intake system to be burned in the cylinders.

CRANKCASE VENTILATION SYSTEM BACKGROUND OF THE INVENTION Thisinvention relates to a crankcase ventilation system for internal combustion engines, and more particularly, to an apparatus for condensing crankcase vapors, separating water therefrom and returning the remaining condensibles to the crankcase.

Crankcase ventilation is necessary to provide a neutral pressure condition in the crankcase. Just as upward motion of the pistonrcompresses the air-fuel mixture, the downward motion tends to compress air in the crankcase. Neither pressure nor vacuum is desirable in the crankcase for reasons to be described herein.

Crankcase ventilation is also necessary to remove harmful elements from the crankcase. It is virtually impossible to keep water out of the crankcase. Drops of gasoline also seep into the crankcase, especially during warm up. Some combustion gases blow past the piston rings into the crankcase. Vapors also originate from the lubricating oil in the crankcase. When such oil vapors are introduced into the atmosphere by any system, they naturally create smog, the undersirable effects of which need not be elaborated upon, since the problem of air pollution is well known. If such oil vapors are induced into the intake manifold for burning in the cylinders, the oils may not burn well at the compression ratios used in internal combustion engines and therefore they emerge through the exhaust system as nonburned hydrocarbons which results in contamination of the atmosphere. In addition, the injection of lubricating oil vapors into the intake manifold tend to destroy the proper fuel-air ration of the combustible mixture and thereby causes inefficient combustion of fuel in the engine cylinders. These factors, as well as the presence of additives in the oil vapors may contribute to fouling of the spark plugs.

Another problem relates to the use of multiple weight or allweather types of motor oil in an internal combustion engine crankcase. Such oils have properties which permit a portion of the oil. to remain at a low viscosity, even during low temperature conditions. These less viscous portions of the oil tend to vaporize more readily than the heavier portions, andtherefore after such oils have been in use for a period of time the lighter portions have tended to vaporize and escape either to the atmosphere or into the engine cylinders where they are burned, so that the oil remaining in the crankcase is of a higher viscosity, and therefore does not afford the advantages of multiple weight range oil.

An additional problem with present day crankcase ventilation systems is that oxygen, which is drawn into the crankcase with the present positive crankcase ventilation systems, can provide a mixture in the crankcase which is explosive. Also, the presence of such oxygen tends to promote the formation of harmful acid sludges in the crankcase.

A notorious problem in the automotive field is the increased oil consumption in older automobiles. Such consumption is ultimately in the form of the release of unburned hydrocarbons into the atmosphere. This increased oil consumption in older engines occurs because of worn or broken rings surrounding the piston head. Since the lubricating oil in the crankcase is always under some pressured gradient, the lubricating oil is forced up between the piston head and the cylinder wall past the formerly tight fitting rings into the compresssion chamber from whence they are exhausted through the outlet valve into the exhaust system of the automobile. Pressure in the crankcase will also force oil past the crankshaft oil seals and up the dipstick tube. If the crankcase can be operated at nearly atmospheric pressure, such a condition can be minimized.

The two systems generally in use in present day automotive engines for ventilating crankcases are: (1) Air enters the engine through the oil filler cap, circulates inside the crankcase, and exhausts through a road draft tube extending out of the crankcase. The road draft tube works only when the vehicle is in motion at speeds above mph. (2) Crankcase gases are induced into the fuel-air induction system by various means,

and are burned in the cylinders. This system, termed PCV (Positive Crankcase Ventilation) depends on a balanced flow rate of air circulation through the crankcase to prevent excessive pressure or vacuum from occurring in the crankcase. Too fast a rate adversely effects oil oxidation in the engine. Also, any alteration of the PC V upsets carburetion and leads to poor gas mileage and rough idling. imbalance in the carburetor leads to incomplete burning-of the mixture in the cylinders and a resulting discharge of unburned hydrocarbons to the atmosphere.

The present systems for crankcase ventilation do not solve the problems associated with crankcase vapor control, some of which have been set forth above. It is therefore and object of the present invention to provide a new and improved crankcase ventilation system.

SUMMARY OF THE INVENTION With this and other objects in view, the present invention contemplates a crankcase ventilation system for disposing of crankcase vapors. The system includes means for venting vapors from the crankcase into a condenser for transforming the vapors to the liquid state whereupon they gravitate through a return line to the crankcase. A water condensate trap is provided in the return line to separate water from the condensibles being returned to the crankcase. A drain is provided on the trap to dispense with separated water. Portions of the vapor which are not condensed are permitted to escape into the air-fuel intake manifold for burning in the engines cylinders.

A complete understanding of this invention may be had by reference to the following detailed description, when read in conjunction with the accompanying drawings illustrating embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial corss-sectional view of an internal combustion engine embodying principals of the crankcase ventilation system of the present invention;

FIG. 2 is an enlarged cross-sectional view of a portion of the ventilation system showing in detail a water condensate trap according to the present invention; and

FIG. 3 is a sectional view of the condensate trap taken along lines 3-3 ofFIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of the drawings, an engine is shown including a crankcase l2 and rocker covers 14 partially defining rocker chambers 16 communicating with the, crankcase 12. The engine further includes a combustion fluid inlet 18 having a carburetor 20 and an air cleaner 22 mounted thereon. A tubular conduit 24 extends from the rocker cover to provide a vent for vapors within the cover. This vent in turn provides a convenient path of communication for crankcase .vapors which are formed within the engine crankcase. The conduit or vent 24 could be connected directly to the crankcase and be equally within the scope of this invention. Hereafter, the vent which is shown in FIG. 1 as extending from the rocker cover, will be described as a crankcase vent whether the vent actually communicates directly with the crankcase, or whether it communicates directly with the rocker cover, and thus indirectly with the crankcase by means of passages within the engine which connect the rocker cover and crankcase. One such communicating passage (not shown) within the engine is provided about the cam follower rod which operates the rocker arms within the rocker cover.

The air cleaner 22 includes parallel, generally circular upper and lower covers 26 and 28 respectively, the upper cover 26 having a cylindrical wall portion 30 extending downwardly therefrom and engaging a resilient seal 32, disposed in a channel 34, formed around the periphe ry of the lower cover 28. An air inlet duct 36 extends outwardly from wall portion 30. A downwardly extending cylindrical portion 38 of the lower cover forms a flange which sealingly engages an air inlet born 40, extending upwardly from the carburetor 20. An annular air filter element 42 is concentrically disposed within the air cleaner 22 so as to sealingly engage upper and lower covers 26 and 28. An opening is formed in the upper cover 26 and is provided with a cover plate 29 which sealingly engages the upper cover 26 when assembled thereto. A small opening is provided in the center of the cover plate for receiving the upper end of a bolt 44, which extends upwardly from the air inlet horn. Bolt 44 is threaded at its upper end for receiving a wing nut 46 to hold the cover plate over the opening in the air cleaner upper cover. The air cleaner arrangement thus far described is basically similar to the type of air cleaner found on most late model automotive type internal combustion engines.

A condenser apparatus is provided in the crankcase ventilation system, and is arranged for positioning within the air cleaner device 22. The condenser which is generally indicated by the reference numeral 50 is in the form of an annular chamber, which is sized for reception within the air cleaner between the air filter element 42 and the air inlet horn 40. The condenser has a conduit 52 extending downwardly therefrom, through a complementary shaped opening in the lowe'r cover 28 of the air filter. Sealing means, such as gaskets, may be provided above and below the top and bottom surfaces respectively of the condenser for providing a sealing engagement between the condenser and the upper and lower covers 26 and 28 respectively, ofthe air filter.

Further details of the construction of the condenser are set forth in a copending application of John D. Bennett, filed the same date as this application. The condenser is comprised of inner and outer circular wall members which by way of different diameters are spaced from one another to form an annular passage or chamber 58 having a central vertical opening. The chamber is enclosed by top and bottom annular cover plates. A plurality of openings in the inner wall member are axially aligned with the openings in the outer wall members to permit the insertion of tubular members 70 between aligned pairs of such openings. The tubular members are then swaged or otherwise attached at their ends to form a connection between the tubular members and the inner and outer wall members. A vapor inlet opening 72, which is provided in the bottom cover, is flush with the surface of the bottom cover so that condensed fluids collecting on the bottom cover may drain into the inlet opening 72 and conduit 52.

A plurality of small diameter openings 74 are provided in the top of the inner wall of the annular chamber 58, which openings provide communication between the interior of the annular chamber 58 and the central vertical opening within the condenser. The small openings 74 at the top of the inner wall are sized to pass noncondensed vapors from the interior of the chamber 58 to the central opening while being small enough to choke off the flow, in the opposite direction, of fire and extreme heat into the interior of the chamber so that any backfire from the carburetor cannot get into the crankcase ventilation system. The openings 74 may be situated in the condenser at any location which will provide for communication of noncondensed vapors from the condensing chamber to the combustion chambers of the engine. The optimum placement of the openings will depend, of course, on the design of the air cleaner. Also, the small openings 74, as well as the tubular members 70 extending through the condenser chamber need not be circular in cross section, but may be shaped in any manner to provide the desired results. The tubular members 70 in the annular chamber may be vertically staggered as shown in FIG. 1 to provide more effective condensing within the chamber 58. Again, this arrangement may be modified to provide desired results.

A tubular connecting member 60 is provided between the conduit 52 at the bottom of the condenser chamber and the vent 24 on the rocker cover. A water condensate trap 62 is provided in the connecting member 60.

The condensate trap 62 is shown in greater detail with reference to FIGS. 2 and 3 of the drawings, and includes a reservoir which is shown in the form of a cylindrical member 64 attached to the underside of connecting member 60. A drain valve 66 and petcock 68 are connected to the lowerend of the reservoir to provide a means for draining fluid from the reservoir 64. Referring to FIG. 3, the underside of connecting member 60 is channeled as at 76 to provide a drainage groove along the bottom side of the member 60. The groove 76 intersects opposite walls of the upper end of the reservoir 64 for purposes to be described herein.

In the operation of the apparatus described above, crankcase vapors within the engine are communicated with the chamber 16 of the valve or rocker cover 14 on top of the cylinder head. These vapors are emitted through the vent 24 on the valve cover, and pass upwardly therefrom through the connecting member 60 and the conduit 52 connecting with the inlet opening 72 on the condenser. Vapors from the engine are then communicated with the interior of the condenser chamber 58. Air entering the air cleaner 22, after passing through the air filter element 42, must pass through the interior bores of the condenser tubular members 70 before entry of the air into the air inlet horn of the carburetor. As the crankcase vapors pass about the tubular members 70, they are condensed by the cooling effect provided by air flow into the air cleaner through the tubular members. The condensed vapors collect on the bottom of the condenser and drain by gravity into the inlet opening 72 for return to the rocker cover and eventual return to the crankcase. Noncondensible fluids will continue to rise upwardly within the condenser chamber where they are expelled through the small openings 74 into the central opening of the air cleaner assembly for passage into the air inlet of the carburetor. These noncondensed fluids are mixed with the carburetor inlet air and then burned within the combustion chambers of the engine.

The condensed fluids which are returned to the crankcase via the connecting member 60 are channeled into groove 76 at the bottom of member 60. Upon the fluids reaching the intersection with the mouth of reservoir 64, such fluids will drop into the reservoir until it is full of fluid up to the groove 76 on the downstream side of the reservoir. At such time the fluids entering the reservoir will be free to float over the surface of fluids already trapped in the reservoir and will continue to flow past the reservoir into the vent 24 on the valve cover. When the reservoir is initially filling, a separation of water and oil will take place in the reservoir with oil floating on top of the water with such a division being represented by the heavy dotted line 78. When the reservoir is full, any water droplets moving across the surface of the reservoir, being heavier than the oil on the surface, will fall into the reservoir and sink therein until they fall below the oil-water interface at 78. The reservoir may be periodically drained by means of the valve 66 at the bottom of the trap so that water will not fill the reservoir and thereby spill over the upper end of the reservoir into the condensate return.

It is emphasized that the particular air cleaner design illustrated is not essential to the invention, nor is an air cleaner essential to the invention. The crankcase ventilating system described is applicable to any air-fuel inlet structure. For practical purposes, when used with an air cleaner, the system would be arranged to fit the various air cleaner designs, or adapted to existing designs currently in use by making necessary modifications to existing air cleaners. It is also pointed out that the subject system is applicable to any of a variety of types of engines, and that the engine and engine components shown are for illustrative purposes only. The vapor outlet conduit may be connected to the engine in the most convenient manner which will provide communication with crankcase vapors, and likewise, the return line from the air cleaner may be connected to the engine at any place where oil introduced therein will be eventually returned to the crankcase. The water condensate trap may be located in any convenient manner in the system as for example, in the condensing means itself, with the object bcing to remove such undesirable fluids before they are returned to the crankcase.

Various constituents of the crankcase vapor. particularly those having a lower dewpoint, will not be condensed in the chamber 58. These vapors will pass through the openings 74 in the condenser where they are mixed with inlet air to the engine combustion chambers for burning. Gasoline, which has a much lower dewpoint than lubricating oil, will therefore tend not to condense in the chamber, and thus will be passed into the engine for burning. In the systems described, the constituents ofcrankcase vapors which will readily burn in the engine, i.e., gasoline, will be passed into the combustion chamhers; while the lubricating grade fluids which do not readily burn will be returned to the crankcase. Such a process will therefore aid in eliminating the emission of noncombustible hydrocarbons to the atmosphere, which emissions are a contributing factor to smog. ln addition, the viscosity of the lubricating oil will be maintained at a more constant level since diluting fluids such as gasoline will vaporize and be passed from the crankcase, and the lower viscosity oils, which normally vaporize first from the lubricating oil, will be returned to the crankcase. This in turn will result in multiple viscosity oils holding their viscosity range for a longer operating period. Any water in the crankcase fluids having a dewpoint between the gasoline and lubricating oil should be condensed for the most part in the condenser and returned toward the crankcase. The trap described herein will remove a substantial portion of such water to prevent the harmful effects of water in the crankcase which are well known.

The crankcase system described above may be modified to provide a closed system, i.e.; one in which the oil filler cap is closed to prevent the entry of air from that source. Thus, inlet air to the system is provided only through the combustion chambers. This has advantages relating to smog control and engine life. In the latter system, since the oil filler cap does not have a breather, vapors cannot escape the crankcase from this point. Also, the vapor condenser-air filter arrangement does not readily permit the escape of crankcase vapor even when the engine is shut down. Such vapors escaping from the crankcase after engine shutdown will be trapped in the air cleaner between the filter and combustion fluid inlet, so that any vapors escaping from the system would necessarily pass through the filter element and thus the heavier air pollutants would be sutstantially stripped from the vapors.

The closed system also offers the advantage of preventing an excess of air and thus oxygen from entering the crankcase. Oxygen, when combined with certain hydrocarbon components will form an acid sludge in the crankcase, which in turn leads to corrosion of engine parts. This same prevention of excess air to the system also deters the entry of moisture to the crankcase, the harmful effects of which are well known. The lack of excess oxygen in the crankcase will also prevent crankcase explosion which is not uncommon in positive crankcase ventilation systems.

It is readily seen that numerous advantages are offered by the system described above. It is pointed out. however. that portions of the system have advantages when taken alone, and do not necessarily depend upon all the features of the system to provide an advance in the state of crankcase ventilation systems.

It is also pointed out that while the condenser embodiments shown utilize the engine air intake system for cooling vapors. other systems could be used for cooling. For example. the vapors could be fan cooled, or water cooled, with condensed fluids being returned to the crankcase, or trapped, and noncondensed fluids vented to the intake manifold.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and therefore. the aim of the appended claims is to cover all such changes and modifications as fall within the true spirit and scope ofthis invention.

We claim: I 1. In an apparatus for use with an internal combustion engine, wherein the engine is provided with an air filter element and housing for filtering air into the air-fuel intake system of the engine, the combination of means for disposing of crankcase vapors emitting from the crankcase of the engine, which means comprises: condenser means having annular inner and outer side walls and top and bottom covers which when assembled form an annular hollow chamber having a central opening therethrough', lateral enlcosed passageways passing through said chamber and providing fluid communication between said inner and outer side walls; said condenser means being sized for reception within the air filter housing between the filter element and the air intake system whereby fresh air passes through said passageways; first port means for passing crankcase vapors into the chamber; second port means for passing noncondensed fluids from said chamber into the air intake system; means arranged between said first port and the crankcase of the engine for trapping nonhydrocarbon constituents of said condensed fluids, said trapping means including passage means, a reservoir in said passage means, and a trough formed in the bottom of said passage means and intersecting said reservoir.

2. A fluid separator apparatus for isolating constituents of crankcase fluids associated with the operation of an internal combustion engine, comprising: passage means for returning the condensate of crankcase vapors to an engine crankcase, reservoir means depending from the bottom side of said passage means and in fluid communication therewith, said reservoir means being arranged to permit gravity separation of fluids therein; means for draining fluids from said reservoir meansz and trough means in said passage means for channel ing the condensate into the reservoir means, said trough means being comprised of a groove formed in the bottom of said passage means.

3. The apparatus of claim 2 wherein the bottom of said groove is arranged to be laterally aligned with the fluid surface in said reservoir means when filled with fluids.

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