Abstract:
Apparatus is provided for removing oil from crankcase gases flowing from an internal combustion engine. The apparatus includes filtration particles, contained within an outer case, that collect oil particles and allow drainage of the oil into an accumulator. The apparatus includes a separation chamber which initially causes the oil to separate from the crankcase gases.

Description:
[0001]    This is a continuation application of U.S. patent application Ser. No. 12/203,815 filed on Sep. 3, 2008. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to internal combustion engines, and specifically to separation of oil from crankcase gases of internal combustion engines. 
         [0004]    2. Description of Related Art 
         [0005]    In automobile racing, and especially in the sport of drag racing, horsepower is very important. Drag races are often decided by thousandths of a second. Even small gains in engine efficiency can lead to victory. One well known method of increasing engine efficiency in the art of engine building is to run a vacuum pump on the crankcase side of the engine. Crankcase gases are often evacuated to a “breather,” which is typically a reservoir with a fiber-based filter element on top. Although these vacuum systems are successful in increasing horsepower, oil particles are typically exhausted from the “breather” at a high rate. This condition pollutes, creates a fire risk, and causes unsafe conditions on race tracks. Because of the way current systems are designed, an oil mist accumulates in the engine compartment (on the engine, underside of the hood and firewall). One of the most annoying responsibilities of a crew chief for drag racing is cleaning the engine compartment between races. If not cleaned between races, this accumulated oil can cause a fire hazard. 
         [0006]    The most common vacuum systems for internal combustion engines are belt driven centrifugal pumps. These pumps are typically driven by the crankshaft. They draw crankcase gases from fittings on valve covers or from the oil valley. The gases are a mixture of the products of combustion that flow past the pistons (“blow-by gases”) and air filled with atomized oil particles created by the rotating action of the crankshaft. Although these systems add weight to a vehicle, in drag racing the net increase in horsepower is thought to offset the undesirable effect of the additional weight. State-of-the-art vacuum systems are commercially available from Aerospace Components of St. Petersburg, Fla. and Moroso of Guilford, Conn., for example. 
         [0007]    Water-cooled engines also need overflow volume for expansion of fluid in the cooling system as the engine heats. This is normally a separate accumulator system on a race car. It requires a second mounting area, extra weight, and reduces the amount of space in the engine compartment area. Current systems on racecars have several parts that work together in an attempt to separate air, oil and water. These include: an oil/air separator prior to the vacuum pump, an atmospheric air volume regulator (pressure regulator) prior to the vacuum pump, an oil accumulator tank, a breather filter on top of the oil accumulator, and a water accumulator for overflow. 
         [0008]    The need for oil-air separators has been felt since the advent of the internal combustion engine. U.S. Pat. No. 973,118, dated Oct. 18, 1910, discloses an apparatus that draws gases out of the crankcase, and recycles those gases into the intake of the cylinders. This early form of the oil-air separator took the form of “a pipe . . . to maintain the air free of oil or dirt . . . .” 
         [0009]    U.S. Pat. No. 5,063,882, titled “Oil Separation for Gases from a Crankcase of an Internal Combustion Engine,” to Dr. Ing.h.c.F. Porsche Aktiengesellschaft discloses an oil separator based on a labyrinth comprising two deceleration paths for oil contained in crankcase gases. 
         [0010]    U.S. Pat. No. 6,167,849 discloses an oil collector particularly adapted to motorcycles. It is said to cool blow-by gases containing oil vapor and particles and then to discharge the gases to the atmosphere through a filter, which is not described, but appears to be conventional pleated air filter. 
         [0011]    U.S. Patent Application Publication No. 2008/0047505 A1, titled “Oil Separator Element,” discloses an oil separator element that operates by setting crankcase gases in rotational motion so that centrifugal forces cause oil droplets to form on the walls of the grooves in the filter element. 
         [0012]    What is needed, especially for race cars, is a system that combines the oil/air/water separation into one unit. Not only could this system eliminate the need for all the separate systems listed above, it would also reduce the weight of the car (each piece above plus all their brackets, clamps). With only one unit (compared to six separate pieces) required to accomplish the tasks, adjustments and replacements would also be much simpler. For race cars, and for crankcase gases from all internal combustion engines, including those in all vehicles and stationary engines, there is a need for a more effective, economical apparatus to separate the oil in crankcase gases from the gas phase and accumulate the separated oil. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The problem of efficiently separating oil from crankcase gases is provided by a combination of centrifugal force, cooling of a surface and a filter made by a bed of particles. A canister for use in race cars is provided by concentric accumulators for water and oil, with the bed of particles collecting oil so that it drains into the oil accumulator. A line for returning separated oil to the engine may be provided, with flow in the line being by pressure control or level control in the oil accumulator. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0014]      FIG. 1  is an elevation view of one embodiment of the device disclosed herein attached to the crankcase gas vacuum system and the cooling system of an engine. 
           [0015]      FIG. 2  is a cross-sectional view of one embodiment of the air-oil separator and liquid accumulator disclosed herein. 
           [0016]      FIG. 3  is a perspective view of a filter support for particles in the air-oil separator. 
           [0017]      FIG. 4  is a perspective view of one embodiment of a particle for the filter. 
           [0018]      FIG. 5  is a perspective view of another embodiment of a particle for the filter. 
           [0019]      FIG. 6  is a cross-sectional perspective view of the lower base of one embodiment of the air-oil separator and liquid accumulator disclosed herein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring to  FIG. 1 , oil-air separator/accumulator  17  installed in the engine compartment of an automobile is illustrated. Also shown is vacuum pump  16 , which is connected to oil valley cover  15  for removing crankcase gases from engine block  10  through hose  16 A. Vacuum pump  16  may not be used, and separator/accumulator  17  may be connected directly to oil valley cover  15  or any other location on the engine for venting crankcase gases. Power for vacuum pump  16  is taken through belt  16 D from crankshaft pulley  11 . Intake manifold  13  feeds fuel and air from carburetor  13 A. Alternatively, electronic fuel injection can deliver fuel and air to intake manifold  13 . Exhaust header  14  evacuates products of combustion from the cylinders of engine block  10 . 
         [0021]    Separator/accumulator  17  may be connected to radiator  19  through hose  19 B, in which case separator/accumulator  17  may serve also as overflow accumulator for radiator  19 . Water drain valve  17 D may be opened to remove accumulated water. A tube connected to radiator  19  may extend into the water accumulator. 
         [0022]    Oil may be drained from separator/accumulator  17  through oil drain valve  17 C, in which case valve  17 C has a drain tube as shown attached to valve  17 D, into a separate container. Alternatively, oil drain valve  17 C may be always open and connected by hose to valve  17 E. Oil may then flow through valve  17 E and return to valve cover  12  through hose  18 . Hose  18  may be attached to the engine in any low-pressure location to return oil to the lubrication system. Oil pan/crankcase  18  is the main lubricating oil reservoir for the engine. 
         [0023]    The reasons to automatically return the separated oil back to the engine through hoses and valve  17 E depend on the environment and use of the engine. In drag racing, after every race the oil is usually drained into a cup or bowl and then discarded. Racing oil is expensive, so automatically returning the oil to the engine will save time and money. For engines running long times or continuously, including engines in automobiles, motorcycles, piston-driven aircraft (where a “wet belly” is common), circuit racing engines (all types), and industrial machines and equipment, returning oil to the engine will reduce air pollution as compared with burning it via the intake system of the engine or otherwise disposing of the oil. 
         [0024]    Valve  17 E may be a check valve supplied by Smart Products of Morgan Hill, Calif. It may be designed to open at selected pressures, for example, in the range of 1-3 psi. Opening pressure may be selected by observing operation of the accumulator/separator on an engine. Alternatively, check valve  17 E may be a valve controlled by the oil level in separator/accumulator  17 . Valves controlled by a fluid level in a container are well known in industry. Electrical signals may be used to control the opening and closing of valve  17 E. 
         [0025]    Crankshaft pulley  11  may rotate up to about 10,000-11,000 RPM, depending on engine design. Vacuum provided by vacuum pump  16  varies, and may reach an absolute pressure of about 18 to 20 in Hg when the engine is operating at high RPM. Discharge pressure from pump  16  is preferably just slightly above atmospheric pressure, so that lower intake pressure will be possible. Discharge pressure will be determined by pressure loss across separator/accumulator  17 . Crankcase gas after removal of oil is discharged from the top of separator/accumulator  17 . 
         [0026]    Separator/accumulator  17  is preferably mounted in the engine compartment in a location where outside air contacts the surface to afford as much cooling of the surface as possible to maximize condensation of any oil vapor in the separator. 
         [0027]    Referring to  FIG. 2 , a preferred embodiment of separator/accumulator  17  is illustrated. Crankcase gas inlet port  21  may be perpendicular to the surface of outer shell  20  or may be oriented at an angle to outer shell  20  to facilitate centrifugal force on particles in the incoming gas. Annular separation chamber  26  is formed by lower base  23 , inner member  24  and outer shell  20 . Oil accumulates in the lower portion of chamber  26  and is removed through oil outlet  65 . 
         [0028]    Base  23  is a cylindrical cup forming the bottom of separator/accumulator  17 . A detailed cut away perspective view of base  23  is shown in  FIG. 6 . Outer shell retainer  60  is a cylindrical wall. The outer surface of outer shell retainer  60  has o-ring grooves  64 , adapted for o-ring seals  63 . Shoulder  67  acts as a seat for outer shell  20 . Inside outer shell retainer  60  is inner shell retainer  61 , with threads  62  on the inner surface of inner shell retainer  61 , formed so as to accept the male threads of inner shell  24  ( FIG. 2 ). The bottom of lower base  23  has oil outlet port  65  and water outlet port  66 . 
         [0029]    Top end piece  25  ( FIG. 2 ) is also a cylindrical cup, and has the same outside and inside dimensions as base  23 . Water inlet port  25 A may be located at the center of top end piece  25 . In the event of greater volume of water overflow than volume  29 , port  25 C may provide pressure relief. Air outlet ports  25 B discharge cleaned gas from separator/accumulator  17 . O-rings  63  seal top end piece  25  to outer shell  20 . The outer casing of separator/accumulator  17  is formed by top end piece  25 , outer shell  20  and base  23 . 
         [0030]    Oil-gas separation begins in chamber  26 , where oil particles impinge on the surfaces. The gas stream then flows through filter section  27  and exhausts through volume  28  to the atmosphere. Filter section  27  may have lower filter particle layer  27 A, middle filter particle layer  27 B, upper filter particle layer  27 C, and filter supports  30 . Ports  31  in filter support  30  are sized to retain filter particles. Lower filter particle layer  27 A may contain a selected amount of smaller filter particles  50 . Middle filter particle layer  27 B may contain a selected amount of larger cylindrical filter particle  40 . Upper filter particle layer  27 C may also contain smaller filter particles  50 . Alternatively, the particles in each layer may be of the same size or any combination of sizes. A range of particle sizes may be placed in each layer. In a preferred embodiment, there is a gap between inner shell  24  and inner diameter  52  of filter supports  30  to allow oil to drain down inner shell  24 . 
         [0031]    Referring to  FIG. 3 , perforated filter support  30  is illustrated. In a preferred embodiment, two filter supports  30  are identical. Preferably, the outer diameter of filter support  30  is approximately equal to the inner diameter of outer shell  20  such that filter support  30  may be pressed into outer shell  20  and held in place inside outer shell  20  without a retainer. Filter support  30  has ports  31  through its surface. Inner diameter  32  is preferably formed to allow a gap between filter support  30  and inner shell  24 . 
         [0032]    Referring to  FIG. 4 , cylindrical filter particle  40  is illustrated, having cylindrical outer surface  41  and channel  42  through the particle. In a preferred embodiment, particle  40  is made of polymer having a high melting point and oil resistance, such as polyethylene, polypropylene, polystyrene, Teflon, or other polymers. Alternatively, filter particle  40  may be made of metal, or any other heat and oil resistant material. Particle  40  may be selected from particles from about 1/16 in diameter and length to about ⅜ in diameter and length. A preferred diameter and length is about 3/16 with a channel diameter of about ⅛ in. Particle  40  preferably has high surface area and sufficient size to cause low pressure drop across a bed of particles. 
         [0033]    Referring to  FIG. 5 , spheroid filter particle  50  is illustrated, having outer surface  51 , conical end surface  52 , and cylindrical channel  53  through the filter particle. In a preferred embodiment, spheroid filter particle  50  may have a composition and size as described for particle  40 . 
         [0034]    To assemble device  17 , press fit lower filter support  30  into outer shell  20 , as shown in  FIG. 2 . Screw inner member  24  into inner member retainer  61  of base  23 . Seat seals  63  into grooves  64  of lower base  23  ( FIG. 6 ). Press fit base  23  into outer shell  20 . Add lower filter particle layer  27 A, add middle filter particle layer  27 B, then add upper filter particle layer  27 C. Smaller particles may be used in one layer, as shown in  FIG. 2 . Any combination of particle sizes may be used, as described above. Press fit filter support  30  so as to contact upper filter particle layer  27 C. Seat seals  63  into grooves  64  of top end piece  25 . Screw upper end piece  25  onto threads of inner shell  24 . The device may then be mounted and connected to an engine as shown in  FIG. 1 . The device may be used for air-oil separation only, in which case the connections to a radiator would not be made. 
         [0035]    In volume  27 , as gas containing oil droplets flows through the filter, oil impacts and wets the filter particles. Oil then drains downward through the filter particles. The individual filter particles preferably have a large surface area for wetting and for oil drainage. Channels through the particles, such as shown in  FIGS. 4 and 5 , are believed to allow greater rate of oil drainage. In all cases, the particles may have only one size or may be made up of intermixed particles. The particles may have one or more channels though the particles. The length of the bed of filter particles is preferably in the range from about ⅙ to about ⅚ of the distance from gas inlet port  21  to outlet ports  25 B. 
         [0036]    Apparatus  17  may be constructed in a wide range of sizes, depending on the engine on which it will be used and the conditions of use. The size of accumulator selected will vary depending on when and how accumulated liquid is to be removed. For example, for a race car for drag racing, outer shell  20  may have an outer diameter of 4 in, an inner diameter of 3⅞ in and a length of 11.5 in. Inlet port  21  may be ⅝ in diameter with center point 3¼ in from the bottom of outer shell  20 . Inner shell  24  may have an outside diameter of 2 in. Ports  31 ,  25 B and  25 C may be about 0.09 inches in diameter. 
         [0037]    The separator/accumulator of  FIG. 2  was placed on a 750 HP racecar during drag races and used under actual race conditions. The engine compartment showed no evidence of oil coating surfaces after a race. Testing consistently resulted in an oil-free system that separated the oil/air/water without an oil/air separator accumulator tank and an air breather and internal baffle. 
         [0038]    A test was also performed while a race shop was “dynoing” a customer&#39;s 1000+ HP engine. The race shop was using a standard system with internal baffles, which was releasing oil despite all attempts to correct it. The apparatus disclosed here was installed without any internal baffling. The water overflow was connected, the engineer made a pull on the dyno, and oil-free oil/air/water separation was observed. 
         [0039]    Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.