Patent Abstract:
A method for cleaning an oil strainer in an oil pan of an internal combustion engine from which substantially all lubricant has been drained, the method comprising connecting a first conduit to said oil pan; introducing a cleaning fluid into said oil pan; connecting a second conduit to an opening on said engine; creating a circuit by a pressure pump wherein said cleaning fluid moves from said oil pan, through said opening, through said oil strainer and back into said oil pan; and evacuating the cleaning fluid from the engine.

Full Description:
FIELD OF THE INVENTION 
   The invention is directed to a method for cleaning an oil strainer in an internal combustion engine. In particular, the invention is directed to a method of cleaning an oil strainer by creating a closed circuit that flows in reverse direction of oil during normal engine operation, thereby dislodging contaminates from the oil strainer and removing them from the engine. The inventive method also facilitates the removal of sludge from an engine and reduces the amount of carry-over contamination, thereby reducing engine wear and enhancing engine performance. 
   BACKGROUND OF THE INVENTION 
   Combustion engines use oil to lubricate and reduce friction between moving parts such as the camshaft and bearings. As the oil circulates through an engine, it collects contaminants such as carbon and the contaminants eventually settle in the oil pan and become lodged in the oil strainer. When particles and contaminants become lodged within the oil strainer, there is a reduction in the rate of oil flow to the engine. Restricted oil flow causes an engine to become less efficient and can eventually result in engine failure or expensive engine repair. 
   Sludge, a by-product of engine use, is known to obstruct oil passages and restrict oil flow, ultimately leading to shortened engine life. Typical factors in the formation of sludge include heat, soot, fuel, water, acids, dirt, and engine coolant in the engine block. Although some sludge can be removed from an engine by changing the oil, common oil changing methods do not clean all of the sludge from an oil pan and oil strainer. When new oil is added to the engine, it mixes with the carry-over contaminants. Thus, the new oil is contaminated even before the engine begins to run. 
   U.S. Pat. Nos. 5,665,171 and 5,816,272, both to Leaphart, are directed to a method and an apparatus for cleaning an oil strainer and pan in an internal combustion engine. U.S. Pat. No. 5,190,120 to Watts is directed to a flushing apparatus for vehicle oil pump pickup tube and screen. The prior art does not address the need to not only remove the restriction and contaminants from the strainer, but also provide an effective means by which to further remove them from the oil pan by adding a strong suction at the drain plug opening. The prior art only displaces the restrictive material and normal engine operation sucks the restrictive material back into the strainer. 
   Despite these developments, there remains a need for an effective method for clearing a restricted oil strainer, removing sludge from an engine, and reducing the amount of carry-over oil contamination. 
   SUMMARY OF THE INVENTION 
   The invention relates to a method for cleaning an oil strainer in an oil pan of an internal combustion engine from which substantially all lubricant has been drained, the method comprising connecting a first conduit to said oil pan; introducing a cleaning fluid into said oil pan; connecting a second conduit to an opening on said engine; creating a circuit by a pressure pump wherein said cleaning fluid moves from said oil pan, through said opening creating enough pressure to hold open the by-pass valve in said oil pump; and then evacuating the cleaning fluid through the oil pump and oil strainer into the oil pan and then from the engine. The pressure pump, which may be a positive displacement pump, creates suction to move the cleaning fluid from the oil pan. The use of suction at the oil plug effectively removes contaminants in the oil pan. Periodic air blasts and changes in pressure create cavitation within the circuit, thereby further assisting the removal of particles. Filter media may be disposed within the conduits connecting the positive displacement pump to the oil plug and the engine. 
   The invention further relates to a method of reducing oil sludge from an internal combustion engine having an oil pump and an oil strainer disposed with an oil pan, the method comprising draining substantially all lubricant from said engine; connecting a first conduit to said oil pan; introducing a cleaning fluid into said oil pan; connecting a second conduit to an opening on said engine; creating a circuit through said conduits using a pressure pump, wherein said cleaning fluid moves from said oil pan, through said opening, through said oil strainer and back into said oil pan; and evacuating the cleaning fluid from the engine at a pressure greater than gravity. 
   Another aspect of the invention is a method for reducing the amount of carry-over oil contamination during an oil changing process for an internal combustion engine having an oil strainer and an oil pan, comprising draining substantially all lubricant from said engine; connecting a first conduit to said oil pan; introducing a cleaning fluid into said oil pan; connecting a second conduit to an opening on said engine; creating a hydraulic/pneumatic circuit with a pressure pump wherein said cleaning fluid moves from said oil pan, through said opening, through said oil strainer and back into said oil pan; filtering said cleaning fluid through a filter media disposed in said first conduit; evacuating the cleaning fluid from the engine at a pressure greater than gravity; and introducing a predetermined amount of clean oil to the engine. The pressure pump may be a positive displacement pump, and the first and second conduits may be connected to the pressure pump. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic of an engine block, illustrating the normal oil path in an engine block; 
       FIG. 2  is a partial cross-sectional view of the normal oil pathway between the oil strainer and oil filter; 
       FIG. 3  is a cross-sectional schematic of an engine block, illustrating the path of cleaning fluid in accordance with a method of the present invention; 
       FIG. 4  is a partial cross-sectional view of an engine block, the oil pan and collector showing the flow of cleaning fluid in accordance with a method of the present invention; and 
       FIG. 5  is a flow chart showing a process of cleaning an oil strainer according to a preferred embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIGS. 1 and 2 , there is illustrated a conventional automobile engine block  10   a  having a pair of engine heads  11 . Attached to engine  10  is an oil reservoir or pan  12 . Oil pan  12  holds oil that is used in the normal operation of the engine. Oil plug  14  is removably attached at the distal end of oil pan  12 . Also attached to engine  10  is an oil filter boss  16 . 
   Suspended within oil pan  12  is oil strainer  18 . Uptake tube  20  is connected to oil strainer  18  and extends to oil pump  22 . Within oil pump  22  are a pair of interconnected gears  23 . Outlet tube  24  extends from oil pump  22  to oil filter boss  16 . Filter boss  16  includes oil filter  30  which has an opening  28  to which tube  24  is sealingly connected and an outlet  32  through which filtered oil exits the oil filter  30  into releaseably attached tube  36 . Tube  36  extends from oil filter  30  and carries oil to other areas of engine block  10   a.    
   During normal engine operation, oil pump  22  draws oil that is resting in oil pan  12  through the oil strainer  18 . As oil travels through tube  20  into oil pump  22 , it passes through interconnected gears  23  which rotate and pass oil to the oil outlet tube  24 . Oil travels under pressure from oil pump  22  through tube  24  to oil filter  30 . After the oil passes through oil filter  30 , clean oil passes through tube  36  to the pressurized oil passages of the engine, such as cams  38  and mains  40 . 
   Oil pump  22  includes any type of oil pump and may be remote mounted, mounted on engine block  10   a  or the main bearing cap therefor, or built into timing covers, and may be rotated by a crank shaft or any other means. Any engine driven oil pump with an internal by-pass valve (all engine oil pumps with by-pass valves in pressure system) may be used. 
   In an embodiment of the present invention illustrated in  FIG. 3 , oil is drained from oil pan  12  by removing oil plug  14 . A predetermined amount of cleaning fluid is introduced into oil pan  12 . Preferably, the cleaning fluid is introduced to oil pan  12  through oil pan plug  14 . The cleaning fluid can be any manner of solvents, transmission fluid, detergents, 0-30 W oil or any combination thereof. Examples of appropriate solvents are products sold commercially such as GUNK® carburetor cleaner, Safe Clean, or Orange. The volume of cleaning fluid required depends upon the size of the engine  10  and oil pan  12 . Preferably, a sufficient amount of cleaning fluid is provided to suspend the contaminants present in oil pan  12  in the cleaning fluid. In an exemplary preferred embodiment, the amount of cleaning fluid used generally may be about the same as the amount of oil used during normal engine operation. 
   An important aspect of the present invention is the creation of a closed circuit through which the cleaning fluid travels in a path that is reverse the flow of oil in an operating internal combustion engine. As shown in  FIG. 4 , pressure pump  48  causes the cleaning fluid to move under pressure in the circuit. Preferably, pressure pump  48  is a positive displacement pump. However, other pumps such as air, turbine, diaphragm, rotary gear, spur gear, or gerotor pumps may also be used. Using a single pressure pump advantageously facilitates regulation of the suction and positive pressure flow. The circuit may be hydraulic or pneumatic, and in a preferred embodiment described below the circuit is hydraulic/pneumatic. 
   To create the closed circuit, one end of a suction hose  42  is sealingly connected to oil pan plug  14  (or an adaptor fitted thereto) and the other end of suction hose  42  is connected to pressure pump  48 , as shown in  FIG. 4 . Oil filter  30  is removed from filter boss  16  and an adaptor  44  seals connector  34 , thereby preventing cleaning fluid from flowing into tube  36 . A first end of pressure hose  46  is connected to opening  26 . The second end of pressure hose  46  is attached to the pressure pump  48 . 
   After the closed circuit is formed, pressure pump  48  is activated, causing the cleaning fluid to flow under pressure through the pressure hose  46  into oil pump  22 . The gears  23  of oil pump  22  will not turn in the direction reverse its rotation during normal operating conditions, so the cleaning fluid builds up within the oil pump  22  until a sufficient amount of pressure is created to force open the pressure relief valve  23   a.  Typical pressure relief valves open at about 30 psi pressure, although less pressure may be required depending upon the tolerances of the valve and possible wear. Pressure pump  48  maintains a pressure sufficient to keep pressure relief valve  23   a  open during operation of the pneumatic cleaning process. 
   The cleaning fluid travels through oil uptake tube  20  to the oil strainer  18  and into oil pan  12 . By forcing cleaning fluid under pressure backwards through oil pump  22 , the oil strainer  18  now serves as a distributor head for the pressurized fluid to cover and clean the sump area on the bottom of oil pan  12 . The cleaning fluid and contaminants exit oil pan  12  through oil plug  14  and travel through suction hose  42  to pump  48 . 
   As the fluid under pressure flows in the hydraulic/pneumatic circuit, contaminants washed off of the surface of the inside oil pan area and the oil strainer restrictive materials are washed loose and sucked out through the suction side of the hydraulic/pneumatic circuit through suction hose  42  which is attached to oil plug  14 . 
   Advantageously, an air injection valve may be added proximate to pump  48  for the operator to intermittently blast air into the liquid line to knock, dislodge, or blow any obstructions loose that may be accumulating in oil strainer  18 . This process may assist in moving any loose material toward the suction line attached to oil plug  14  of oil pan  12 . The air blast can also accelerate the flow of the cleaning fluid. Air blast pressure is dependant on available shop air pressure, but generally should be at a minimum of generally 45 psi, or at least greater than the pressure of the cleaning fluid. In some embodiments, the air blast is at a pressure of at least about 110 psi. Pressure above that point may be acceptable if regulated properly. Any safe fluid pressure capable of removing unwanted material in its path is acceptable. 
   In an embodiment of the invention, a vent to atmosphere (VTA) valve assembly is provided to vent the suction side of the pressure pump to atmosphere for a brief, timed instance, causing the pump to cavitate and condense the air bubbles, sending them through the oil pump and on through the suction tube and strainer, thereby aiding in removing restrictions from the strainer surface area. Optional heating of the cleaning fluid above 140° F. may be beneficial. Internal pulsation of the fluid is also desirable. 
   The course of the fluid/air/cavitation process is as follows: through oil filter boss  16 , through by-pass valve  23   a  in oil pump  22 , through tube  20  and oil strainer  18 , into oil pan  12  and through suction hose  42 . Pulsation of the fluid, heated or non-heated, is very beneficial as it does an excellent job of cleaning oil strainer  18  and bottom of oil pan  12 . 
   In a preferred embodiment of the present invention, filter media is placed within suction hose transverse to the flow of cleaning fluid. The filter media may be removeably attached to suction hose  42  and may be periodically disconnected to remove contaminants from the cleaning fluid. Optionally, more than one filter media may be placed in the path of the hydraulic/pneumatic circuit. 
   As shown in  FIG. 5 , a process for cleaning an oil strainer according to a preferred embodiment of the present invention includes: heating the engine, draining oil from the engine, selecting a drainplug adaptor, removing the oil filter and installing a filter adaptor, attaching a hose to the drainplug adaptor, attaching the hose to the filter adaptor, filling the oil pan with cleaning fluid, activating the pump, cycling air blast and pressure, and suction cleaning fluid from the oil pan. 
   It will be appreciated by one skilled in the art that the invention is useful for removing oil sludge from an internal combustion engine. It may also be beneficial to perform the claimed method of at least twice, such as a second time after the engine has been allowed to operate and additional contaminants have moved from the top of the engine to the oil pan and oil strainer. 
   It will also be appreciated by one skilled in the art that the invention is particularly useful for reducing the amount of carry-over contamination that occurs during the oil change process. The invention permits a more complete removal of contaminants than oil change methods that rely upon gravity to evacuate the oil pan. In most oil pans found in internal combustion engines, oil plug  14  is not located at the lowest point of oil pan  12 . Therefore, when oil is drained by gravity through oil plug  14 , a substantial amount of dirty oil remains in oil pan  12 . When clean oil is added to the engine, it contacts the contaminated oil and, as a result, itself becomes contaminated. The present invention substantially reduces the amount of carry-over oil contamination. 
   It will be obvious to one of ordinary skill in the art that various modifications and variations can be made without departing from the scope of the invention as defined in the following claims.

Technology Classification (CPC): 5