Patent Publication Number: US-6213173-B1

Title: Engine air purge apparatus and method

Description:
This application claims priority of provisional patent application 60/081,872 filed on Apr. 15, 1998. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to an apparatus and method for purging engine oil filters and lubricating passages with air during the oil changing procedure of a vehicle. More particularly, this invention relates to a method for sensing and controlling the pressure when air purging the lubrication passages to expediently remove the oil therefrom. 
     BACKGROUND OF THE INVENTION 
     The benefits of routine oil changes in an internal combustion engine are well known. Routine oil changes have been shown to increase engine life and performance. With repeated prolonged use, motor oil builds up suspended particles, metallic and non-metallic, from the abrasive and adhesive wear of engine parts against one another and from products of incomplete combustion and improper air intake. The particles in turn cause abrasive wear of the engine bearings, piston rings and other moving parts and the reduction of the motor oil lubricity as various additives and lubricating components become depleted. This adversely affects engine performance and if left unchanged can destroy or cripple the engine performance. It is recommended by at least one oil manufacturer that the level of total solid concentration be limited to levels below 3.0%. 
     To obtain satisfactory engine performance, and maintain solids concentration levels in the motor oil lower than the recommended 3.0%, changing the motor oil in an internal combustion engine is necessary. In currently designed vehicles, the oil pan serves the purpose of a reservoir for circulation of engine oil. Engine lubrication is generally accomplished through a gear-type pump. Oil from the pump passes through the oil filter before going to the engine oil galleries from where it provides lubrication to the various engine components. 
     To remove the contaminated oil, the drain plug, generally located in the lowermost region of the oil pan, is opened. The spent oil containing suspended particles is permitted to flow under gravity out of the pan into a suitable receptacle. After the spent oil is removed, the plug is replaced and fresh oil is added to the engine through a separate opening in the engine valve cover. The process of gravity drainage does not remove all of the spent oil with its metallic and non-metallic particles which stick to the oil pan container walls, as well as engine components such as the crank shaft, connecting rods, pistons and the like which are exposed to the motor oil spray lubrication. These particles remain to be mixed with fresh motor oil Thus the concentration of contaminants is lowered by dilution and only a part of the total contaminates are actually eliminated. 
     Therefore, it would be desirable to provide a method which removes spent oil more completely and easily from the internal combustion engine. It would also be desirable to provide a system which reduces the amount of spent oil handling as required in the conventional oil change service method. 
     It is further desirable to provide an automated system that includes a source of compressed air and a means for supplying the compressed air for purging fluid from the internal combustion engine. It is finally desirable to provide a means for automatically sensing and controlling the air pressure inside the crankcase as well as deactivating the compressed air at a predetermined time to prevent over pressurizing of the crankcase and thereby adversely affecting the seals. 
     SUMMARY OF THE INVENTION 
     The present invention includes an apparatus for changing oil that is external and separable from the internal combustion engine. The external device would be operably connectible to fresh oil storage means and waste oil storage means. The external apparatus preferably includes air purge means for purging fluid retained within the oil filter and any fluid remaining in the lubrication system passages of the internal combustion engine, such that all waste fluid can be deposited within the oil pan reservoir. The pump means of the external apparatus draws waste fluid from the oil pan reservoir for deposit in the appropriate waste storage means. 
     In operation, the present invention provides a method for quickly and efficiently removing waste oil from an internal combustion engine and replenishing the lubrication system of the internal combustion engine with fresh oil. Additionally, the present invention provides purging of fluid from the oil filter and lubrication passages of the internal combustion engine with pressurized air means. The current invention provides a means for deactivating the compressed air after purging the engine oil filter and lubrication passages of liquid in order to prevent overpressurizing of the crankcase. 
     The means for deactivating the air purge includes a computer monitored program. The computer monitors the air pressure leaving the oil changing apparatus. When the purged air initially enters the oil filter and lubrication passages, there will be resistance and a corresponding back pressure due to the fact that the filter and passages are still full of oil. This initial back pressure is averaged over the first few seconds and this becomes the average base pressure. The purge air pressure gradually forces the oil out of the filter and passages into the oil pan. As the passages are being cleared, the resistance will decrease, resulting in a corresponding drop in back pressure. At the same time the air will enter the crankcase, which may result in the build up of pressure inside the crankcase. Crankcases are typically equipped with positive crankcase ventilation devices (PCV valves), which prevent overpressurizing of the crankcase, which may cause seals to fail, resulting in loss of lubricating oil. It is desirable however to have an additional safeguard to prevent pressure buildup resulting from the purge air entering the crankcase, in case of malfunction of the PCV device. The present invention monitors the back pressure of the purge air and deactivates the flow of purge air when the pressure drop exceeds a certain predetermined value from the average base pressure. Thus the present invention will ensure the completion of the purging of the oil filter and passages, while preventing undesirable pressure build up inside the crankcase. 
     Other modifications, characteristics, features and benefits of the present invention will become apparent upon reading the following detailed description of the invention in conjunction with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
     FIG. 1 is a schematic view of an oil change apparatus incorporating the air purge pressure sensing and control apparatus of the present invention; 
     FIG. 2 is a flow chart of the method for sensing and controlling the air purge pressure during the oil change procedure; 
     FIG. 3 is a graph of the relationship of compressed air pressure and crankcase pressure during the air purge procedure; and 
     FIG. 4 is a schematic view of the air purge system of the current invention in the oil change apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In an oil changing apparatus such as disclosed in U.S. Pat. No. 5,062,398 issued to the subject inventors and incorporated herein by reference, one or more coupling connections from the apparatus  14  may be connected to the internal combustion engine  10  to facilitate proper connection of the external oil changing apparatus  14  to the lubrication system of the engine  10 . In the broadest sense, one coupling connection  16  will be in fluid communication with the lowermost portion of the oil pan reservoir  18  for draining the spent and waste oil therefrom. A second coupling connection  20  will be located in fluid communication with the internal oil lubrication distribution passage system  22 , preferably between the oil pump  24  and the oil filter element  26 . Preferably both coupling connections  16 ,  20  will be provided with quick connect couplings as is conventional and known in the art. The oil changing apparatus  14  is connectible to a plurality of external storage means. Storage means includes a waste oil storage receptacle  28  and a fresh motor oil supply receptacle  30 . The oil changing apparatus  14  also includes a connection to a source of compressed air  32 , an electrical connection to a power source  34  and connection to a computer or control module  36 . The connection to the source of compressed air  32  is controlled by appropriate valve means for opening and closing the communication of the compressed air with the oil changing apparatus  14 . The oil changing apparatus  14  further includes pump means (not shown) for evacuating fluid from the internal combustion engine  10  and pump means for introducing fluid into the internal oil lubrication distribution passage system  22  of the internal combustion engine  10 . 
     In operation the internal combustion engine  10  is brought into proximity with the oil changing apparatus  14 . A fluid conduit hose  35  having a preferably quick connect coupling  16  is connected to the appropriate outlet connection  37  of the internal combustion engine  10  for drawing fluid from the reservoir of the internal combustion engine. A second hose  38  with a second preferably quick connect coupling is connected to the appropriate connection  40  of the internal combustion engine  10  for introducing fluid into the internal combustion engine  10  through the filter  26  and the internal oil lubrication distribution passage system  22  of the internal combustion engine  10  for subsequent accumulation in the oil pan reservoir  18  of the internal combustion engine  10 . 
     Pump means is energized to draw fluid from the oil pan reservoir  18  of the internal combustion engine  10  for discharge into the spent/waste oil storage receptacle  28 . At the same time, a control valve  59  (FIG. 4) is energized to provide flow and actuation of pressurized air  32  into the system to purge fluid from the oil filter  26  and lubricating passages  22  thereby causing the residual spent oil retained within the filter and lubricating passages  22  to be discharged  22  to the oil pan reservoir  18  of the internal combustion engine  10 . Various filters  52 ,  54  are provided to ensure that the pressurized air  32  is clean and moisture is removed therefrom. Check valve  42  in the fresh oil line prevents air from entering into the oil line during the purge process and check valve  43  in the purge air prevents oil from entering into the air line during the oil replenishing process. Air forces oil out of the oil filter and lubricating passages  22  by the compressed air  32  prior to being deposited in the oil pan reservoir  18  of the internal combustion engine  10 . Currently, the compressed air  32  is deactivated after a predetermined time monitored by the computer  36 . The improvement of the current invention to the oil changing apparatus as described with more detail in U.S. Pat. No. 5,062,398 is to provide an alternative means and method for determining when to deactivate the air purge system by anticipating or measuring the pressure in the crankcase  18 . A general relationship of the compressed air pressure and the crankcase pressure during the oil evacuation and compressed air purge portion of the oil changing procedure is shown in FIG.  3 . Initially during the evacuation portion, the crankcase pressure  70  is negative or is a vacuum. The compressed air purge pressure at the oil change apparatus  14  is a relative constant pressure predetermined by the operator. When the purge air has cleared the engine oil filter and lubrication passages, the purge air enters the crankcase, and the compressed air pressure at the oil changing apparatus drops. At the same time the air entering the crankcase may cause the pressure of the crankcase to increase. To prevent overpressurizing of the crankcase which can adversely affect the engine seals, the compressed air pressure should be deactivated before the crankcase pressure rises to an unacceptable level. One method to determine this event is to provide a pressure transducer  55  located in the oil reservoir  18  that can be monitored for crankcase pressure. When the crankcase pressure reaches a certain predetermined level, the compressed air pressure can be deactivated. The transducer  55  in the oil reservoir  18  therefore requires an electrical connection from the transducer  55  to the oil changing apparatus  14  so that the computer  36  of the oil change apparatus  14  can monitor the crankcase pressure to determine when to deactivate the compressed air. When the crankcase pressure reached a predetermined value the computer  36  would deactivate the compressed air  32 . 
     Another method is to provide a look-up table in the computer  36  so that based upon certain parameters such as engine, size vehicle model, etc. the air compressor is deactivated after a predetermined time interval. Each parameter will have a specific time interval assigned based upon previous test data which included monitoring of crankcase pressure. It is also conceivable to provide a single time interval for all parameters. The time interval will be an amount that would be safe for even the smallest engine. A clock in the computer will count down the time and the computer would deactivate the air purge when the time on the clock equals zero. Although, this method would not optionally discharge all of the residual spent oil through the internal oil lubrication distribution passage system, the added spent oil discharged into the oil reservoir would significantly lower the concentration of contaminants mixed with the fresh oil. 
     An alternative and preferred method as shown in FIG. 2, is to use the relationship of the crankcase pressure and the compressed air pressure as shown in FIG. 3 such that a transducer  44  is put in line of the air purge system of the oil changing apparatus  14  (FIG. 4) to monitor the pressure drop of the compressed air when the spent oil has been removed from the engine  10 . Therefore the improved method includes activating the pump to draw fluid from the oil pan reservoir  18  of the internal combustion engine  10  for discharge into the spent oil storage receptacle and activating the delivery of the compressed air by activating valve  59 . Initially there is a short time elapse “T 1 ” before the compressed air reaches the full pressure “P” when entering the internal combustion engine  10 . After this elapsed time “T 1 ”, the transducer  44  monitors the pressure of the compressed air over a very short interval of time “T 2 ”, and takes multiple pressure readings during the short interval. The multiple pressure readings are then averaged. This average will provide a base value for the initial pressure of the compressed air “P”. A percentage threshold pressure drop AP of the compressed air will have been previously determined to indicate that the spent oil has been removed from the oil filter and passages and that the crankcase pressure may start to rise. 
     After the base value pressure “P” has been established, the compressed air  32  will be continually read and monitor at specified intervals while the engine  10  is being purged of oil. The monitored air pressure  32  will be compared to the base value air pressure and determined whether the difference exceeds the percentage threshold pressure drop ΔP. When the percentage threshold pressure drop has been met or exceeded, the oil changing apparatus  14  will automatically deactivate the compressed air purge. The percentage threshold pressure drop ΔP may have been calculated from previous test data, which closely monitored the relationship of pressure in the air purge system with crankcase pressure. The percentage threshold pressure drop ΔP may be a single value for all engines and vehicles or may be a unique value for each engine configuration. 
     After the oil pan reservoir  18  of the internal combustion engine  10  has been emptied, and the compressed air purge has been deactivated, the filter element  26  of the internal combustion engine  10  can be removed and replaced with a clean filter element  26 . Fresh oil can then be introduced into the internal oil lubrication distribution passage system  22  by actuating a directional control valve (not shown) to allow flow to draw fresh motor oil from the fresh oil supply receptacle  30  for discharge into the internal combustion engine through the oil filter element  26  and internal oil lubrication distribution passage system  22  for accumulation in the oil pan reservoir  18  of the internal combustion engine  10 . When an adequate amount of fresh motor oil has been delivered to the internal combustion engine the quick disconnect couplings are disconnected from the internal combustion engine. The internal combustion engine  10  is now ready for normal use with the oil filter element being precharged with fresh oil and engine components prelubricated prior to starting the engine. 
     While the invention has been described in detail, it will be apparent to those skilled in the art that the disclosed invention may be modified. Therefore, the foregoing description is to be considered exemplary, rather than limiting and the true scope of the invention is that defined in the following claims.