Engine air purge apparatus and method

An apparatus for changing oil in a vehicle having an internal combustion engine with lubrication passages, the apparatus having a system for air purging the lubrication passages to expediently remove the oil. The apparatus includes a pressure transducer in the fluid line of the air purge system to monitor a pressure drop of the compressed air when the spent oil has been removed from the engine. When the pressure drop exceeds a predetermined value the air purge system automatically deactivates.

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.

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.sub.1 " before the compressed air reaches the full
 pressure "P" when entering the internal combustion engine 10. After this
 elapsed time "T.sub.1 ", the transducer 44 monitors the pressure of the
 compressed air over a very short interval of time "T.sub.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 .DELTA.P. 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 .DELTA.P 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 .DELTA.P 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.