Abstract:
An improved crankcase ventilation system including an improved blow-by gas separator wherein it will be insured that oil cannot accumulate in the separator chamber under any running conditions so that the oil is totally precluded from being able to pass into the induction system.

Description:
BACKGROUND OF INVENTION 
     This invention relates to a blow-by gas separator and more particularly to an improved separation system for use with internal combustion engines in connection with crankcase gas recirculation. 
     In order to improve the emission qualities of internal combustion engines, they have been provided with recirculated crankcase ventilation systems wherein the blow-by gases from the crankcase are returned to the combustion chambers for further combustion of undesirable constituents such as hydrocarbons. The conventional type of system employs a combined oil separator and oil return device that receives the crankcase gases and separates oil from them with the separated oil being returned to the crankcase chamber. The thus purified crankcase gases are then delivered to the induction system for introduction into the combustion chambers wherein any unburned hydrocarbons that have not been separated can be reduced by further combustion. 
       FIGS. 1 through 3  are cross sectional views taken through a portion of the induction system utilized in conventional engines wherein the crankcase ventilation system is shown partially and identified generally by the reference numeral  21 . The crankcase ventilation system  21  includes an oil separator, indicated generally by the reference numeral  22 . This oil separator  22  is positioned in a first conduit  23  that receives crankcase gases from the crankcase ventilation system via a positive crankcase ventilation valve, which is not shown in this figure, in the flow direction indicated by the arrow A in FIG.  1 . 
     The oil separator  22  is comprised of an outer housing that defines an oil separating chamber  24  which functions to remove oil from the blow-by gases in any suitable manner. In these and subsequent figures, a centrifugal type separator is depicted wherein the crankcase gases are delivered in a tangential direction to the chamber  24  so that the swirling will cause oil to deposit on the inner wall of the chamber. Of course, there are other types of oil separators with which this invention can be utilized. 
     The crankcase gases from which the oil is separated are then returned to the induction system through the conduit  21  and specifically through a return path  25  that flows in a direction indicated by the arrow B in FIG.  1 . At the lower end of the separation chamber  24 , there is provided an oil accumulating or oil return chamber  26 . This chamber  26  communicates with the lower part of the separator  24  through a flow opening  27 , which is valved by a drain valve  28 . The drain valve  28  is pressure responsive and opens and closes in response to differences in the pressure in the chambers  24  and  26  (intake pressure and crankcase pressure). 
     The oil return chamber  26 , in turn, has a discharge opening that communicates with the crankcase chamber through an oil return line  29 . This opening is controlled by a pressure responsive valve  31 , which, in most instances, is of the duck bill type and will open in response to pressure differences between the oil reservoir  26  and the oil return line  29 . 
     Basically, the theory of operation is that as the engine is running, oil will be separated in the oil separator chamber  24  and under some running conditions will flow to the return chamber  26  when the pressure responsive valve  28  is opened as shown in FIG.  1 . Under other running conditions, the pressure in the oil return chamber  26  will be greater than the pressure in the crankcase chamber and return line  29  and the check valve  31  will open and the oil will be returned to the crankcase. 
     However, the desired performance does not always occur under all running conditions and with all engines, particularly with engines where pressure in the induction system can at times be greater than atmospheric. This happens with supercharged engines of various forms such as turbocharged engines although it may occur in other types of engines as well. 
     The problem with this type of construction can be best understood by reference to  FIGS. 1 through 3  with  FIG. 1  showing the condition in a normal engine having a pressurized induction system such as a turbocharged engine when operating at idle.  FIG. 2  shows the condition when operating under full load with the throttle open.  FIG. 3  shows how the problem can arise with this type of construction. 
     Referring first to  FIG. 1 , when the engine is operating at idle, the crankcase ventilating gases from the PCV valve are delivered through the conduit  23  to the separator chamber  24  as shown by the arrow A. When this occurs, the pressure in the intake manifold is in the range of −70 to −60 kPa. At that time, the pressure in the crankcase chamber and the conduit  29  will be in the range of −0.2 to 0 kPa. Thus, under this condition, the pressure in the crankcase chamber is always higher than the pressure in the intake chamber and hence, the pressure responsive valve  28  will be opened and oil can flow through the passage  28  to accumulate in the oil return chamber  26  as shown by the shaded area indicated in the oil in this figure. As a result, no oil will be accumulating in the separator chamber  24  and oil free crankcase ventilating gases will be returned to the induction system so that any hydrocarbons that are present can be burned by further combustion in the combustion chamber. 
     As the load on the engine increases and the throttle valve is opened, the pressure in the intake manifold and hence, conduit  23  can rise to pressures in the range of −50 to +90 kPa. Under the same conditions, the crankcase chamber pressure ranges from −6.5 to +0.5 kPa. When this occurs, the check valve  28  will close as shown in FIG.  2  and when the pressure in the crankcase chamber is below the trapped pressure in the oil reservoir chamber  28 , the drain check valve  31  will open and oil can flow to the crankcase. This does not occur, under all running conditions, however. 
     Thus, there may exist a condition where oil has been accumulated in the return chamber  26  as shown in  FIG.1 , but the pressure in the induction system is high enough to close the pressure response valve  28  before the drain check valve  31  has had a chance to open. As a result, further oil will accumulate in the separator chamber  24  and this oil can then pass into the induction system, a condition which is not desirable. 
     It is, therefore, a principal object to this invention to providean improved crankcase ventilation system including an improved blow-by gas separator wherein it will be insured that oil cannot accumulate in the separator chamber under any running conditions so that the oil is totally precluded from being able to pass into the induction system. 
     SUMMARY OF INVENTION 
     This invention is adapted to be embodied in a crankcase ventilation oil separator for an internal combustion engine. The separator comprises a housing defining an oil separation chamber having a blow-by inlet receiving crankcase blow-by gasses from the associated engine. A separated gas return delivers gasses from which oil has been separated to an induction system of the associated engine. A separated oil receiving chamber is formed at a lower portion of the oil separation chamber for receiving oil separated from the crankcase blow-by gasses. An oil return passage is formed in a lower portion of the separated oil receiving chamber communicating with the crankcase of the associated engine. The oil return passage includes a flow opening for providing the communication with the crankcase of the associated engine. A pressure responsive flow control valve controls the flow through the flow opening. The pressure responsive valve comprises a first valve element disposed on one side of the flow opening and a second, interconnected valve element disposed on the other side of the flow opening. The first valve element restricts the flow opening when the pressure in the oil separating chamber is greater than the pressure in the oil return passage, The second valve element restricts the flow opening when the pressure in the oil return passage is greater than the pressure in the oil separating chamber. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1-3  are cross sectional views taken through a prior art type of blow-by gas oil separator under such running conditions as idle (FIG.  1 ), open throttle (FIG.  2 ), and the resulting problem with this type of device (FIG.  3 ). 
         FIGS. 4 and 5  are cross sectional views of an internal combustion engine having a blow-by gas oil separator constructed in accordance with the invention under such running conditions as partially open throttle ( FIG. 4 ) and wide open throttle (WOT) (FIG.  5 ). 
         FIGS. 6-8  are cross sectional views in part similar to  FIGS. 1-3 , but showing how a first embodiment of the invention avoids the problem of the prior art under the same running conditions. 
         FIGS. 9-11  are cross sectional views in part similar to  FIGS. 1-3  and  6 - 8 , but showing how a second embodiment of the invention avoids the problem of the prior art under the same running conditions. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now in detail to the drawings and initially to  FIGS. 4 and 5 , these are cross sectional views taken through a single cylinder of an internal combustion engine constructed in accordance with an embodiment of the invention, which engine is indicated generally by the reference numeral  51 . Basically, except for the crankcase ventilation system and the oil separator therefore, the engine  51  may be of any general type and although the invention has particular utility in conjunction with engines that are either supercharged by turbo charging or otherwise. 
     The engine  51  includes a cylinder block assembly  52  in which a plurality of cylinder bores are formed. Although the described embodiment illustrates an in-line engine, it should be readily apparent that the engine may be of any type including V-type or opposed engines and engines having any number of cylinders. At the lower end of the cylinder block  52  there is formed a crankcase chamber  53  in which lubricant is contained at a level indicated at  54 . A crankshaft  55  driven by the pistons of the engine through connecting rods is rotatably journalled in the crankcase chamber  53  in a known manner. 
     A cylinder head assembly, indicated by the reference numeral  56 , is affixed to the cylinder block  52  in a suitable manner, including an integral construction. The cylinder head assembly  56  contains the intake and exhaust valves for the engine, which are not shown, and which are operated by camshafts contained within cam chambers  57  and  58  associated with an exhaust camshaft  59  and an intake camshaft  61 , respectively. 
     The engine  51  is provided with an induction system many components of which are shown schematically for the aforenoted reasons (ie., they may be of any desired type). This includes an air inlet device  62  that may include a filter and which supplies this atmospheric air to the inlet side of a turbocharger, indicated generally by the reference numeral  63 , through an intake pipe  64 . The turbocharger  63  is driven by an exhaust turbine as is well known in this art and compresses the inducted air. 
     The compressed air is discharged through the turbocharger outlet  65  to an intake manifold plenum chamber  66 . This plenum chamber  66  has individual runner sections  67  that extend to the intake ports of the engine, which are valved by the aforenoted poppet valves, controlled by the intake camshaft  61 . 
     Lubricating oil is circulated through the engine  51  in any appropriate manner. The engine body is provided with a pair of communication passages  68  and  69  on the exhaust and intake sides respectively that communicate the valve chambers  57  and  58  with the crankcase chamber  53  and which permit return oil to flow thereto as well as ventilating air circulation, as will be described. 
     The turbocharger  63  may be also lubricated and it has a return path  71  that extends from its lubricant sump back to the crankcase chamber  53 . 
     The engine  51  is provided with a crankcase ventilating system which includes a PVC valve  72  that is mounted in an exhaust cam cover  73  fixed over and clothing the exhaust cam chamber  57 . This PVC valve  72  delivers blow-by gases as shown by the solid line arrows to a pair of conduits  74  and  75  which extend to the inlet and outlet sides of an oil separator, indicated generally by the reference numeral  76 , and which has a construction as will be described shortly by reference to either  FIGS. 6 through 8  and  9  through  11 . 
     The conduit  75  delivers the ventilating gases back to the intake system for example to the intake runners  67  or any other appropriate location as is known in this art. Oil removed by the separator  76  is returned, in a manner to be described, to the crankcase chamber  53  through a return conduit  77 . 
     The ventilating system includes a further ventilating path which is operates to provide atmospheric air to the engine under certain running conditions such as idle or less than wide open throttle. This includes an inlet conduit  78  that extends from a second oil separator, also indicated by the reference numeral  76 , and second conduit  79 , which communicates with the intake camshaft chamber  58 . 
     For oil draining purposes, an oil drain  81  extends from the second vapor separator  76  to the supercharger return line  71  and, accordingly, to the crankcase chamber  53 . Under these other certain running conditions, all of the ventilating air will flow through both of these paths. 
     On the other hand, when operating under wide open throttle when the intake manifold pressure is higher than the crankcase chamber pressure the flow path is as shown in FIG.  5 . In this condition, the intake air for the ventilating system is delivered through the PVC valve  72  a shown by the white arrows in  FIG. 5  from the first vapor separator  76  disposed on the intake side of the engine. This atmospheric air is drawn from the intake system and specifically one or more of the intake manifold runners  67  and flows through the conduits  75  and  74  into the exhaust cam chamber  57  through the PVC valve  72 . 
     Under this condition, the blow-by gases are delivered to the induction system upstream of the turbocharger  63  through the passages  79  and  78  and the second oil separator  76  associated with the exhaust side of the engine. Thus, it should be radially apparently that the construction permits a very effective flow of filtered atmospheric air to the crankcase chamber  53  for ventilation under all running conditions and also insures that any oil contained in the crankcase gases that are discharged back into the induction system will be separated by either or both of the separators  76 . 
     The construction of one embodiment of the separators  76  will now be described by reference to  FIGS. 6 through 8 . In this embodiment, the separator  76  is identified generally by the same reference numeral and includes an outer housing that forms an oil separation chamber  82  that communicates with the engine ventilation system through conduits indicated generally at  83 . In the case of the vapor separator associated with the exhaust chamber  57 , these includes the conduits  74  and  75  while if it is the separator  76  associated with the intake chamber  58 , it would include the conduits  78  and  79 . The former numbers are employed in the description of this embodiment. 
     Unlike the prior art arrangements, the lower end of the oil separation chamber  82  communicates with a valve mechanism, indicated generally by the reference numeral  84  which includes an internal chamber that is divided into an upper portion and a lower portion by a dividing wall  85  having a flow opening  86  formed therein. The upper of these two portions above the wall  85  communicates with the discharge end of the oil separating chamber  82  through a restricted by un-valved opening  87 . The lower portion below the wall  85  communicates with a discharge nipple  88  which communicates with either of the oil return passages  77  or  81  of the previously mentioned constructions in  FIGS. 4 and 5  and thus returns oil to the crankcase chamber  53 . 
     The valve mechanism  84  further includes an upper disk valve  89  and a lower disk valve  91  that are interconnected to each other in spaced relationship by a cylindrical portion  92  that passes through the opening  86  with a substantial clearance. Under normal idle operation as shown in  FIG. 6 , the crankcase pressure is greater than the induction system pressure and the valve disk  91  is held in flow restricting position with the underside of the wall  82  and, in this embodiment, completely closes the opening  86 . Thus, the separated oil will accumulate as indicated by the oil level “Oil” in this figure. However, the amount of accumulated oil is such that the oil will be separated from the separator chamber  82  by the restricted opening  87 . Thus this separated oil cannot reenter the induction system for ventilating air. 
     Under normal running off idle as shown in  FIG. 7 , the valve disk will be moved between the position shown in FIG.  7  and the position shown in FIG.  8 . Thus, for the most part the passage  86  will be maintained opened and can drain oil. Even during those periods when it is closed, as shown in  FIG. 8 , the amount of accumulated oil will be relatively small and still well below the opening  87  so reentry to the ventilating air is not permitted. 
       FIGS. 9 through 11  shows another embodiment, which is substantially the same as embodiment of  FIGS. 6 through 8 . For that reasons, components of this embodiment, which are the same, have been identified by the same reference numerals and will not be described again. 
     In this embodiment, the condition shown in  FIG. 8  is precluded by providing a small slotted opening  101  on the upper surface of the wall  85  from an area radially outwardly beyond the periphery of the valved disk  89  so that even when the valve is in its flow restricting position of  FIG. 11 , an oil drain clearance  102  will be provided so that oil can continue to drain. Thus no oil will be accumulated that could in any way enter the ventilating air system. 
     Thus, from the foregoing description, it should be readily apparent that the described embodiments of the invention provide a very effective oil separation system for the crankcase ventilation of an engine and particularly one such as a supercharged engine when at times the intake manifold pressure may be greater than the pressure in the crankcase chamber. Thus, the problem of oil accumulation with the previously proposed types of devices are avoided. Of course, the foregoing description is that of preferred embodiments of the invention and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.