Abstract:
A PCV valve that also monitors the flow of gases produced by use of a turbocharger. A spring biased plunger member is used to restrict and meter the flow of gases through the PCV valve. A nozzle member with a Venturi throat is used to allow back flow caused by use of a turbocharger. The nozzle member can be part of a module including a passageway member that can be closed by the plunger member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/698,207, filed Sep. 7, 2012, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to PCV valves, particularly for use with engines with turbochargers. 
     BACKGROUND OF THE INVENTION 
     The Positive Crankcase Ventilation (PCV) valve is a part of the PCV system where the engine passes harmful crankcase combustion gases to the air intake. Instead of venting the crankcase gases to the atmosphere, they are fed into the intake manifold where they can be re-entered into the engine combustion chambers as part of the air/fuel mixture and burned. This results in lower pollution and extended engine oil life. PCV valves act as both a crankcase ventilation system and as a pollution control device. 
     The PCV valve performs a complicated, but necessary, control function and can act to restrict the amount of air passing through it. When the engine is running under light loads, the intake manifold air pressure is less than the crankcase air pressure. Under these conditions, the crankcase gases are drawn through the PCV valve and into the intake manifold. 
     At idle, the intake manifold vacuum is near maximum. This results in the least amount of blow-by and the PCV valve provides the largest amount of restriction. As engine load increases, vacuum on the valve decreases proportionally and blow-by increases proportionally. At a low level of vacuum, the PCV valve allows more air flow. 
     When the engine is running at wide open throttle, the manifold pressure is about the same level as the engine crankcase, and the function of the PCV valve is minimal. When the manifold pressure is considerably higher than that of the crankcase, the PCV valve is closed to prevent reversal of the exhausted gases back into the crankcase. 
     The operation of a turbocharger in a turbocharged engine is similar to that of an engine running at wide open throttle. During boost from a turbocharger, additional pressure is built up that needs to be relieved. 
     It is an object of the present invention to provide an improved PCV valve for use in engine systems which have turbochargers. 
     SUMMARY OF THE INVENTION 
     The present invention provides a PCV valve with a tubular-shaped outer housing, a spring biased plunger member and two passageways for passage of gases. In accordance with a preferred embodiment of the invention, the plunger has a tapering narrow end which is positioned in an annular washer. As the plunger moves longitudinally in the housing, it acts as a restrictor valve to regulate the amount of crankcase combustion air which can pass to the intake manifold. 
     Also in accordance with a preferred embodiment of the invention, a first passageway member is positioned below the plunger. The lower end of the plunger is positioned to close the first passageway when the pressures of the crankcase and manifold are approximately equal. A second passageway is positioned adjacent the first passageway and preferably has an internal Venturi nozzle. An orifice can also be used depending on the flow curve desired. The second passageway allows air flow due to the turbocharger to pass through the housing in a controlled manner. 
     Additional features and benefits of the present invention will become apparent from the following description of the preferred embodiment of the invention when viewed in accordance with the attached drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a PCV valve in accordance with a preferred embodiment of the invention. 
         FIG. 2  is a cross-section of the PCV valve in  FIG. 1 . 
         FIG. 2A  depicts an enlarged view of the nozzle member as shown in  FIG. 2 . 
         FIG. 3  is an expedited view of the components of the PCV valve of  FIG. 2 . 
         FIG. 4  is a cross-sectional view taken along lines  4 - 4  in  FIG. 2 . 
         FIG. 5  is a cross-sectional view taken along lines  5 - 5  in  FIG. 2 . 
         FIG. 6  is a cross-sectional view taken along lines  6 - 6  in  FIG. 2 . 
         FIG. 7  is another cross-sectional view of a preferred embodiment of the invention when in operation; 
         FIG. 8  is a cross-sectional view taken along lines  8 - 8  in  FIG. 7 . 
         FIGS. 9 and 10  are additional cross-sectional views of an embodiment of the invention in different operational situations. 
         FIG. 11  depicts another embodiment of the invention. 
         FIG. 12  is a graph depicting flow rates. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIGS. 1 and 2  depict a preferred embodiment  20  of the PCV valve invention.  FIG. 1  is a perspective view highlighting the tubular shape of the PCV housing member  22 .  FIG. 2  is a cross-sectional view of the PCV valve  20 . The housing member  22  is preferably made of plastic in two or more sections, and preferably made by injection molding. The housing  22  has a central elongated cavity or passageway  24 . The cavity has a first section  26  and a second section  28 . The second section  28  has a larger diameter than the first section  26  for a reason that will become apparent from the description below. 
     The housing member  22  has a first end  30  which is adapted to be connected to a tube or the like (not shown) for passage of crankcase combustion gases to an intake manifold. For purpose of securely connecting or attaching the housing member at the first end  30  to a tube or the like, a pair of annular flanges  32  and  34  can be provided. It is to be understood, however, that any other conventional ways of connecting or attaching the PCV housing to a manifold can be utilized. 
     The housing member  22  also has a second end  40  which is adapted to be connected to the crankcase or to another member which is associated with the crankcase or engine. The second end  40  as shown in the drawings is provided with a cam-twist structure  42  for secure connection to a conventional crankcase cover member (not shown). 
     The second end  40  also has a third annular flange member  44  which is used to assist in securely attaching the PCV valve to the crankcase or other accessory. An O-ring  50  positioned in annular groove  52  is also provided adjacent the second end  40  in order to seal the attachment of the PCV valve to the crankcase or crankcase cover. 
     In order to assist in securely attaching the PCV valve in place, one or more of the annular flanges can have flattened areas for mating with a wrench or other tool. In the drawings, flange member  34  is depicted as having such flat areas  35  for that purpose. 
     As shown in the Figures, particularly  FIG. 3 , the PCV valve includes a housing member  22 , a plunger member  60 , a spring member  70 , a washer member  75 , an O-ring member  50 , and a co-passageway module  80 . These components are also shown in one or more of  FIGS. 2 and 4-10  and indicated by the same reference numerals. 
     The plunger member  60  is preferably made of a metal material, such as cold formed steel, although the plunger member could be made of a plastic material or any other material that would accomplish the same purpose and operation. The member  60  has a body portion  62 , a narrower end portion  64  and a lower flange or base member  66 . The narrow end portion  64  is provided to fit within the center opening of washer member  75 . 
     It is also to be understood that the form and shape of the plunger and spring assembly shown in the drawings is merely exemplary. There are numerous plunger and spring assemblies for PCV valves known in the art, such as ball and spring mechanisms, which can be used in the present invention. 
     The washer member  75  is preferably any standard metal washer and is fixedly attached in the sidewall of the housing member  22  in the cavity  26 . Preferably, the washer member  75  is insert molded in the housing when the housing is injection molded. It should be noted that the washer could also be made from plastic or other material that fits the function. 
     The spring member  70  is preferably a metal coil spring as shown in the drawings, but can be any type of biasing member that would accomplish the same purpose and reach the same results. 
     The base member  66  on the plunger member  60  has a plurality of tab members  68 , as particularly shown in  FIGS. 3 and 5 . The diameter of the base member is also preferably larger than the diameter of the body member  62 , although this is not critical. The base member can also be circular or square or any other shape as desired. The tab members  68  are used as a stop for the spring member  70 , and also assist in keeping the plunger member  60  centered in the housing cavity. This allows uniform flow of gases around the plunger member  60  and through and around the spring member  70 . 
     Also, as shown in  FIG. 5 , one or more elongated ridge members  69  are provided inside the housing. These ribs secure the molded in washer more steadfastly, and ensure that the washer stays in location. The ribs also prevent the plunger member  60  from rotating in the housing. Although four tab members  68  and four ridge members  69  are shown, the number is not critical. More or less than four tab members and ridge members  69  can be provided. 
     The co-passageway module  80  is preferably a plastic molded member that is inserted and positioned in cavity section  28  in the lower end  40  of the housing member  22 . Preferably the module is press-fit in the end  40  of the housing  22 . The module  80  has a cylindrical outer shell member and a pair of upstanding passageway members positioned or integrally formed within it. The co-passageway module  80  includes a first passageway member  82 . The first passageway member  82  is a hollow tubular member having a central channel or passageway  84  which extends the entire length thereof. The passageway member  82  can be any cross-sectional shape, such as the arcuate shape shown in  FIG. 6 . 
     The second passageway member, also referred to as nozzle member  90 , similarly has a central channel or passageway  92 . In the cross-section of member  90 , as shown in  FIGS. 2, 2A and 7 , the channel  92  is a Venturi-type nozzle. The nozzle or passageway  92  has a radius-shaped inlet end  94 , a throat area  95  and a cone-shaped exit end  96 . 
     The nozzle member  90  has a length L as shown in  FIG. 2A . The radius-shaped end  94  is less than 50% of the length L, and preferably about 25%. Gases passing through the nozzle member are increased in velocity in the inlet end as they pass through the throat area  95 . The velocity of the gases decreases in the cone-shaped exit end  96 , preferably to a velocity and pressure substantially the same as the velocity and pressure that the gases had when they entered the inlet end  94 . 
     The nozzle  92  with the throat area acts as a flow restrictor with a controlled response and reinstates the velocity of the gases passing through it without a significant pressure loss. 
     The nozzle member  90  is shorter in length than the passageway member  82 , such that the plunger member cannot seat on it and block passage of gases through it. The structure of the nozzle passage in the nozzle member  90  also prevents or minimizes any differential in pressure between one end or the other as gases pass through it. The nozzle controls engine bypass gases when the function of the turbocharger increases in magnitude. When the engine runs in normally aspirated mode, the nozzle provides minimal function. In some situations, it may be necessary to utilize a flow control orifice in place of a nozzle. In those cases, the internal dimensions will change accordingly. 
     The size of the flow nozzle member  90  is selected depending on the blowby data and flow curve utilized for the vehicle or vehicles with which the PCV valve will be used. A graph  300  depicting blowby flow curve data for representative vehicles is shown in  FIG. 12 . The flow curve relative to cars is shown by line  350 , and the flow curve relative to trucks is shown by line  400 . The reverse flow required for the nozzle member  90  is shown by line  450 . Based on this data and shape of the flow curves, a flow nozzle with a throat size of 0.087 inches would meet the flow requirement. 
     It is also possible in an alternate embodiment to provide a module with a nozzle member and an opening in a plate member adjacent the plunger member, such that the plunger member can cover and seal the opening in the plate member. 
     The basic operation of the biased plunger member and washer are similar to conventional PCV valves. The PCV valve  20  acts to restrict and meter the flow of gases passing through it. When the pressure of the crankcase gases are more than the pressures of the gases at the intake manifold, a vacuum is created which moves the plunger toward the inlet end  30  of the housing. With a significant difference in the pressures, the plunger compresses the spring member against the washer member and restricts and limits the amount of the gases which can pass through the valve. This prevents too much air being added to the intake manifold and causing the fuel/air mixture to be too lean. 
       FIGS. 9 and 10  depict two different points in time in the operation of the disclosed embodiment of the invention. In  FIG. 9 , the plunger member  60  has been moved in the direction of the arrow  100  due to the differential difference in pressure between the crankcase  110  and the intake manifold  120 . The higher pressure in the crankcase has pushed the plunger against the bias of the spring member toward the intake manifold. This also opens the channel  82  in the passageway member  82  by moving the base  66  of the plunger member away from the opening  84 . In this condition, all of the passage of gases through the PCV valve are in the direction of the arrow  100 . 
     As indicated by arrow  102  in  FIG. 9 , some of the gases may also be passing through the passage in the nozzle member  90 . These will be in the same direction as arrow  100 . 
     In  FIG. 10 , the pressure differential between the crankcase and intake manifold is minimal or non-existent. As such, the plunger member  60  is positioned (or seated) firmly on the end of the passageway member  82  and blocking the channel  84 . Under this condition, a backflow of gas can flow back through the PCV valve when the turbocharger is operating, or when there is a boost of air from the turbocharger. In this situation, the passage of gases flow through the nozzle member  90 , as shown by arrow  115 . 
       FIG. 11  depicts an alternate PCV embodiment  200  in accordance with the invention. In this embodiment, the housing member  202  has an auxiliary housing member  204  added on the end of the tubular member  206 . The auxiliary housing member  204  houses a nozzle member  210  which is the same as the nozzle member  90  described above. 
     The plunger member  220  and its operation are the same as that of plunger member  60  described above. A biasing spring member  230  assists in the operation of the plunger member. The base  222  of the plunger member seats on the open end of passageway member  230 , which preferably is substantially the same as passageway member  82  described above. 
     The airflow around the plunger member caused by operation of a turbocharger is indicated by arrow  250 . 
     While preferred embodiments of the present invention have been shown and described herein, numerous variations and alternative embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention is not limited to the preferred embodiments described herein but instead limited to the terms of the appended claims.