Abstract:
A vacuum enhancing check valve for direct connection to a vehicle brake booster which increases the partial vacuum provided thereto and restricts possible air back flow into the brake booster. The valve comprises a venturi for reducing the pressure of air induced to flow between a first air inlet and an air outlet by a partial vacuum at a vehicle engine&#39;s intake manifold. By significantly reducing the air pressure, the valve enhances the partial vacuum available for provision to the brake booster. The venturi is also in air communication with a second air inlet directly attachable to the brake booster such that the air pressure at the second air inlet tends toward the enhanced partial vacuum within the venturi. A valve seat and seal member within the valve are cooperative to allow air flow from the second air inlet toward the venturi, but not in the reverse direction.

Description:
FIELDS OF THE INVENTION  
       [0001]     The present invention relates, generally, to the fields of check valves and vehicle braking systems and, more specifically, to aspirating check valves for use with vehicle braking system boosters.  
       BACKGROUND OF THE INVENTION  
       [0002]     Most of today&#39;s vehicle power braking systems utilize vacuum developed at the intake manifold of a vehicle&#39;s internal combustion engine to assist in their operation. Such vehicle power braking systems, generally, include a brake booster having a housing that encloses a front chamber and a rear chamber which is separated from the front chamber by a moveable wall. The vacuum developed at the intake manifold is communicated to the front chamber by a conduit to create a partial vacuum in the front and rear chambers which suspends the moveable wall. Thereafter, when a driver of the vehicle presses on the vehicle&#39;s brake pedal to apply braking, the vacuum provided to the rear chamber is interrupted and the rear chamber is opened to atmospheric pressure, thereby creating a pressure differential across the moveable wall. The pressure differential causes the moveable wall to translate toward the front chamber which, in turn, causes a force to be transmitted by a push rod to a master brake cylinder connected to the brake booster. The force causes the brake fluid to become pressurized and to then be supplied through a conduit to the brake actuators located at the vehicle&#39;s front and rear wheels, thus causing braking of the vehicle.  
         [0003]     As the vehicle&#39;s driver withdraws pressure from the vehicle&#39;s brake pedal, air at atmospheric pressure is allowed to flow from the rear chamber toward the front chamber. The air is evacuated from the front chamber by the vacuum developed at the intake manifold, thereby creating a partial vacuum once again in the front chamber and causing the moveable wall to be returned toward its suspended location. A check valve, which may be fixed to the outside of the brake booster housing or located within the brake booster housing, permits the flow of air from the front chamber.  
         [0004]     According to certain safety standards established by the U.S. Department of Transportation, the pressure differential across the moveable wall of the brake booster cannot be less than a value specified for a vehicle. Unfortunately, the partial vacuum developed at the intake manifold may be lower under certain conditions and, hence, the pressure differential may not be sufficient at all times during operation of a vehicle for the vehicle to meet such standards. For example, during cold start conditions or when a vehicle&#39;s transmission, power steering, or climate control compressor is engaged, a loss of vacuum at the brake booster may occur. Further, a vehicle may use vacuum assist for many other purposes or systems such as climate control blend doors, parking brake release actuation, engine mount modulation, and fuel purge. As a consequence, less vacuum may be available for the vehicle&#39;s brake booster.  
         [0005]     Therefore, there exists in the industry, a need for a check valve fixable to a brake booster which is operable to aspirate air from the brake booster and to enhance, or increase, the vacuum available to the brake booster, and that addresses these and other problems or difficulties which exist now or in the future.  
       SUMMARY OF THE INVENTION  
       [0006]     Broadly described, the present invention comprises a vacuum enhancing check valve for direct connection to a vehicle brake booster which increases the partial vacuum provided to the brake booster and restricts the possible back flow of air into the brake booster. The vacuum enhancing check valve, in accordance with an exemplary embodiment thereof, comprises a valve body having a first air inlet port for connection through a conduit to an air intake of a vehicle internal combustion engine, a second air inlet port adapted for direct connection to a brake booster of a vehicle braking system, and an air outlet port adapted for connection through a conduit to an intake manifold of the vehicle internal combustion engine. The valve body defines a venturi therein which allows air to flow between the first air inlet port and the air outlet port in response to the partial vacuum present at the intake manifold and which reduces the pressure of the flowing air to a minimum at a throat portion of the venturi such that the air pressure at the throat portion is lower than the air pressure at the intake manifold. Thus, the partial vacuum present at the intake manifold is enhanced by the venturi to produce a greater partial vacuum at the throat portion of the venturi. By virtue of the throat portion of the venturi being in air communication with the second air inlet port, the air pressure at the second air inlet port tends toward the partial vacuum present at the throat portion, thereby providing a greater partial vacuum to a vehicle brake booster than would, otherwise, be available from the intake manifold.  
         [0007]     The valve body, according to the exemplary embodiment, further defines a valve seat therein interposed between the venturi and the second air inlet port. A seal member located within the valve seat is adapted for movement between a first position in which air is induced to flow from the second air inlet port toward the venturi by the reduced air pressure at the throat portion of the venturi and a second position in which air is restricted from flowing from the venturi toward the second air inlet port.  
         [0008]     Advantageously, the vacuum enhancing check valve of the present invention attaches directly to the brake booster of a vehicle braking system and enables the flow of air from the front chamber of the brake booster, but not into the front chamber. Thus, the vacuum enhancing check valve eliminates the need for a check valve located within the brake booster to perform the same function. The vacuum enhancing check valve of the present invention also operates as an aspirator to increase the partial vacuum produced by the intake manifold of a vehicle&#39;s internal combustion engine for use by the vehicle&#39;s braking system and, potentially, by other vehicle devices or systems which require a vacuum assist. Formerly, such vacuum enhancement was performed by an aspirator positioned within a conduit between the intake manifold and braking system of a vehicle. Therefore, the vacuum enhancing check valve also eliminates the need for an aspirator located within a conduit and the need for a conduit extending between the aspirator and brake booster. Hence, the vacuum enhancing check valve replaces at least three or more components within a vehicle, thereby reducing the vehicle&#39;s cost and complexity and improving the vehicle&#39;s reliability. Further, the relative orientation of the air inlet ports and air outlet port of the vacuum enhancing check valve enables easy insertion of the second air inlet port directly into a brake booster absent interference with a conduit(s) attached before or after such insertion.  
         [0009]     Other objects, features, and advantages of the present invention will become apparent upon reading and understanding the present specification when taken in conjunction with the appended drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  displays a side, elevational view of a vacuum enhancing check valve in accordance with an exemplary embodiment of the present invention.  
         [0011]      FIG. 2  displays a top, plan view of the vacuum enhancing check valve of  FIG. 1 .  
         [0012]      FIG. 3  displays a sectional view of the vacuum enhancing check valve of  FIG. 2  taken along lines  3 - 3  and with the first and second portions separated to improve clarity.  
         [0013]      FIG. 4  displays a bottom, plan view of the first portion of the vacuum enhancing check valve of  FIG. 1 .  
         [0014]      FIG. 5  displays a top, plan view of a portion of a vehicle braking system equipped with the vacuum enhancing check valve of  FIG. 1 .  
         [0015]      FIG. 6  displays a left side, elevational view of the portion of the vehicle braking system of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring now to the drawings in which like numerals represent like elements throughout the several views,  FIG. 1  displays a side, elevational view of a vacuum enhancing check valve  10  in accordance with an exemplary embodiment of the present invention. The vacuum enhancing check valve  10  comprises a substantially one piece valve body  12  which is, generally, formed from a first valve portion  14  and a second valve portion  16  (see  FIG. 3 ). The valve portions  14 ,  16  are, preferably, manufactured from an injection-molded, heat resistant, rigid plastic which can withstand the forces, pressures, and temperatures present during use attached to a braking system booster in a vehicle&#39;s engine compartment. The valve portions  14 ,  16  are securely joined together during manufacture by sonic welding, heating, or other appropriate method or technique. It should be understood that the valve portions  14 ,  16  may be manufactured from other suitable plastics, metals, or combinations thereof.  
         [0017]     The first valve portion  14  has an air inlet port  18  and an opposed air outlet port  20  which are collinearly disposed along a longitudinal axis  22  extending therebetween as seen in  FIGS. 1 and 2 . The first valve portion comprises a wall  24  which defines a first opening  26  therein at air inlet port  18  and a second opening  28  therein at air outlet port  20 . The first and second openings  26 ,  28  have a, generally, circular cross-section. The wall  24  has respective pluralities of barbs  30 ,  32  at air inlet port  18  and air outlet port  20  which extend around the first and second openings  26 ,  28 . The plurality of barbs  30  at air inlet port  18  aid in retaining a conduit, or hose, which is attached to the vacuum enhancing check valve  10  at air inlet port  18  and between air inlet port  18  and a vehicle&#39;s air intake snorkel when the vacuum enhancing check valve  10  is in use. Similarly, the plurality of barbs  32  at air outlet port  20  aid in retaining a conduit, or hose, which is attached to the vacuum enhancing check valve  10  at air outlet port  20  and between air outlet port  20  and the intake manifold of a vehicle engine block.  
         [0018]     The wall  24  also defines, as illustrated in the sectional view of  FIG. 3 , a passageway  34  that extends within first valve portion  14  between first and second openings  26 ,  28 . By virtue of the presence of passageway  34 , the first and second openings  26 ,  28  (and, hence, air inlet port  18  and air outlet port  20 ) are in direct air flow communication. Passageway  34  includes a first portion  36 , a second portion  38 , and a throat portion  40  which connects the first and second portions  36 ,  38  for the communication of air therebetween. The first portion  36  extends between the first opening  26  and the throat portion  40 , and tapers in cross-sectional area between the first opening  26  and the throat portion  40  such that the cross-sectional area is largest at the first opening  26 . Similarly, the second portion  38  extends between a second bore  48  (described below) of a first portion valve seat  42  (described below) and the throat portion  40 , and tapers in cross-sectional area between second bore  48  and the throat portion  40  with the largest cross-sectional area of the second portion is present near the second bore  48 . Together, the first portion  36 , second portion  38 , and throat portion  40  comprise a converging-diverging, or venturi, nozzle arrangement which accelerates the velocity of air traveling therethrough, while reducing the air pressure. The maximum air velocity and minimum air pressure are, generally, present at the throat portion  40 .  
         [0019]     The first valve portion  14  further comprises first portion valve seats  42 ,  44  which, respectively, include first and second bores  46 ,  48  defined by wall  24 . The first and second bores  46 ,  48 , generally, have circular cross-sections. Wall  24  further defines a channel  50  extending between the first bore  46  and the throat portion  40  of passageway  34  to enable the passage of air between first bore  46  and passageway  34  (and, hence, between first portion valve seat  42  and passageway  34 ). Second bore  48  is in direct air communication with passageway  34 . Wall  24  also has tongues  52 ,  54  which improve and enable mating of first portion valve seats  42 ,  44  with second portion valve seats  74 ,  76  (described below) during joining of the first and second valve portions  14 ,  16  together. Wall  24  additionally, as viewed best in the bottom plan view of  FIG. 4 , has protruding fingers  56 ,  58  which partially extend into the respective first and second bores  46 ,  48  along angularly spaced apart radii to support flexible, moveable seal members  60 ,  61 . Generally, seal members  60 ,  61  are relatively thin and have a circular shape.  
         [0020]     The second valve portion  16  is adapted to mate with the first valve portion  14  during the manufacture of the vacuum enhancing check valve  10 . The second valve portion  16 , as displayed in  FIGS. 1 and 3 , has an air inlet port  62  disposed about a transverse axis  64 . According to the exemplary embodiment of the present invention, the transverse axis  64  is perpendicular to longitudinal axis  22 . By orienting air inlet port  62  about transverse axis  64  and air inlet port  18  and air outlet port  20  coaxially aligned along longitudinal axis  22 , air inlet port  62  may be inserted into a housing  100  of a brake booster  96 , as described below, with a conduit attached to air inlet port  18  and a conduit attached to air outlet port  20  absent interference with either conduit. Alternatively, by virtue of such orientation, conduits may be easily attached to air inlet port  18  and air outlet port  20  after insertion of air inlet port  62  into the housing  100  of the brake booster  96 . Similarly, by virtue of such orientation, the vacuum enhancing check valve  10  may be readily removed from a brake booster. Thus, the relative orientation of air inlet ports  18 ,  62  and air outlet port  20  provides substantial flexibility with respect to the insertion and removal of the vacuum enhancing check valve  10  to or from a vehicle brake booster.  
         [0021]     The second valve portion  16  comprises a wall  66  which defines an opening  68  therein at air inlet port  62 . The openings  68  has a, generally, circular cross-section. The wall  66  has a brake booster interface  70  at air inlet port  62  for improving the retention and securing of air inlet port  62  within an opening  104  and grommet  108  of the housing  100  of a vehicle brake booster  96 , as described below, when the vacuum enhancing check valve  10  is in use. In the exemplary embodiment, the brake booster interface  70  comprises a plurality of barbs protruding at air inlet port  62  and extending around opening  68 . The wall  66  also has a shoulder  72  which extends around the air inlet port  62  inboard of the brake booster interface  70 . The shoulder  72  serves as a stop which limits travel of the air inlet port  62  into the opening  104  and grommet  108  of a housing  100  of a vehicle brake booster  96  during insertion of the air inlet port  62  therein.  
         [0022]     As illustrated in  FIG. 3 , the second valve portion  16  further comprises second portion valve seats  74 ,  76  which, respectively, include first and second bores  78 ,  80  defined by wall  66 . The first and second bores  78 ,  80 , generally, have circular cross-sections. Wall  66  further defines a chamber  82  extending between the first and second bores  78 ,  80  and defines a passageway  84  extending about transverse axis  64  within air inlet port  62  between chamber  82  and opening  68 . The chamber  82  is in air communication with first and second bores  78 ,  80  and passageway  84 , thereby enabling air to pass between first and second bores  78 ,  80  and passageway  84  (and, hence, between second portion valve seats  74 ,  76  and passageway  84 ). Wall  66 , at the second portion valve seats  74 ,  76 , has first and second concave portions  86 ,  88  with outer diameters which are slightly smaller than the diameters of seal members  60 ,  61 . Wall  66  still further defines first and second grooves  90 ,  92  therein at second portion valve seats  74 ,  76  which are complementary to the tongues  52 ,  54  of wall  24  of the first valve portion  14  and receive the tongues  52 ,  54  when the first and second valve portions  14 ,  16  are joined during manufacture of the vacuum enhancing check valve  10 .  
         [0023]     It should be noted that, in other exemplary embodiments of the present invention, wall  66  may define additional air inlet ports which are in air communication with chamber  82 . The additional air inlet ports may be connected to other vehicle devices or systems which may require vacuum or vacuum-assist such as, for example and not limitation, a climate control compressor, climate control blend doors, transmission, cruise control system, parking brake release actuator, engine mount modulator, and fuel purge system.  
         [0024]     The vacuum enhancing check valve  10  is assembled by aligning first portion valve seats  42 ,  44  and second portion valve seats  74 ,  76  such that the tongues  52 ,  54  of wall  24  are aligned with grooves  90 ,  92  of wall  66 . Seal members  60 ,  61  are then positioned in contact with and resting on the protruding fingers  56 ,  58  of wall  24 . The first and second valve portions  14 ,  16  are subsequently pressed together and joined by sonic welding, heating, or other appropriate method or technique. The particular method or technique used to join the first and second valve portions  14 ,  16  generally depends on the material from which they are formed.  
         [0025]     The vacuum enhancing check valve  10  is, generally, for use in conjunction with a vehicle braking system  94  having a brake booster  96  and master cylinder  98  assembly adapted for use therewith as displayed in the top plan and left side, elevational views of  FIGS. 5 and 6 . Such a brake booster  96  comprises a housing  100  which at least partially encloses front and rear chambers. The front and rear chambers are substantially similar to those found in conventional vehicle braking systems and operate in a substantially similar manner. The housing  100  has a wall  102  which defines an opening  104  therein and a passageway (not visible) therethrough. The passageway (not visible) extends between the opening  104  and the front chamber such that air may pass between the opening  104  and front chamber via the passageway (not visible). A grommet  108  resides within opening  104  for receipt and retention of the air inlet port  62  of the vacuum enhancing check valve  10 .  
         [0026]     In use, the vacuum enhancing check valve  10  is secured directly to the housing  100  of a vehicle&#39;s brake booster  96 , as illustrated in  FIGS. 5 and 6 , by inserting air inlet port  62  into the opening  104  and grommet  108 . The grommet  108  aids in preventing the air inlet port  62  from becoming detached from the housing  100  and in sealing the opening  104  so that air does not enter the front chamber of the brake booster  96  from the engine compartment between air inlet port  62  and opening  104 . After air inlet port  62  is positioned within opening  104  and grommet  108 , a first conduit, or hose, is attached to the vacuum enhancing check valve  10  at air inlet port  18  by pushing the opening in a first end of the first conduit over the plurality of barbs  30  of air inlet port  62  to secure the first end of the first conduit to the vacuum enhancing check valve  10 . The second end of the first conduit is then attached to a fitting of a vehicle&#39;s air intake snorkel or other air intake device, thereby enabling the flow of air between air inlet port  62  of the vacuum enhancing check valve  10  and the air intake snorkel or device. Next, a second conduit, or hose, is attached to the vacuum enhancing check valve  10  at air outlet port  20  by pushing the opening in a first end of the second conduit over the plurality of barbs  32  of air outlet port  20  to affix the first end of the second conduit to the vacuum enhancing check valve  10 . The second end of the second conduit is then secured to a fitting at the intake manifold of the vehicle&#39;s engine block, thereby allowing air to flow between the air outlet port  20  of the vacuum enhancing check valve  10  and the intake manifold.  
         [0027]     During operation of the vehicle with the vacuum enhancing check valve  10  installed as described above, the vehicle&#39;s engine creates a partial vacuum at its intake manifold causing air to flow through the first and second conduits and, hence, through air inlet port  18  and air outlet port  20 . As air is drawn through air inlet port  18  toward air outlet port  20 , the air is accelerated as it passes through passageway  34  with its velocity being increased and pressure further reduced by the venturi of passageway  34 . By virtue of the further reduction in the pressure of the air caused by the venturi, the partial vacuum created by the vehicle&#39;s engine is significantly enhanced by the vacuum enhancing check valve  10 . The further reduction in pressure (i.e., the significant enhancing of the partial vacuum) within passageway  34  causes the seal members  60 ,  61  to be drawn against the protruding fingers  56 ,  58  extending within first and second bores  46 ,  48  of first portion valve seats  42 ,  44 . With the seal members  60 ,  61  in such position, air is allowed to flow from chamber  82  to passageway  34  via the first and second portion valve seats  42 ,  44 ,  74 ,  76 . As a consequence, air is also drawn into chamber  82  through air inlet port  62 , thereby creating a partial vacuum within air inlet port  62  and providing a vacuum assist to the brake booster  96  (and, hence, to the vehicle&#39;s braking system).  
         [0028]     Typically, a conventional vehicle internal combustion engine creates a partial vacuum of approximately seven inches of mercury (7″ Hg) at its intake manifold during operation. The vacuum enhancing check valve  10  of the present invention enhances this partial vacuum such that the partial vacuum at air inlet port  62  is approximately eighteen inches of mercury (18″ Hg). This enhancement constitutes a 157% increase in partial vacuum which is due, at least in part, to the venturi configuration of passageway  34 .  
         [0029]     If, for any reason, the direction of air flow is caused to be reversed in chamber  82  and air inlet port  62 , seal members  60 ,  61  are drawn against the first and second concave portions  86 ,  88  of second portion valve seats  74 ,  76 . Thus, the vacuum enhancing check valve  10  also operates as a check valve similar to those check valves employed within or attached to brake boosters of many vehicle braking systems.  
         [0030]     Whereas the present invention has been described in detail above with respect to an exemplary embodiment thereof, it is understood that variations and modifications can be effected within the spirit and scope of the invention, as described herein before and as defined in the appended claims.