Patent Description:
In automotive engines, on/off operation of a vacuum generator and/or accessory is frequently controlled by a gate valve in which a rigid gate is deployed across a conduit to stop the flow of a fluid (in this exemplary application, air) through the valve. Within automated or "commanded" valves, the gate is typically actuated by a solenoid and opened or closed in response to an electrical current applied to the solenoid coil. These solenoid-powered gate valves also tend to include a coil spring, diaphragm, or other biasing element which biases the gate towards an unpowered, 'normally open' or 'normally closed' position.

The pressure in an engine crankcase is ideally maintained near atmospheric pressure (ATM pressure +/- <NUM> kPa). Furthermore, it is desirable to be able to detect any leak in the crankcase ventilation system (path from fresh air to the manifold, including all flow passageways and passageway connections) to ensure crankcase gasses are appropriately managed to avoid excessive pollutants being discharged into the atmosphere. In order to achieve these conditions, free flow (minimal restriction) of air into the crankcase is needed, which can be switched to a restricted opening, in order to conduct a pressure integrity check (and not create an excessively negative pressure in the crankcase). The gate valve approach while successful, is more expensive, heavier, and takes up engine space. A more cost effective and compact system to enable the pressure integrity check of the crankcase ventilation system is desirable, especially one as disclosed herein that does not require any electrical connections to move an actuator, such as a solenoid, to operate a valve.

Examples of known systems are disclosed in publications <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT>.

In all aspects, a breach detection system for an internal combustion engine having a crankcase, an intake manifold, a positive crankcase ventilation valve, a crankcase ventilation tube with a flow control system therein, and a pressure sensor between the flow control system and the crankcase is disclosed. The flow control system subdivides the crankcase ventilation tube into a plurality of parallel conduits - a first conduit having a normally closed check valve that opens under a first preselected pressure drop in a first direction from the air intake to the crankcase, and a second conduit having either a second check valve that opens under a second preselected pressure drop in a second direction opposite the first direction or a restriction profile having a third preselected pressure drop that is the same in both the first and second direction. When the pressure sensor detects no pressure drop there is a breach in the system.

The aforementioned crankcase ventilation breach detection system is realized according to the appended set of claims.

The following detailed description will illustrate the general principles of the invention, examples of which are additionally illustrated in the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements.

As used herein, "fluid" means any liquid, suspension, colloid, gas, plasma, or combinations thereof.

As used herein, a "normally closed" check valve is in the closed position until the pressure differential (change in pressure) between the inlet and the outlet is sufficient to overcome the spring holding the poppet in the closed position. A "normally neutral" check valve is neither open or closed and depends on sufficient pressure differential to overcome the minimal mass of the poppet to be in either the open or closed position, depending on the flow direction.

<FIG> illustrate one embodiment of an engine system <NUM>, which may be a vehicle engine system that is a turbocharged or supercharged system. However, in other embodiments, such as <FIG>, the engine system can be a naturally aspirated engine. The engine system <NUM> is configured for combusting fuel vapor accumulated in at least one component thereof and includes a multi-cylinder internal combustion engine <NUM>. The engine system <NUM> receives air from an air intake <NUM>, which may include an air filter <NUM> (also known as an air cleaner). The engine system of <FIG> is a turbocharged engine system, but could just as equally be a supercharged engine system, having a turbocharger <NUM>. The compressor <NUM> of the turbocharger <NUM> receives air from the air intake <NUM>, compresses the air, and directs a flow of compressed air (or boosted air) downstream through a charge air cooler or intercooler <NUM> and then to a throttle <NUM>. The throttle <NUM> controls fluid communication between the compressor <NUM> and the intake manifold <NUM> of the engine <NUM>. The throttle <NUM> is operable using known techniques to vary an amount of intake air provided to the intake manifold <NUM> and the cylinders of the engine. In alternative embodiments, the intercooler <NUM> may be positioned downstream of the throttle, and as such, may be housed in the intake manifold.

Intake manifold <NUM> is configured to supply intake air or an air-fuel mixture to a plurality of combustion chambers of engine <NUM> located within the engine block <NUM>. The combustion chambers are typically arranged above a lubricant-filled crankcase <NUM> such that reciprocating pistons of the combustion chambers rotate a crankshaft (not shown) located in the crankcase <NUM>. Unburned fuel and other combustion products may escape past each piston and/or valve guides from the engine block into the crankcase <NUM>. The resulting gases in the crankcase, often referred to as "blow-by" gases may excessively pressurize the crankcase <NUM> if not vented therefrom. Engine <NUM> includes a crankcase ventilation (CV) system, which serves to vent blow-by gases from the crankcase <NUM> to intake manifold <NUM>.

Still referring to <FIG>, the CV system includes a positive crankcase ventilation valve <NUM> in fluid communication between the crankcase <NUM> and the intake manifold <NUM>, to regulate the flow of blow-by gases from the crankcase to the intake manifold, and a conduit known as a crankcase ventilation tube <NUM> placing the crankcase <NUM>, in particular, the blow-by gas in fluid communication with clean air from the air intake <NUM>. Here, the crankcase ventilation tube <NUM> is in fluid communication upstream of the compressor <NUM>. The crankcase ventilation tube <NUM> divides into a flow control system <NUM> that includes a pressure sensor <NUM> positioned between the flow control system <NUM> and the crankcase <NUM>. In the flow control system detection of no pressure drop by the pressure sensor <NUM> indicates a breach in the system.

The flow control system <NUM> in the embodiment of <FIG> includes three parallel conduits, one conduit <NUM> defines a restriction profile <NUM>, another conduit <NUM> has a normally closed check valve <NUM> controlling flow therethrough from the air intake to the crankcase, and yet another conduit <NUM> has a second check valve <NUM> controlling flow therethrough from the crankcase to the air intake. The normally closed check valve <NUM> opens under a first preselected pressure drop, the second check valve opens under a second preselected pressure drop, and the restriction profile has a third preselected pressure drop that is the same in either direction of flow therethrough. A first direction D<NUM> (the normal flow direction) is from the air intake upstream of the compressor to the crankcase and the second direction D<NUM> is the opposite of the first direction.

The flow control system of <FIG> is set to have the first preselected pressure drop of the normally closed check valve <NUM> greater than the third pressure drop of the restrictor <NUM>, and the second pressure drop of the second check valve <NUM> is the same or less than the third pressure drop of the restrictor <NUM>. The first, second and third pressure drops are in a range of about <NUM> kPa to about <NUM> kPa, and more preferably about <NUM> kPa to about <NUM> kPa. "About" herein means +/- <NUM> kPa. In one embodiment, the third pressure drop is set at about <NUM> kPa.

Embodiments of a normally closed check valve <NUM> are described in detail below with reference to <FIG> and <FIG>. The second check valve <NUM> is described in detail below with reference to <FIG>.

Referring to <FIG>, a restrictor profile <NUM> for the conduit pathway <NUM> is illustrated. The restrictor profile <NUM> has symmetrical, mirror image upstream and downstream portions <NUM>, <NUM>. Both portions <NUM>, <NUM> are circular, when viewed in a transverse cross-section, and each narrow according to a parabolic or hyperbolic function along its length, which meet at the throat <NUM>. The throat diameter is the parameter that determines or sets the maximum mass flow rate. A larger diameter for the throat equates to a larger mass flow rate. Here, the throat diameter is in a range of about <NUM> to <NUM>, more preferably about <NUM> to about <NUM>. For the throat diameter, "about" means +/- <NUM>.

Referring now to <FIG>, a naturally aspirated engine system <NUM>' is shown. The engine system <NUM>' receives air from an air intake <NUM>, which may include an air filter <NUM> (also known as an air cleaner), and directs the air to a throttle <NUM>. The throttle <NUM> controls fluid communication between the air intake <NUM> and the intake manifold <NUM> of the engine <NUM>. The throttle <NUM> is operable using known techniques to vary an amount of intake air provided to the intake manifold <NUM> and the cylinders of the engine. Intake manifold <NUM> is configured to supply intake air or an air-fuel mixture to a plurality of combustion chambers of engine <NUM> located within the engine block <NUM>. The combustion chambers are typically arranged above a lubricant-filled crankcase <NUM> such that reciprocating pistons of the combustion chambers rotate a crankshaft (not shown) located in the crankcase <NUM>. Unburned fuel and other combustion products may escape past each piston and/or valve guides from the engine block into the crankcase <NUM>. The resulting gases in the crankcase, often referred to as "blow-by" gases may excessively pressurize the crankcase <NUM> if not vented therefrom. Engine <NUM> includes a crankcase ventilation (CV) system, which serves to vent blow-by gases from the crankcase <NUM> to intake manifold <NUM>.

Still referring to <FIG>, the CV system includes a positive crankcase ventilation valve <NUM> in fluid communication between the crankcase <NUM> and the intake manifold <NUM>, to regulate the flow of blow-by gases from the crankcase to the intake manifold, and a conduit known as a crankcase ventilation tube <NUM> placing the crankcase <NUM>, in particular, the blow-by gas in fluid communication with clean air from the air intake <NUM>. Here, the crankcase ventilation tube <NUM> is in fluid communication upstream of the throttle <NUM>. The crankcase ventilation tube <NUM> divides into a flow control system <NUM>' that includes a pressure sensor <NUM> positioned between the flow control system <NUM>' and the crankcase <NUM>. In the flow control system detection of no pressure drop by the pressure sensor <NUM> indicates a breach in the system.

The flow control system <NUM>' in the embodiment of <FIG> includes two parallel conduits, one conduit <NUM> defines a restriction profile <NUM>, another conduit <NUM> has a normally closed check valve <NUM> controlling flow therethrough from the air intake to the crankcase. The normally closed check valve <NUM> opens under a preselected pressure drop and the restriction profile has a preselected pressure drop that is the same in either direction of flow therethrough. The flow control system of <FIG> is set to have the preselected pressure drop of the normally closed check valve <NUM> greater than the pressure drop of the restrictor <NUM>. The pressure drops are in a range of about <NUM> kPa to about <NUM> kPa, more preferably about <NUM> kPa to about <NUM> kPa. "About" herein means +/- <NUM> kPa. In one embodiment, the pressure drop selected for the restrictor <NUM> is about <NUM> kPa.

Referring now to <FIG>, an engine system <NUM>" is shown that is similar to the engine system <NUM> of <FIG> except that the flow control system, here referred to as flow system <NUM>", has two parallel check valves controlling flow in opposite directions without the presence of the conduit pathway having the restrictor. Here, one conduit <NUM> has a normally closed check valve <NUM> controlling flow therethrough from the air intake to the crankcase, and another conduit <NUM> has a second check valve <NUM> controlling flow therethrough from the crankcase to the air intake. The normally closed check valve <NUM> opens under a first preselected pressure drop to control flow in the first direction D<NUM> (the normal flow direction), and the second check valve opens under a second preselected pressure drop to control flow in the second direction D<NUM>, which is opposite of the first direction.

The flow control system <NUM>" of <FIG> is set to have the second pressure drop of the second check valve <NUM> equal to or less than the first pressure drop of the normally closed check valve <NUM>. The first and second pressure drops are in a range of about <NUM> kPa to about <NUM> kPa, more preferably about <NUM> kPa to about <NUM> kPa, more preferably about <NUM> kPa to about <NUM> kPa. "About" herein means +/- <NUM> kPa. In one embodiment, the first pressure drop is set at about <NUM> kPa.

The normally closed check valve <NUM> of all the embodiments may be a "forced closed" check valve as illustrated in <FIG> and <FIG>, without the presence of a spring. The normally closed check valve <NUM> defines an internal cavity <NUM> in which an elastically flexible disk <NUM> is seated and is held in the closed position of <FIG> against a first seat <NUM> by a plurality of fingers <NUM> extending into the internal cavity, wherein a pressure drop across the elastically flexible disk <NUM> from the first seat <NUM> to the plurality of fingers <NUM> flexes the elastically flexible disk into an open position shown in <FIG>.

The check valve <NUM> includes a housing <NUM> defining an internal cavity <NUM> having a pin <NUM> therein upon which is seated a sealing disk <NUM>. The housing <NUM> defines a first port <NUM> in fluid communication with the internal cavity <NUM> and a second port <NUM> in fluid communication with the internal cavity <NUM>. The housing <NUM> may be a multiple piece housing with pieces connected together with a fluid-tight seal <NUM>. The internal cavity <NUM> typically has larger dimensions than the first port <NUM> and the second port <NUM>. The pin <NUM> is centrally positioned within the internal cavity <NUM> and a plurality of ribs <NUM> comprising connecting ribs <NUM> and/or partial ribs <NUM>, as shown in <FIG>, in any of the configurations disclosed in <CIT> extend radially outward from the pin <NUM> or toward the pin <NUM> to subdivide the flow path leading into the internal cavity <NUM> into a plurality of conduits to direct the fluid flow around the periphery of the sealing disk <NUM> when the check valve <NUM> is elastically flexed into the open position shown in <FIG>.

The plurality of ribs <NUM> may be all connecting ribs <NUM> or may include both connecting ribs <NUM> and one or more partial ribs <NUM> between neighboring connecting ribs. When the plurality of ribs <NUM> are all connecting ribs <NUM> there are typically five or six thereof, but is not limited thereto. <FIG> is an example of a six connecting ribs <NUM> configuration with partial ribs <NUM>. The partial ribs may have the same length, axially, or the partial ribs may have different lengths as shown in <FIG>, which has a <NUM>×<NUM> rib configuration. The description of the rib configuration as a number by a number represents the number of connecting ribs by the number of partial ribs in between neighboring connecting ribs. Other example embodiments may have a <NUM>×<NUM> rib configuration, a <NUM>×<NUM> rib configuration, or a <NUM>×<NUM> rib configuration, and many other variations.

In the illustrated embodiment, the first port <NUM> and the second port <NUM> are positioned opposite one another, but is not limited to this configuration. In another embodiment, the first and second ports may be positioned relative to one another at an angle of less than <NUM> degrees. The portion of the housing <NUM> defining the internal cavity <NUM> includes an internal first seat <NUM>, here collectively a first annular seal bead <NUM> and a second annular seal bead <NUM>, upon which the sealing disk <NUM> seats when the check valve is "closed. " The second annular seal bead <NUM> is radially inward of the first annular seal bead <NUM>. A second seat <NUM> is defined by a plurality of radially spaced fingers <NUM> extending into the internal cavity <NUM> from an interior surface of the internal cavity <NUM> that is more proximate the second port <NUM>. The plurality of radially spaced apart fingers <NUM> have a pre-selected length that places the plurality of radially spaced apart fingers <NUM> in direct contact with the sealing disk <NUM> while the sealing disk <NUM> is seated against the first seat <NUM>, thereby holding or forcing the sealing disk <NUM> in the closed position shown in <FIG>.

The first port <NUM> and the second port <NUM> may each define or include an elongate connector extending away from the internal cavity <NUM> having a connector feature <NUM> on the outer surface thereof or at the end thereof for connecting the internal passageway for fluid communication within the crankcase ventilation breach detection system of any of <FIG>.

The sealing disk <NUM> illustrated in <FIG> and <FIG> is a stepped disk as described in co-owned patent <CIT>, but is not necessarily limited thereto. The disk <NUM> could be a flat planar disk. A stepped disk is one having a shape and configuration relative to the first seat <NUM> and its first annular seal bead <NUM>, its second annular seal bead <NUM>, and its ribs <NUM>. The sealing disk <NUM> has a stepped longitudinal cross-section profile, from the outer diameter inward toward the inner diameter there are in order, two mirror image upward steps and then one mirror image downward step on the opposing upper and lower faces <NUM>, <NUM> of the disk. Described another way, with reference to <FIG>, the sealing disk <NUM> has a first sealing portion <NUM> seatable against the first annular seal bead <NUM> and a second sealing portion <NUM> seatable against the second annular seal bead <NUM>. The first sealing portion <NUM> and the second sealing portion <NUM> each have a first thickness T<NUM> (i.e., generally the same thickness). The sealing disk <NUM> has an intermediate portion <NUM> between the first sealing portion <NUM> and the second sealing portion <NUM> that has a second thickness T<NUM> that is greater than the first thickness T<NUM>, and has a lip portion <NUM> defining the outer periphery of the seal disk <NUM> and having a third thickness T<NUM> that is less than the first thickness T<NUM>. T<NUM> is about <NUM>% to about <NUM>% greater than T<NUM>, and more preferably about <NUM>% to about <NUM>% greater than T<NUM>. The thickness T<NUM> of the lip portion <NUM> is about <NUM>% to about <NUM>% less than T<NUM>, and more preferably about <NUM>% to about <NUM>% less than T<NUM>. The sealing disk <NUM> is held against the first seat <NUM> by the fingers <NUM> in the closed position and is elastically flexible to bend toward the second seat <NUM> in response to a preselected pressure drop across the check valve <NUM>. The sealing disc <NUM> transforms between a flat shape in the closed position to a shallow bowl shape in the open position and back again. The sealing disc <NUM> readily flexes when there is a pressure drop from the side of the first seat <NUM> to the second seat <NUM>, i.e., the first port <NUM> to the second port <NUM>.

The sealing disk <NUM> has a central bore <NUM> (labeled in <FIG>) therethrough that receives the pin <NUM>. The pin <NUM> acts as an alignment member to hold the sealing disk <NUM> in its operating position, such that the elastic flexing of the disk does not cause the disk to travel within the chamber <NUM>. The sealing disk <NUM> may be or includes an elastomeric material suitable for use in fluid communication with blow-by-gas from the crankcase ventilation system of an internal combustion engine, i.e., is durable when exposed to temperatures and pressures associated with such an environment. In one embodiment, the sealing disk <NUM> may be or include one or more of a natural rubber, synthetic rubber, silicone rubber, fluorosilicone rubber, fluorocarbon rubber, nitrile rubber, EPDM, PTFE, and combinations thereof, but is not limited thereto.

Referring now to <FIG>, the second check valve <NUM>, which is a normally neutral check valve, defines an internal cavity <NUM> in which a sealing disk <NUM> floats and translates between an open position and a closed position based on pressure drops in the system. The check valve <NUM> has a housing <NUM> defining an internal cavity <NUM> having a pin <NUM> therein upon which is seated a sealing member <NUM>, such as a stepped disk described above, and defining a first port <NUM> in fluid communication with the internal cavity <NUM> and a second fluid port <NUM> in fluid communication with the internal cavity <NUM>. The housing <NUM> may be a multiple piece housing with pieces connected together with a fluid-tight seal. The internal cavity <NUM> typically has larger dimensions than the first port <NUM> and the second port <NUM>. The pin <NUM> is seen centrally positioned within the internal cavity <NUM> and a plurality of ribs <NUM> made up of connecting ribs <NUM> and/or partial ribs <NUM> as illustrated in <FIG> in any of the configurations noted above extend radially outward from the pin <NUM> or toward the pin <NUM> to subdivide the flow path leading into the internal cavity into a plurality of conduits to direct the fluid flow around the periphery of the sealing member <NUM> when the check valve <NUM> is in an open position as shown in <FIG>.

In the illustrated embodiment, the first port <NUM> and the second port <NUM> are positioned opposite one another, but is not limited to this configuration. In another embodiment, the first and second ports <NUM>, <NUM> may be positioned relative to one another at an angle of less than <NUM>. The portion of the housing <NUM> defining the internal cavity <NUM> includes an internal first seat <NUM> (here collectively first seal bead <NUM> and second seal bead <NUM>) upon which the sealing member <NUM> seats when the check valve is "closed" and a second seat <NUM> upon which the sealing member seats when the check valve is "open. " Here, the second seat <NUM> is a plurality of radially spaced fingers <NUM> extending into the internal cavity <NUM> from an interior surface of the internal cavity <NUM> that is more proximate the second port <NUM>.

The first port <NUM> and the second port <NUM> may each include a portion of a conduit extending therefrom that may include a connector feature on the outer surface thereof or at the end thereof for connecting the internal passageway defined by the conduit for fluid communication within a system.

Turning now to <FIG>, an alternate embodiment for the normally closed check valve <NUM> is disclosed. The check valve <NUM> has a housing <NUM> having a first housing portion <NUM> defining a first port <NUM> and a second housing portion <NUM> defining a second port <NUM> that are sealingly fixed together with a fluid-tight seal at flange <NUM> and collectively define an internal cavity <NUM>. The first port <NUM> and the second port <NUM> are both in fluid communication with the internal cavity <NUM>. The internal cavity <NUM> typically has larger dimensions than the first port <NUM> and the second port <NUM>. In the illustrated embodiment, the first port <NUM> and the second port <NUM> are positioned opposite one another to define a generally linear flow path through the check valve <NUM>, when the hemispherical poppet sealing member <NUM> is not present, but is not limited to this configuration. In another embodiment, the first and second ports may be positioned relative to one another at an angle of less than <NUM> degrees.

The internal cavity <NUM> is generally spherically shaped and defines an annular seat <NUM> for engagement with a hemispherical poppet sealing member <NUM>, which is translatable between a closed position against the annular seat <NUM> (<FIG>) and an open position (<FIG>). The generally spherical shape of the internal cavity <NUM> complements the shape of the hemispherical poppet sealing member <NUM> and provides a low restriction flow path in the open position. The annular seat <NUM> in a longitudinal cross-section through the check valve <NUM>, as shown in <FIG> and <FIG>, defines a convex spherical radius as indicated by arrow <NUM> in <FIG>. The convex spherical radius of the annular seat is preferably positioned or formed at a transition from the first port <NUM> into the internal cavity <NUM>. The internal cavity <NUM> has a generally spherical shape and, in the closed position, a convex surface of the hemispherical poppet sealing member <NUM> as indicated by arrow <NUM> in <FIG> is engaged with the convex spherical radius <NUM> of the annular seat <NUM>.

Referring to <FIG>, the convex surface-convex surface seal is shown as an enlarged image. This seal forms a tangent seal interface that is insensitive to slight misalignment of the hemispherical poppet sealing member <NUM> when closing. A slightly misaligned hemispherical poppet sealing member will still have good seal integrity, approximately <NUM> scc/m or less. As seen, the interior of the housing <NUM> has, in a longitudinal cross-section, a partial "S" shaped curve centered about the convex spherical radius <NUM>, which defines gaps <NUM>, <NUM> between the hemispherical poppet sealing member and the housing above and below the convex surface-convex surface seal, based on the orientation of the figure to the page.

Turning back to <FIG> and <FIG>, to aid in seal alignment, the internal cavity <NUM> has a pin <NUM> centrally positioned and protruding into the cavity opposite the annual seat <NUM>. The hemispherical poppet valve <NUM> has a cupped underside <NUM> defining a first seat <NUM> for an optional spring <NUM> and has a hollow stem <NUM> protruding from the cupped underside <NUM> toward the pin <NUM> and receives the pin <NUM> therein for translation of the hemispherical poppet sealing member <NUM> along the pin <NUM>. When spring <NUM> is present, a first end <NUM> of the spring <NUM> is seated and retained by first seat <NUM> in the cupped underside <NUM> of the hemispherical poppet sealing member <NUM> and a second end <NUM> of the spring <NUM> is seated and retained be a second seat <NUM> defined by the housing <NUM> and protruding into the internal cavity proximate a base <NUM> of the pin <NUM>. The cupped underside <NUM> of the hemispherical poppet sealing member <NUM> provides a large restriction to fluid flow in the "non-flow direction" represented by the arrows in <FIG>, thereby producing sufficient force to translate the sealing member to the closed position, even without the spring force provided by the spring, if desired.

Referring to <FIG>, in all embodiments, one or both of the annular seat <NUM> and the hemispherical poppet sealing member <NUM> include a ring of elastomeric sealing material <NUM> (<FIG>) to define the convex spherical radius <NUM> of the annular seat <NUM> or to define the portion of the convex surface <NUM> of the hemispherical poppet sealing member <NUM> (<FIG>) that engages the annular seat <NUM> in the closed position. The ring of elastomeric sealing material <NUM> matches (is flush with) the partial "S" shaped curved contour of the first housing portion <NUM> so as not to create a flow restriction, in the open position and the ring of elastomeric sealing material <NUM> matches (is flush with) the hemispherical surface of the hemispherical poppet sealing member <NUM> so as not to create a flow restriction, in the open position. The ring of elastomeric sealing material <NUM>, <NUM> is insert molded or co-molded as part of one or both of the annular seat <NUM>, i.e., first housing portion <NUM>, and the hemispherical poppet sealing member <NUM>. Either or both of the rings of elastomeric sealing material <NUM>, <NUM> may include an annular lip <NUM> best seen in <FIG> to help retain the molded elastomeric sealing material <NUM>, <NUM> in place in its respective member.

The ring of elastomeric sealing material <NUM>, <NUM> may be formed of a fluoroelastomer. Suitable fluoroelastomers include, but are not limited to, polyvinyl fluoride, polyvinylidene fluorides, polytrifluoromonochloroethylene, polytetrafluoroethylene, polyhexafluoropropylene, polydifluoroethylene, polytetrafluoroethylene, fluorosilicone, ethylene-tetrafluoroethylene copolymer, hexafluoropropylene-tetrafluoroethylene copolymer, hexafluoropropylene-difluoroethylene copolymer, perfluoroalkoxytetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer, or other commercially available elastomeric material that will provide seal integrity at both low pressure differentials (such as <NUM> kPa) and at high pressure differentials (such as <NUM> kPa), and blends thereof. Ethylene propylene diene monomer and derivatives thereof are also suitable for the ring of elastomeric sealing material.

In all embodiments, the hemispherical poppet sealing member <NUM> has a cupped underside <NUM> defining an outer rim <NUM>. The poppet can be made of polyoxymethylene, polyamides, polypropylene, polyphenylene ether or polyphenylene oxide, or other commercially available polymers that would meet the temperature and strength requirements of the application.

Referring now to <FIG>, the outer rim <NUM> can include an elastomeric flange <NUM> extending radially outward that, in the closed positioned, forms a clearance fit or an interference fit with a surface of the internal cavity <NUM>. This elastomeric flange <NUM> enhances the ability of the hemispherical poppet sealing member <NUM> to close under low reverse flow conditions. The elastomeric flange <NUM> is insert molded or co-molded to the hemispherical poppet sealing member <NUM> and may include a head <NUM> inserted into the hemispherical poppet sealing member <NUM> as shown in <FIG>. The elastomeric flange <NUM> as shown in <FIG> may include a hinge feature <NUM> that allows the elastomeric flange <NUM> to bend out of the way in response to the pressure differentials in the system to maintain minimal restrictions on the fluid flow through the check valve in the open position, i.e., the flange <NUM> bends away from the surface of the internal cavity <NUM> toward the stem <NUM> and the pin <NUM>.

With reference to all the figures, the first housing portion <NUM> terminates away from the first port <NUM> with a double flanged end <NUM>, wherein an interior flange <NUM> of the double flange is shorter than an exterior flange <NUM> of the double flange and the interior flange <NUM> is contoured to lie radially inward of a rim <NUM> of the second housing portion <NUM> to collectively define the generally spherical shape of the internal cavity <NUM>. The spherical radius and/or the radial position of spherical radius center of the first housing portion's profile is slightly less than the spherical radius and/or the radial position of spherical radius center of the second housing portion's profile, which creates an "overlap" of the interior flange <NUM> with the rim <NUM> described above and provides a low restriction flow path as well as low audible noise in the check valves <NUM>.

The exterior flange <NUM> of the first housing portion <NUM> and the rim <NUM> of the second housing portion <NUM> can have a snap-fit connection <NUM> as shown in <FIG>. In all embodiments, the first housing portion <NUM> and the second housing portion <NUM> can be formed of a plastic material suitable for combustion engine environments and can be spin-welded together. As shown in <FIG>, the double flange end <NUM> of the first housing portion <NUM> can include an annular bead of sealing material <NUM> between the interior flange <NUM> and the exterior flange <NUM> to provide additional material for the spin weld.

Referring again to <FIG>, the open end <NUM> of the stem <NUM> and the head <NUM> of the pin <NUM> can have snap-fit features <NUM> to assist in maintaining the position of the hemispherical poppet sealing member <NUM> during assembly of the check valve <NUM>.

In all aspects, the housing <NUM> is typically molded of plastic, such as, but not limited to, nylon <NUM>, nylon <NUM>/<NUM>, nylon <NUM>/<NUM>, polyoxymethylene, and/or other commercially available plastics that will provide fluid tight seal integrity at both low pressure differentials (such as <NUM> kPa) and at high pressure differentials (such as <NUM> kPa) and are suitable for engine operating systems that can experience pressures between <NUM> kPa to -80kPa and temperatures between -<NUM> to <NUM>. , as well as road and weather conditions and debris.

The check valve <NUM> has several advantages over other check valves. One advantage is that the check valves open under low differential pressure, such as but not limited to a difference of 5kPA and has low flow restriction once open. The low flow restriction in the open position is a result of the combined shapes of the generally spherical internal cavity and the upper surface of the hemispherical poppet sealing member (see the flow arrows in <FIG>), more particularly, the internal flange of the first housing portion overlapping the rim of the second housing portion and defining matching contours once sealingly fixed together. This configuration also provides low audible noise when open and a no-leak seal when closed.

It should be noted that the embodiments are not limited in their application or use to the details of construction and arrangement of parts and steps illustrated in the drawings and description.

Claim 1:
A crankcase ventilation breach detection system (<NUM>) of an internal combustion engine comprising:
an internal combustion engine (<NUM>) having a crankcase (<NUM>) and an intake manifold (<NUM>);
a positive crankcase ventilation valve (<NUM>) in fluid communication between the crankcase (<NUM>) and intake manifold (<NUM>) that regulates the flow of blow-by-gas from the crankcase (<NUM>) to the intake manifold (<NUM>);
a crankcase ventilation tube (<NUM>) in fluid communication with air from an air intake (<NUM>) and the blow-by-gas and subdividing into a flow control system (<NUM>);
wherein the flow control system (<NUM>) comprises:
a plurality of parallel conduits (<NUM>, <NUM>, <NUM>) comprising a first conduit (<NUM>) having a normally closed check valve (<NUM>) controlling flow through the first conduit, the normally closed check valve opening under a first preselected pressure drop in a first direction of flow from the air intake (<NUM>) to the crankcase (<NUM>), and a second conduit (<NUM>, <NUM>) having a second check valve (<NUM>) that opens under a second preselected pressure drop in a second direction of flow from the crankcase (<NUM>) to the air intake (<NUM>), characterized in that the second preselected pressure drop is the same or lower than the first preselected pressure drop ; and
a pressure sensor (<NUM>) positioned between the parallel conduits (<NUM>, <NUM>, <NUM>) and the crankcase (<NUM>), wherein detection of no pressure drop by the pressure sensor (<NUM>) indicates a breach in the system,
wherein the internal combustion engine (<NUM>) has a turbocharger (<NUM>, <NUM>) and the crankcase ventilation tube (<NUM>) connects upstream of the compressor (<NUM>) of turbocharger