Patent Description:
Fuel vapor emission or purge control systems are implemented in internal combustion engine systems to comply with environmental and safety regulations. These systems prevent fuel vapor from escaping to the atmosphere, for example, by venting fuel vapors to a purge canister which contains charcoal. Under preselected engine conditions, a purge valve opens and vacuum from the intake manifold draws the vapor to the engine's combustion chamber to be burned as part of the aggregate fuel-air mixture.

Another requirement of such systems is a leak-detection system. Some systems have been implemented that utilize a two-way airflow system between the purge valve and the intake manifold. However, typically fuel tanks are made of plastic, which are susceptible to expansion and contraction if internal tank pressure become excessively high or excessively low (deep vacuum). Such physical characteristics of the fuel tank can pose a problem of tank burst or tank collapse, respectively.

An example of known arrangement in the art is disclosed in <CIT>.

There is a need to protect the fuel tank from extreme pressures, especially excessive negative (vacuum) pressure that can cause a sudden evacuation of the fuel vapors from the fuel tank. A device that allows lower volumetric evacuation of the fuel vapors form a same volume is desired.

The aforementioned aims are reached by a fuel tank protector valve and a fuel vapor purge system according to the appended set of claims.

The following detailed description will illustrate an embodiment 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.

Referring now to <FIG>, an engine system <NUM>, which is a turbocharged or supercharged system having a turbocharger, a supercharger or the like, referred to herein collectively as turbocharger <NUM>, is shown. However, in other embodiments, (not shown), the engine system can be a naturally aspirated engine. The engine system <NUM> is configured for combusting fuel vapor from a fuel tank <NUM> which accumulates 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 turbocharger <NUM> has a turbine <NUM> operating a compressor <NUM>, which receives air from the air intake <NUM>, compresses the air, and directs a flow of compressed air <NUM> (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.

The fuel tank <NUM> is a reservoir for holding fuel to be supplied to the internal combustion engine <NUM> via a fuel delivery system such as a fuel pump (not shown) and includes a filler neck <NUM>. A controller can regulate the operation of the engine and its fuel delivery and/or the evaporative emissions. A bypass conduit <NUM> is included around the turbocharger <NUM>. The bypass conduit <NUM> in <FIG> has an entrance <NUM> downstream of the compressor <NUM> and upstream of the throttle <NUM> and has an exit <NUM> upstream of the compressor <NUM>. The entrance <NUM> may be upstream or downstream of the intercooler <NUM>. The bypass conduit <NUM> includes a Venturi device <NUM> for generating vacuum. The Venturi device <NUM> has a motive entrance <NUM> in fluid communication with the entrance <NUM>, a discharge exit <NUM> in fluid communication with the exit <NUM>, and a suction portion <NUM> in fluid communication with the fuel tank <NUM> and the purge canister <NUM> via a suction conduit <NUM>. The Venturi device <NUM> may have the particulars of any of the devices in any of Applicant's co-pending applications or granted patents, e.g., <CIT> and <CIT>, and may include an integral check valve <NUM> preventing flow from the Venturi device <NUM> through the suction port <NUM> toward the fuel tank <NUM>. Otherwise, the check valve <NUM> may be a separate check valve in the suction conduit <NUM>.

Here, the fuel tank <NUM> is operatively connected to an evaporative emissions control system <NUM>. The purge canister <NUM> is connected to the fuel tank <NUM> for fluid communication therewith through a first conduit <NUM> having a vapor control valve <NUM>. The first conduit <NUM> provides fluid communication with vapors in a head space <NUM> within the fuel tank <NUM> and the purge canister <NUM>. The evaporative emissions control system <NUM> also includes a fuel tank protector valve <NUM> positioned in fluid communication between the fuel tank <NUM> and the purge canister <NUM>, more specifically in a bypass loop <NUM> around the vapor control valve165. The fuel tank protector valve <NUM> is described in detail subsequently with respect to <FIG>. In the bypass loop <NUM> the fuel tank protector valve <NUM> is positioned with a normally open valve most proximate the fuel tank <NUM> and with a normally closed valve most proximate the purge canister <NUM>. The purge canister <NUM> has a second conduit <NUM> in fluid communication with atmosphere (ATM). A canister vent valve <NUM> is present in the second conduit <NUM> and controls the fluid communication between the purge canister <NUM> and ATM.

Still referring to <FIG>, the vapor control valve <NUM> controls the fluid communication from the fuel tank <NUM> and the purge canister <NUM> to the engine <NUM>, i.e., controlling the release of fuel vapor to the engine's intake manifold <NUM> via vapor conduit <NUM>, and vapor conduit <NUM> includes a canister purge valve <NUM> to regulate the flow to the intake manifold. The canister purge valve <NUM> can be a high restriction flow and metered flow valve. Fuel vapors enter the purge canister through the first conduit <NUM> and gasses after being acted upon by the charcoal or other adsorbent material in the purge canister can exit the purge canister through the fresh air conduit <NUM>. The vapor conduit <NUM> may also include a vapor check valve <NUM> preventing flow from the intake manifold <NUM> toward the fuel tank <NUM>.

Referring now to <FIG>, the fuel tank protector valve <NUM> is shown in more detail. The fuel tank protector valve <NUM> has dual inline check valves having a normally open check valve <NUM> most proximate a first port <NUM> in fluid communication with the fuel tank <NUM>, thereby being most proximate the fuel tank, and a normally closed check valve <NUM> most proximate a second port <NUM> in fluid communication with the purge canister <NUM>, thereby being most proximate the purge canister. The normally open check valve <NUM> and the normally closed check valve <NUM> are independently tunable and are tuned for the normally closed check valve <NUM> to open at a preselected pressure differential before the normally open check valve <NUM> moves to a closed position. As such, the valve <NUM> allows fluid flow in one direction under preselected conditions, i.e., pressure differential and flow rate, and prevents fluid flow in an opposite higher flow condition, which creates a tunable hysteresis pressure and flow dependent valve. In the engine system of <FIG>, the valve <NUM>, at low flow rates and low pressure differential allows flow to pass from the fuel tank <NUM> to the purge canister <NUM>, but during high flow rates and high differential pressure, the valve is closed to prevent sudden low pressures in the fuel tank <NUM>, which could damage or collapse the fuel tank.

The normally open valve can be tuned to close within <NUM> kPa to <NUM> kPa of the preselected requirement of a control system for a particular engine system based on the setpoints selected for said engine system.

The flow direction though the protector valve <NUM> is indicated by arrows in <FIG>, which is from the fuel tank to the purge canister when both of the check valves <NUM>, <NUM> are in the open position. The protector valve <NUM> includes a housing <NUM> defining an internal cavity <NUM> and 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 internal cavity <NUM> has a transversely oriented divider <NUM> defining a plurality of apertures <NUM> for fluid flow from the first port to the second port. The divider <NUM> separates the internal cavity <NUM> into a first check valve chamber <NUM> and a second check valve chamber <NUM>. A first seal disk <NUM> is positioned in the first check valve chamber <NUM> and is normally biased to an open position by a first biasing member <NUM> having a first biasing force, and a second seal disk <NUM> is positioned in the second check valve chamber <NUM> and is normally biased to a closed position by a second biasing member <NUM> having a second biasing force.

As illustrated in <FIG>, the divider <NUM> is shaped as central hub <NUM> with a plurality of spokes <NUM> extending radially outward and join a wall <NUM> of the housing <NUM>. As best seen in <FIG>, extending axially from the divider <NUM> toward the first port is a first shaft <NUM> upon which is seated a first biasing member <NUM>. The first biasing member <NUM> is seated against the divider <NUM> in compression thereagainst by an adjustable fastener <NUM>. The first biasing member <NUM> is operatively biasing a first seal disk <NUM> to an open position toward the first port <NUM>, and hence toward the fuel tank, against the fastener <NUM>. The fastener <NUM> is releasably, adjustably fastened to the shaft <NUM>. Additionally, extending axially form the divider <NUM> toward the second port is a second shaft <NUM> upon which is seated a second biasing member <NUM>. The second biasing member <NUM> is operative biasing a second seal disk <NUM> to a closed position against the divider 212in a direction toward the first port, and hence toward the fuel tank. The second biasing member is held in selectable compression by a fastener <NUM> releasably, adjustably fastened to the second shaft <NUM>. Each fastener <NUM>, <NUM> being releasably, adjustably attached to its shaft <NUM>, <NUM> makes each check valve <NUM>, <NUM> independently tunable.

Still referring to <FIG>, the portion of the housing <NUM> defining the first check valve chamber <NUM> defines a first seat <NUM> for the closed position of the first check valve <NUM>. The first seat <NUM> may be in the form of an annular step or shoulder defined in an interior wall of the housing <NUM>. The divider <NUM> defines a second seat <NUM>, which may be a first annular seal bead, upon which the seal disk <NUM> seats when the second check valve <NUM> is closed. If desired, a second annular seal bead (not shown) may be present at the central hub <NUM>, which is radially inward of the first annular seal bead. Alternately, the portion of the housing <NUM> defining the second check valve chamber <NUM> could define the second seat in the same manner as in the first check valve, i.e., an annular step or shoulder defined in an interior wall of the housing. Based on the positions of the first seat <NUM> and the second seat <NUM>, the closed position of the first seal disk and the closed position of the second seal disk are spaced apart a distance from one another to define a sealed subchamber <NUM>, and movement of first seal disk <NUM> and the second seal disk <NUM> to the closed positions is toward one another.

The housing <NUM> may be a multiple piece housing with pieces connected together with a fluid-tight seal. As best seen in <FIG>, the housing <NUM> may have a central body <NUM> having two open ends <NUM>, <NUM> that are capped with generally funnel shaped caps <NUM>, <NUM> that define the first port <NUM> and second port <NUM>, respectively. The first port <NUM> and the second port <NUM> may each define or include an elongate connector extending away from the central body <NUM> and may each include a connector feature <NUM> shown on the outer surface of the second port <NUM> in <FIG> or at the end thereof. The internal cavity <NUM> typically has larger dimensions than the first port <NUM> and the second port <NUM> to provide adequate dimensions for receipt of the first and second seal disks <NUM>, <NUM>. 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.

In all embodiments, the biasing members may be springs, such as coil springs, or tubularly-shaped, compressible elastomeric members.

In one embodiment, the shafts <NUM>, <NUM> are each threaded and the fastener is a nut, which may be lockable once the protector valve <NUM> is tuned. In another embodiment, the shaft may include a plurality of spaced apart radially extending bores for receipt of a cotter pin fastener (not shown). In yet another embodiment, the shaft is not threaded and the fastener is a clamp affixable to the shaft.

The seal disks <NUM>, <NUM> are each a generally flat planar disk having a central bore <NUM>, <NUM> (labeled in <FIG>) therethrough that receive the shaft <NUM>, <NUM>, respectively. The seal disks may be or include an elastomeric material suitable for use in fluid communication with fuel vapors of an internal combustion engine, i.e., are durable when exposed to chemicals, temperatures, and pressures associated with such an environment. In one embodiment, the seal disks 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 are not limited thereto. Further, the seal disks may be or include metal, plastic, and/or rubber composite.

The protector valve <NUM> is tuned to have a first preselected pressure drop to open the normally closed check valve (the second check valve <NUM>) before the first check valve <NUM> closes, but both check valves <NUM>, <NUM> close under the conditions present during a purge canister evacuation event and both open for fluid flow from the fuel tank to the purge canister during operation of the engine and/or engine off conditions. For example, the protector valve <NUM> may be tuned to have the normally open and normally closed check valves both closed when the pressure differential between the fuel tank and the purge canister are appropriate for a particular engine system.

The advantages and/or benefits of the fuel tank protector valve include a simplified design, not requiring electromotive controls, separately tunable biasing members for customization of the same device for multiple engine systems, but most importantly the protection afforded to the fuel tank to avoid damage from extreme low or high pressure.

Claim 1:
A fuel tank protector valve (<NUM>) comprising:
a housing (<NUM>) having a first port (<NUM>) and a second port (<NUM>), and defining an internal chamber (<NUM>) having a transversely oriented divider (<NUM>) defining a plurality of apertures (<NUM>) for fluid flow from the first port to the second port, wherein the divider (<NUM>) separates the internal chamber into a first check valve chamber (<NUM>) and a second check valve chamber (<NUM>);
a first seal disk (<NUM>) positioned in the first check valve chamber (<NUM>) and normally biased to an open position by a first biasing member (<NUM>) having a first biasing force; and
a second seal disk (<NUM>) positioned in the second check valve chamber (<NUM>) and normally biased to a closed position by a second biasing (<NUM>) member having a second biasing force;
wherein, when the first seal disk (<NUM>) and the second seal disk (<NUM>) move to a closed position, the direction of movement is toward one another;
wherein the second biasing force is set to a preselected pressure differential that moves the second seal disk (<NUM>) to an open position before the first seal disk (<NUM>) moves to a closed position;
wherein, when the first seal disk (<NUM>) is in the open position, fluid flows from the first port (<NUM>) through the first check valve chamber (<NUM>) and acts on the second seal disk (<NUM>) to move the second seal disk (<NUM>) to the open position when the preselected pressure differential is exceeded,
wherein the first and second biasing members (<NUM>, <NUM>) are independently tunable to set the first biasing force and the second biasing force, and wherein the first biasing member (<NUM>) is seated against the divider (<NUM>) and is compressed against the divider (<NUM>) by an adjustable first fastener (<NUM>).