CA2249678A1 - Combination fluid level control and pressure relief valve for fuel tanks - Google Patents
Combination fluid level control and pressure relief valve for fuel tanks Download PDFInfo
- Publication number
- CA2249678A1 CA2249678A1 CA 2249678 CA2249678A CA2249678A1 CA 2249678 A1 CA2249678 A1 CA 2249678A1 CA 2249678 CA2249678 CA 2249678 CA 2249678 A CA2249678 A CA 2249678A CA 2249678 A1 CA2249678 A1 CA 2249678A1
- Authority
- CA
- Canada
- Prior art keywords
- tank
- valve
- fuel
- combination valve
- pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Landscapes
- Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)
Abstract
A combination valve for use in the fuel tank of a vehicle is provided. The valve advantageously combines a fuel level control valve with an over-pressure relief valve. The over-pressure relief valve is located in a housing which has an inlet from the fuel tank and an outlet to atmosphere, and comprises a poppet located in thehousing. The poppet is moveable between a normally closed position in which the poppet seals the inlet from the fuel tank and an open position in which the poppet exposes the inlet allowing the tank to release built-up pressure. The fuel level control valve comprises a level sensing body which extends into the tank and communicates with the fuel in the tank, a float associated with this body which comes into contact with the fuel in the tank as the tank is filled and a stopper adapted to allow the tank to vent during filling of the tank and to prevent tank venting when the tank is full. The fuel level control valve and the pressure-relief valve are connected via a vent passage.
The vent passage enters the pressure-relief valve at the housing inlet and is sealed by the stopper when the tank is full. The combination valve is compact and particularly useful in vehicles where installation space for fuel tank accessories is minimal.
The vent passage enters the pressure-relief valve at the housing inlet and is sealed by the stopper when the tank is full. The combination valve is compact and particularly useful in vehicles where installation space for fuel tank accessories is minimal.
Description
COMBINATION FLUID LEVEL CONTROL AND PRESSURE RELIEF
VALVE FOR FUEL TANKS
Field of the Invention The present invention generally relates to vehicle fuel tanks and devices used in conjunction with such fuel tanks for fuel level control, vapor release, over-pressure relief and prevention of fuel escape under vehicle roll-over conditions.
More particularly, the present invention relates to a combination device which is capable of monitoring fuel fill level in a fuel tank while providing over-pressure 0 relief when required.
Back~round of the Invention In fuel tank systems used to date, fuel level and vapor release are monitored by a fuel level control valve. The valve comprises a level sensing body and a passage for venting vapor from the tank. The level sensing body contains three spherical balls which can move freely in the vertical direction. The upperball has a moderate degree of flotation and is generally made of aluminum or other suitable material, such as high density plastic, that will render a degree of flotation equivalent to that of an aluminum ball. The middle ball is made of epoxy-coated 20 cork and has a high degree of flotation. The lower ball is made of solid steel.
During refueling, the fuel nozzle is locked onto an adapter on the fuel tank and the connection is sealed against leaks to the atmosphere. As fuel enters thetank, at rates typically ranging from 20 to 60 gallons per minute, an equivalentvolume of air or vapor is displaced from the level control valve through a venting 25 passage. When the fuel level reaches the two upper balls in the level controlvalve, they float upwards until the uppermost ball engages a seat in the top of the level sensing body effectively sealing the vent passage to any further flow of air or vapor out of the tank. This causes a build-up of back-pressure. The nozzle senses the back-pressure in the tank and will automatically shut off the fuel supply when 30 the back-pressure reaches 1.1 to 1.5 psi. The steel ball is provided to prevent leakage of fuel through the level control valve in the event that the vehicle should roll over. In such a case, when the roll-over exceeds 90~ from the vertical, theheavier steel ball forces the lighter upper and middle balls against the valve seat, again sealing the vent passage to prevent undesirable leakage of fuel through the valve.
s The conventional over-pressure relief valve is separate from the fuel level control valve. This valve includes a poppet which incorporates a sealing gasket,the latter being compressed by spring loading against a valve seat. The axial alignment of the poppet is m~int~ined by a poppet guide which is attached to thevalve seat by means of spider arms.
o The internal pressure in the tank acts against the underface of the poppet.
If the internal pressure becomes high enough (typically about 3 psi) that the force generated against the underface of the poppet is greater than the compressive force exerted by the spring, the spring will be compressed further and the poppet willlift off its seat. This allows relief of the internal tank pressure into an overflow handling system. When the internal pressure falls sufficiently, the force actingagainst the poppet is reduced. The poppet and its gasket are then forced back onto the valve seat by the spring's force thereby resealing the tank.
Since the trend in new vehicle design restricts the space available above the fuel tank, a major disadvantage of the conventional systems described above is the requirement for independent devices to monitor fuel fill level and provide over-pressure relief. Not only do such devices restrict the opening of the fuel tank, but they are also time-consuming to install. The provision of a compact valve incorporating both fluid level control and an over-pressure relief function would be most advantageous particularly with the advent of lower floor model commercial vehicles which are now required by law in order to provide easier passenger access. Moreover, it would be desirable to provide fuel tank attachments that are suitable for retrofitting onto existing tanks since the size of fuel tank openings are generally fixed by the fuel tank m~nuf~turer. It would also be desirable to provide an assembly in which restrictions at the tank opening are minimi7ed since the rate of discharge of vapour during fueling and the outflow of fuel in case of an over-pressure condition are affected not only by the size of the opening in the fuel tank but also by restrictive attachments installed at that opening.
s Summarv of the Invention A combination valve has now been developed which provides fuel level control and over-pressure relief in a single compact unit thereby overcoming thedisadvantages associated with prior systems which comprise more than one unit.
The valve is more easily installed in the confined spaces now provided above fuel o tanks and minim~lly restricts the opening of the fuel tank.
Accordingly, a combination valve for use in a fuel tank is provided comprising:
a pressure-relief valve seated in a housing wherein said housing is open to atmosphere and has an inlet from the fuel tank, said pressure-relief valve 5 comprising a poppet and biasing means associated therewith which allow said poppet to move between a normally closed position and an open position when the pressure in the tank increases to an over-pressure value thereby relieving said pressure; and a fuel level control valve in communication with said pressure-relief valve 20 via a vent passage, said fuel level control valve comprising a fuel level sensing body which extends into the tank, float means associated with said body and stopper means adapted to control tank venting, wherein said float means causes said stopper means to seal the vent passage when the tank is full.
In another aspect of the present invention, there is provided an assembly 25 comprising a combination valve as described which further incorporates a filler neck.
Description of the Drawin~s FIGURE lA is a cross-sectional view of a combination valve according to one 30 embodiment of the present invention resting in a low fuel level position;
FIGURE lB is a cross-sectional view of the valve of Fig. lA in a fuel shut-off posltlon;
FIGURE lC is a cross-sectional view of the valve of Fig. lA in an over-pressure relief position;
5 FIGURE 2A is a cross-sectional view of a modified version of the valve of Fig. 1 in a low fuel level position;
FIGURE 2B is a cross-sectional view of the valve of Fig. 2A in a fuel shut-off position;
FIGURE 2C is a cross-sectional view of the valve of Fig. 2A in an over-pressure I o relief position;
FIGURE 3A is a cross-sectional view of a combination valve according to another embodiment of the present invention in a low fuel level position;
FIGURE 3B is a cross-sectional view of the valve of Fig. 3A in a fuel shut-off position;
FIGURE 3C is a cross-sectional view of the valve of Fig. 3A in an over-pressure relief position;
FIGURE 3D is a cross-sectional view of the valve of Fig. 3A in a roll-over position;
FIGURE 4A is a cross-sectional view of a modified version of the valve of Fig. 320 in a low fuel level position;.
FIGURE 4B is a cross-sectional view of the valve of Fig.4A in a fuel shut-off poslhon;
FIGURE 4C is a cross-sectional view of the valve of Fig.4A in an over-pressure relief condition;
25 FIGURE 4D is a cross-sectional view of an expanded portion of the fuel level control valve of the combination valve of Fig. 4A;
FIGURE 4E is partial cut-away view taken on the arrow shown in Fig. 4B;
FIGURE 4F is an expanded view of a portion of Fig. 4E;
FIGURE 4G is a cross-sectional view of the valve of Fig.4A in a roll-over 30 position;
FIGURE 5 is a cross-sectional view of a combination valve filler neck assembly incorporating the valve of Fig.1;
FIGURE 6 is a cross-sectional view of a combination valve filler neck assembly according to another embodiment of the invention;
s FIGURE 7A is a cross-sectional view of a combination valve filler neck assembly according to a further embodiment of the invention; and FIGURE 7B is a partial view taken along the arrow shown in Fig. 7A.
Description of Specific Embodiments of the Invention o A combination valve 10 according to the present invention is illustrated in Figure 1. The valve 10 includes a fuel level control valve 12 and an over-pressure reliefvalve 14.
The over-pressure relief valve 14 of the combination valve 10 is contained in housing 16. The housing 16 comprises a bottom inlet 18 from the fuel tank anda side outlet 20 to atmosphere. A valve seat 22 is secured by a plurality of fastening means 24, such as bolts, to a tank outlet flange 26. An annular seal 28 is compressed between the valve seat 22 and the tank outlet flange 26 to create an airtight seal. The housing 16 is similarly secured to the valve seat 22 by a plurality of fastening means 30 and the connection is sealed by compression of an 20 annular seal 32. A poppet 34 sits in valve seat 22 and encircles a vent passage 36 such that it is able to slide freely on the outer diameter of vent passage 36. An O-ring reciprocating seal 38 is retained on the interior circumscribing wall of poppet 34 to create an air-tight seal between the tank and the interior of housing 16. A
surface 40 is machined in the form of a conical frustum on the outer diameter of2s poppet 34. Surface 40 is dimensionally replicated in female configuration in a matching surface 42 machined in the edges of valve seat 22 which accommodates poppet 34. An O-ring seal 44 is retained in a recess 46 formed in surface 40 on poppet 34 to create an air-tight seal when conical surfaces 40 and 42 come in contact.
A biasing means 48, such as a spring, is compressed between the upper surface of poppet 34 and the interior opposing surface of housing 16 such that pressure is applied to poppet 34 causing surface 40 and seal 44 to be forced against surface 42 to provide an airtight seal. The force applied to poppet 34 by biasing means 48 is such that a predetermined "over-pressure" (typically about 3psi) on the lower surface of poppet 34 will compress the spring causing O-ring 44 and surface 40 to move out of contact with surface 42 and valve seat 22. The poppet 34 can be provided already pre-assembled with a biasing means 48 in housing 16. Such a pre-assembled poppet 34 is retained against the pressure of the biasing means 48 by a retaining ring 49 that is seated in a groove 50 formed in o the outer surface of vent passage 36.
The fuel level control valve 12 of the combination valve 10 includes a level sensing body 52 that may be in the form of a hollow cylinder as shown in Fig. 1. The body 52 is fitted to the vent passage 36 which is seated in the over-pressure relief valve 14 and connects the fuel level control valve 12 to the over-s pressure relief valve 14. The level sensing body 52 and the vent passage 36 preferably exist as two distinct parts; however, they can also be integrally formed.
As shown in Fig. 1, particularly Fig. lD, body 52 and vent passage 36 exist as two parts, the body 52 being machined internally at its upper end to create an interference fit with a mating surface on the vent passage 36. These two surfaces 20 are dimensioned such that press fitting results in a permanent assembly of the body 52 to the vent passage 36. An elastomeric O-ring seal 56 is retained in a recess 58 formed at the interface between the body 52 and the vent passage 36.
The vent passage 36 is secured to housing 16 of the over-pressure relief valve 14 by fastening means 60, such as, for example a machine screw and lockwasher. A
25 compressible gasket 62 is inserted between the vent passage 36 and the housing 16 to enable an air tight seal between the interior of the housing 16 and the atmosphere when fastening means 60 are tightened. The wall of the vent passage 36 is provided with holes 64 to allow the free passage of vapor from the interior of the tank, to which valve l O is appended.
The level sensing body 52 is open at the bottom and includes holes 66 in the wall near its top edge to allow free flow of vapor and liquid as required.
Contained in the level sensing body 52 is stopper means 68, float means 70 and sealing means 72, each of which are in the form of a spherical ball for the purposes of this embodiment. The three spherical balls 68, 70 and 72, have a s diameter that is slightly less than the diameter of the body 52, and are loosely retained in the body 52 by means of a retaining pin 74 which is pressed into thewall at the bottom of the body 52. The upper ball 68 is made of a material that imparts on it the property of moderate buoyancy, thereby allowing it to float onfuels such as diesel oil while a significant portion of its volume is submerged.o Moreover, the material forming the upper ball 68 will provide it with a smoothdense surface to allow it to function as a stopper as will be described. However, upper ball 68 is not relied upon to exert sufficient buoyant compressive force to perform the stopper function. Typically, upper ball 68 is made of hollow aluminum or high density plastic of about the same weight. The middle ball 70, on the other hand, is made of a very low density material that imparts on it theproperty of high buoyancy, i.e. greater buoyancy than upper ball 68. The middle ball 70, thus, can be made of a material such as epoxy-coated cork which allows it to function as a float. Unfortunately, materials that impart high buoyancy, such as cork, yield a ball having surface irregularities which render it unsuitable to 20 function as a stopper. The lower ball 72 is made of a high density material of low buoyancy, i.e. a material that is less buoyant than that of the upper and middleballs, such as solid steel. The lower ball 72 is functional as a means to seal the tank in the event of vehicle roll-over to prevent fuel leakage.
In use, the combination valve 10 is installed at an opening in a fuel tank.
2s When the level of the fuel in the tank is below the level sensing valve 12, the three balls 68, 70 and 72 rest in the lower part of the body 52 as shown in Fig. 1 A.
During filling of the tank, fuel under pressure flows into the tank and displaces air or vapor through the body 52 into the vent passage 36 which vents it into housing 16 and to the atmosphere via housing outlet 20. This arrangement prevents any 30 significant build up of pressure within the tank during filling. As the fuel level in the tank rises, upper stopper ball 68 and middle float ball 70 also rise. Since float ball 70 is constrained within the body 52 to an approximately vertical alignmentwith stopper ball 68, it is completely submerged when the fuel level is sufficiently high. As a result, float ball 70 exerts a greater buoyant vertical force than if it was only partly submerged thereby enabling it to force stopper ball 68 against seal 56 sealing the communication between the body 52 and the vent passage 36. This sealing action achieves the fuel shut-off condition shown in Fig.1 B and prevents any further venting of air or vapor from the tank to the atmosphere. Consequently, the continued flow of incoming fuel causes the pressure in the tank to increase.o This pressure can be monitored externally and when it reaches a predeterminedvalue (typically from about 1.1 to 1.5 psi), the fuel flow into the tank is shut off.
Most commonly, the tank is advantageously filled using a nozzle having an internal automatic shut-off mechanism which is triggered by a predetermined pressure. Such a nozzle is attached to the fill neck of the tank so that the interior ofthe tank is sealed to atmosphere with the exception ofthe vent passage 36 leading from the body 52 into housing 16 which provides outlet 20.
In the event that there is a build-up of pressure in the tank, due for example to a malfunction in the fuel nozzle whereby fuel flow into the tank is not shut off at the predetermined pressure, the over-pressure relief condition shown in Fig. 1 C
20 occurs. When the internal pressure in the tank increases to a value at which the force applied to the lower surface of poppet 34 is greater than the force exerted by biasing means 48, i.e. an over-pressure value, the biasing means 48 is forced tocompress. This compression causes poppet 34 to move away from its seat on valve seat 22, thereby allowing fuel flow into the interior of housing 16 and out 25 through the housing outlet 20. This action will effectively relieve the internal pressure in the tank so that it does not exceed the value determined by the force of biasing means 48.
The valve also functions to prevent leakage from the fuel tank of a vehicle that rolls over. When the roll-over angle exceeds 90~ from the vertical and the 30 fuel level is above the level sensing valve 12, stopper ball 68 and float ball 70 will have a tendency to move away from O-ring seal 56 resulting in an outflow of fuelthrough the valve 10. However, lower ball 72 being of much higher density than balls 68 and 70 will roll against float ball 70 pushing it in turn against stopper ball 68, the mass of ball 72 being sufficient to force stopper ball 68 to engage O-ring seal 56, thereby preventing leakage of fuel through the valve 10.
Figure 2 illustrates an alternative combination valve 100 to that shown in Fig. 1. This valve was developed to minimi7P friction that can occur between thepoppet 34 and the vent passage 36 by replacing the reciprocating seal 38 with anO-ring face seal 102. The face seal 102 functions by axial compression thereby o elimin~ting the radial friction that can occur between the reciprocating seal 38 and the vent passage 36 in the combination valve 10 of Fig. 1. While those of skill in the art will recognize that the friction between the reciprocating seal 38 and the vent passage 36 may be minimi7ed by accurately machining the outside diameter of the vent passage 36 so that the squeeze on the inside diameter of O-ring seal 38 s is of small magnitude, normal variations in manufacturing tolerances of the three components can lead to variations in the force required to overcome the friction.
With reference to Figs. 2A-2C, a cylindrical recess 104 of slightly smaller diameter than O-ring seal 102 is machined in the lower surface of poppet 106.
The top of recess 104 is enlarged in diameter locally so that O-ring seal 102 can be 20 inserted and loosely retained in position. A flange 108 is formed on the outside diameter of vent passage 110 such that the outside diameter of flange 108 slidingly engages recess 104 and compresses O-ring seal 102 on contact. This effectively provides an airtight seal between the tank interior and the interior of housing 112.
Although vent passage 110 may be rigidly attached to housing 112, as is the vent passage 36 of valve l O shown in Fig. l, and the compression of seal 102 effected by the action of a biasing means against poppet 106, normal manufacturing tolerances and discrepancies may result in either of seal 102 or seal 114, which is also compressed by the movement of poppet 106, not being properly 30 engaged. Accordingly, in this embodiment, the upper end of vent passage 110 is .
preferably unthreaded thereby allowing passage 110 to slide freely on a stub 116that protrudes therein. The stub 116 is securely fastened to housing 112 by, forexample means such as a nut 118 and lock washer 120. A collar 122 is threaded internally to engage with corresponding threads externally on the upper end of vent passage 110. Biasing means 106 are positioned between collar 120 and poppet 106. Seal 102 becomes fully engaged by the action of biasing means 124 while seal 114 becomes fully engaged by the action of biasing means 126 with no interference therebetween. To ensure free movement of vent passage 110 in the compression of seal 102, a small clearance (typically about 0.03 inches) is o provided between collar 122 and housing 112 under normal conditions. The operation of the combination valves of Fig.1 and Fig.2 are otherwise identical.
Another embodiment of the present invention is illustrated in Fig. 3 in which a combination valve 200 comprises a pressure relief valve 230 and a level sensing valve 240. In this embodiment, a valve seat 201 provides a base for valve 200 and a seat for the pressure relief valve 230. It is fastened to a machined flange 202 on the tank. An O-ring seal 203 is inserted between valve seat 201 and tank flange 202 to provide an airtight seal. A housing 204 is fastened to the valve seat 201. O-ring seal 205 is interposed between housing 204 and valve seat 201 to provide an airtight seal. Housing 204 serves as a cover for the internal 20 components of the valve 200 and is machined internally in cylindrical fashion to provide a guide for the poppet 206. Poppet 206 engages the valve seat 201, via interface surfaces, surface 207 on poppet 206 and surface 208 on valve seat 201,which are machined in a conical fashion with the same apex angle (typically about 60~). An O-ring seal 209 is fitted in a groove formed in the exterior surface of25 poppet 206 to provide an airtight seal when poppet 206 and valve seat 201 engage.
Poppet 206 includes a plurality of circumferential ribs 210 which are machined cylindrically on their outside diameter to allow poppet 206 to slide easily in housing 204. Biasing means 211 is seated in a recess formed in the upper end of poppet 206 and bears against housing 204. The biasing means 211, thus, forces 30 interfacing surfaces 207 and 208 together thereby compressing seal 209 to perform its sealing function. Poppet 206 can be provided pre-assembled, together with biasing means 211, in housing 204 and retained against the pressure of the biasing means 211 by a retaining ring 212 fitted in a groove in housing 204.
A plurality of tapered vanes 213 extend from the bottom of poppet 206 forming a "cage" for stopper 214 which is, for the purposes of this embodiment, a floating poppet. Vanes 213 are machined cylindrically on their interior edges toallow stopper 214 to slide freely in a vertical direction between the vanes 213 with a small radial clearance. A cylindrical vent passage 215 on the axial centre line of poppet 206 allows free passage of air or vapor from the tank during filling o operations. Two diametrically opposed arms 216 extend inward radially from the interior edges of valve seat 201 to a central hub 217. The body 218 of the fuel level sensing valve 240 rests in a hole on the centre line of hub 217 and is free to move axially therein. Body 218 may be cylindrical in shape formed from, for example, aluminum tubing. A thin circular disk 219 is permanently attached to the upper end of body 218 and prevents body 218 from falling out of the hole in hub 217 while providing a platform for stopper 214. A float 220, drilled on its centre line, fits slidingly onto body 218 where it is retained, for example, between two washers 221 and pins 222, pins 222 being inserted into holes 223 drilled in body 218 at spacings which allow a number of optional positions for float 220. In 20 this specific embodiment, the float is cylindrical in shape with conically-tapered shoulders to minimi7e obstruction to flow through the tank opening. The float ismade out of a very buoyant material such as epoxy-coated cork.
Stopper 214 functions to block vent passage 215 when a fuel tank is full, or in the event of roll-over of the vehicle. Accordingly, it must be shaped to fulfill 25 this function. The stopper 214 exemplified in this embodiment is a hemisphereshape, formed from a material such as aluminum or plastic (e.g. nylon or teflon), and can be either hollow or solid.
During a typical filling operation, a nozzle, preferably with an internal automatic shut-off mech~ni~m, is attached to the fill neck of the tank so that the 30 interior of the tank is sealed to atmosphere except through the vent passage 215 formed in poppet 206. When the nozzle is actuated, fuel under pressure flows into the tank and displaces air or vapor through passage 215. This prevents any significant build-up of pressure in the tank. Referring to Fig. 3A, while the fuel level in the tank is below float 220, disk 219 rests on the top of hub 217 and s stopper 214 rests on disk 219 allowing air or vapor to vent through passage 215 by passing freely around stopper 214. When the fuel level in the tank nears the top of float 220, the buoyancy of the float overcomes the combined weights of the levelsensing body 218, the appendages thereto and stopper 214 causing body 218 to rise. This action lifts the stopper 214 upwards until it engages and blocks vento passage 215, as shown in Fig. 3B, thereby preventing further venting of air or vapor from the tank. The continued flow of fuel into the tank causes an increaseof pressure in the tank. When the pressure reaches a predetermined value (typically from about 1.1 to 1.5 psi), this signals shut-off of the nozzle, either m~n~ lly or automatically, and further fuel flow into the tank is prevented.
Should a malfunction result in the nozzle, for example, and fuel flow into the tank is not shut off after stopper 214 engages the vent passage 215, or an internal pressure increase in the tank results for any other reason, the over-pressure relief valve 230 of the valve 200 will allow further venting to occur. The pressure in the tank will be allowed to increase until it approaches the value at which the 20 pressure force applied to the lower surface of poppet 206 is greater than theopposing force exerted on poppet 206 by the biasing means 211. As a result, the biasing means 211 is compressed and poppet 206 is allowed to move away from its seat on valve seat 201, as shown in Fig. 3C. This allows fuel to overflow into the interior of housing 204 and out through the housing outlet, effectively 2s relieving the internal pressure in the tank such that it does not exceed the value determined by the force of spring 211.
The action of the stopper 214 in the event of a vehicle roll-over is illustrated in Fig. 3D. The centre of gravity of the hemispherical stopper 214 is offset significantly from the plane passing through the geometric centre of the 30 hemisphere. Consequently, as the roll-over progresses, when the centre of gravity of the stopper 214 passes over the point 223 at which its mass is supported, stopper 214 will unbalance and roll in the direction of vent passage 215 until it rests against poppet 206 and seals passage 215. Moreover, if the stopper 214 is submerged in fuel, the dynamic action of the fuel will expedite engagement of the s stopper 214 with vent passage 215, and the static head of the fuel in the tank will further add to the sealing action of the stopper 214. If the stopper 214 is a thin-walled hollow hemisphere, its centre of gravity is such that the stopper 214 will unbalance when the vehicle reaches an angle of about 65~ from the vertical. If the stopper 214 is a solid hemisphere, unbalance will take place when the vehicle o reaches an angle of about 70~ from the vertical.
It will appreciated that if a vehicle rolls over when the fuel tank is full, or substantially so, the float mechanism of the present invention will cause the vent to be sealed before any fuel leakage occurs. Similarly, if the fuel level is so low that it does not cover the vent opening before the vehicle has rolled more than 90~, vent sealing will have taken place to prevent leakage through the vent. However,if the fuel level is such that it covers the vent opening at an angle slightly less than 90~ from the vertical, the embodiment of Figs.1 or 2 can be subject to sufficient frictional resistance to overcome the buoyant action of the floating balls thus preventing sealing of the vent. If the vehicle should come to rest at this angle20 from the vertical, considerable leakage could take place.
Figure 4 illustrates yet another embodiment of the present invention. A
combination valve 300, which represents an alternative to valve 200 illustrated in Fig.3, comprises a modified fuel level sensing valve 320. In this embodiment, the hub 302 of the fuel level sensing valve 320 is extended downwards and is formed 25 with a bracket 304 which projects at an angle to the hub 302. A fuel level sensing body 306 of the fuel level sensing valve 320 rests in a hole on the centre line of hub 302 and is free to move axially therein as described with respect to valve 200.
An arm 308 is pivotally fastened to the projected end of the bracket 304 which functions as a fulcrum for arm 308. A pivot pin and push-on fastener, such30 as the type commonly available under the trade name, Tinnerman, can be used to pivotally fasten the arm 308 to the bracket 304. Such push-on fasteners can readily be used with unthreaded pins and provide the advantages of being low weight and easily applied. These fasteners are applied with a force sufficient only to retain the pivot pins in place, for example, in assembly without restricting free pivotal motion. The arm 308 is preferably made of stainless steel in proportionsas narrow as possible in order to minimi7e its weight. The arm 308 is formed in a symmetrical fashion around bracket 304, as is seen best by reference to Fig. 4E,termin~ting adjacent to body 306 at one side and extending at its other side to form a support for float 310. The float 310, which is made of a highly buoyant o material such as epoxy-coated cork, is secured to arm 308 by any suitable fastening means 312 such as a screw. The upper end of a pair of identical links 314, preferably made of narrowly cut stainless steel to minimi7P weight, are pivotally fastened to opposing sides of arm 308 by means similarly used to fasten the arm 308 to bracket 304, e.g. pivot pins and push-on fasteners, as shown in Fig.
4F. The holes in arm 308 which receive these fastening means are located such that when the arm 308 is horizontal, the axial center line through the fasteningmeans passes through the axial center line of body 306. The links 314 are similarly fastened at their lower ends to the body 306.
Disc 316 is attached to the upper end of the body 306 onto which is seated 20 stopper 318, as described with respect to combination valve 200.
Under low fuel level conditions, as depicted in Figs. 4A and 4D, arm 308 rests at an angle of about 15~ below the horizontal, the weight of the float 310maintaining the body 306 in its lowermost position. In this position, links 314 are slightly laterally displaced but are still very close to being parallel to body 306.
25 Consequently, lateral forces which could produce friction between body 306 and hub 302 are negligible.
During fueling of the tank, the float 310 floats on top of the fuel. As the fuel level increases, the fuel pushes float 310 upwards causing the arm 308 to rotate on bracket 304. This rotation transmits a vertical motion to body 306 30 through links 314 with no lateral force being applied to body 306. When the tank is filled, the arm 308 will be in an approximately horizontal position, the body 306 will be vertically extended causing the stopper 318 to engage the vent passage, as illustrated in Fig. 4B, preventing further venting of the tank. This results in an increase in internal tank pressure which results in fuel shut-off. The function of s the over-pressure relief valve 330 of this combination valve 300 is the same as that of the over-pressure relief valve described with respect to the combination valve 200 as can be seen by reference to Fig.4C. Moreover, the function of the combination valve 300 in the event of vehicle roll-over is illustrated in Fig. 4G, and it is also the same as that described for combination valve 200.
o A number of advantages are associated with combination valve 300 illustrated in Figs. 4A-4G. At the outset, the likelihood of body 306 j~mming inthe hub 304 is reduced by the increased length of bearing between body 306 and hub 304, by minim~l lateral forces on the body 306 and by minim~l weight directly on the body 306. Further, the positioning of the float 310 to one side of the tank opening minimi7es restriction of fuel flow from the tank in an over-pressure condition. It also allows the volume of the float 310 to be increased, which results in a corresponding increase in flotation, without interfering with fuel flow. Another benefit of this embodiment is that the lifting force exerted on the body 306 by the float 310 is proportional to the ratio of the distance from the pivot 20 point of arm 308 on bracket 304 to the centre of gravity of float 310 to the distance from this pivot point to the pivot point of links 314 on arm 308. Thus,the lifting force can be increased by increasing this ratio, for example, by increasing the length of the float side of arm 308.
Referring now to Figure 5, an assembly is illustrated in which a 2s combination valve 400 in accordance with the present invention is combined with a filler neck 401. The filler neck 401 is made, by casting or other means, integral with a base plate 402 which covers an opening 403 in the tank top 404. Base plate 402 is bolted to tank top 404, with the interposition of a sealing gasket 405, by means of a plurality of fastening means (not shown). A self sealing adapter 406 is attached to the inlet flange 407 of filler neck 401. Such adapters are commonly used in conjunction with automatic shut-off nozzles and provide an air tight seal between the interior of the tank and the atmosphere. Hinged cap 408 protects adapter 406 from environmental damage when fueling is not taking place. The hinged cap described, for example, in C:~n~ n Patent Application Serial No.
s 2,168,797, can be used as hinged cap 408.
The combination valve 400 of Fig. 5 is identical to the combination valve 10 illustrated in Fig.1 with the exception that the function of valve seat 22 isperformed by base plate 402. Base plate 402 has a conically machined female surface 410 which mates with surface 412 of the valve 400 thereby replacing o surface 42 of valve 10. It should be noted that valve 400 and filler neck 401 are preferably offset from one another in a direction normal to the plane of the view of Fig.5 in order to prevent disruption of the fuel level control function of the valve 400 by the turbulence of incoming fuel.
The combination valve filler neck assembly advantageously provides a more compact assembly than the individual combination valve and filler neck components. Such an assembly requires at least 1/4 of an inch less space than that of the individual components themselves. It will, of course, be appreciated by those of skill in the art that the combination valves of Figs. 2, 3 and 4, or any other combination valve in accordance with the present invention, could similarly be 20 combined with a filler neck, including the filler neck shown in Fig. 5, to form an assembly in accordance with the present invention. In this regard, reference is made to Figs. 6 and 7 in which further combination valve filler neck assemblies in accordance with the present invention are illustrated. Figure 6 shows a compact assembly in which the combination valve comprises an exterior male pipe thread 2s at the housing outlet rather than the interior female pipe thread of the combination valve of Fig. 1. A further space saving measure shown in the valve of Fig. 6 is the use of a countersunk flat head screw which elimin~tes the protrusion caused by ahexagon cap screw. An even more compact embodiment of the present assembly is shown in Fig. 7A in which the combination valve includes a barbed hose 30 connection of elliptical rather than circular cross-section (see Fig. 7B). Moreover, a socket head cap screw applied from the inside of the valve fitted into a hole in the valve housing allows a further reduction in the overall height of the valve,along with the use of a conical-shaped spring as the biasing means. These variations in the combination valve to increase its compactness can be used in any 5 variety of combinations to attain the most beneficial arrangement for a given situation. Accordingly, the variations described above are not particularly restricted to the combinations specifically illustrated in any of the Figures.
It will be understood by those of skill in the art that the specific embodiments described herein are illustrative of the present invention only and o other embodiments are possible that are within the scope of the invention as defined in the attached claims. Moreover, in the description of the embodiments,one of skill in the art will further appreciate that non-essential elements can readily be substituted with elements that perform the sarne function. For example, the term fastening means is used herein to mean screws, bolts, pins and any other 5 appropriate means for fastening as would be appreciated by one of skill in the art.
Likewise, the term biasing means is used herein to refer to springs as well as other biasing means such as resilient bands. By reference to O-ring seals, it will be appreciated that any appropriate sealing means could be substituted. O-ring seals are, however, the preferred means for creating a sealed condition due to the fact 20 that they seat in recesses, thus providing a more compact combination valve.
VALVE FOR FUEL TANKS
Field of the Invention The present invention generally relates to vehicle fuel tanks and devices used in conjunction with such fuel tanks for fuel level control, vapor release, over-pressure relief and prevention of fuel escape under vehicle roll-over conditions.
More particularly, the present invention relates to a combination device which is capable of monitoring fuel fill level in a fuel tank while providing over-pressure 0 relief when required.
Back~round of the Invention In fuel tank systems used to date, fuel level and vapor release are monitored by a fuel level control valve. The valve comprises a level sensing body and a passage for venting vapor from the tank. The level sensing body contains three spherical balls which can move freely in the vertical direction. The upperball has a moderate degree of flotation and is generally made of aluminum or other suitable material, such as high density plastic, that will render a degree of flotation equivalent to that of an aluminum ball. The middle ball is made of epoxy-coated 20 cork and has a high degree of flotation. The lower ball is made of solid steel.
During refueling, the fuel nozzle is locked onto an adapter on the fuel tank and the connection is sealed against leaks to the atmosphere. As fuel enters thetank, at rates typically ranging from 20 to 60 gallons per minute, an equivalentvolume of air or vapor is displaced from the level control valve through a venting 25 passage. When the fuel level reaches the two upper balls in the level controlvalve, they float upwards until the uppermost ball engages a seat in the top of the level sensing body effectively sealing the vent passage to any further flow of air or vapor out of the tank. This causes a build-up of back-pressure. The nozzle senses the back-pressure in the tank and will automatically shut off the fuel supply when 30 the back-pressure reaches 1.1 to 1.5 psi. The steel ball is provided to prevent leakage of fuel through the level control valve in the event that the vehicle should roll over. In such a case, when the roll-over exceeds 90~ from the vertical, theheavier steel ball forces the lighter upper and middle balls against the valve seat, again sealing the vent passage to prevent undesirable leakage of fuel through the valve.
s The conventional over-pressure relief valve is separate from the fuel level control valve. This valve includes a poppet which incorporates a sealing gasket,the latter being compressed by spring loading against a valve seat. The axial alignment of the poppet is m~int~ined by a poppet guide which is attached to thevalve seat by means of spider arms.
o The internal pressure in the tank acts against the underface of the poppet.
If the internal pressure becomes high enough (typically about 3 psi) that the force generated against the underface of the poppet is greater than the compressive force exerted by the spring, the spring will be compressed further and the poppet willlift off its seat. This allows relief of the internal tank pressure into an overflow handling system. When the internal pressure falls sufficiently, the force actingagainst the poppet is reduced. The poppet and its gasket are then forced back onto the valve seat by the spring's force thereby resealing the tank.
Since the trend in new vehicle design restricts the space available above the fuel tank, a major disadvantage of the conventional systems described above is the requirement for independent devices to monitor fuel fill level and provide over-pressure relief. Not only do such devices restrict the opening of the fuel tank, but they are also time-consuming to install. The provision of a compact valve incorporating both fluid level control and an over-pressure relief function would be most advantageous particularly with the advent of lower floor model commercial vehicles which are now required by law in order to provide easier passenger access. Moreover, it would be desirable to provide fuel tank attachments that are suitable for retrofitting onto existing tanks since the size of fuel tank openings are generally fixed by the fuel tank m~nuf~turer. It would also be desirable to provide an assembly in which restrictions at the tank opening are minimi7ed since the rate of discharge of vapour during fueling and the outflow of fuel in case of an over-pressure condition are affected not only by the size of the opening in the fuel tank but also by restrictive attachments installed at that opening.
s Summarv of the Invention A combination valve has now been developed which provides fuel level control and over-pressure relief in a single compact unit thereby overcoming thedisadvantages associated with prior systems which comprise more than one unit.
The valve is more easily installed in the confined spaces now provided above fuel o tanks and minim~lly restricts the opening of the fuel tank.
Accordingly, a combination valve for use in a fuel tank is provided comprising:
a pressure-relief valve seated in a housing wherein said housing is open to atmosphere and has an inlet from the fuel tank, said pressure-relief valve 5 comprising a poppet and biasing means associated therewith which allow said poppet to move between a normally closed position and an open position when the pressure in the tank increases to an over-pressure value thereby relieving said pressure; and a fuel level control valve in communication with said pressure-relief valve 20 via a vent passage, said fuel level control valve comprising a fuel level sensing body which extends into the tank, float means associated with said body and stopper means adapted to control tank venting, wherein said float means causes said stopper means to seal the vent passage when the tank is full.
In another aspect of the present invention, there is provided an assembly 25 comprising a combination valve as described which further incorporates a filler neck.
Description of the Drawin~s FIGURE lA is a cross-sectional view of a combination valve according to one 30 embodiment of the present invention resting in a low fuel level position;
FIGURE lB is a cross-sectional view of the valve of Fig. lA in a fuel shut-off posltlon;
FIGURE lC is a cross-sectional view of the valve of Fig. lA in an over-pressure relief position;
5 FIGURE 2A is a cross-sectional view of a modified version of the valve of Fig. 1 in a low fuel level position;
FIGURE 2B is a cross-sectional view of the valve of Fig. 2A in a fuel shut-off position;
FIGURE 2C is a cross-sectional view of the valve of Fig. 2A in an over-pressure I o relief position;
FIGURE 3A is a cross-sectional view of a combination valve according to another embodiment of the present invention in a low fuel level position;
FIGURE 3B is a cross-sectional view of the valve of Fig. 3A in a fuel shut-off position;
FIGURE 3C is a cross-sectional view of the valve of Fig. 3A in an over-pressure relief position;
FIGURE 3D is a cross-sectional view of the valve of Fig. 3A in a roll-over position;
FIGURE 4A is a cross-sectional view of a modified version of the valve of Fig. 320 in a low fuel level position;.
FIGURE 4B is a cross-sectional view of the valve of Fig.4A in a fuel shut-off poslhon;
FIGURE 4C is a cross-sectional view of the valve of Fig.4A in an over-pressure relief condition;
25 FIGURE 4D is a cross-sectional view of an expanded portion of the fuel level control valve of the combination valve of Fig. 4A;
FIGURE 4E is partial cut-away view taken on the arrow shown in Fig. 4B;
FIGURE 4F is an expanded view of a portion of Fig. 4E;
FIGURE 4G is a cross-sectional view of the valve of Fig.4A in a roll-over 30 position;
FIGURE 5 is a cross-sectional view of a combination valve filler neck assembly incorporating the valve of Fig.1;
FIGURE 6 is a cross-sectional view of a combination valve filler neck assembly according to another embodiment of the invention;
s FIGURE 7A is a cross-sectional view of a combination valve filler neck assembly according to a further embodiment of the invention; and FIGURE 7B is a partial view taken along the arrow shown in Fig. 7A.
Description of Specific Embodiments of the Invention o A combination valve 10 according to the present invention is illustrated in Figure 1. The valve 10 includes a fuel level control valve 12 and an over-pressure reliefvalve 14.
The over-pressure relief valve 14 of the combination valve 10 is contained in housing 16. The housing 16 comprises a bottom inlet 18 from the fuel tank anda side outlet 20 to atmosphere. A valve seat 22 is secured by a plurality of fastening means 24, such as bolts, to a tank outlet flange 26. An annular seal 28 is compressed between the valve seat 22 and the tank outlet flange 26 to create an airtight seal. The housing 16 is similarly secured to the valve seat 22 by a plurality of fastening means 30 and the connection is sealed by compression of an 20 annular seal 32. A poppet 34 sits in valve seat 22 and encircles a vent passage 36 such that it is able to slide freely on the outer diameter of vent passage 36. An O-ring reciprocating seal 38 is retained on the interior circumscribing wall of poppet 34 to create an air-tight seal between the tank and the interior of housing 16. A
surface 40 is machined in the form of a conical frustum on the outer diameter of2s poppet 34. Surface 40 is dimensionally replicated in female configuration in a matching surface 42 machined in the edges of valve seat 22 which accommodates poppet 34. An O-ring seal 44 is retained in a recess 46 formed in surface 40 on poppet 34 to create an air-tight seal when conical surfaces 40 and 42 come in contact.
A biasing means 48, such as a spring, is compressed between the upper surface of poppet 34 and the interior opposing surface of housing 16 such that pressure is applied to poppet 34 causing surface 40 and seal 44 to be forced against surface 42 to provide an airtight seal. The force applied to poppet 34 by biasing means 48 is such that a predetermined "over-pressure" (typically about 3psi) on the lower surface of poppet 34 will compress the spring causing O-ring 44 and surface 40 to move out of contact with surface 42 and valve seat 22. The poppet 34 can be provided already pre-assembled with a biasing means 48 in housing 16. Such a pre-assembled poppet 34 is retained against the pressure of the biasing means 48 by a retaining ring 49 that is seated in a groove 50 formed in o the outer surface of vent passage 36.
The fuel level control valve 12 of the combination valve 10 includes a level sensing body 52 that may be in the form of a hollow cylinder as shown in Fig. 1. The body 52 is fitted to the vent passage 36 which is seated in the over-pressure relief valve 14 and connects the fuel level control valve 12 to the over-s pressure relief valve 14. The level sensing body 52 and the vent passage 36 preferably exist as two distinct parts; however, they can also be integrally formed.
As shown in Fig. 1, particularly Fig. lD, body 52 and vent passage 36 exist as two parts, the body 52 being machined internally at its upper end to create an interference fit with a mating surface on the vent passage 36. These two surfaces 20 are dimensioned such that press fitting results in a permanent assembly of the body 52 to the vent passage 36. An elastomeric O-ring seal 56 is retained in a recess 58 formed at the interface between the body 52 and the vent passage 36.
The vent passage 36 is secured to housing 16 of the over-pressure relief valve 14 by fastening means 60, such as, for example a machine screw and lockwasher. A
25 compressible gasket 62 is inserted between the vent passage 36 and the housing 16 to enable an air tight seal between the interior of the housing 16 and the atmosphere when fastening means 60 are tightened. The wall of the vent passage 36 is provided with holes 64 to allow the free passage of vapor from the interior of the tank, to which valve l O is appended.
The level sensing body 52 is open at the bottom and includes holes 66 in the wall near its top edge to allow free flow of vapor and liquid as required.
Contained in the level sensing body 52 is stopper means 68, float means 70 and sealing means 72, each of which are in the form of a spherical ball for the purposes of this embodiment. The three spherical balls 68, 70 and 72, have a s diameter that is slightly less than the diameter of the body 52, and are loosely retained in the body 52 by means of a retaining pin 74 which is pressed into thewall at the bottom of the body 52. The upper ball 68 is made of a material that imparts on it the property of moderate buoyancy, thereby allowing it to float onfuels such as diesel oil while a significant portion of its volume is submerged.o Moreover, the material forming the upper ball 68 will provide it with a smoothdense surface to allow it to function as a stopper as will be described. However, upper ball 68 is not relied upon to exert sufficient buoyant compressive force to perform the stopper function. Typically, upper ball 68 is made of hollow aluminum or high density plastic of about the same weight. The middle ball 70, on the other hand, is made of a very low density material that imparts on it theproperty of high buoyancy, i.e. greater buoyancy than upper ball 68. The middle ball 70, thus, can be made of a material such as epoxy-coated cork which allows it to function as a float. Unfortunately, materials that impart high buoyancy, such as cork, yield a ball having surface irregularities which render it unsuitable to 20 function as a stopper. The lower ball 72 is made of a high density material of low buoyancy, i.e. a material that is less buoyant than that of the upper and middleballs, such as solid steel. The lower ball 72 is functional as a means to seal the tank in the event of vehicle roll-over to prevent fuel leakage.
In use, the combination valve 10 is installed at an opening in a fuel tank.
2s When the level of the fuel in the tank is below the level sensing valve 12, the three balls 68, 70 and 72 rest in the lower part of the body 52 as shown in Fig. 1 A.
During filling of the tank, fuel under pressure flows into the tank and displaces air or vapor through the body 52 into the vent passage 36 which vents it into housing 16 and to the atmosphere via housing outlet 20. This arrangement prevents any 30 significant build up of pressure within the tank during filling. As the fuel level in the tank rises, upper stopper ball 68 and middle float ball 70 also rise. Since float ball 70 is constrained within the body 52 to an approximately vertical alignmentwith stopper ball 68, it is completely submerged when the fuel level is sufficiently high. As a result, float ball 70 exerts a greater buoyant vertical force than if it was only partly submerged thereby enabling it to force stopper ball 68 against seal 56 sealing the communication between the body 52 and the vent passage 36. This sealing action achieves the fuel shut-off condition shown in Fig.1 B and prevents any further venting of air or vapor from the tank to the atmosphere. Consequently, the continued flow of incoming fuel causes the pressure in the tank to increase.o This pressure can be monitored externally and when it reaches a predeterminedvalue (typically from about 1.1 to 1.5 psi), the fuel flow into the tank is shut off.
Most commonly, the tank is advantageously filled using a nozzle having an internal automatic shut-off mechanism which is triggered by a predetermined pressure. Such a nozzle is attached to the fill neck of the tank so that the interior ofthe tank is sealed to atmosphere with the exception ofthe vent passage 36 leading from the body 52 into housing 16 which provides outlet 20.
In the event that there is a build-up of pressure in the tank, due for example to a malfunction in the fuel nozzle whereby fuel flow into the tank is not shut off at the predetermined pressure, the over-pressure relief condition shown in Fig. 1 C
20 occurs. When the internal pressure in the tank increases to a value at which the force applied to the lower surface of poppet 34 is greater than the force exerted by biasing means 48, i.e. an over-pressure value, the biasing means 48 is forced tocompress. This compression causes poppet 34 to move away from its seat on valve seat 22, thereby allowing fuel flow into the interior of housing 16 and out 25 through the housing outlet 20. This action will effectively relieve the internal pressure in the tank so that it does not exceed the value determined by the force of biasing means 48.
The valve also functions to prevent leakage from the fuel tank of a vehicle that rolls over. When the roll-over angle exceeds 90~ from the vertical and the 30 fuel level is above the level sensing valve 12, stopper ball 68 and float ball 70 will have a tendency to move away from O-ring seal 56 resulting in an outflow of fuelthrough the valve 10. However, lower ball 72 being of much higher density than balls 68 and 70 will roll against float ball 70 pushing it in turn against stopper ball 68, the mass of ball 72 being sufficient to force stopper ball 68 to engage O-ring seal 56, thereby preventing leakage of fuel through the valve 10.
Figure 2 illustrates an alternative combination valve 100 to that shown in Fig. 1. This valve was developed to minimi7P friction that can occur between thepoppet 34 and the vent passage 36 by replacing the reciprocating seal 38 with anO-ring face seal 102. The face seal 102 functions by axial compression thereby o elimin~ting the radial friction that can occur between the reciprocating seal 38 and the vent passage 36 in the combination valve 10 of Fig. 1. While those of skill in the art will recognize that the friction between the reciprocating seal 38 and the vent passage 36 may be minimi7ed by accurately machining the outside diameter of the vent passage 36 so that the squeeze on the inside diameter of O-ring seal 38 s is of small magnitude, normal variations in manufacturing tolerances of the three components can lead to variations in the force required to overcome the friction.
With reference to Figs. 2A-2C, a cylindrical recess 104 of slightly smaller diameter than O-ring seal 102 is machined in the lower surface of poppet 106.
The top of recess 104 is enlarged in diameter locally so that O-ring seal 102 can be 20 inserted and loosely retained in position. A flange 108 is formed on the outside diameter of vent passage 110 such that the outside diameter of flange 108 slidingly engages recess 104 and compresses O-ring seal 102 on contact. This effectively provides an airtight seal between the tank interior and the interior of housing 112.
Although vent passage 110 may be rigidly attached to housing 112, as is the vent passage 36 of valve l O shown in Fig. l, and the compression of seal 102 effected by the action of a biasing means against poppet 106, normal manufacturing tolerances and discrepancies may result in either of seal 102 or seal 114, which is also compressed by the movement of poppet 106, not being properly 30 engaged. Accordingly, in this embodiment, the upper end of vent passage 110 is .
preferably unthreaded thereby allowing passage 110 to slide freely on a stub 116that protrudes therein. The stub 116 is securely fastened to housing 112 by, forexample means such as a nut 118 and lock washer 120. A collar 122 is threaded internally to engage with corresponding threads externally on the upper end of vent passage 110. Biasing means 106 are positioned between collar 120 and poppet 106. Seal 102 becomes fully engaged by the action of biasing means 124 while seal 114 becomes fully engaged by the action of biasing means 126 with no interference therebetween. To ensure free movement of vent passage 110 in the compression of seal 102, a small clearance (typically about 0.03 inches) is o provided between collar 122 and housing 112 under normal conditions. The operation of the combination valves of Fig.1 and Fig.2 are otherwise identical.
Another embodiment of the present invention is illustrated in Fig. 3 in which a combination valve 200 comprises a pressure relief valve 230 and a level sensing valve 240. In this embodiment, a valve seat 201 provides a base for valve 200 and a seat for the pressure relief valve 230. It is fastened to a machined flange 202 on the tank. An O-ring seal 203 is inserted between valve seat 201 and tank flange 202 to provide an airtight seal. A housing 204 is fastened to the valve seat 201. O-ring seal 205 is interposed between housing 204 and valve seat 201 to provide an airtight seal. Housing 204 serves as a cover for the internal 20 components of the valve 200 and is machined internally in cylindrical fashion to provide a guide for the poppet 206. Poppet 206 engages the valve seat 201, via interface surfaces, surface 207 on poppet 206 and surface 208 on valve seat 201,which are machined in a conical fashion with the same apex angle (typically about 60~). An O-ring seal 209 is fitted in a groove formed in the exterior surface of25 poppet 206 to provide an airtight seal when poppet 206 and valve seat 201 engage.
Poppet 206 includes a plurality of circumferential ribs 210 which are machined cylindrically on their outside diameter to allow poppet 206 to slide easily in housing 204. Biasing means 211 is seated in a recess formed in the upper end of poppet 206 and bears against housing 204. The biasing means 211, thus, forces 30 interfacing surfaces 207 and 208 together thereby compressing seal 209 to perform its sealing function. Poppet 206 can be provided pre-assembled, together with biasing means 211, in housing 204 and retained against the pressure of the biasing means 211 by a retaining ring 212 fitted in a groove in housing 204.
A plurality of tapered vanes 213 extend from the bottom of poppet 206 forming a "cage" for stopper 214 which is, for the purposes of this embodiment, a floating poppet. Vanes 213 are machined cylindrically on their interior edges toallow stopper 214 to slide freely in a vertical direction between the vanes 213 with a small radial clearance. A cylindrical vent passage 215 on the axial centre line of poppet 206 allows free passage of air or vapor from the tank during filling o operations. Two diametrically opposed arms 216 extend inward radially from the interior edges of valve seat 201 to a central hub 217. The body 218 of the fuel level sensing valve 240 rests in a hole on the centre line of hub 217 and is free to move axially therein. Body 218 may be cylindrical in shape formed from, for example, aluminum tubing. A thin circular disk 219 is permanently attached to the upper end of body 218 and prevents body 218 from falling out of the hole in hub 217 while providing a platform for stopper 214. A float 220, drilled on its centre line, fits slidingly onto body 218 where it is retained, for example, between two washers 221 and pins 222, pins 222 being inserted into holes 223 drilled in body 218 at spacings which allow a number of optional positions for float 220. In 20 this specific embodiment, the float is cylindrical in shape with conically-tapered shoulders to minimi7e obstruction to flow through the tank opening. The float ismade out of a very buoyant material such as epoxy-coated cork.
Stopper 214 functions to block vent passage 215 when a fuel tank is full, or in the event of roll-over of the vehicle. Accordingly, it must be shaped to fulfill 25 this function. The stopper 214 exemplified in this embodiment is a hemisphereshape, formed from a material such as aluminum or plastic (e.g. nylon or teflon), and can be either hollow or solid.
During a typical filling operation, a nozzle, preferably with an internal automatic shut-off mech~ni~m, is attached to the fill neck of the tank so that the 30 interior of the tank is sealed to atmosphere except through the vent passage 215 formed in poppet 206. When the nozzle is actuated, fuel under pressure flows into the tank and displaces air or vapor through passage 215. This prevents any significant build-up of pressure in the tank. Referring to Fig. 3A, while the fuel level in the tank is below float 220, disk 219 rests on the top of hub 217 and s stopper 214 rests on disk 219 allowing air or vapor to vent through passage 215 by passing freely around stopper 214. When the fuel level in the tank nears the top of float 220, the buoyancy of the float overcomes the combined weights of the levelsensing body 218, the appendages thereto and stopper 214 causing body 218 to rise. This action lifts the stopper 214 upwards until it engages and blocks vento passage 215, as shown in Fig. 3B, thereby preventing further venting of air or vapor from the tank. The continued flow of fuel into the tank causes an increaseof pressure in the tank. When the pressure reaches a predetermined value (typically from about 1.1 to 1.5 psi), this signals shut-off of the nozzle, either m~n~ lly or automatically, and further fuel flow into the tank is prevented.
Should a malfunction result in the nozzle, for example, and fuel flow into the tank is not shut off after stopper 214 engages the vent passage 215, or an internal pressure increase in the tank results for any other reason, the over-pressure relief valve 230 of the valve 200 will allow further venting to occur. The pressure in the tank will be allowed to increase until it approaches the value at which the 20 pressure force applied to the lower surface of poppet 206 is greater than theopposing force exerted on poppet 206 by the biasing means 211. As a result, the biasing means 211 is compressed and poppet 206 is allowed to move away from its seat on valve seat 201, as shown in Fig. 3C. This allows fuel to overflow into the interior of housing 204 and out through the housing outlet, effectively 2s relieving the internal pressure in the tank such that it does not exceed the value determined by the force of spring 211.
The action of the stopper 214 in the event of a vehicle roll-over is illustrated in Fig. 3D. The centre of gravity of the hemispherical stopper 214 is offset significantly from the plane passing through the geometric centre of the 30 hemisphere. Consequently, as the roll-over progresses, when the centre of gravity of the stopper 214 passes over the point 223 at which its mass is supported, stopper 214 will unbalance and roll in the direction of vent passage 215 until it rests against poppet 206 and seals passage 215. Moreover, if the stopper 214 is submerged in fuel, the dynamic action of the fuel will expedite engagement of the s stopper 214 with vent passage 215, and the static head of the fuel in the tank will further add to the sealing action of the stopper 214. If the stopper 214 is a thin-walled hollow hemisphere, its centre of gravity is such that the stopper 214 will unbalance when the vehicle reaches an angle of about 65~ from the vertical. If the stopper 214 is a solid hemisphere, unbalance will take place when the vehicle o reaches an angle of about 70~ from the vertical.
It will appreciated that if a vehicle rolls over when the fuel tank is full, or substantially so, the float mechanism of the present invention will cause the vent to be sealed before any fuel leakage occurs. Similarly, if the fuel level is so low that it does not cover the vent opening before the vehicle has rolled more than 90~, vent sealing will have taken place to prevent leakage through the vent. However,if the fuel level is such that it covers the vent opening at an angle slightly less than 90~ from the vertical, the embodiment of Figs.1 or 2 can be subject to sufficient frictional resistance to overcome the buoyant action of the floating balls thus preventing sealing of the vent. If the vehicle should come to rest at this angle20 from the vertical, considerable leakage could take place.
Figure 4 illustrates yet another embodiment of the present invention. A
combination valve 300, which represents an alternative to valve 200 illustrated in Fig.3, comprises a modified fuel level sensing valve 320. In this embodiment, the hub 302 of the fuel level sensing valve 320 is extended downwards and is formed 25 with a bracket 304 which projects at an angle to the hub 302. A fuel level sensing body 306 of the fuel level sensing valve 320 rests in a hole on the centre line of hub 302 and is free to move axially therein as described with respect to valve 200.
An arm 308 is pivotally fastened to the projected end of the bracket 304 which functions as a fulcrum for arm 308. A pivot pin and push-on fastener, such30 as the type commonly available under the trade name, Tinnerman, can be used to pivotally fasten the arm 308 to the bracket 304. Such push-on fasteners can readily be used with unthreaded pins and provide the advantages of being low weight and easily applied. These fasteners are applied with a force sufficient only to retain the pivot pins in place, for example, in assembly without restricting free pivotal motion. The arm 308 is preferably made of stainless steel in proportionsas narrow as possible in order to minimi7e its weight. The arm 308 is formed in a symmetrical fashion around bracket 304, as is seen best by reference to Fig. 4E,termin~ting adjacent to body 306 at one side and extending at its other side to form a support for float 310. The float 310, which is made of a highly buoyant o material such as epoxy-coated cork, is secured to arm 308 by any suitable fastening means 312 such as a screw. The upper end of a pair of identical links 314, preferably made of narrowly cut stainless steel to minimi7P weight, are pivotally fastened to opposing sides of arm 308 by means similarly used to fasten the arm 308 to bracket 304, e.g. pivot pins and push-on fasteners, as shown in Fig.
4F. The holes in arm 308 which receive these fastening means are located such that when the arm 308 is horizontal, the axial center line through the fasteningmeans passes through the axial center line of body 306. The links 314 are similarly fastened at their lower ends to the body 306.
Disc 316 is attached to the upper end of the body 306 onto which is seated 20 stopper 318, as described with respect to combination valve 200.
Under low fuel level conditions, as depicted in Figs. 4A and 4D, arm 308 rests at an angle of about 15~ below the horizontal, the weight of the float 310maintaining the body 306 in its lowermost position. In this position, links 314 are slightly laterally displaced but are still very close to being parallel to body 306.
25 Consequently, lateral forces which could produce friction between body 306 and hub 302 are negligible.
During fueling of the tank, the float 310 floats on top of the fuel. As the fuel level increases, the fuel pushes float 310 upwards causing the arm 308 to rotate on bracket 304. This rotation transmits a vertical motion to body 306 30 through links 314 with no lateral force being applied to body 306. When the tank is filled, the arm 308 will be in an approximately horizontal position, the body 306 will be vertically extended causing the stopper 318 to engage the vent passage, as illustrated in Fig. 4B, preventing further venting of the tank. This results in an increase in internal tank pressure which results in fuel shut-off. The function of s the over-pressure relief valve 330 of this combination valve 300 is the same as that of the over-pressure relief valve described with respect to the combination valve 200 as can be seen by reference to Fig.4C. Moreover, the function of the combination valve 300 in the event of vehicle roll-over is illustrated in Fig. 4G, and it is also the same as that described for combination valve 200.
o A number of advantages are associated with combination valve 300 illustrated in Figs. 4A-4G. At the outset, the likelihood of body 306 j~mming inthe hub 304 is reduced by the increased length of bearing between body 306 and hub 304, by minim~l lateral forces on the body 306 and by minim~l weight directly on the body 306. Further, the positioning of the float 310 to one side of the tank opening minimi7es restriction of fuel flow from the tank in an over-pressure condition. It also allows the volume of the float 310 to be increased, which results in a corresponding increase in flotation, without interfering with fuel flow. Another benefit of this embodiment is that the lifting force exerted on the body 306 by the float 310 is proportional to the ratio of the distance from the pivot 20 point of arm 308 on bracket 304 to the centre of gravity of float 310 to the distance from this pivot point to the pivot point of links 314 on arm 308. Thus,the lifting force can be increased by increasing this ratio, for example, by increasing the length of the float side of arm 308.
Referring now to Figure 5, an assembly is illustrated in which a 2s combination valve 400 in accordance with the present invention is combined with a filler neck 401. The filler neck 401 is made, by casting or other means, integral with a base plate 402 which covers an opening 403 in the tank top 404. Base plate 402 is bolted to tank top 404, with the interposition of a sealing gasket 405, by means of a plurality of fastening means (not shown). A self sealing adapter 406 is attached to the inlet flange 407 of filler neck 401. Such adapters are commonly used in conjunction with automatic shut-off nozzles and provide an air tight seal between the interior of the tank and the atmosphere. Hinged cap 408 protects adapter 406 from environmental damage when fueling is not taking place. The hinged cap described, for example, in C:~n~ n Patent Application Serial No.
s 2,168,797, can be used as hinged cap 408.
The combination valve 400 of Fig. 5 is identical to the combination valve 10 illustrated in Fig.1 with the exception that the function of valve seat 22 isperformed by base plate 402. Base plate 402 has a conically machined female surface 410 which mates with surface 412 of the valve 400 thereby replacing o surface 42 of valve 10. It should be noted that valve 400 and filler neck 401 are preferably offset from one another in a direction normal to the plane of the view of Fig.5 in order to prevent disruption of the fuel level control function of the valve 400 by the turbulence of incoming fuel.
The combination valve filler neck assembly advantageously provides a more compact assembly than the individual combination valve and filler neck components. Such an assembly requires at least 1/4 of an inch less space than that of the individual components themselves. It will, of course, be appreciated by those of skill in the art that the combination valves of Figs. 2, 3 and 4, or any other combination valve in accordance with the present invention, could similarly be 20 combined with a filler neck, including the filler neck shown in Fig. 5, to form an assembly in accordance with the present invention. In this regard, reference is made to Figs. 6 and 7 in which further combination valve filler neck assemblies in accordance with the present invention are illustrated. Figure 6 shows a compact assembly in which the combination valve comprises an exterior male pipe thread 2s at the housing outlet rather than the interior female pipe thread of the combination valve of Fig. 1. A further space saving measure shown in the valve of Fig. 6 is the use of a countersunk flat head screw which elimin~tes the protrusion caused by ahexagon cap screw. An even more compact embodiment of the present assembly is shown in Fig. 7A in which the combination valve includes a barbed hose 30 connection of elliptical rather than circular cross-section (see Fig. 7B). Moreover, a socket head cap screw applied from the inside of the valve fitted into a hole in the valve housing allows a further reduction in the overall height of the valve,along with the use of a conical-shaped spring as the biasing means. These variations in the combination valve to increase its compactness can be used in any 5 variety of combinations to attain the most beneficial arrangement for a given situation. Accordingly, the variations described above are not particularly restricted to the combinations specifically illustrated in any of the Figures.
It will be understood by those of skill in the art that the specific embodiments described herein are illustrative of the present invention only and o other embodiments are possible that are within the scope of the invention as defined in the attached claims. Moreover, in the description of the embodiments,one of skill in the art will further appreciate that non-essential elements can readily be substituted with elements that perform the sarne function. For example, the term fastening means is used herein to mean screws, bolts, pins and any other 5 appropriate means for fastening as would be appreciated by one of skill in the art.
Likewise, the term biasing means is used herein to refer to springs as well as other biasing means such as resilient bands. By reference to O-ring seals, it will be appreciated that any appropriate sealing means could be substituted. O-ring seals are, however, the preferred means for creating a sealed condition due to the fact 20 that they seat in recesses, thus providing a more compact combination valve.
Claims (26)
1. A combination valve for use in a fuel tank comprising:
a pressure-relief valve seated in a housing wherein said housing is open to atmosphere and has an inlet from the fuel tank, said pressure-relief valve comprising a poppet and biasing means associated therewith which allow said poppet to move between a normally closed position and an open position when the pressure in thetank increases to an over-pressure value thereby relieving said pressure; and a fuel level control valve in communication with said pressure-relief valve via a vent passage, said fuel level control valve comprising a fuel level sensing body which extends into the tank, float means associated with said body and stopper means adapted to control tank venting, wherein said float means causes said stopper means to seal the vent passage when the tank is full.
a pressure-relief valve seated in a housing wherein said housing is open to atmosphere and has an inlet from the fuel tank, said pressure-relief valve comprising a poppet and biasing means associated therewith which allow said poppet to move between a normally closed position and an open position when the pressure in thetank increases to an over-pressure value thereby relieving said pressure; and a fuel level control valve in communication with said pressure-relief valve via a vent passage, said fuel level control valve comprising a fuel level sensing body which extends into the tank, float means associated with said body and stopper means adapted to control tank venting, wherein said float means causes said stopper means to seal the vent passage when the tank is full.
2. A combination valve as defined in claim 1, wherein the poppet of said pressure-relief valve seals the housing inlet from the tank in its normally closed position and exposes the inlet in its open position.
3. A combination valve as defined in claim 2, wherein said over-pressure value is greater than or equal to a pressure of about 3 psi.
4. A combination valve as defined in claim 1, wherein said vent passage is formed through said poppet.
5. A combination valve as defined in claim 1, wherein the float means and the stopper means of said fuel level control valve are contained within said fuel level sensing body.
6. A combination valve as defined in claim 5, wherein each of said float means and stopper means are made of a buoyant material, said float means and said stopper means being vertically aligned in said body such that said stopper means is above said float means.
7. A combination valve as defined in claim 6, wherein each of said float means and stopper means is a ball.
8. A combination valve as defined in claim 6, wherein said float means is more buoyant than said stopper means.
9. A combination valve as defined in claim 8, wherein said float means is made of cork and said stopper means is made of a material selected from the group consisting of aluminum and plastic.
10. A combination valve as defined in claim 1, wherein the float means is fastened to said fuel level sensing body and said stopper means is positioned on top of said fuel level sensing body such that a rising fuel level in the fuel tank lifts the fuel sensing body causing the stopper means to seal the vent passage.
1 1. A combination valve as defined in claim 10, wherein said stopper means is apoppet.
12. A combination valve as defined in claim 11, wherein said poppet is in the shape of a hemisphere.
13. A combination valve as defined in claim 1 1, wherein said poppet is made outof a material selected from the group consisting of aluminum or plastic.
14. A combination valve as defined in claim 10, wherein said float is made of epoxy coated cork.
15. A combination valve as defined in claim 1, additionally comprising means to seal the tank to prevent fuel leakage from the tank in the event of a vehicle roll-over.
16. A combination valve as defined in claim 6, additionally comprising means to seal the tank to prevent fuel leakage from the tank in the event of a vehicle roll-over of 90° or more, said sealing means being vertically aligned with said stopper means and said float means such that it is beneath said float means.
17. A combination valve as defined in claim 16, wherein said sealing means is a ball made of solid steel.
18. A combination valve as defined in claim 10, additionally comprising means toseal the tank to prevent fuel leakage from the tank in the event of a vehicle roll-over of 65° or more.
19. A combination valve as defined in claim 18, wherein said tank sealing means is the stopper means.
20. A combination valve as defined in claim 19, wherein said stopper means is a floating poppet.
21. A combination valve as defined in claim 1, wherein the biasing means of saidover-pressure relief valve is a spring.
22. A combination valve as defined in claim 21, wherein said spring is conical-shaped.
23. A combination valve as defined in claim 1, wherein the outlet is an elliptically shaped barbed hose connection.
24. A combination valve filler neck assembly for use in a fuel tank comprising acombination valve as defined in claim 1 and a filler neck.
25. An assembly as defined in claim 24, wherein said filler neck comprises a neck which extends into the fuel tank; an adapter to allow attachment of the neck to a nozzle; and a base plate which fastens the filler neck to the tank.
26. An assembly as defined in claim 25, wherein said base plate forms a seat on which the poppet of the pressure relief valve of the combination valve rests when it is in its normally closed position.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US94826197A | 1997-10-09 | 1997-10-09 | |
| US08/948,261 | 1997-10-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2249678A1 true CA2249678A1 (en) | 1999-04-09 |
Family
ID=25487555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2249678 Abandoned CA2249678A1 (en) | 1997-10-09 | 1998-10-06 | Combination fluid level control and pressure relief valve for fuel tanks |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2249678A1 (en) |
-
1998
- 1998-10-06 CA CA 2249678 patent/CA2249678A1/en not_active Abandoned
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4402340A (en) | Pressure-responsive shut-off valve | |
| EP0023072B1 (en) | Filler valve for a liquefied gas tank | |
| US5125429A (en) | Piston pressure-type vacuum breaker | |
| US5832947A (en) | Gas shut-off and pressure relief valve for a high pressure gas vessel | |
| CA2187601C (en) | Pilot operated fluid valve | |
| CA2041590A1 (en) | High volume fuel vapor release valve | |
| KR19990044928A (en) | Control Valves and Systems for Fuel Vapor Recovery | |
| US6056005A (en) | Vent valve with liquid seal | |
| US4068680A (en) | Self-contained vent valve unit and system utilizing the same | |
| US3429321A (en) | Safety valve actuator | |
| US5511575A (en) | Apparatus for permitting uninterrupted relief of cargo tank compartment internal pressure and preventing leakage of lading from the cargo tank during dynamic pressure surges | |
| US5511581A (en) | Vent valve | |
| EP0961061B1 (en) | Improved automatic bleeding valve for hydraulic systems | |
| US4721289A (en) | Combined check and exhaust valve for high pressure gas spring | |
| AU597370B2 (en) | Relieving valve with surge control for fluid storage tank | |
| JPS62141379A (en) | Safety valve means for centralized control | |
| US3426779A (en) | Pressure actuated relief valve | |
| US4877218A (en) | Drain valve device | |
| US5234023A (en) | Pressure relief valve with auxiliary loading device | |
| US4015627A (en) | Pressure relief valve | |
| US5014735A (en) | Automatic drain valve | |
| CA2249678A1 (en) | Combination fluid level control and pressure relief valve for fuel tanks | |
| US6488049B2 (en) | Super sensitive, full flow, adjustable pressure valve | |
| US4366669A (en) | Tank closure apparatus with safety feature | |
| JP2815445B2 (en) | Valve devices, especially vent valves for vent pipes in vehicle fuel tanks |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |