WO2001040105A1

WO2001040105A1 - Fuel nozzle and filler tube system adapted for robotic refueling systems

Info

Publication number: WO2001040105A1
Application number: PCT/US2000/032807
Authority: WO
Inventors: Delton M. Boardman
Original assignee: Shell Oil Company
Priority date: 1999-12-06
Filing date: 2000-12-05
Publication date: 2001-06-07
Also published as: AU1813501A

Abstract

A liquid fuel docking nozzle structure and associated fuel filler tube adapter are used to implement a robotic refueling system. A front surface of the docking nozzle tip is formed to have an outwardly spherical presentation while a mouth of the filler tube adapter is formed of a metallic material shaped as an inwardly tapering truncated conical section. The spherical nozzle tip is readily guided into position by the conical mouth of the filler tube adapter and maintains a seal therebetween appropriate to accommodate refueling even with slight movement of the vehicle being refueled such as might be caused by passengers exiting or entering the vehicle. Sensors spaced about a periphery of a boot surrounding the docking nozzle tip detect proper engagement of the docking nozzle into the mouth of the filler tube adapter. The sensors may be in the form of discrete pressure or proximity activated electrical switches. Alternatively, the sensors may be formed by three or more electrical contact terminals formed in the docking nozzle tip so as to create low current electrical contacts through the conical mouth section of the filler tube adapter. Refueling is commenced only after all nozzle sensor locations are detected to be properly positioned relative to the mouth of the filler tube adapter, while refueling operations are immediately terminated upon detecting a misalignment of any one of the sensors.

Description

FUEL NOZZLE AND FILLER TUBE SYSTEM

ADAPTED FOR ROBOTIC REFUELING SYSTEMS

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to an apparatus for refueling vehicles and more particularly to an automatic robotic refueling system for automotive vehicles having a unique end effector docking structure.

Background of the Invention A great deal of effort has been expended to develop a system for robotically refueling automotive vehicles. Such systems may include an overhead gantry which supports a carriage upon which a robot is supported for appropriate movement relative to the vehicle to position the robot adjacent the fuel door on the vehicle. Alternatively, the robotic system may be supported on an island adjacent the vehicle and then moved to a position adjacent the fuel door. As another alternative, the robotic system may be stored underground and, after positioning of the vehicle, retrieved and moved to a point adjacent the fuel door.

Irrespective of the position in which the robot is stored or the manner in which it is moved, all such robotic refueling systems require an appropriate mechanism to insert a hose assembly which includes a nozzle for delivery of fuel into the fuel tank of the vehicle. The fuel hose must be inserted through the vehicle fuel filler pipe and into a position internally of the vehicle fuel filler pipe such that the nozzle is appropriately positioned and fuel can easily flow from the nozzle into the vehicle fuel tank without obstruction. Typically, the fuel hose assembly is extended from the robot arm in accordance with appropriate signals received from a control mechanism. After refueling, the fuel hose assembly is extracted from the fuel filler pipe so that the robot may be returned to its stored position and the refueled vehicle may leave the robotic refueling station.

One form of robotic refueling apparatus is shown and described in United States Patents No. 5,609,190 and 5,655,577 which are assigned to the assignee of the present application, the disclosures of which are incorporated herein by reference. As is therein shown, a robot is stored on an overhead carriage which in turn is supported for movement upon a gantry so that the robot may be positioned on either side of the vehicle in accordance with the position of the fuel filler door. After the robot is appropriately positioned the fuel filler door is automatically opened and the fuel hose inserted into the fuel filler pipe on the vehicle so that fuel may be inserted into the vehicle fuel tank. After the vehicle fuel tank is appropriately filled, the fuel hose assembly is extracted from the fuel filler pipe, retracted into the robot arm, and the robot is then appropriately stored on the carriage and returned to its stowed position on the gantry until it is reactivated for refueling another vehicle.

It is important to establish a good seal between the fuel nozzle assembly and the fuel filler tube to avoid spillage and escape of fuel vapors into the atmosphere. While modern robotic positioning systems provide a high degree of positioning accuracy, some mispositioning errors must be accommodated. Thus, the fuel nozzle assembly and fuel filler pipe should be configured to readily engage each other, mate, and establish an appropriate seal without requiring or generating excessive force. Further, during fueling operations it is necessary to maintain the seal between the fuel tube nozzle assembly and the fuel filler pipe of the vehicle being fueled. Maintaining a seal can be a problem as there is often slight relative movement between the refueling apparatus and vehicle caused by such things as passengers exiting and entering the vehicle, the added weight of the fuel being pumped into the vehicle, etc. Thus, it is desirable that the fuel nozzle assembly and fuel filler pipe be adapted to maintain an appropriate seal while accommodating slight movements typically encountered during fueling operations. It is further desirable that the refueling apparatus have means to detect any disengagement of the nozzle from the filler pipe that would break the seal so that fuel flow to the vehicle can then be stopped.

SUMMARY OF THE INVENTION

The present invention is an improvement to a vehicle refueling system having an automatically controlled robot for inserting fuel through the vehicle filler pipe into the vehicle fuel tank and includes a fuel tube for carrying fuel to the vehicle and a hose assembly adapted to be inserted into the vehicle fuel filler pipe. A boot portion of the fuel tube cooperates with a filler pipe adapter to provide an improved seal accommodating slight movement of the vehicle being fueled. An array of pressure switches sense proper positioning and seal establishment between the boot and fuel filler pipe to initiate fuel flow and abort fueling in the event the boot becomes unseated from the fuel filler pipe adapter. When accomplishing docking of the fuel tube boot with the receptacle on the fuel filler pipe of a vehicle, the inventors have determined that a better seal is accomplished if the structure which is attached as the adapter to the fuel filler pipe is in the form of a truncated cone receptacle device and if the tip portion of the fuel tube boot which contacts and engages the fuel filler pipe adapter be formed in the shape of a sector of a sphere. The combination of a spherical nozzle tip engaging a conically shaped filler tube provides an appropriate primary seal and allows docking using a force which is just sufficient to align the fuel nozzle assembly with the receptacle. Employing such a sphere to cone system also provides a substantial amount of freedom of angular movement as the fuel nozzle assembly approaches the adapter on the fuel filler pipe and still maintains the seal between the two parts.

The portion of the adapter that sits on the fuel filler pipe is a nickel plated metallic structure, while the tip end of the fuel tube boot is made of a hard plastic. This particular configuration provides an appropriate seal between the nozzle and filler pipe while providing a degree of rotational freedom sufficient to accommodate normal vehicle movements. Thus, if an individual leaves or gets into the vehicle during the fueling process, up and down movement of the vehicle is accommodated without breaking or substantially degrading the seal.

Thus, according to one aspect of the invention, a vehicle refueling system having an automatically controlled robot for inserting fuel through a vehicle filler pipe into a vehicle fuel tank includes a filler tube adapter and a nozzle assembly. The filler tube adapter is removably mountable atop the fuel filler tube for receiving fuel into the vehicle, the filler tube adapter having a mouth opening with inwardly tapering walls in a shape of a truncated cone. The nozzle assembly has a boot at a distal end adapted to be received by said filler tube adapter. A tip of the boot is formed as a section of a convex sphere centered along a longitudinal axis of the boot. The sphere has a radius of 1.5 to 2 times that of the radius of the nozzle and preferably within a range of 1.8 to 1.9.

According to a feature of the invention, the boot includes sensors positioned on the boot to detect an engagement or mating of the boot within the mouth of the boot filler tube adapter. The positional sensors may be in the form of at least three discrete electrical switches equally spaced about a circumference of a mounting ring positioned substantially coaxial with and rearward of the tip of the boot. Each of the switches may be separately and individually activated in response to engagement of a corresponding portion of the boot by the filler tube adapter. Alternatively, the sensors may be formed as at least three electrical contacts spaced equally about and expressed on the external surface of the boot.

According to another feature of the invention, a resiliently deformable boot surrounds a portion of the nozzle assembly, the boot including a plurality of sensors operable to detect corresponding deformations of the boot indicating engagement of the nozzle assembly by the filler tube adapter.

According to another feature of the invention, the walls of the filler tube adapter have a metallic surface, e.g., are plated with a corrosive resistant metal such as nickel. The walls may inwardly converge toward each other to form an extended angle therebetween within a range of 90 and 120 degrees and preferably within a range of 100 and 105 degrees.

According to a still further feature of the invention, the filler tube adapter has an interstitial cavity vented to an outside atmosphere. The adapter may further include a door or flap biased to close an opening through the mouth when the fuel nozzle is not otherwise engaged with or inserted into the filler tube adapter. The filler tube adapter may also include an annular conductive plastic cover surrounding the mouth opening.

According to a still further feature of the invention, the nozzle is mounted on a distal end of a robotic end effector.

According to another aspect of the invention, a method of robotically refueling a vehicle includes a step of mounting a filler tube adapter on a fuel tube of the vehicle, the filler tube formed to have a mouth opening with inwardly tapering walls in a shape of a truncated cone. A fuel nozzle assembly having a spherical tip portion is then positioned into engagement with the filler tube. Engagement of said fuel nozzle by the filler tube is detected and, in response, a flow of fuel is initiated to the vehicle through the fuel nozzle assembly and filler tube adapter. According to a feature of the method, detection of fuel nozzle assembly engagement is performed by sensing a position of at least three points of the fuel nozzle assembly. This may be accomplished by passing an electrical current through at least three distinct regions of contact of the filler tube adapter with a boot on the fuel nozzle. Alternatively, proper mating of the nozzle with the filler tube is detected by positioning the nozzle assembly so as to compress or deform an elastomeric boot surrounding the nozzle assembly and then detecting a position of the nozzle assembly in at least three separate locations along a periphery of the elastomeric boot. Fuel flow may be discontinued upon detecting a disengagement of the fuel nozzle assembly from the filler tube.

According to another feature of the method, fuel vapors, condensation and/or fuel are vented from an internal cavity formed in the filler tube adapter to an external atmosphere. Additional advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of an end effector having a nozzle assembly and mating sensor and a mechanism to insert the nozzle into a fuel inlet according to the present invention;

FIG. 2 is a perspective view of a boot assembly forming a distal portion for fuel nozzle assembly of a refueling end effector, as shown in FIG. 1; FIG. 3 is a top view of the boot assembly shown in FIG. 2;

FIG. 4 is a cross sectional view of the boot assembly shown in FIG. 3 taken about line AA thereof;

FIG. 5 is a sectional view of the boot assembly shown in FIG. 4 taken about line AA thereof and showing a portion of a circuit board assembly; FIG. 6 is a cross sectional view of the boot portion of the assembly of FIG. 2;

FIG. 7 is a side view of the boot shown in FIG. 6; FIG. 8 is a perspective view of the open tip of the boot shown in FIG. 6; FIG. 9 is a frontal view of the boot shown in FIG. 6;

FIG. 10 is a cross sectional view of the boot shown in FIG. 7 taken about line DD thereof; FIG. 11 is a cross sectional view of the boot shown in FIG. 6 at location E showing circumferential ribs for retaining a rubber diaphragm in place about the boot;

FIG. 12 is a perspective view of a proximal end of the boot shown in FIG. 6; FIG. 13 is a sectional view of the boot shown in FIG. 7 taken about line BB thereof; FIG. 14 is a perspective view of the boot of FIGS. 6-13; FIG. 15 is a front view of a circuit board assembly;

FIG. 16 is a side view of the circuit board assembly shown in FIG. 15; FIG. 17 is a schematic diagram of an electrical circuit of the circuit board assembly shown in FIG. 15;

FIG. 18 is a top view of a filler tube adapter; and FIG. 19 is a cross sectional view of the filler tube adapter shown in FIG. 18 taken about line AA thereof.

DETAILED DESCRIPTION

Referring now, or particularly to FIG. 1, there is provided a schematic illustration of one form of end effector, which is part of a manipulator arm, utilized for inserting fuel from a source thereof, into the fuel tank of a vehicle while employing an automatic robotic refueling apparatus. As is generally shown, there is an end effector 100, which includes a fuel hose assembly 102, shown in dashed lines, which terminates in a fuel nozzle 104, which is disposed internally of a fuel tube (not shown), which is covered by a flexible sheet or cover, manufactured from a rubber like, or plastic material 106. Disposed at the end 108, of the end effector 100 is a docking member 110, which is surrounded by a rubber diaphragm 112, which assists in providing a seal about the adaptor, which is affixed to the opening in the vehicle fuel pipe. Disposed internally within an outer cylindrical member 114, are appropriate actuator assemblies(not shown) which are utilized to extend and retract the fuel hose assembly 102 outwardly through the docking member 1 10 when the docking member and the diaphragm are appropriately seated on the adaptor affixed to the vehicle fuel filler pipe. Appropriate fittings such as shown at 1 16 are provided on the end effector 100 for such purposes as providing air under pressure to move the actuators or to provide a path for the collection of vapor which is extracted from the fuel tank aps fuel is inserted therein. The details of the end effector 100, other than the seal boot assembly 121, form no part of the present invention, but is provided generally for the overall environment, in which the present invention operates. For further information with regard to this environment, reference is made to the patent applications above preferred to.

Details of seal boot assembly 121 are shown in FIGS.2-17. As shown in FIGS.2-4, the boot assembly 121 has a hard plastic inner conduit in the shape of a cylindrical tube forming a docking member or nozzlel32. A central axis of nozzle 132 is angled downward from a central axis of fuel conduit 101 enabling easier alignment with a fuel fill tube of a vehicle. Open end 134 of nozzle 132 has an exposed wall rim 136 at its opening with a convexly formed forward surface such that the exposed surface of the opening is outwardly spherical. The radius of the sphere defining the front of the nozzle is between 1.5 to 2.0, and preferably 1.8 to 1.9, times that of the radius of the opening. Surrounding the distal end portion of the tube is a rubber diaphragm 1 12 forming boot seal 138. Boot seal 138 is attached aft of the sphere end portion of nozzle 132 where an inner surface of boot seal 138 has ridges 140 engaging circumferential grooves 142 and 144 formed in the outer wall of nozzle 132 into which ridges 140 snap fit. A flat face surface 146 of boot seal 138 extends radially inward with a central aperture through which nozzle 132 extends. Rearward movement of face surface 146 is transmitted through flexible side walls of boot seal 138 to an inwardly projecting collar 148. A rear inner surface of collar 148 is spaced apart from a stainless steel ring 150 under bias produced by structural area 152 of boot seal 138 so that a rearward movement of face surface 146 causes collar 148 to move into contact with underlying ring 150. Underlying stainless steel ring 150 is nylon washer 154 and circuit board assembly 156.

Referring to FIGS. 15-17, circuit board assembly 156 is formed as a flat ring or washer with at least three electrical switches SW1, SW2 and SW3 mounted and oriented to operate in response to a pressure applied against a front face of the assembly by ring 150 being rearwardly displaced by movement of boot seal 138. The switches are positioned at 120° intervals about circuit board assembly 154. Connector pins P1-P4 (FIG. 5) provide an electrical interface between switches SW1-SW3 and electrical cable 158 (FIG. 4) to fuel supply control systems so that fuel flow is not initiated until, and maintained only while, all switches are activated indicating proper engagement of boot seal 138 with an adapter position on a vehicular fuel fill tube. Referring to FIGS. 18 and 19, a filler tube adapter 200 is removably installed on the top end of a vehicle fuel fill tube to provide a compatible fueling interface for nozzle assembly 130. Filler tube adapter 200 includes a lower tubular neck 202 and upper collar 204. Neck 202 is made of a conductive plastic tube with threads 206 formed on an outer surface for engaging the inner surface of a fuel fill tube to attach adapter 200 thereto. An upper end of neck 202 terminates in a flange with an annular gasket 208 positioned below the rim of the flanged portion to provide a seal between neck 202 and the vehicle fuel fill tube. A metallic collar 210 is mounted atop and partially extends into a central opening of neck 202. Upwardly exposed frusto-conical inner walls 212 of multi coil wave spring 210 are formed to present an opening angle of approximately 103° for the insertion of nozzle 130 whereby inner walls 212 are angled in a range of 45° to 55° off vertical and, preferably, 512° from vertical. The resultant conically shaped orifice is designed to engage and mate with the spherically shaped end of boot assembly 130 so as to assist proper alignment of the nozzle to the filler tube and maintain a seal therebetween which is relatively insensitive to any slight movement of a vehicle being refueled. The exposed surface of collar 210 including walls 212 are preferably chrome or nickel plated to resist corrosion caused by fuel, moisture, and other environment effects while maintaining a low electrical resistivity.

Collar 204 is made of plastic and is attached to a top of neck 202 and extends radially inward to partially cover a flat outer rim portion of collar 210 which surround its truncated conical walls. When installed atop a fuel fill tube, inwardly sloping wall 214 would be positioned upward (i.e., at A12 o=clock relative to an angled filler neck of a fuel fill tube) so as to align and help guide insertion of nozzle 130 from above, downward toward and into a mouth formed by central cavity 222 providing an entrance to neck 202. In the absence of a removable fuel cap, hanged flap 216 forms a door biased upwardly by spring 218 to close off the top of neck 202 except when flap 216 is swivelled outwardly against an inner surface of neck 202 by insertion of nozzle 130.

An interstitial cavity 224 is vented to the outside through openings 226 and 228. When installed on a fuel filler tube, interstitial cavity 224 would be positioned downward (i.e., at the A6 o=clock position) so as to collect and drain water condensation and provide a path for fuel backwash and vapor venting during fueling operations in the event of accidental over filling of the vehicle fuel tank. Operationally, when the end of the nozzle 130 engages the truncated cone surface of filler tube adapter 200, the flat surface 146 of the rubber boot seal 138 engages the outer surface 230 of the filler tube adapter and causes the rubber diaphragm to move backwardly in the direction shown by the arrow 160 (FIG. 4) which is allowed to happen by flexing of the structural area 152 on the boot. When this occurs, the surface 148 engages stainless steel plate 150 which pushes that structure back. On the reverse side of stainless steel plate 150 is a nylon plate 154 which as it moves backward, activates three switches SW1, SW2, SW3 which are appropriately angularly displaced at 120° intervals around circuit board 156. Although three switches are shown and have been determined to be effective, a multiplicity of switches other than three can be utilized. All three of the switches must be activated before fueling will commence.

As an alternative arrangement to detecting when an appropriate seal has been made before refueling is to start, discrete unitized switches SW1, SW2, SW3 may be replaced by 3 electrical contact regions or pads which would be embedded within the hard plastic of exposed spherical surface 136 of nozzle 130. This could be accomplished by molding the contacts into the structure and then, when the sphere is formed by grinding, those contact ends would be exposed. Two of the contacts would be active, i.e., supplied with small sensing voltage, while the other one of the three would be a ground. A current sensor would either detect presence of a current flow through the individual active contacts or measure a current flow though the ground terminal equal to the total current supplied by the two active contacts so as to determine that both circuit paths were complete. Thus, when the sphere surface 136 of nozzle 130 contacted the truncated cone metal nickel plated walls 212 of collar 210, the electrical circuit would be completed and as long as appropriate contact was maintained, the electrical circuit would remain completed and the refueling process would continue. This provides a positive indication that the filler pipe adapter and nozzle are in the appropriate position for refueling and would enable elimination of the circuit board assembly and the boot assembly insofar as the switching is concerned.

As mentioned above, it is important to have at least the three switches or contacts as discussed above and to have all of them activated simultaneously to commence the refueling process to guarantee that the fuel nozzle is in the appropriate position. If the nozzle is misaligned all three of the contacts will not be completed and the refueling process cannot commence. As an added safety feature, if the individual in the automobile were to drive away while refueling were in progress, the electrical circuit would be broken thus indicating the drive off. Upon deactivation of the switches or breaking of the electrical circuits through the exposed electrical contacts, the drive off would cause an immediate shut down of the refueling process.

It is further important that the switches or electrical contacts be suitable for use in the presence of highly flammable liquids and vapors, that is the electrical energy that is applied in the refueling area must be intrinsically safe. Thus, the amount of electrical energy which is available in the vicinity of the refueling equipment must be maintained at a safe level such that there would be insufficient electrical energy to create a spark capable of causing ignition of the fuel or fumes. To maintain sensor related electrical signals at a safe level, solid state components may be used to remotely amplify and detect switch activation and/or current through the various contacts.

The filler tube adapter not only provides a compatible coupling with which a robotically controlled nozzle can easily mate, but also accommodates over pressure in the fuel tank of the automobile as a result of the refueling. During refueling it often becomes necessary to relieve the over pressure or to provide a way of getting rid of the excess fuel if there is over filling of the tank. The filler tube adapter is designed in such a way that if there is not a perfect seal between the truncated cone fill tube adapter and the sphere surface nozzle contacting it (in fact, it is typical that a perfect bubble proof seal would not exist) then the excess pressure or excess fuel will be received in interstitial cavity 224 and will travel downwardly through slotted openings 226 or 228 to the atmosphere and then be dissipated. It should also be understood that while this is occurring the vapor vacuum pump will also be operating as rapidly as possible to pull the fuel vapor back through the system. This same venting system is utilized to allow water which may have collected in the fuel filler tube to be dissipated in that it will flow through interstitial cavity 224 and out openings 226 and 228 as described. A requirement to dissipate collected water may be caused by manual refueling of the vehicle with the filler tube adapter in place when water has collected. When such vehicles operate with a positive pressure in the fuel tank, manual nozzle insertion will release the pressure causing a blow out toward the customer of the water which has collected. This problem is eliminated by incorporation of the venting system. In summary, the present invention is directed to a docking nozzle structure and associated fuel filler tube adapter for use in a robotic refueling system. A front surface of the docking nozzle tip is formed to have an outwardly spherical presentation while a mouth of the filler tube adapter is formed of a metallic material shaped as an inwardly tapering truncated conical section. The spherical docking nozzle tip is readily guided into position by the conical mouth of the filler tube adapter and maintains an adequate seal therebetween to accommodate refueling even with slight movement of the vehicle being refueled such as might be caused by passengers exiting or entering the vehicle. Sensors spaced about a periphery of a boot surrounding the nozzle tip detect proper engagement of the nozzle into the mouth of the filler tube adapter. The sensors may be in the form of discrete pressure or proximity activated electrical switches. Alternatively, the sensors may be formed by three or more electrical contact terminals formed on the docking nozzle tip so as to create low current electrical contacts through the conical mouth section of the filler tube adapter. Refueling is commenced only after all nozzle sensor locations are detected to be properly positioned relative to the mouth of the filler tube adapter, while refueling operations are immediately terminated upon detecting a misalignment of any one of the sensors.

In this disclosure there is shown and described only the preferred embodiments of the invention and but a few examples of its versatility. It is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.

Claims

What is Claimed is:

1. A vehicle refueling system having an automatically controlled robot for inserting fuel through a vehicle filler pipe into a vehicle fuel tank, comprising: a filler tube adapter mountable on the fuel tube for receiving fuel into said vehicle, said filler tube adapter having a mouth opening with inwardly converging walls in a shape of a truncated cone; a hose assembly having a fuel nozzle at a distal end adapted to be inserted into said filler tube adapter; and a nozzle having a tip formed as a section of a convex sphere centered along a longitudinal axis of said nozzle.

2. The vehicle refueling system according to claim 1 wherein said fuel nozzle includes sensors positioned on said fuel nozzle to detect an engagement of said fuel nozzle by said mouth of said filler tube adapter.

3. The vehicle refueling system according to claim 2 wherein said sensors comprise a plurality of at least three electrical switches equally spaced about a circumference of a mounting ring positioned substantially coaxial with and rearward of said docking nozzle tip, each of said switches being separately activated in response to engagement of a corresponding portion of said docking nozzle by said filler tube adapter.

4. The vehicle refueling system according to claim 2 wherein said sensors comprise a plurality of at least three electrical contacts spaced equally about said docking nozzle tip.

5. The vehicle refueling system according to claim 1 further comprising a resiliently deformable boot surrounding a portion of said docking nozzle, said boot including a plurality of sensors operable to detect corresponding deformations of said boot indicating engagement of said docking nozzle by said filler tube adapter.

6. The vehicle refueling system according to claim 1 wherein said walls of said filler tube adapter have an exposed metallic surface.

7. The vehicle refueling system according to claim 1 wherein said filler tube adapter include an interstitial cavity vented to an outside atmosphere.

8. The vehicle refueling system according to claim 1 wherein said filler tube adapter includes a flap biased to close an opening through said mouth when said nozzle is not engaged with said filler tube adapter.

9. The vehicle refueling system according to claim 1 wherein said docking nozzle is mounted on a distal end of a robotic end effector.

10. The vehicle refueling system according to claim 1 wherein inwardly tapering walls of said filler tube adapter form an angle therebetween within a range of 90 and 120 degrees.

11. The vehicle refueling system according to claim 10 wherein said angle is within a range of 100 and 105 degrees.

12. The vehicle refueling system according to claim 1, said filler tube adapter including an annular plastic cover surrounding said mouth.

13. A method of robotically refueling a vehicle comprising the steps of: mounting a filler tube adapter on a fuel tube of the vehicle, the filler tube formed to have a mouth opening with inwardly converging walls in a shape of a truncated cone; positioning a docking nozzle having a spherical tip portion into engagement with said filler tube adapter; detecting the engagement of said docking nozzle by said filler tube; and initiating a flow of fuel to the vehicle through said fuel nozzle and filler tube adapter.

14. The method according to claim 13 wherein said detecting step includes a step of sensing a position of at least three points of said docking nozzle.

15. The method according to claim 14 wherein said detecting step includes a step of passing an electrical current through at least three distinct regions of contact of said filler tube adapter with said docking nozzle.

16. The method according to claim 14 wherein said detecting step includes the steps of compressing an elastomeric boot surrounding said docking nozzle and detecting a position of said docking nozzle in at least three separate locations along a periphery of said docking nozzle.

17. The method according to claim 13 further comprising a step of venting an internal cavity formed in said filler tube adapter to an external atmosphere.

18. The method according to claim 13 further comprising the steps of detecting a disengagement of said docking nozzle and said filler tube and, in response, stopping the flow of fuel to the vehicle.