US3823751A

US3823751A - Fluid dispenser control system

Info

Publication number: US3823751A
Application number: US00369460A
Authority: US
Inventors: J Healy
Original assignee: AUTOMATIC SYST Inc
Current assignee: AUTOMATIC SYST Inc
Priority date: 1973-06-13
Filing date: 1973-06-13
Publication date: 1974-07-16
Anticipated expiration: 1991-07-16
Also published as: DE2428288A1; JPS5069629A; CA1005024A

Abstract

A system for use with a fluid dispensing apparatus having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated full tank shutoff. The system comprises a holding tank, means for maintaining the pressure in the tank at a differential with respect to atmospheric pressure and for connecting the holding tank to the nozzle to actuate the shutoff, and a mechanical selector operatively linked to the metering sustem and to the first mentioned means for actuating those means when substantially a predetermined amount of fluid has been dispensed through the nozzle.

Description

United States Patent [191 Healy [451 July 16,1974

[ FLUID DISPENSER CONTROL SYSTEM Primary Examiner-Robert B. Reeves [75] Inventor. James W. Healy, Wakefield, Mass. Assistant Examiner joseph J. Rona I Asslgneel Automatic y Waltham, Attorney, Agent, or Firm-Gordon R. Williamson, Esq.

Mass. 22 Filed: June 13, 1973 L f f f g g I system or use wit a w rspensmg apparatus [21] Appl' 369460 having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated 52 us. 01 141/198, 222/20, 222/33 full tank shuteff- The System comprises a holding tank, [51] Int. Cl B65b l/30 means for maintaining the Pressure in the tank in a 58 Field of Search 222/14 23, differential with respect to atmospheric Pressure and 2112/3144 57; 194 5 13; 141 192 229 for connecting the holding tank to the nozzle to actuate the shutoff, and a mechanical selector operatively [5 References Ci d linked to the metering sustem and to the first men- UNITED STATES PATENTS tioned means for actuating those means when substan- 2 080 535 5/1937 D ZZZ/l4 tially a predetermined amount of fluid has been dis- 2:906:30 9/1959 pensed through the nozzle. 3,005,476 10/1961 Klaus 141/225 20 Claims, 6 Drawing Figures PAIENI JUL 1 61974 SHEET 3 BF 4 FIG. 4

FIG. 5

PATENTED JUL'] 81974 saw a nr 4 Om mm mm FLUID DISPENSER CONTROL SYSTEM BACKGROUND OF THE INVENTION This invention relates to an automatic fluid flow shutoff system. The system is particularly suitable for use with gasoline pumps.

Presently, most gasoline stations dispense gasoline through conventional pumps having mechanical computers which meter flow and indicate the dollar and cents amount of gasoline pumped, as well as nozzles which incorporatevacuum actuated, full tank shutoff valves. Thus, an attendant can latch an automatic hose nozzle shutoff topermit the flow of gasoline knowing that when a full tank condition exists in the car being serviced, the flow of gasoline will automatically be interrupted. This, of course, allows the attendant to be free for checking oil and batteries and attending to other operations while the tank is filling.

On many occasions,however, a customer orders less than the amount of gas that is required to fill the vehicle gasoline tank. Usually such orders are given in dollar amounts such as $1, $2 or more dollars. In such cases, it is common for the gasoline attendant to manually operate the nozzle valve until the dollar amount is pumped. It has long been recognized that an automatic device for interrupting gasoline flow at a predetermined dollar or gallon amount prior to filling of the tank would be highly desirable and useful to allow the gasoline attendant to service a plurality of vehicles and- /or provide auxiliary services to a single vehicle while gasoline is being pumped. e

In fact, many attempts to provide a predetermined dollar volume automatic gasoline pump shutoff have been made. In most cases, such proposed constructions have been extremely costly, complicated, dangerous, and/or required extensive re-design of existing conventional pumping equipment.

Thus, there is a present day need in the industry for an automatically operating, shutoff system for use with conventional pumping apparatus to provide for automatic gasoline flow cutoff at a predetermined dollar or volume amount less than that required to fill a gas tank.

SUMMARY OF THE INVENTION It is an important object of this invention to provide an efficient system for automatically interrupting fluid flow from a pump nozzle when, or shortly before, a predetermined dollar or volume amount of fluid has been dispensed.

Other objects include the provision of such a system which is relatively low in cost and can be easily installed on a wide variety of presently existing gasoline pumping apparatus, which is extremely uncomplicated and highly reliable in operation, and which does not require electrical circuitry.

According to the invention, a system is provided for attachment to a pumping apparatus which has a flow metering mechanism such as a conventional computer, and a conventional hose nozzle having an automatic vacuum actuated full tank shutoff. The system has first means for supplying a predetermined volume of air at either low positive pressure or at negative pressure (with respect to atmospheric) to theautomatic hose nozzle to actuate the valve shutoff when substantially a predetermined amount of fluid has been pumped through the nozzle. A mechanical selector means is operatively linked to the conventional metering mechanism for actuating the first means at any one of a number of predetermined values in response to movement of the conventional metering mechanism. Preferably the first means comprises a pressurized air supply interconnected with an automatic hose nozzle shutoff valve to provide a positive air pressure pulse to the atmospheric pressure side of the diaphragm within a conventional automatic shutoff mechanism. Preferably, the mechanical selector means comprise rotatable elements which can be hand set to a predetermined dollar value and then rotationally driven with an internal source of power to actuate an internal valve at a predetermined rotational orientation of the rotatable elements (when the predetermined value is reached, or shortly therebefore) and thereby release the air pulse which causes the nozzle valve to close and thus stop fluid flow through the nozzle.

In the preferred embodiment, pacing means are provided in the form of a worm gear linked to the gear system of a conventional gasoline pump dollar and cents computer and to the selector rotatable elements. The worm rotation is proportional to the rate of fluid flow (as measured by the computer) and thus the worm paces or permits the rotation of the selector means, as driven by its internal spring, at the proper rate.

It is a feature of this invention that conventional automatic full tank shutoff nozzles can be rapidly and inexpensively modified by addition of a small number of parts to provide for the positive air pressure actuation of the shutoff means in the hose nozzle. In addition, the mechanical selector meanscan be easily installed on existing pumps and rapidly and easily interengaged with conventional computers therein.

. The invention provides for cutting off gasoline flow at dollar volumes from $1 to $7 or higher if desired. Moreover, the automatic shutoff apparatus of this invention can be manually overridden if a mistake is made in dialing in the dollar volume desired or if the customer changes his mind. The operator can merely reset the dial, if required. The conventional automatic full tank shutoff function is not in any way impaired by the addition of the apparatus of this invention and it continues to function as designed. The apparatus of this invention can be easily maintained with a low frequency of repair. Installation is rapid on existing conventional equipment so that such equipment is not placed out of service for any extended period of time. A safety feature is provided which prevents transmission of force to the pump computer from the mechanical selector and the mechanical selector depends on the computer only for metering correlation while providing its own operational force.

In another aspect the invention features a fluid flow shutoff apparatus for interrupting the flow of fluid in a conduit which acts in a precise, reproducible, and rapid manner much as the operation of an electrical snapaction switch, but without requiring electrical circuitry. The apparatus comprises a rotatable cam member which includes a cam surface and a first portion clutch. Means are provided for rotating the cam member and a cam follower unit is disposed adjacent the cam surface with a cam follower riding on that surface, biasing means maintaining the follower in contact with the surface. A valve device is provided in the conduit and includes a blocking member, means biasing the blocking member towards a position in which the conduit is blocked, movable means operative to overcome the biasing force thus applied, and means linking those movable means to the cam follower unit. A single direction clutch is also provided and comprises the first clutch portion mentioned above, a second clutch portion linked to pacing means, and a clutching member for coupling those clutch portions. A clutch release includes means disposed to engage said clutching member at a predetermined rotational orientation of said cam member.

In the preferred form of this apparatus each of the clutch portions comprises a cylindrical surface; the clutching member comprises a wrap spring engaging those surfaces and having a projecting tang, and the clutch release comprises a member fixed with respect to said cam member and disposed to engage the tang at the predetermined rotational orientation. With this structure, movement of the cam follower at a predetermined or base position on the cam surface can be employed to operate the valve device movable means which ultimately causes the interruption of fluid flow in the conduit. The amount of fluid permitted to flow prior to the interruption thereof is determined by the original rotational orientation of the cam and the angle of rotation required to reach the original or base orientation. In that base orientation the cam surface and follower are operative, through the linking means, to so activate the movable means of the valve device when the tang of the wrap spring engages the clutch release. When, in the rotation of the cam member toward the base orientation, the tang engages the clutch release, drag on the cam member (transmitted through the wrap spring clutch) will be eliminated so that the cam member, under the influence of the means for rotating the same, can then snap quickly into the base position. This snap action causes the cam follower, in the critical range of the cam surface, to have a sudden and reproducible snap action which, through the means discussed above, causes the interruption of fluid flow. Without such snap action it would be extremely difficult to design and manufacture a cam surface and follower which would actuate the valve device at precisely the same rotational orientation of the cam during each usage of the device, especially where the cam member rotates at a relatively slow rate. In the preferred embodiment wherein the appropriate portion of the cam surface (which engages the cam follower in the base position of the cam member) is a detent, without such snap action the surface of the follower which rides on the caming surface could teeter on the brink of the detent during the slow rotation of the cam member and actually drop into the detent at different elapsed times in successive uses of the device. This, of course, would lead to nonreproducible results and at least the occasional dispensing of more fluid than was desired.

When the cam is in the base position, the wrap spring clutch is disengaged from both clutch portions and thus inputs to the pacing means from the pumps computer are not transmitted to other elements of the mechanical selector.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features, and advantages of the invention will appear from the following description of a particular preferred embodiment, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a partially schematic view of a system in accordance with the present invention;

FIG. 2 is a plan view of the mechanical selector portion of the system;

FIG. 3 is a view taken at 33 of FIG. 2;

FIG. 4 is a view taken at 4-4 of FIG. 3;

FIG. 5 is a view taken at 55 of FIG. 3; and

FIG. 6 is a partially broken away side elevation of a conventional gasoline pump nozzle (including conventional vacuum operated automatic full tank gasoline shutoff) as modified in accordance with the present invention.

DESCRIPTION OF A PARTICULAR PREFERRED EMBODIMENT With reference to FIG. 1, an improved system of this invention is shown for use with a conventional gasoline pumping apparatus (indicated schematically at 10) of the type commonly found at gasoline service stations. The system comprises a mechanical selector means 11 in accordance with this invention, an air pressure means 12 in accordance with this invention, and a conventional, pressure-differential (e.g., vacuum) actuated, gasoline hose nozzle 14 (including full tank shutoff) as modified in accordance with this invention.

The hose nozzle 14 is basically any one-of a number of known conventional automatic, gas-pressureactuated, full tank shutoff valve hose nozzles preferably of the type which are negative pressure (i. e., vacuum) actuated. The nozzle is modified to provide for the additional feature of automatic shutoff at a predetermined dollar value, or shortly therebefore. Nozzle 14 may be substantially similar to the hose nozzle described in US. Pat. No. 2,582,l95,'the basic structure of which is exemplified by the O.P.W. Division of Dover Corporation, Type IA hose nozzle.

Referring to FIG. 6, the automatic nozzle comprises a body casting 16 having a gasoline conduit 18 extending from the gasoline pump side of the nozzle to the spout end 20 throughvwhich the gasoline flows. A first biased-closed valve closure 22 seats on an annular seat 24 to shut off gasoline flow through the conduit 18 I A lever arm 36 is pivoted on a pin of a fulcrum point 38 for motion within an open-sided guard 40 and includes a seat 42 for receiving the rounded end 27 of shaft 26. Fulcrum point 38 is in the form of a yoke 44 depending from a reciprocable plunger 46 disposed for sliding motion in a cylindrical recess 48 in body casting 16. The plunger 46, as is known in the art, is urged to the position shown in FIG. 6 by an upper spring 50 against the counter of the bias of a lower spring 52. A series of balls 54 (as described in US. Pat. No. 2,582,195) lock the plunger in the position shown in FIG. 6. An impervious flexible diaphragm 56 is clamped in an internal recess of the body casting 16 to define chambers 58, 60 on its opposite sides. Vacuum chamber 58 is provided with a vacuum passageway 62 leading to the outlet end 20 of spout assembly 64 and also communicates with the gasoline conduit 18 in the area 66 where the spout assembly 64 connects to the body casting 16. The chamber 60 is open to the atmosphere through a small amount of air leakage around the plunger 46.

In the operation of such a conventional unit, the lever 36 can be pivoted about point 38 in the counterclockwise direction (as viewed in FIG. 6) so as to engage the rounded end 27 of shaft 26 in the seat 42 to apply force against the closure 22 and thereby overcome the influence of biasing spring 30. Such rotation of the lever 36 thus opens the valve permitting the flow of gasoline through the conduit 18 past the valve and eventually out of the spout end 20 of the nozzle unit 14. As is well known, the free end 67 of lever 36 may be engaged with a conventional holding clip 68 to maintain the valve closure 22 in an open position. With the lever 36 thus engaged with the clip 68, the flow of gasoline can still be stopped manually by raising the lever to release its end 67 from the clip 68 and then releasing the lever to allow the spring to once again force the valve closure 22 against the valve seat 24.

The conventional full tank automatic shutoff operates, as is well known in the art, when the gasoline in the automobiles gas tank reaches a level to cover the opening of the vacuum passageway 62 at the end 20 of the spout assembly 64. At that point in time the flow of gasoline past the area 66 causes a drop in pressure in the chamber 58. The diaphragm 56 is thus drawn upwardly and with it pin 70 to which it isattached. Pin 70 extends into the plunger 46 and includes a tapered portion at a location slightly below the balls 54. As the pin is raised to a position where the tapered portion is adjacent the balls, the plunger 54 is no longer restrained by the wcdging of the balls between the pin 70 and surfaces on the plunger and is free to move downwardly (as viewed in FIG. 6) under the influence of spring 30 overcoming the force of spring 52. The yoke 44 and the fulcrum point 38 thus also move downwardly. This shifting of the fulcrum point, as is well known, in conjunction with the shape and location of the holding clip 68 causes the lever 36 to disengagefrom the holding clip 68 thus freeing the lever 36 and allowing the return of valve closure 22 to a position of sealing contact with valve seat 24 under the influence of spring 30.

In accordance with the present invention, the conventional structure as recited above, is modified to provide an air passageway to the chamber 60. This is accomplished by the connection of flexible air tube 72 withtube element 74 concentric with conduit 18. Element 74 exits valve handle 16 and provides air passage into adapter block 76 (see FIG. 1) which forms a sealed air passage along the external surface of valve body casting 16 to a hole communicating with chamber 60.

The tube 72 extends through the conventional flexible hose 100 extending between the nozzle 14 and the pumping system 77 of a conventional gasoline station pump (see FIG. 1).

From the above construction, it will be understood that when a pulse of positive pressure air is passed through the

tubes

72 and 74 to the chamber 60, the diaphragm 56 moves upwardly releasing the plunger 46 and allowing it to move downwardly (under the influence of spring 30) displacing the fulcrum point 38 with the consequences as discussed above. This structure does not in any way disturb the normalvacuumoperated full tank shutoff feature of the nozzle. With a conventional construction of diaphragm 56, once a positive pressure of, for example, 5 psi. is built ,up in the chamber 60, and the fulcrum point 38 is lowered to cause automatic shutoff. The positive air pressure bleeds out between the unsealed recess 48 and the plunger 46 allowing the plunger to move the fulcrum point to its normal rest position shown in FIG. 6.

The modification of the conventional nozzle as described above, is comparatively simple to carry out with a small number of special parts needed, all of which parts are relatively inexpensive. Moreover, there is no disruption of the normal functions of the nozzle to provide automatic full tank shutoff even though the system has been set for a specific dollar amount. If the tank fills prior to that dollar amount, the nozzle will still interrupt gasoline flow.

Turning now to FIG. 1, the air pressure supply means 12 is preferably disposed within the conventional pump casing 10 at the service island of a gasoline service station. The means 12 include a supply tank or reservoir which, for example, has a volume of cubic inches and contains a supply of compressed air at 100 psi. A connector 91 may be provided on the external surface of the pump casing 10 through which the tank 90 may be replenished from, the external source of An air pulse supplied from the valve 94 is passed by the fitting 98 to the air tube 72 disposed within the flexible hose 100. The valve 94 is controlled by the mechanical selector 11 (as further described below) such that, while gasoline is flowing through the nozzle 14, the regulator 92 is connected to the tank 96 in order to accumulate a predetermined volume of positive pressure air within tank 96 and, when the appropriate volume of gasoline has been dispensed and shutoff is required, valve 94 connects the tank 96 to the fitting 98 thereby supplying a pulse of positive pressure air to the tube 72. (Alternatively, the tank 96 could be used alone and connected to a vacuum pump which would operate only as gasoline was being pumped. The adapter block 76 wouldthen have to communicate with chamber 58. When shutoff was required, a valve would interconnect the tank 96 and the tube 72.) I

'The construction of the mechanical selector 11 and its interaction with the two-way valve 94 may be described to FIGS. 2-5. The selector 11 comprises a base 102 secured to the gasoline pump housing 10 by screws 104 and a cover 106 which encloses the working parts of the selector and which is secured to the base by screws 108. The valve 94 is mounted on the base 102 and openings 103, are cut in the base 102 and housing 10 to permit the'passage of air lines 110 from the interior of the housing 10. The two states of the two-way valve 94 are determined by the position of a valve stem 112 (see FIG. 5). The valve stem is, in turn, engaged by an actuator arm 114 pivoted at 116 and including a bearing 118 which rides on a generally cylindrical outer cam surface 120 of cam 122. A detent 124 (see FIG. 5) in that surface is provided and the surface 120 and detent 124 combine to provide two positions for the actuator arm 114 and, consequently, the valve stem 112. As best seen in FIG. 3, the cam 122 is secured to a central shaft 126 by a pin 128. The shaft 126 7 rotates in upper and

lower bushings

130, 132 respectively.

A drive spring 134 is disposed in a well 136 which is integral with base 102 and is secured at opposite ends to the well 136 and cam 122. A dial 138 is secured by means of screw 140 to the portion of shaft 126 which projects above the cover 106. The dial includes a series of finger openings 142 and appropriate dollar amounts may be indicated on the surface of the dial adjacent each opening or on the surface of the cover 106 beneath each opening when the dial is in its rest position (the position in FIG. 2). A conventional finger stop 144 is mounted on the cover 106 and overlies the dial 138 at the radial distance of the finger holes from the center of the dial 138.

The selector 11 includes a first, single-direction clutch which comprises a wrap spring 146 which is disposed around a pair of cylindrical surfaces. The first cylindrical surface is provided by an upward extension 148 of the hub portion of cam 122 and the second cylindrical surface is provided by a lower extension 150 of the hub portion of a member 152 which, as will be seen below, is itself a clutch body of a second clutch. With respect to the inner diameter of the wrap spring 146 in its relaxed state, the member 148 has an outer diameter 0.007 inch more than that diameter and the member 150 has an outer diameter 0.004 inch more than that diameter. At its lower end spring 146 projects radially from the member 148 and is provided with a downwardly projecting tang 154 which projects through an opening 156 in the cam 122. An upstanding clutch release member 158 is integral with a spring cover 160 mounted on well 136. The clutch release 158 is disposed the same radial distance from the shaft 126 keyed to a shaft 174 which is supported on portions of base 102. Also keyed to shaft 174 is a sprocket 176 which engages a chain 178. At its opposite end the 'chain is trained about a sprocket (not shown) in the gear train between the gasoline pump computer and the dollar (or gallon) indicator wheels. The chain also engages idler 177 (see FIG. 4) which is slidably maintained in slot 179 on base 102 for adjusting tension in the chain.

As best seen in FIG. 5, the spring cover 160 has a notch 180 cut into its periphery adjacent the clutch release 158. Indicia 182 are provided on the upper sur-.

face of the wall of well 136 and are visable in the region of the notch 180. As will be discussed below, the notch 180 and indicia 182 assist in the final calibration of the unit.

The operation of the mechanical selector is as follows. When the appropriate dollar amount is dialed in using the dial 138 and finger stop 144, energy is stored in the drive spring 134 since its opposite ends are affixed to the stationary well 136 and the cam 122, the latter itself keyed to the shaft 126. The worm 172 is effectively locked to the gear train between the pump computer and indicator wheels by the chain 178. When the attendant rotates the nozzle lever 36 and engages it with the holding clip 68, the valve closure 22 is lifted from the seat 24 and the flow of gasoline which results causes the operation of the computer and hence rotation of the worm 72. The worm thus paces the rotation of the Worm gear 164 and permits the rotation of cam 122 at a speed determined by the pump computer in response to the rateof gasoline flow. The force causing this rotation is actually supplied by the drive spring 134. With this arrangement, excessive strain on the typically delicate computer mechanism is avoided.

When the appropriate dollar amount is dialed in the rotation of cam 122 causes the bearing 118 to ride up out of the detent 124 and onto the cylindrical surface 120. Asa result, the valve stem 112 of two-way valve 94 is depressed. With the valve stem so depresed, the valve 94 is in a state that transmits air at 30 psi. from the regulator 92 (see FIG. 1) to the one-shot holding tank 96. As the cam 122 rotates back to its original orientation and the bearing 118 drops again into detent 124, the internal connections in the valve '94 will be changed and the tank 96 will be connected to the fitting 98 disposed in the flexiblev gasoline hose so that a pulse of air will be delivered through the air tube 72 to the chamber 60 (see FIG. 6) in the nozzle with the resultant re-seating of the valve closure 22 on the valve seat 24, as described above.

The clutch release tang 154 must be reset to a repeatable location with respect to cam 122 when dialing in. This is accomplished by dimensioning projection 148 slightly smaller than projection 150. On dialing in therefore wrap spring 146 will slip on projection 148 until tang 154 is picked up by an end wall of slot 156. At this point slip will occur between the wrap spring clutch and projection up to the point of the operators finger engaging the finger stop.

The slip clutch provided at interface 162 protects the sensitive computer against the transmission of excessive force through the worm .172, sprocket 176, and

chain 178 to the computer. Furthermore, it permits manual override so that once a particular dollar amount has been dialed in, the operator can simply dial it out again and assume manual control of the filling operation. This would be advantageous in a number of circumstances, of course, including where the operator incorrectly dialed or where the customer decided to change its order after filling had commenced.

The retainer clip 169, wafer 168, and wave spring washer bear-down upon the worm gear 164 so that there is a suitable friction at the clutch interface 162. The keys 166 which rotationally lock the wafer 168 to the clutch body 152 guarantee that any slippage will occur at the clutch interface 162 and not at the retainer clip 169 which would degrade rapidly.

The single-direction, wrap spring clutch transmits the rotational force from the driven cam 122 to the clutch member 152. When, during the rotation of the cam 122, the spring tang 154 strikes the clutch release 158, the compressional force of the wrap spring 146 is lessened. Since the portion 148 of cam 122 has a smaller outer diameter than the portion 150 ofv clutch body 152, the wrap spring 146 will disengage first from the cam. Thus, as the tang 154 engages the clutch release 158 and the cam 122 is thereby disengaged from the member 152 (and thus from the spacing effect of the worm 172), the force of the drive spring 134 will cause a very rapid rotation of the clutch 122 causing the bearing 118 to seat almost instantaneously in the detent 124. As the bearing 118 drops into detent 124, of course, the valve 94 is switched to its alternative internal connection and the pulse of air is delivered to the nozzle with the consequent interruption of the flow of gasoline. The action of the wrap spring clutch, the cam, and the clutch release, therefore, is analagous to an electrical snap action switch.

From the foregoing, it will be seen that the precise rotational orientation of the clutch release 158 is important to assure the interruption of gasoline flow at the appropriate point in the dispensing of a predetermined amount. Typically, it is desirable to interrupt the flow of gasoline a few cents (e.g., less than 10 cents) before the dollar amount has been reached. This allows the service station attendant to top off the order to precisely the dollar amount requested. The notch 180 in spring cover 160 and the indicia 182 assist in properly locating the correct rotational orientation of the clutch release 158. If, after initial installation, it is found that the gasoline flow is being interrupted somewhat too soon or somewhat too late for any given dollar amount of gasoline dialed in, the spring cover 116 may be rotated with respect to the well 136 (by means of arcuate slots 184 in earsl86; see (FIG. 5) by a known amount, using the indicia 182 as a guide, to attain the correct shutoff point.

From the foregoing it will be seen that a metering in fluid shutoff device is provided which is economical to manufacture and install, rugged in construction, and compatable with the existing gasoline pumps with a minimum of modification. Without requiring any electrical circuitry and employing only compressed air (commonly available at service stations) a specific dollar amount of gasoline (or, in other circumstances, other fluids) can be dispensed without requiring the constant attention of the pump operator. Furthermore, a snap action action is achieved which assures the rapid and accurate interruption of the flow at a reproducible dollar volume of fuiid dependent upon the location of the adjustable clutch release 158. Absent the,

novel features which achieve this snap action arrangement, therelatively slow rotation of the cam 122 and the spherical shape of the bearing 118 would make the exact point of gasoline shutoff, as the bearing 118 eases into the detent 124, indeterminant. Furthermore, shutoff may not occur at all. Slow actuation of the threeway valve 94 would result in a gradual discharge of the air in the one shot tank 96. Thus, the air pressure on the diaphragm 56 in the automatic shutoff nozzle 14 may never reach a sufficient pressure level to trip the valve.

While a particular preferred embodiment of the invention has been described in detail and shown in the accompanying drawings, other embodiments are within the scope of the invention and the following claims.

I claim:

1. A system for use with a fluid dispensing apparatus having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated full tank shutoff, the system comprising a holding tank, means for maintaining the pressure in said tank at a differential with respect to atmospheric pressure and for connecting said holding tank to said nozzle for actuation of said shutoff, and mechanical selector means operatively linked to said metering system and to said first mentioned means for actuating the same when substantially a predetermined amount of fluid has been dispensed through said nozzle.

2. A system for use with a fluid dispensing apparatus having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated full tank shutoff, the system comprising first means for supplying a predetermined volume of positive pressure air to said nozzle to actuate said shutoff and mechanical selector means operatively linked to said metering mechanism and to said first means for actuating said first means when substantially a predetermined amount of fluid has been dispensed through said nozzle.

2. A system for use with a fluid dispensing apparatus having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated full tank shutoff, the system comprising first means for supplying a predetermined volume of positive pressure air to said nozzle to actuate said shutoff and mechanical selector means operatively linked to said metering mechanism and to said first means for actuating said first means when substantially a predetermined amount of fluid has been dispensed through said nozzle, said first means comprising a compressed air reservoir, a holding tank for accumulating said predetermined volume of positive pressure air, conduit means intercon necting said reservoir and said holding tank and also interconnecting said holding tank and said nozzle, and valve means disposed in said conduit means operative to interconnect said reservoir and said holding tank prior to said actuation by said mechanical selector means and to disconnect said reservoir from said holding tank and connect said holding tank to said nozzle upon said actuation by said mechanical selector means.

3. The system as claimed in claim 2 further including regulator means in said conduit means between said reservoir and said valve means.

4. The system as claimed in claim 3 wherein said fluid dispensing apparatus is a conventional gasoline pump and said reservoir comprises a compressed air tank disposed within the gasoline pump housing, said system further including a reservoir filling connector mounted on said housing to project externally therefrom and additional conduit means extending between said connector and said reservoir tank.

5. The system as claimed in claim 2, wherein said fluid dispensing apparatus comprises a conventional gasoline pump including a flexible gasoline hose to which said nozzle is connected, said conduit means comprising tubing extending between said valve means and said nozzle, at least a portion of said tubing being flexible and disposedwithin said-flexible hose.

6. A system for use with a fluid dispensing apparatus having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated full tank shutoff, the system comprising first means for supplying a predetermined volume of positive pressure air to said nozzle to actuate said shutoff and mechanical selector means operatively linked to said metering mechanism and to said first means for actuating said first means when substantially a predetermined amount of fluid has been dispensed through said nozzle, said mechanical selector means comprising an internal source of power for rotating portions of said selector means as fluid is being dispensed and pacing means for limiting the rate of said rotation to an amount dependant upon the rate at which fluid is being dispensed.

7. The system as claimed in claim 6 wherein said source of power comprises a spiral spring secured at one end to fixed portions of said selector means and at the other end to rotatable portions of said selector means.

8. The system as claimed in claim 7 wherein said pacing means comprise a worm gear operatively connected to said spiral spring for rotation about an axis in a predetermined sense, a worm engaged with said worm gear, and means limiting the rate of rotation of said worm to a value dependent upon the rate of flow of said fluid.

9. The system as claimed in claim 6 wherein said mechanical selector means comprise rotatable elements and stationary elements, said rotatable elements in cluding a cam member driven by said internal source of power, said cam member being linked to said pacing means by a single direction clutch.

10. The system as claimed in claim 9 wherein said single direction clutch comprises a wrap spring clutch including a wrap spring and a pair of cylindrical clutch surfaces, one of said cylindrical clutch surfaces being secured for rotation with said cam member, said one of said surfaces of a smaller diameter than said other surface.

11. The system as claimed in claim 10 wherein a slip clutch is provided between said pacing means and said single direction clutch.

12. The system as claimed in claim 10 wherein said wrap spring includes a projecting tang, said system also including a clutch release, comprising a fixed member mounted to engage said tang at a predetermined rotational orientation of said tang.

13. The system as claimed in claim 12 wherein said first means comprise a compressed air reservoir, a holding tank for accumulating said predetermined volume of positive pressure air, conduit means interconnecting said reservoir and said holding tank and also interconnecting said holding tank and said nozzle, and valve means disposed in said conduit means operative to interconnect said reservoir and said holding tank prior to said actuation by said mechanical selector means and to disconnect said reservoir from said holding tank and connect said holding tank to said nozzle upon said actuation by said mechanical selector means.

14. The system as claimed in claim 13 further including regulator means in said conduit means between said reservoir and said valve means.

15. The system as claimed in claim 14 wherein said fluid dispensing apparatus is a conventional gasoline pump and said reservoir comprises a compressed air tank disposed within the gasoline pump housing, said system further including a reservoir filling connector mounted on said housing to project externally therefrom and additional conduit means extending between said connector and said reservoir tank.

16. Fluid flow shutoff apparatus for interrupting the flow of fluid in a conduit comprising a rotatable cam member including a cam surface,

a first clutch portion, secured to said cam member for rotation therewith,

drive means for rotating said cam member,

a cam follower unit including a member for contact with said cam surface and biasing means for maintaining said member in contact with said surface,

a valve device in said conduit including a conduit blocking member, means biasing said blocking member toward a position in which said conduit is blocked, movable means operative to overcome the biasing force thus applied, and means linking said movable means to said cam follower unit,

a single direction clutch comprising said first clutch portion, a rotatable second clutch portion linked to pacing means which pace the rotation of said cam member under the influence of said drive means, and clutching member for selectively coupling said clutch portions, and

a clutch release comprising means disposed to engage said clutching member at apredetermined rotational-orientation of said cam member so as to uncouple said clutch portions, whereby said cam member is disengaged from said pacing means.

17. Apparatus as claimed in claim 16 wherein each of said clutch portions comprises a cylindrical surface, said clutching member comprises a wrap spring engaging said surfaces and having a projecting tang, and said clutch release comprises a member fixed with respect to said cam member and disposed to engage said tang at said predetermined rotational orientation.

18. In a gasoline pump hose nozzle having a biasedclosed dispensing valve, a dispensing lever for opening said valve, holder means for retaining said lever such that said valve is open, a diaphragm defining first and second air chambers, means comprising first gas passage means for sensing a full gasoline tank condition and for creating a reduced pressure in said first chamber in response thereto to move said diaphragm, and means responsive to movement of said diaphragm to disengage said handle from said holder means thereby closing said dispensing valve, the improvement comprising additional gas passage means opening into one of said chambers, whereby gas at a pressure differential with respect to atmospheric pressure may be introduced into said one of said chambers prior to said full tank condition.

19. The improvement of claim 18 further comprising a source of gas under pressure higher than atmospheric interconnected with said gas passage means, said gas passage means opening into said second chamber.

20. The improvement of claim 19 wherein said source of gas under pressure comprises a first holding tank having a predetermined volume of compressed gas sufficient to move said diaphragm, and means for interconnecting said tank with said gas passageway when a predetermined amount of gasoline has been pumped.

, UMTED STATES PATENT' OFFICE v CEBTEFECATE OFF CUREEUEKGN Ptent 3,823,751 I Dated July 16, 197 4 Inventor(s) James I eaIy It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line 57 change "wall" to ---walls--.,

Column 8, line #8 change "it s" as --his--..

Column 9, line 27 delete che parenthesis before (Fig. 5).

Column 9, line 42 change '.'fuiid" to- -fluidr' Column 10-, 'lines's-lude ete claim'2.

Signed and sealed this 3rd day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

2. A system for use with a fluid dispensing apparatus having a fluid flow metering mechanism and a nozzle including an automatic pressure differential-actuated full tank shutoff, the system comprising first means for supplying a predetermined volume of positive pressure air to said nozzle to actuate said shutoff and mechanical selector means operatively linked to said metering mechanism and to said first means for actuating said first means when substantially a predetermined amount of fluid has been dispensed through said nozzle, said first means comprising a compressed air reservoir, a holding tank for accumulating said predetermined volume of positive pressure air, conduit means interconnecting said reservoir and said holding tank and also interconnecting said holding tank and said nozzle, and valve means disposed in said conduit means operative to interconnect said reservoir and said holding tank prior to said actuation by said mechanical selector means and to disconnect said reservoir from said holding tank and connect said holding tank to said nozzle upon said actuation by said mechanical selector means.

5. The system as claimed in claim 2, wherein said fluid dispensing apparatus comprises a conventional gasoline pump including a flexible gasoline hose to which said nozzle is connected, said conduit means comprising tubing extending between said valve means and said nozzle, at least a portion of said tubing being flexible and disposed within said flexible hose.

9. The system as claimed in claim 6 wherein said mechanical selector means comprise rotatable elements and stationary elements, said rotatable elements including a cam member driven by said internal source of power, said cam member being linked to said Pacing means by a single direction clutch.

12. The system as claimed in claim 10 wherein said wrap spring includes a projecting tang, said system also including a clutch release comprising a fixed member mounted to engage said tang at a predetermined rotational orientation of said tang.

16. Fluid flow shutoff apparatus for interrupting the flow of fluid in a conduit comprising a rotatable cam member including a cam surface, a first clutch portion, secured to said cam member for rotation therewith, drive means for rotating said cam member, a cam follower unit including a member for contact with said cam surface and biasing means for maintaining said member in contact with said surface, a valve device in said conduit including a conduit blocking member, means biasing said blocking member toward a position in which said conduit is blocked, movable means operative to overcome the biasing force thus applied, and means linking said movable means to said cam follower unit, a single direction clutch comprising said first clutch portion, a rotatable second clutch portion linked to pacing means which pace the rotation of said cam member under the influence of said drive means, and clutching member for selectively coupling said clutch portions, and a clutch release comprising means disposed to engage said clutching member at a predetermined rotational orientation of said cam member so as to uncouple said clutch portions, whereby said cam member is disengaged from said pacing means.

18. In a gasoline pump hose nozzle having a biased-closed dispensing valve, a dispensing lever for opening said valve, holder means for retaining said lever such that said valve is open, a diaphragm defining first and second air chambers, means comprising first gas passage means for sensing a full gasoline tank condition and for creating a reduced pressure in said first chamber in response thereto to move said diaphragm, and means responsive to movement of said diaphragm to disengage said handle from said holder means thereby closing said dispensing valve, the improvement comprising additional gas passage means opening into one of said chambers, whereby gas at a pressure differential with respect to atmospheric pressure may be introduced into said one of said chambers prior to said full tank condition.