US3851127A

US3851127A - Hot liquid dispenser reverse flow sensor with check valve slider and magnetically operated switch

Info

Publication number: US3851127A
Application number: US00387004A
Authority: US
Inventors: J Gardner; M Brown
Original assignee: Jet Spray Cooler Inc
Current assignee: Jet Spray Cooler Inc
Priority date: 1971-09-03
Filing date: 1973-08-09
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

A reverse flow sensor for permitting flow of fluid in one direction while sensing backflow of fluid to actuate circuitry to activate a suitable response in a backflow condition. The reverse flow sensor comprises a housing defining a chamber with a check valve slider in the chamber. A magnet is carried by the slider for movement therewith. The slider has an opening permitting flow of fluid therethrough in one direction and impeding fluid flow in a second direction so that fluid flow toward the second direction acts to move the slider in the second direction. Magnetic responsive means are associated with the housing for reacting to movement of the slider.

Description

United States Patent 1191 1111 3,851,127

Gardner, Jr. et al. Nov. 26, 1974 HOT LIQUID DISPENSER REVERSE FLOW 3,200,214 8/1965 Aubert 200/61.86 x 3,507,359 4/1970 Warnock 200 81.9 M ux 3,551,620 12/1970 Hoover 200/81.9 M ux SWITCH 3,608,472 9/1971 Pelster et al. 200/81.9 M x [75] Inventors: John A. Gardner, Jr., Tewksbury;

Merle S. Brown, Cohasset, both of Primary ExamineFJames R. Scott Mass Attorney, Agent, or FirmWolf, Greenfield & Sachs [73] Assignee: Jet- Spray Cooler, lnc., Waltham,

Mass.

22 Filed: Aug. 9, 1973 [57] ABSTRACT [2]] Appl. No.: 387,004 A reverse flow sensor for permitting flow of fluid in Related U S Application Data one direction while sensing backflow of fluid to actuate circuitry to activate a suitable response in a backflow condition. The reverse flow sensor comprises a housing defining a chamberwith a check valve slider in the chamber. A magnet is carried by the slider for movement therewith. The slider has an opening per- S 200/6186 200/8L9 mitting flow of fluid therethrough in one direction and [58] Field of Search 200/61 86 81 9 R 81 9 M impeding fluid flow in a second direction so that fluid R 82 4 f. flow toward the second direction acts to move the 137/625 25 5'1 625 slider in the second direction. Magnetic responsive 130 318 324 325 349 351 353 333 334 means are associated with the housing for reacting to movement of the slider.

[60] Division of Ser. No. 177,597, Sept. 3, 1971, Pat. No. 3,790,028, which is a continuation-in-part of Ser. No. 887,671, Dec. 23, 1969, abandoned.

[56] References Cited 4 c1 13 n F UNITED STATES PATENTS raw'ng 3,l74,5l9 3/1965 Pizzurro et al 251/353 X 'l V e lllllllz f.

PATENIEL REV 26 I974 SHEET 10F 8 -FIG.4

PATENTEL NOV 2 8 I974 FIG. 6

SHEEI 5 BF 8 ZIIIIIIIIIZ HOT LIQUID DISPENSER REVERSE FLOW SENSOR WITH CHECK VALVE SLIDER AND MAGNETICALLY OPERATED SWITCH RELATED APPLICATION This application is a division of copending U.S. application Ser. No. 177,597 filed Sept. 3, 1971 now issued as U.S. Pat. No. 3,790,028 dated Feb. 5, 1974, which is a continuation-in-part of U.S. application Ser. No. 887,671 filed Dec. 23, 1969 and now abandoned.

This invention relates to beverage dispensers and more particularly comprises a new and improved dispenser for hot chocolate or other liquid food made up of a combination of two liquid parts. The invention also Another object of this invention is to'provide a hot reverse flow sensor which is highly accurate, reliable,

relates to a sensor for monitoring flow and sensing unacceptable backflow of fluids. The sensor is particularly useful when incorporated in a beverage dispenser to sense an out-of-syrup condition.

Most beverage dispensers handling hot chocolate now available include a hot water tank, a syrup or powder container of ready-to-mix concentrate, a flow metering system to control the flow rate of water and concentrate, and a programmer for controlling the size of the drink. All of the machines heretofore available have deficiencies in one or more of the standards established to measure acceptability. These standards include simplicity of operation, reliability, cleanability, accuracy of metering, ease of portion control, and speed of operation. For example, in all hot chocolate dispensers known to applicant, in order to clean the machine it is necessary to disassemble much of the flavor circuit and submerge the parts in a sanitizing solution in order to meet the standards of cleanliness imposed by federal, state and local health agencies. The hot chocolate dispensers which use powder concentrate do not precisely meter the mixture of water and powder, and are not capable of accurately preserving the ratio of powder to water when dispensing portions of different sizes. And all of the prior art hot chocolate dispensers known to applicant have a time cycle which varies with the size of the portions dispensed and employ relatively complex and expensive control and programming techniques.

A variety of devices have been used in the past to indicate the absence of fluid, reverse fluid flow or some predetermined point just prior to the absence of fluid in various systems. Such devices can comprise any of a number of systems including float systems, optical systems, conductive or resistive systems, ultrasonic systems, pneumatic systems, weight sensing systems, mechanicalsystems and the like. Most such devices suffer from one or more undesirable features which include necessity for precise orientation, high cost, complexity, erroneous signal indications, lack of adaptability, unacceptable free moving parts, complicated cross wall linkages and others. Thus, there are difficulties in adopting a reverse flow sensor in hot chocolate dispensers to indicate an out-of-syrup condition which would activate a dispenser shut off, or give some other indication to the user. Yet, it is desirable to have an out-of-syrup condition indicated to a hot chocolate dispenser operator in order to prevent less than a predetermined ratio of syrup to water being dispensed from a dispenser.

One object of this invention is to provide a hot chocolate dispenser which is extremely simple to operate.

and sensitive to unwanted reverse flow.

Still another object of this invention is to provide a sensor in accordance with the preceding objects which is highly useful to indicate an out-of-syrup condition in hot chocolate dispensers of this invention.

Still another object of this invention is to provide a reverse flow sensor in accordance with the preceding objects which is highly compact, relatively low in cost, easily reset after shut down, capable of operating with out auxiliary equipment and does not require frequent adjustments in use.

Still another object of this invention is to provide a reverse flow sensor in accordance with the preceding objects which is .unaffected by changes in physical properties of chocolate syrups, has an easily discernible signal output, is relatively insensitive to damage by handling and is capable of being sanitized while in place in a hot chocolate dispenser.

To accomplish these and other objects, the hot chocolate dispenser of this invention includes a syrup and water control assembly which in cooperation with the water and syrup sources preserves a fixed ratio between water and syrup for large and small portions. A syrup circuit which includes the control assembly also includes a positive displacement pump that moves a constant volume of syrup in the system during each cycle. The assembly for small portions diverts a part of the output of the positive displacement pump and simultaneously reduces the total water flow, and by means of a single control knob the portion selection is made.

The reverse flow sensor comprises a check valve slider carrying a magnet and positioned in operative relationship to a magnet sensitive means for opening and closing an electrical circuit. Movement of the magnet along with the slider in response to fluid pressures, actuates the means responsive to the magnet to indicate an out-of-syrup or reverse flow condition.

Typically two-portion hot chocolate dispensers are designed to give six and eight ounce servings. The flavor concentrates now used for best results employ a 5:1 ratio of water to syrup. In accordance with the present invention the positive displacement pump in the syrup circuit moves the full volume of syrup required'for the larger portion, and when a smaller portion is to be served, the syrup and water control assembly divertsa portion of that syrup so that it does not reach the discharge nozzle of the machine.

In the drawing one embodiment of this invention is illustrated, wherein:

FIG. 1 is a perspective view of a hot chocolate dispenser constructed in accordance with this invention;

FIG. 2 is a perspective view, partially broken away, of the dispenser shown in FIG. 1 with only the syrup circuit being illustrated for purpose of clarity;

FIG. 3 is a side view of the dispenser shown in FIG. 1 with only the water circuit shown;

FIG. 4 is an enlarged cross sectional view of the syrup and water control assembly;

FIG. 5 is a schematic diagram of the electrical control circuit of the present invention;

FIG. 6 is a cross sectional view through a preferred embodiment of a reverse flow sensor in accordance with the present invention;

FIG. 7 is a cross sectional view of the slider thereof taken along line 7-7 of FIG. 6;

FIG. 7A is a bottom view thereof;

FIG. 8 is a schematic diagram of the electrical control circuit utilizing the sensor of FIG. 6;

FIG. 9 is a cross sectional view through the center of an alternate embodiment of a reverse flow sensor in accordance with the present invention;

FIG. 10 is a schematic diagram of the electrical control circuit utilizing the sensor of FIG. 9;

FIG. 11 is a cross sectional view through the center of an alternate embodiment of a syrup supply can and associated structure for use in the beverage dispenser of FIG. 1; and

FIG. 12 is a cross sectional view through a modified portion of a syrup and water control assembly showing a modification of the assembly shown in FIG. 4.

The beverage dispenser of this invention is designed to serve two different size portions of hot chocolate. Before the machine is actuated, the selection is made by means of a control knob provided on the front panel of the machine. The beverage dispenser shown includes a housing 10 which contains a syrup delivery circuit 12 (FIG. 2), a water delivery circuit 14 (FIG. 3), and an electrical control circuit 16 (FIG. 5). The housing 10 has a drip tray 18 attached to the bottom of its front wall and a mixing assembly 20 mounted above it. The assembly 20 is shown and described in detail in US. Pat. No. 3,568,887 entitled HOT BEVERAGE DIS- PENSER. Included as part of the syrup circuit and the water circuit is a reserve cylinder and water control assembly 22 (FIG. 4) attached on the inside of the housing 10 to the front panel 24.

The syrup circuit 12 is shown in FIG. 2, isolated both from the electrical circuit and the water circuit for clarity. Chocolate syrup can 30 is mounted on shelf 32 forming part of the housing 10 and is covered by the hood 34 (see FIG. 1) forming part of the housing; A dip tube 36 carried by the can cover 38 extends downwardly into the can to the region of the can bottom, and the top of the dip tube is connected by means of a quick connect fitting and check valve assembly 40 to duct 42 in turn connected to the cylinder 44 of positive displacement pump 45 in the syrup circuit.

The pump 45 includes a piston 46 movable in the cylinder 44 and carried on the end of piston rod 48 in turn operated by crank 50 connected to the rotating cam 52 driven by the cam motor 54. As the cam 52 rotates, the crank 50 moves the piston 46 up and down in the cylinder 44 through each revolution. The pump 45 is shown in the drawing to be mounted on partition 56 in housing 10.

The outlet duct 58 of pump 45 is connectedto the reserve cylinder and water control assembly 22 whose syrup outlet 60 in turn extends out of the housing to the mixing chamber 20. The discharge duct 60 carries a check valve 62 at its discharge end to prevent air or other matter from entering the duct 60 and fouling or contaminating the syrup circuit and for cutting off flow at the end of the pump cycle to eliminate after-drip.

In FIG. 4 the syrup or reserve cylinder and water control assembly is shown in detail. The assembly 22 in cludes a metering chamber 64 controlled by sliding piston 66. The chamber 64 serves as a reservoir for the system so as to permit the syrup circuit to discharge either one of two selected volumes of syrup. When the reserve piston 66 is locked in the position shown in FIG. 4 the same volume of syrup drawn into cylinder 44 of pump 45 during the down stroke of the piston 46 will be expelled through the check valve 62 when the piston rises during its discharge stroke. A recess 68 cut in the face of the reserve piston 66 allows the syrup to flow from the duct 58 to the discharge duct 60 during the positive stroke of the pump. The pump acts as a positive displacement pump, and the amount of the syrup displaced in the system will be exactly equal to the volume of displacement of the piston in a cylinder.

The push rod 70 is provided to lock the reserve piston 66 in place so that the amount of syrup discharged exactly equals the amount displaced by the pump 45. The push rod 70 carries a pair of ears 74' that are disposed in slots 76 adjacent chamber 64. When the push rod is moved to the right so that its end 78 engages the inner face 80 of the reserve piston 66, the ears 74 will just clear the ends of the slots 76, and the push rod may be rotated so as to misalign the ears with the slots. When this is done, the ears 74 will bear against the face 82 of flange 84 of watercontrol housing 72 so as to retain the rod in its depressed position. Consequently the reserve piston 66 will not be permitted to move to the left as shown in the figure, and the chamber 64 will not collect any of the syrup displaced by the pump 45. However, when the rod 70 is in the position shown in FIG. 4 so that it does not interfere with movement of the reserve piston 66, it will be appreciated that when the piston 46 of the pump displaces syrup from its cylinder, a portion of that syrup will be allowed to collect in the chamber 64 as the reserve piston 66 moves to the left. So long as the volume displaced by pump 45 exceeds the maximum volume of the chamber 64, the difference between the volumes will be dispensed through check valve 62 of outlet duct 60. Whatever syrup collects in the chamber 64 due to displacement of the reserve piston 66 will be recollected in the cylinder 44 during the return stroke of piston 46. Thus by disabling the reserve piston 66 so that it cannot move, the quantity dispensed through the check valve 62 will equal the quantity of syrup displaced by the pump 45. If the reserve piston 66 is allowed to move to the left so as to expand the chamber 64, then the amount of syrup discharged through the check valve 62 will be equal to the quantity of syrup displaced by the pump 45 minus that which is allowed to collect in the expanded chamber 64. Knob 86 secured to the front end of the push rod 70 and extending out of the housing at the front panel 24 enables an operator to select the amount of syrup to be discharged by the syrup circuit 12.

The water circuit 14 shown in FIG. 3 is very similar to that shown in US. Pat. No. 3,568,887 supra, and therefore it will be described only briefly. The water circuit includes heating tank supported on the bottom of the housing 10.- The heating tank 100 is fed water through inlet duct 102 solenoid valve 104, reserve cylinder and water Control assembly 22, and filler duct 106. Heated wateris discharged from tank 100 through outlet 108 which is connected through an expansion chamber 110 to discharge duct 112. An overflow line 114 is connected to the expansion chamber 110 and is shown to have a discharge port 116 immediately above drip tray 18. In order to discharge water from the tank 100, the water must be displaced from the top by water fed into it through duct 106. This is in turn controlled by the solenoid valve 104. It will be noted that the solenoid valve 104 is on the cold water side of the tank, which effectively prolongs the life of the rubber parts of the valve.

The reserve cylinder and water control assembly 22 not only serves to meter the amount of syrup discharged into the mixing chamber 20, but also serves to meter the quantity of water displaced from the tank 100. Reference again is made to FIG. 4 to illustrate this function. In that figure water control housing 72 is shown to include a main water inlet 118, a water outlet 120, and a secondary water inlet 122. Secondary water inlet 122 is connected to the outlet 120 through a valve 124 defined by the conical configuration of push rod 70 which cooperates with the conical seat 126 in housing 72. When the valve is closed as illustrated in FIG. 4, no water is allowed to pass from the secondary inlet 122 to outlet 120, and the only water allowed to flow through the system is that which enters inlet 118. The push rod 70 does not interfere with the flow of water between the inlet 118 and the outlet 120. In FIG. 3 the solenoid valve 104 in the water circuit is shown to be connected through flow control 128 to the primary inlet 118 of the reserve cylinder and water control assembly 22, and the outlet of the solenoid 104 is also shown connected by means of duct 130 to the secondary inlet 122 of the housing 72. The flow control 128 is of standard design and the details form no part of this invention. Suffice it to say that it includes a needle valve adjustable through the front of the housing as it extends out panel 24, and it also includes a rubber annular gasket which varies in size under pressure so as to provide constant flow regardless of line pressure. A flow control 129 located at the inlet 122 performs the same function, but it is not adjustable.

To discharge water through duct 112 into the mixing chamber 20, the solenoid valve 104 is opened, and the amount of water which flows through the assembly 22 into the tank 100 exactly equals the amount of water which is discharged through the duct 112 into the mixing chamber. The quantity of water fed to the tank 100 in a given interval depends upon the position of push rod 70. When the push rod is moved to the right from the position shown in FIG. 4 so as to disable the reserve piston 66, the valve 124 .unseats so as to allow secondary water as well as primary water to flow through the water control housing 72. However, when push rod 70 is in the position shown in FIG. 4,-the valve 124 is closed and only primary water flows. Thus, when a greater quantity of syrup is discharged through assembly 22 caused by the disabling of reserve piston 66, a greater quantity of water. also discharges into the mixing chamber. This is explained more fully in connection with the operation of the machine below.

Push rod 70 carries an O-ring 132 to prevent water from entering the chamber 64. Another O-ring 134 is carried on the push rod adjacent its other end and prevents water from leaking about the rod in the direction of the knob 86.

The mixing chamber 20 identical to that shown in US. Pat. No. 3,568,887 supra, contains a mixing impeller 136 driven by a whipper motor 138. The whipper motor 138, gear motor 54, and solenoid valve 104 are all operated by the control circuit shown in FIG. 5.

Connected across lines L1 and L-2 in the control circuit is heater 140 of tank 100, which is controlled by thermostat'l42 that may be set to control water temperature. A pilot light 144 is also connected across the line, which indicates when the machine is on. The machine is tumed on by switch 146.

To dispense hot chocolate from the machine. starter switch 148 is depressed, which immediately closes the circuit for gear motor 54, and the motor starts to run and rotates cam 52. The crank 50 moves the piston 46 upwardly in the cylinder to discharge syrup from the syrup circuit. Simultaneously a pair of

microswitches

150 and 152 shown in FIG. 5 move from their normally open position to the closed position. When the starter switch 148 is closed, it temporarily completes the circuit for the motor 138, and switch 150 immediately thereafter is closed by the cam driven by motor 54 so as to connect the whipper motor 138 across the line through switch 154 forming part of the sanitizing switch assembly 156 described below and thus the whipper motor continues to run after the switch 148 is released. As the gear motor 54 turns, the whipper motor and solenoid valve circuits are both closed through the

switches

150 and 152 controlled by the cam 52, and water is discharged through the water circuit 14 into the mixing chamber 20 and chocolate syrup is discharged into the mixing chamber through the syrup circuit 12. When the gear cam 52 turns through 180, the syrup feed will discontinue, and the piston 46 will move downwardly in the pump 45 to refill the cylinder. Typically, the gear motor 54 may rotate at 6 rpm, and one revolution or cycle of the cam 52 takes 10 seconds. In this arrangement discharge of syrup from the syrup circuit consumes one-half cycle or 5 seconds. The remaining 5 seconds of the cycle is consumed in refilling the pump 45. The cam 52 which operates the switch 152 is designed to reopen the switch 152 after 5 seconds of the cycle, so that water flow is limited to that duration. During the remaining 5 seconds of the cycle, the whipper motor 138 continues to operate to provide an after whip which is described fully in US. Pat. No. 3,568,887 supra. When the cam completes its cycle, the normally open switch 150 reopens. The foregoing description of the control circuit cycle applies equally to situations where the dispenser is discharging either a small or a large portion. That is, the lO-second cycle described applies whether or not the push rod 70 is in the depressed or released position.

The control circuit of FIG. 5 permits hot water to be drawn from the dispenser without syrup. Switch 160 is provided for that purpose. When that switch is closed, the solenoid valve 104 is connected across the lines L1 and L2, and it is energized without energizing the

motors

54 and 138 which drive the whipper and the cam. So long as the switch 160 is closed the hot water will discharge from the machine.

As is evident above, with the assembly 22 an operator may select between two sizes of drinks which may be dispensed by the machine. Typically the two sizes are six and eight ounces. A conventional chocolate syrup to hot water ratio is 1:5, and therefore in a 6 ounce drink, one ounce of syrup is mixed with ounces of water. To preserve the ratio, in an 8 ounce drink, 1.33 ounces of syrup are mixed with 6.67 ounces of water. In the machine described, the pump 45 is designed to deliver 1.33 fluid ounces of chocolate in the pump cycle. It will be understood that this quantity may be varied by changing the length of the crank arm 50 established by the cam 52. The capacity of the chamber 64 in the assembly 22 is 0.33 fluid ounces of syrup. Therefore, if the push rod 70 is in its depressed position barring operation of the reserve piston 66, 1.33 ounces of chocolate will be dispensed from the pump 44 through the system into the mixing chamber 20. If on the other hand the reserve piston is allowed to move in response to operation of the pump 45, of the 1.33 ounces displaced by the pump, 0.33 ounces will be captured in the expansion chamber 64 so that only one ounce of chocolate will be discharged into the mixing chamber 20. As for the water circuit, if the stem 70 is depressed to disable the reserve piston, the secondary water inlet 122 is open so as to allow 1.67 ounces of water to flow in 4 seconds through the water control housing to the discharge por 120 and into the mixing chamber 20. The water circuit is designed also to pump 5 ounces of water through inlet 118 of the water control housing and into the mixing chamber during the 4 second operation of the solenoid valve. Consequently with the push rod depressed, 1.33 ounces of chocolate are mixed with 6.67 ounces of water, while with the push rod in its outer position, 1 ounce of chocolate is discharged with 5 ounces of water.

A desirable feature of any consumable beverage dispenser is that it be capable of being cleaned and sanitized easily and effectively. Most dispensers require some dismantling of the flavor concentrate flow circuit with subsequent sanitizing by immersing and washing in a sanitizing solution. This dispenser however, may be sanitized very easily as follows: the main on-off switch 146 is turned off, the chocolate syrup container 30 is replaced by a container of hot sanitizing solution, and an empty container is placed beneath the mixing chamber nozzle 21. By throwing the sanitizing switch 156 to the on position (opposite to that illustrated), the gear motor 54 rotates and the hot water solution is fed through the syrup circuit. By allowing the solution to run through the machine for perhaps 3 minutes allowing solution to remain in the syrup circuit for an additional minute or two, and then again flushing the system, the solution will totally clean the syrup circuit of all residual chocolate. By this means all of the internal parts in contact with the syrup are cleansed, including the pump and reserve system, check valves and associated transport tubing. Thus this operation may be carried out without dismantling the machine other than the chocolate syrup container itself.

Turning now to FIG. 12 a modification of the sliding piston arrangement within the reserve cylinder and water control assembly 22 is shown. In this modification, the reserve cylinder and water control assembly are identical to that described with respect to FIG. 4 except that the sliding piston 66 and its associated O- ring type gasket 66A is replaced with a diaphragm piston member indicated generally at 200. The diaphragm piston member comprises a rubber or other resilient plastic diaphragm 201 mounted in the walls of the metering chamber or reservoir 64 by clamps 202. A central portion of the diaphragm 201 defines a circular flat area 203 to which is attached a piston head 204. The

piston head 204 is not connected to the end of push rod but contacts the end of push rod 70 in the furthest extremity of travel to left of the head 204. The head 204 is preferably of a rigid plastic in disc form although other rigid materials can be used. The push rod 70 and its associated spring 70A operate in exactly the same manner as described with respect to the embodiment of FIG. 4. Thus spring 70A acts to hold the push rod 70 in its withdrawn position (i.e., small volume position) to thereby block the secondary water path and reduce the volume of water dispensed in a single cycle. The full lines of the diaphragm shown in FIG. 12 indicate the small volume drink position of the piston head 204 and associated diaphragm. Movement to the right to the dotted line position shown in FIG. 12 indicates the large volume position of the piston head 204 and diaphragm portion 201. Thus, the piston diaphragm arrangement of FIG. .12 operates as does the sliding piston 66 and is actuated in the same manner within the reserve cylinder and water control assembly 22. However, since the diaphragm is continuous, there is no chance of leakage through a gasket seal such as gasket 66A of FIG. 4.

With reference now to FIG. 11, an alternate syrup supply structure is shown which is more fully described in copending application Ser. No. 36,863 filed May 13, 1970 entitled LIQUID DISPENSING SYSTEM (now abandoned) which application is incorporated by reference herein. As described in that application, the syrup supply portion of the dispenser shown in FIG. 2 is modified as shown in FIG. 11 to obtain an improved fluid hopper. In the embodiment of FIG. 11, the duct 42 passes upwardly to the can 30 which is supported on the shelf 32 forming part of the housing 10. The can 30 is connected by means of the duct 42 to the cylinder 44 of the pump. The can 30 has an opened bottom end 260. The can can be opened by a common electric or manual knurled wheel drive can opener or any other convenient tool. The opened end 260 of the can is covered by a lid 262 having a closure wall 264 and an upwardly extending peripheral skirt 266 which lies about the outer surface of the lower end of the cylindrical wall of the can. The lid 262 is preferably formed of a resilient plastic material. A pair of tabs 268 extend from opposite sides of the top edge of the skirt to facilitate removal and installation of the lid 262.

A dispensing nipple 270 in the formof a duck bill check is formed at the center of the closure wall 264. The nipple 270 has a generally cylindrical body 272 which terminates in converging walls 274 and a downwardly extending central flap 276. The flap is cut as shown at 278 but no material is removed so that no stresses are applied to the nipple and the flap sides are engaged to close the cut or slit and prevent flow through the nipple. I

A second nipple 280.in the form-of a duck bill check extends upwardly from the closure wall 264 of the lid adjacent its periphery and has a cylindrical wall 282, converging wall 284 and flap 286 with a slit 288 that may be identical to the corresponding parts of the nipple 270.

A rigid backup plate 290 lies within the closure wall 264 of the lid 262 and has an opening 292 through 9 which the nipple 280 extends into the interior of the can 30. The periphery 294 of the backup plate 290 rests on the bead 261 of the can 30 to provide stiffness for the lid 262 and perform other functions. The backup plate 290 also carries as an integral part thereof a cylindrical sleeve 296 which fits withinthe nipple 270 and supports it in the position shown. The sleeve 296 has a bead 298 on its outer surface, which stretches the nipple 270 and forms a corresponding bead 300 on the nipple wall 272.

A check housing 302 is mounted on the platform 32 of the dispenserhousing l and its lower end 304 of reduced diameter is connected to the end of the duct 42 which carries the syrup from the can 30 to the pump. The check housing 302 is sized to receive the nipple 270 when supported on the sleeve 296, and a circular seat 306 is provided on the inner surface of the housing 302 so as to receive the bead 300 formed in the nipple 270 by the corresponding bead 298 on the sleeve 296.

In operation, the

nipples

270 and 280 perform two separate but interrelated functions. By making the

slits

278 and 288 sharp and cleanly defined slices without removing material, thin hairline slits are formed which will close by elastomeric memory once the slitting knife or tool used to form it is removed. Thus, each nipple serves as a check valve which will not leak liquid during the normal gravity head conditions. When the lid 262 is used in the dispenser of FIGS. 1-5, check valve 40 can be eliminated since the nipple 270 functions as a backflow prevention check valve to stop all substantial backflow in the system.

The nipple 270 serves an a unidirectional flow check valve in the syrup inlet to the pump. Nipple 280 allows air intake into the can to relieve pressure differences. Thus, the

nipples

270 and 280 keep the system in pressure equilibrium during the dispensing cycle as more fully described in the above-noted copending US. patent application Ser. No. 36,863.

As described above, with either the syrup supply of FIG. 2 or that of FIG. 11, the drink dispense button results in water and syrup being delivered to a mixing chamber in proper ratio in amount for apreset size drink. For example, when using the syrup supply of FIG. 11, this may be a 6 fluid ounce drink comprising 1 fluid ounce of syrup and fluid ounces of water. Under these conditions, a 2% size syrup can gives approximately 26 drinks before emptying the can, excluding the roughly 4 fluid ounces required to fill the syrup circuit, while a No. 10 size can would give approximately 96 drinks.

Using the dispenser as described above, the advantages described above are obtained; however, the syrup can be exhausted from the syrup container before an operator is alerted to the fact that a weak drink is about to be dispensed. Under most conditions, the dispenser is installed in so-called fast service restaurants where little time or attention is allowed to check the amount of syrup left in the can. Since the syrup level is not readily observable, it is common for the can and syrup circuits to be exhausted of syrup without the knowledge of the operater. For this reason, it is preferred to have a device which alerts the operator to the instant in time when the can is just becoming empty but the syrup circuit is still virtually full.

As noted above, the flow of syrup in the syrup circuit is only in one direction and is governed by-the orientation of the check valves such as 40 and 62 or 270 in place of 40. However, in one condition there is a slight reversal of syrup flow which occurs when the syrup reservoir does not contain enough syrup to fill the syrup circuit and air has been drawn into the syrup circuit. During the pump discharge stroke, pressure is developed in the syrup transport tubing which causes flow and discharge of syrup through the outlet check valve 60. During this pressure period the syrup in the transport tubing leading to the pump from the syrup reservoir is stationary. However, if a small amount of air is drawn into the syrup line between the syrup reservoir and pump, this column of air becomes compressed during the pump discharge stroke and a small amount of reverse flow of the syrup results. This small reverse flow is utilized in the reverse flow indicator of this invention the preferred embodiment of which is illustrated in FIGS. 6, 7, 7A and 8 at 400.

The sensor 400 has a hollow cylindrical housing formed of upper and

lower halves

401 and 402 joined midway in their cylindrical wall at 403 with upper and lower duct fitting ends 404 and 405. Flow through the sensor is normally in the direction of arrow 419 when the sensor is connected in duct 42 preferably between the first check valve such as 40 or 270 and the cylinder The inner configuration of the housing is in the form of an upper cylindrical section or chamber 406 which houses an upper umbrella-shaped portion 407 of a check valve slider 408. A lower, smaller diameter cylindrical section 409 houses a cylindrical magnet 410. A bottom cylindrical section 411 of still smaller diameter houses a duck bill 414 of the slider 408.

The magnet 410 is a permanent magnet whose dimensions are such that its outer cylindrical surface is slightly smaller than the housing section 409 and its inner diametric surface is sized to coincide with the outside diameter of the cylindrical portion of the slider which is preferably elastomeric. The entire slider is preferably formed of a rubber or other elasotmeric or resilient material. A flat, upper end of the magnet is preferably dimensioned to underlie a flat portion 413 of the slider. The longitudinal length of the magnet provides guidingof the magnet in the housing through its normal distance of operating travel.

The slider 408 acts as a check valve and is of generally cylindrical shape having an internal, cylindrical, syrup passageway which converges to a rectangular shape of narrow clearance 414 opened at the end by a slit 415 and is thus in the general shape of a duck bill nipple such as 280. The cylindrical portion of the slider coincides with the longitudinal extent of the magnet while the rectangular portion extends beyond the magnet into the lower cylindrical section of the housing. The upper, umbrella-shaped slider portion of the check valve slider has an outer diameter such that it nonnally grips the inside diameter of the cylindrical portion 406 and provides a slight degree of resistance to movement. The magnet and slider are mechanically linked together so as to move together as a single unit.

A magnetic reed switch 420 having

electrical leads

421 and 423 is positioned in operative association with the magnet 410. As known in the art, the reed switch has an evacuated and sealed glass envelope 422 with metallic contacts 424 mounted on spring strips and constituting an electrical, signal output portion of the sensor. The magnetic susceptibility of the spring strips is such that an influencing magnetic field of sufficient strength overcomes the biasing force of the springs and causes the contacts to close to complete a circuit. The

leads 421 and 423 can be interconnected to suitable electrical circuitry as will be described, as in the dispenser 10, to interrupt operation of the dispenser on proper demand. The position of the reed switch as shown in FIG. 6 is such that the magnet 410 holds the switch in its closed position when the syrup container fully supplies the syrup circuit. The reed switch opens upon movement of the magnet in an upward direction from that shown in FIG. 6.

The sensor 400 is installed in the syrup line such as 42 between the syrup reservoir and the pump and when the syrup circuit is full, the sensor remains in the posi tion shown in FIG. 6. Unidirectional flow of syrup in the direction of arrow 419 results in a pressure differential across the slit of the check valveslider which keeps the movable portion of the sensor in position since the only path for syrup flow is through the area of the slit.

Preferably the sensor 400 is far enough away from the syrup reservoir to permit an optimum amount of air to enter the syrup reservoirto permit an optimum amount of air to enter the syrup circuit upon exhaustion of the syrup reservoir and thus result in a measurable amount of compression of the air and reverse flow of syrup during the pump stroke without air going beyond the sensor in the syrup circuit.

Once the syrup reservoir has been drained of syrup,

on the next refill stroke of the pump, air is drawn into.

the syrup circuit. This column of air is of sufficient size to be compressed or displaced during the pump stroke, yet, not so large as to exhaust the system of syrup. The air must be upstream of the sensor to permit the syrup in the pump to reverse flow in the direction of the sensor. However, the duck bill prevents reverse flow through the slit 415.

In one application, the sensor 400 is located right at the inlet to the pump thus resulting in approximately 12 inches of inch inside diameter, reinforced flexible tubing between the sensor and the syrup reservoir. Typically, about 4 inches of this tubing is filled with air during the pump refill stroke at the instant the syrup reservoir is exhausted of syrup. This represents approximately 0.44-cubic inches or A fluid ounce. During the pressure stroke the system pressure builds up to as high as psig, resulting in this column of air being compressed from 4 inches in length of tubing to approximately 1.3 inches or a resultant reverse movement of syrup of 2.7 inches. Since the sensor slider 408 need move only approximately inch to deactivate the reed switch, adequate reverse movement of the slider can easily be achieved.

Once reverse flow of the syrup begins, the slit in the sensor valve closes tightly due to the pressure differential. This syrup pressure then acts against the projected area of the magnet and check valve thereby causing the slider and magnet to move upwardly.

The umbrella section at the top of the check valve slider 408 serves two purposes. First, it prevents air from bypassing around the check valve during reverse flow and second it serves to hold the magnet in place in the raised position by virtue of the friction resulting from the slight interference between the rubber or elastomeric material of the slider and the housing.

The associated electric circuitry for the sensor 400 is illustrated in FIG. 8 where the circuit 450 is basically identical to the circuit described with regard to FIG. 5 with the additional reed switch component added along with a relay 451 and an out-of-syrup light 452 connected as shown. This circuitry assures that continuous operation of the dispenser is interrupted whenever the reed contacts are open. Voltage to the pump drive or gear motor 54 is dependent upon a continuous circuit through the reed switch. To initiate a drink dispense cycle, the push start button 146 is suppressed and released. The momentary contact of the normally opened switch starts the gear motor which through a cam arrangement depresses the button of the cam operated microswitch which maintains the voltage to the gear motor 54 until the motor output shaft has made one revolution. At this point, the cam disengages the switch and the motor stops. This constitutes one drink dispense cycle. Whenever air is drawn into the syrup circuit, the reverse travel of the sensor slider 408 causes the reed switch to open, thus stopping the gear motor 54 in midpump stroke. Depressing the push start button will not restart the cycle until the reed switch is again closed.

A neon bulb 452 with high resistance is located in parallel with the reed switch. During periods when the reed switch contacts are closed, the current flow is principally through the reed switch, thus, there is insufficient voltage to the neon bulb 452 to activate it due to the high resistance. When the reed switch contacts are opened, current flow is through the neon bulb and the resistance is sufficiently high to drop the voltage to the relay coil of relay 51 to a point where it will not operate. In this way a visual warning is provided which automatically indicates when the dispenser is out of syrup. The out-of-syrup light 452 can be located on the front panel of the dispenser.

The electromagnetic relay 451 which is preferably a single pole, single throw electromagnetic relay is used between the reed switch and the gear motor to isolate the current load of the motor from the reedcontacts. This eliminates the tendency for arcing to take place at the reed switch contacts thus giving prolonged switch life.

When the dispenser is stopped due to movement of the slider 408, the empty syrup reservoir is replaced with a full one and the fill or sanitizer switch 156 is engaged. This switch bypasses all other circuitry and operates the gear motor independently. Since the gear motor (pump) 54 is stopped on midpump stroke it completes the pump stroke and proceeds to a refill stroke, thus drawing new syrup into the syrup circuit. This results in entrapped air being drawn along with the syrup, through the sensor and into the pump where it can no longer affect the sensor. Ordinarily this takes just the remaining cycle of the pump to transfer the air and reset the magnet which re-engages the reed switch in the closed position. At this point, the light 452 goes verse flow sensor is ideally suited to many applications including use in the hot drink dispensers of this invention. The sensor is capable of being sanitized without dismantling. Thus, the magnet is inert and nonporous and the check valve can be formulated of FDA approved plastics and the like enabling easy cleaning with hot water during periodic sanitizing of the hot drink dispenser. The sensor is highly reliable and accurate and relatively insensitive to damage by handling since the magnet and check valve slider are not free to move within the sensor unless influenced by the flow of syrup avoiding damage or displacement due to dropping or jarring in shipment or use. The signal output from the reed switch is easily discernible to the naked eye from the outside of the machine. Changes in physical properties of the chocolate syrups used due to atmospheric changes and the like do not affect the sensor since the flow characteristics which activate the sensor are not thereby affected. No ancillary equipment is necessary in the circuitry of the hot drink dispensers and no field changes or adjustments need be made. Moreover, the sensor is easily and simply reset after shut down as described above. The sensor is further low in cost, compact and integral with the dispensers of this invention.

In an alternative sensor system shown in FIGS. 9 and 10, a sensor 500 is used with all parts being identical to corresponding numbered parts of the sensor of FIG. 6.

The only difference is that the check valve slider does not have the umbrella-shaped section at its upper end but rather merely the flat portion 413 completely overlying the magnet and having an outer diameter spaced from the inner diameter of the cylindrical chamber 501. The system shown in FIGS. 9 and 10 allows the magnet to free move in the straight cylindrical wall of the valve housing. Thus, the magnet is not held in position once it has been raised by reverse flow, but, is allowed to seek a reset position both by free settling and influence of restored normal flow.

In the embodiment of FIG. 9, gravity is used to return the slider to its lowermost position when the back pressure is released. However, if desired, a low force return spring can be used in chamber 510 to bias the slider to its lowermost or seated position. Because of the close fit of the rim 413 and the cylindrical chamber 510 only an extremely small insignificant amount of syrup leakage occurs past the check valve slider during compression of the air.

The electrical circuitry is slightly modified over that shown in FIG. 8 in that, in palce of a single pole, single throw electromagnetic relay used in FIG. 8, a double pole, double throw relay 460 is used. The double pole, double throw relay 460 acts as a holding relay, maintaining the pump circuit inoperative regardless of whether the reed switch is closed or opened once it has been opened by one backflow pulse and upward movement of. the magnet.

The circuit of FIG. 10 functions as follows: power to energize the relay coil of relay 460 comes from the output side (common) of a cam operated gear motor switch 461 (B to 4) or directly from the power input (D to 2) depending upon whether the reed switch is closed and sequence of events leading up to the contacts closing. On initial start up of the hot drink dispenser, the

sanitize switch 156 is engaged through the normally closedcontacts (upper half of the switch) which supplies input power to the gear motor 54. As the gear motor rotates the drive cam, the cam operated gear motor switch is closed and power is fed through B to the relay coil through 4. Since the magnet will be down due to free settling, the reed switch is closed and the relay closes, making the circuit from D to 4. In this condition, the relay coil is maintained energized as long as the reed switch is closed. At the same time, the power input through D-2-4 is fed to 3, thus establishing a working circuit to the push start switch I48 and the lower half of the sanitize switch to permit normal operation of the dispenser on demand.

As previously described, the cam operated gear motor switch sustains the operation of the gear motor through one revolution of the drive cam (one drink dispense cycle) after the push start button has been released. As long as the reed switch is closed, the circuit remains and power is available for normal operation.

However, when air is drawn into the syrup circuit upon exhaustion of the reservoir, the magnet is raised as in the embodiment of FIG. 6 thus permitting the reed switch contacts to open. When this happens, the relay coil circuit is opened and the relay contacts revert back to the normally opened condition where they are maintained by a biased spring. Should the magnet settle back into place and reclose the reed switch contacts, the relay coil cannot be. re-energized because the power circuit from D is being maintained open.

A warning light 452 (out-of-syrup light) is used as in the embodiment of FIG. 6 through the circuit D to neon bulb to 1 to 4 to B through the cam operated gear motor switch which is still made at the point where the gear motor is shut down at midcycle, then to F, through the gear motor to G. Because of the high resistance of the neon bulb, the voltage drop is sufficient to prevent the gear motor from running.

To restart the system with a replenished syrup reservoir, the procedure is basically the same as with the embodiment of FIG. 6. Engaging the sanitize switch runs the gear motor to refill the pump, thus removing the air from the inlet tubing and simultaneously restoring the voltage to the relay coil thus resetting it for normal operation.

While the reverse flow sensors of this invention have been described in connection with hot drink dispensers, the sensors can be used in any system which depends upon a preferred direction of flow of a gas or liqaid for normal. operation in which reverse flow is deemed unacceptable. Other systems in which the reverse flow sensor could be used include effluent treatment systems where it is undesirable for untreated waste materials to contaminate treated effluents. Similar in carbonated water transfer systems, uncarbonated water being transported in conventional copper pipe lines to a carbonating system can be monitored by the sensors of this invention. A reverse flow indicator is important here to prevent backflow of carbonated water.

What is claimed is:

l. A reverse flow sensor comprising,

a housing having a chamber with an inlet and an outlet,

a magnet carried by a slider for movement within said chamber, said slider having a passageway permitting all flow of fluid from said inlet therethrough in one direction and impeding fluid flow from said resilient duck bill slit end and said first fluid flow passes outlet in a second direction so that fluid flow tothrough said cylindrical body out of said duck bill end, ward said second direction acts to move said slider in said .second direction to block flow from said said duck bill end providing for urging of said slider outlet to said inlet, in said first direction during fluid flow therethrough and magnetic responsive means associated with said in said first direction and for urging of said slider housing for reacting to movement of said slider. in said second direction during fluid flow in said 2. A reverse flow sensor in accordance with claim 1 second direction toward said slider. wherein said magnetic responsive means is a reed 4. A reverse flow sensor in accordance with claim 3 switch responsive to movement of said magnet to make wherein said slider carries an outwardly extending rim. and break an electrical circuit. said chamber defining a wall with said rim engaging 3. A reverse flow sensor in accordance with claim 2 said wall in sliding frictional engagement therewith. wherein said slider comprises a cylindrical body with a UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. D ted NOVGmbGI Inventor(s) John A. Gardner, Jr. and Merle S. Brown It is certified that error appears in the above-identified patent and thatvsaid Letters Patent are hereby corrected as shown below:

Column 7; line 26, change "por" to --port--.

Signed and Scaled this Tenth Day Of April I979 [SEAL] Arrest:

NALD mm! c. MASON D0 W BANNER Attestiug Oflicer Commissioner of Patents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3,851,127 Dated 26 November 1974 Inventor(s) John A. Gardner, Jr. and Merle S. Brown 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 26, change "por" to -port.

Tenth Day Of April 1979 [SEAL] Attest:

RUTH C. MASON DONALD W-. BANNER Arresting Ojficer Commissioner of Patents and Trademarks

Claims

1. A reverse flow sensor comprising, a housing having a chamber with an inlet and an outlet, a magnet carried by a slider for movement within said chamber, said slider having a passageway permitting all flow of fluid from said inlet therethrough in one direction and impeding fluid flow from said outlet in a second direction so that fluid flow toward said second direction acts to move said slider in said second direction to block flow from said outlet to said inlet, and magnetic responsive means associated with said housing for reacting to movement of said slider.

2. A reverse flow sensor in accordance with claim 1 wherein said magnetic responsive means is a reed switch responsive to movement of said magnet to make and break an electrical circuit.

3. A reverse flow sensor in accordance with claim 2 wherein said slider comprises a cylindrical body with a resilient duck bill slit end and said first fluid flow passes through said cylindrical body out of said duck bill end, said duck bill end providing for urging of said slider in said first direction during fluid flow therethrough in said first direction and for urging of said slider in said second direction during fluid flow in said second direction toward said slider.

4. A reverse flow sensor in accordance with claim 3 wherein said slider carries an outwardly extending rim, said chamber defining a wall with said rim engaging said wall in sliding frictional engagement therewith.