Title: Blending-type motor fuel dispensing apparatus

Description: This invention relates to motor fuel dispensing apparatus and more particularly to dispensing apparatus of the so-called "multigrade" type, wherein a plurality of different grades of fuel (each having a different octane rating) are selectively dispensed by a single apparatus; these various grades are provided by various blends of two fuel components of different octane ratings, and in addition by solely one component and solely the other component. Since such apparatus provides blends, it may be termed "blending-type" apparatus.

Examples of blending-type motor fuel dispensing apparatus according to the prior art are described in Young U.S. Pat. No. 2,880,908, referred to hereinafter as the '908 patent, and in Young U.S. Pat. No. 3,587,337, referred to hereinafter as the '337 patent. The '908 patent discloses a blending-type dispensing apparatus which is now being used to a considerable extent in gasoline marketing operations, in service stations; this apparatus is 100% mechanical in construction. The '337 patent discloses a simplified blending-type dispensing apparatus which utilizes pushbuttons for motor fuel grade selection; here again, however, the apparatus is essentially entirely mechanical in construction.

An electronic blending apparatus offers several advantages, as compared to a mechanical apparatus. In the first place, since there are very few moving parts to wear out, the maintenance costs are lower. Again, since an electronic apparatus is more compact than a mechanical one, and is in general of modularized construction, all units are readily accessible, and may be easily replaced.

In addition, the electronic blending apparatus of the invention, utilizing pushbuttons, is easy to operate. This makes it attractive to customers, for self-service, and makes it highly beneficial even for attended operation.

The electronic blending apparatus of this invention provides improved accuracy, due to an automatic pre-positioning of the blend control valve effected before actual dispensing begins. As compared to the mechanical apparatus typefied by the above-mentioned patents, the starting error is reduced by at least a factor of five.

An electronic blending apparatus can provide for extreme flexibility in price settings. By way of example, any product (i.e., any "grade" of gasoline, the number of "grades" usually being two greater than the number of "blends") can be priced independently, anywhere within the range of 0.1.cent. to 99.9.cent. per gallon (or per liter).

An electronic blending apparatus can provide for extreme flexibility in blend percent settings. By way of example, the percentage of one component (a certain one, of two components) in any blend can be set independently, anywhere within the range of 1% to 99%, in steps of 1%.

An electronic blending apparatus enables convenient data collection. Data on total gallons of any selected liquid fuel (blend, or individual component) sold, total dollars, etc., can be made available in the service station building, for local collection, or for transmittal over lines.

Prior gasoline blending apparatus, such as that described in the '908 patent, is quite bulky and voluminous. The electronic blending apparatus of this invention, on the other hand, is much less bulky, so that the apparatus readily lends itself to the design of dual blenders, with a resulting first cost per outlet less than is possible with known apparatus. Also, the apparatus of this invention costs less to install, since one set of suction pipes and one electrical conduit will serve two outlets.

The electronic blending apparatus of the invention provides improved flexibility in arrangement, since the blend control box and the hose can be located remotely from the remainder of the components. This flexibility would allow various special arrangements; one possibility would be pedestal mounting, as described hereinafter.

An object of this invention is to provide a novel electronic blending-type gasoline dispensing apparatus.

Another object is to provide an electronic blending-type gasoline dispensing apparatus which is of greatly simplified operation and is therefore eminently suitable for self-service.

A further object is to provide an electronic blending apparatus which entails the advantages (as compared to a mechanical blending apparatus) previously set out.

A detailed description of the invention follows, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram illustrating the liquid, mechanical, and electrical connections of various elements involved in a dispensing apparatus according to this invention;

FIG. 2 is a block diagram illustrating the electronic circuitry utilized in the dispensing apparatus of this invention;

FIG. 3 is a logic diagram of a flow pulse adder and synchronized keyer utilized in this invention;

FIG. 4 (made up of two parts, FIG. 4a and FIG. 4b) is a logic diagram of the gallons counters, associated decoders, and the gallons display;

FIG. 5 is a timing-coding diagram useful in explaining the invention;

FIG. 6 is a segment-digit key for FIG. 5;

FIG. 7 is a schematic circuit diagram of the blend select, percent "hi" select, and price select portions of the apparatus;

FIG. 8 is a plan view of a price selector printed circuit board;

FIG. 9 is a front elevation, partly in section, of a set of price selector switches;

FIG. 10 is a block diagram of the dollars counters and dollars display;

FIG. 11 is a schematic plan view of a percent selector switch arrangement;

FIG. 12 (made up of two parts, FIG. 12a and FIG. 12b) is a logic diagram of the motor control portion of the apparatus;

FIG. 13 is a face view of the mechanism which operates the blend control valves;

FIG. 14 is a side view, partly in section along line 14--14 of FIG. 14a, of the mechanism of FIG. 13;

FIG. 14a is a face view of a portion of the mechanism of FIG. 13;

FIG. 15 is a face view of a blend control valve, taken in the direction 15--15 of FIG. 14;

FIG. 16 is a logic diagram of a start-up strobe generator;

FIG. 17 is a logic diagram of a position detector, used in pre-positioning of the blend control valves; and

FIG. 18 is a diagrammatic view of a physical layout utilizing the apparatus of the invention.

Refer first to FIG. 1, for a somewhat generalized description of the apparatus of the invention. A "lo" (for relatively low-octane liquid fuel component) pump 1 is driven by a motor as is usual and is arranged to receive through pipe 2 from a supply tank the lower-octane gasoline referred to above. In FIG. 1, for convenience, the pump 1 is illustrated as being located in the dispensing apparatus housing or casing; however, in many instances this pump would be of the submersible type and would be located in the underground supply tank or storage tank containing the "lo" fuel. In the usual fashion, the "lo" pump 1 is provided with a bypass 3 in which is located a loaded relief valve 4 so that if the delivery hose outlet is shut off the "lo" pump may continue to operate, recirculating the "lo" gasoline through the valve 4 from its outlet to its inlet. Delivery of gasoline from the "lo" pump takes place through a pipe 5 which delivers the gasoline through a check valve 12 into a "lo" meter 6 which meter may be of conventional type. The meter 6 accurately measures the liquid flowing therethrough; this meter has an output shaft, schematically indicated at 7, which rotates at a rate proportional to the volumetric flow of liquid (gasoline) through such meter.

The meter shaft 7 mechanically drives a "lo" pulse generator 8 (later detailed) which operates to produce output pulses at 9 at the rate of 1000 pulses per gallon of "lo" gasoline flowing through the meter 6. The pulse output of generator 8 is fed to a pulse adder 10 as one of the two inputs to such adder.

From the meter 6, the "lo" gasoline is delivered through a pipe 11 to a "lo" blend control valve 13 (later detailed) from which it is delivered through a conduit 14 extending to a blending-type nozzle (not shown).

A "hi" (for relatively high-octane liquid fuel component) pump 15 draws its supply of "hi" gasoline from a tank through pipe connection 16. This pump 15 may be of the same type as the "lo" pump 1 and has provided in association with it a bypass 17 incorporating a relief valve 18.

The "hi" pump 15 delivers "hi" gasoline through line 19 containing a check valve 26 to the meter 20 which may be of the type serving to meter the "lo" gasoline (to wit, meter 6). The output shaft 21 of meter 20 (which rotates at a rate proportional to the volumetric flow of liquid such as gasoline passing through this meter) mechanically drives a "hi" pulse generator 22 which operates to produce output pulses at 23 and 24 at the rate of 1000 pulses per gallon of "hi" gasoline flowing through the meter 20. Output pulses are fed at 23 from the generator 22 to the adder 10, as the other of the two inputs to such adder.

Delivery from the meter 20 takes place through piping 25 to a "hi" blend control valve 27 (later detailed) from which it is delivered through a conduit 28 to the nozzle aforementioned.

The valves 13 and 27 deliver the "lo" and "hi" gasolines through a twin hose arrangement (involving the conduits 14 and 28) which provides for admixture of the "lo" and "hi" liquid fuel components at the location of the manually-operated control valve of a dispensing nozzle.

The solid connecting lines provided with arrows in FIG. 1 indicate electrical connections; the dotted connecting lines indicate mechanical connections; and the double lines indicate fluid connections (piping).

For purposes of the present invention, and for simplicity in showing, it may be assumed that the apparatus is capable of delivering five different grades of motor fuel, including as one grade the "lo" gasoline alone and as another grade the "hi" gasoline alone. By way of illustration, these five grades may be denoted by the following terms, beginning with the highest octane fuel and proceeding downwardly, in the direction of decreasing octane: "super premium" ("hi" gasoline only); "premium" (herein termed Blend A); "super regular" (herein termed Blend B); "regular" (herein termed Blend C); and "economy regular" ("lo" gasoline only). On the face of a dispensing apparatus enclosure or housing according to this invention, there is an array of five blend select pushbuttons 29, one adjacent to and correlated with each respective one of the above terms (imprinted as legends on the housing face). These pushbuttons are manually operable individually to select for dispensing any one of the five grades.

Also on the housing face is a set of three openings for each one of the five grades, and positioned behind each of these openings is an individual manually-operable selector switch (thumbwheel switch) 30, the switches being settable (when the transparent protective cover for the face is removed) to establish the prices per gallon for the various grades. Thus, the cents-per-gallon selector switches are settable by the service station operator (dealer). Each of the individual switches contains a series of numerals ranging from zero to nine, the particular numeral corresponding to the switch position selected being visible through the housing face opening for that switch. There are three price selector switches 30, related to each other in decade fashion, for each of the five grades, so that by setting these switches any grade (i.e., any dispensed product) can be priced independently anywhere within the range of 0.1 cent to 99.9 cents per gallon.

As previously described, the pulse output of generator 8 (representing the flow of "lo" gasoline through the meter 6) and the pulse output of generator 22 (representing the flow of "hi" gasoline through the meter 20) are summed or added in the pulse adder 10, to provide an output from this adder representing the combined flow of both liquids. Since the number of pulses in the output of each of the generators 8 and 22 corresponds to the quantity of fuel measured by the associated meter, the pulse summation (output of adder 10) represents the total quantity of fuel delivered or dispensed.

The output of pulse adder 10 is passed through a divide-by-ten circuit 31 and then applied to a decade arrangement 32 of total gallons counters, for counting the number of pulses in the output of divider 31.

A train of pulses, corresponding to the summed-pulse output of divider 31, is taken off at 33 and fed to the selector switch arrangement 30. Each of the five sets (of three each) of switches in the arrangement 30, in effect, selects for utilization in a price-per-gallon multiplier arrangement 34 (which may be simply an amplifier) a certain number of pulses which is determined by the switch settings. The particular set of selector switches in 30 which is utilized in a dispensing operation depends upon which of the five "blend select" pushbuttons in 29 has been operated; this is indicated by the connection 35. It may be noted that the pulses selected by the switches 30 are selected from the summed (total-quantity-of-liquid) pulses supplied thereto via 33.

The selection of a certain number of pulses (which number corresponds to the price, to the tenth of a cent, per gallon of gasoline being dispensed), from the summed, total-quantity pulses, has the effect of a multiplication of the quantity (gallons) of liquid dispensed times the price per gallon (in cents), developing at the output 36 of the multipliers 34 a number of pulses directly indicative of the cost of the liquid fuel (gasoline) dispensed. These pulses are counted by a decade arrangement 37 of dollars counters, and these last-mentioned counters provide an output to a four-digit dollars diplay (total price exhibiting means) 38. The four digits of the dollars display give the price of the fuel dispensed to the hundredth of a dollar (that is, to whole cents). The display 38 is preferably a seven-segment, liquid crystal display (that is, one wherein seven segments are used in combinations to form the various numerals zero through nine, for each digit). The four-digit dollars display 38 is mounted in close juxtaposition to the face of the dispensing apparatus housing, so that the digits thereof are visible through suitable openings in the housing face.

The summed, total-quantity-of-liquid pulse train output of divider 31 is counted by the gallons counters 32, and these last-mentioned counters provide an output to a four-digit gallons display (total volume or quantity exhibiting means) 39. The four digits of the gallons display give the total volume of fuel dispensed to the hundredth of a gallon. The display 39, like display 38, is a seven-segment, liquid crystal display, and, like the latter, is mounted in close juxtaposition to the housing face so that the digits of display 39 are visible through openings provided in the housing face.

The dispensing apparatus of this invention also includes a set of two manually-operable selector switches 40 for each of the three blended products A, B, and C, these switches being set-table to pre-set or establish the percent of "hi" gasoline in each of these three blends. The percent switches 40, unlike the price switches 30, are not accessible to the service station operator or dealer, but only to authorized maintenance personnel. Each of the percent switches 40 is settable to any one of ten positions, labeled respectively zero through nine, and since the two switches of each set are related to each other in decade fashion, any of the three blends A, B, or C can be set independently (by setting the appropriate set of switches 40) within the range of 1% "hi" to 99% "hi", in steps of 1%.

The connection 33 branches off to the percent selector switch arrangement 40, so that the summed-pulse output of divider 31 is also fed to the percent switches 40. Also pulses are taken off from divider 31 (which pulses are in effect generated within this divider) and fed by connection 128 to percent switches 40. Each of the three sets (of two each) of switches in the arrangement 40 selects for utilization in a percent "hi" circuit 41 (which may be simply an amplifier), from the summed (total-quantity-of-liquid) pulses supplied thereto, a certain percentage of the pulses which is determined by the switching settings. The particular set of selector switches in 40 which is utilized in a dispensing operation depends upon whether or not one of the three blends A, B, or C has been selected by the pushbuttons 29, and if so, which one of the three; this is indicated by the connection 42.

The certain percentage of pulses selected (according to the preset percent switches 40) from the summed, total-quantity pulses represents the flow of "hi" gasoline which is desired to be taking place through line 25 (and meter 20) for the blend being dispensed; this flow would be the preset percent "hi" (set on switches 40) multiplied by the total flow of both of the blending components (represented by the summed, total-quantity pulses).

The pulses selected by the arrangement 40, 41 appear at the output 43 of the circuit 41 and are fed as one of the two inputs to a differential comparison circuit and motor drive unit 44. The other input to the comparison circuit is obtained at 24 from the "hi" pulse generator 22; it should be understood that the pulse repetition rate in the output of generator 22 is directly proportional to the actual flow of "hi" gasoline through the meter 20.

Output from unit 44 is fed to a stepping motor 45 which mechanically drives as at 46 a double-acting cam 47 which simultaneously actuates the "lo" valve 13 and the "hi" valve 27, but in opposite senses.

Operation of the automatic blend control portion of the dispensing apparatus will now be explained. During dispensing of any one of the blends A, B or C, the "desired flow" pulses appearing at 43 are differentially compared (in unit 44) with the "actual flow" pulses appearing at 24; if the pulses from 41 and 22 do not appear alternately and one at a time at unit 44, the motor drive in unit 44 energizes the motor 45 to adjust the positions of the blend control valves (proportioning valves) 13 and 27 to reduce this difference to substantially zero, thereby to maintain the desired proportion of "hi" gasoline in the blend. If the "actual flow" of "hi" gasoline (through meter 20) is less than the "desired flow" (i.e., the preset percentage of the total flow of both liquids), motor 45 is energized to actuate "hi" valve 27 toward the fully open position, and to actuate "lo" valve 13 toward the fully closed position. If, on the other hand, the "actual flow" of "hi" gasoline is in excess of the "desired flow", motor 45 is energized to actuate "hi" valve 27 toward the fully closed position, and to actuate "lo" valve 13 toward the fully open position.

The first step in the recommended procedure for the operation of the dispensing apparatus of the invention would be the removal of the dispensing nozzle from its rest or storage position, for example in a "boot" formed in the outside of the apparatus housing. As will be later detailed, this automatically puts into operation a start-up sequencer, which effects certain resetting and enabling operations, including the enabling of the "blend select" pushbuttons (switches) 29 (which latter might be more aptly termed "grade select" switches, since the product selected for dispensing may be solely one of the components, rather than an actual blend).

The second step in the standard operating procedure for the dispensing apparatus would be the selection of a product for dispensing by operating the appropriate pushbutton 29. When the selected pushbutton has been actuated, the pumps 1 and 15 are started, the gallons 32 and dollars 37 counters are reset (as will be explained), and in addition a pre-position control circuit 48 is enabled, as indicated by the connection 49. The circuit 48 operates through the motor drive unit 44 to energize the stepping motor 45 in such a way as to pre-position the control valves 13 and 27 in accordance with the particular grade of gasoline desired to be dispensed. Once this pre-positioning has been effected, gasoline is pumped through one or both of the lines 11 and 25.

At the end of each dispensing operation, the nozzle is returned to its rest position. This automatically turns off the pumps 1 and 15 and operates the valves 13 and 27 to their "off" or fully closed positions, as will be explained further hereinafter.

All of the apparatus previously described in connection with FIG. 1 is electronic, except of course the actual pumps 1 and 15, the motor-cam arrangement 45-47, and the blend control valves 13, 27. All of the calculation, display, and control operations utilize digital logic circuitry.

Refer again to FIG. 1 for additional details of the "lo" pulse generator 8; the "hi" pulse generator 22 is very similar so will not be described in detail. The volumetric meter 6 is provided with an output shaft 7 the rotations of which correspond to the quantity of fuel delivered (i.e., dispensed); purely by way of example, eight rotations of the shaft correspond to one gallon delivered. The output shaft 7 drives the pulse generator 8 to produce one thousand pulses per gallon. A perforated disc 50 is driven by the meter output shaft 7 through a gear drive having a step-up ratio of 2.5 to 1, so that the disc rotates through 20 revolutions for each gallon of "lo" fuel measured by meter 6. The disc has 50 equally spaced holes therein near its periphery, but is otherwise imperforate, and is arranged to interrupt a beam of light passing from a lamp 51 to a photocell 52 the pulsating output of which (1000 pulses per gallon of liquid flowing through meter 6) is fed via coupling 9 to the adder 10. Preferably, the lamp 51 is a light-emitting diode (LED) and the photocell 52 is a phototransistor; both of these items are contained in a single housing of U-shaped configuration which surrounds the edge of the disc.

Refer now to FIG. 2, which is a representation in block diagram form of the electronic circuitry involved in the apparatus of this invention. An oscillator 53, which is energized continuously regardless of whether or not the apparatus is actually being used for dispensing, generates a 10 kHz square wave which appears at the oscillator output 54. The square wave output of the oscillator is divided by ten in a unit 55, which may be a conventional binary/decimal counter with the connection 54 coupled to the "clock" terminal of the counter, the 1 kHz square wave output of unit 55 then appearing on a lead 56 connected to the "carry out" terminal of such unit.

Lead 56 feeds the output of unit 55 to a combination divide-by-four and two-phase generator 57, which may comprise a pair of flip-flops of the toggle, trigger, or complementary type connected in cascade, the two-phase output leads 58 (.PHI.2) and 59 (.PHI.1) being connected to the respective outputs of the second flip-flop. The elements 53, 55, and 57 together comprise a 250 Hz two-phase generator which produces pulses at the rate of 250 Hz. The outputs of the second flip-flop are gated with the input to that flip-flop, so that the two-phase pulses are separated in time.

Refer now to FIG. 3, which is a logic diagram of the flow pulse adder and "hi" and "lo" synchronized keyer 10. During dispensing, the "lo" pulses from the "lo" pulse generator 8 (produced at the rate of 1000 pulses per gallon of liquid flowing through the meter 6) appear on lead 9, and are applied to the toggle (trigger) input T of a flip-flop 60 one of whose outputs is connected to one of the two inputs of an AND circuit 61 with logic negation at its output. Keying pulses (250 Hz, .PHI.2) are taken off from lead 58 by way of lead 62 and utilized as the other input for the AND 61. Each pulse coming in from the pulser 8 reverses the state of the flip-flop 60, and this reversal of state is transferred over to the OR circuit 63 at the time of occurence of the next keying pulse appearing on lead 62. The 250 Hz pulses, .PHI.2, are applied to the input of a single shot (one shot) 64, which produces for each input pulse an output pulse of very short duration (e.g., 2 microseconds); these latter pulses are applied by way of lead 65 to the clear (reset) input C of the flip-flop 60, to reset this flip-flop at the 250 Hz frequency. The flip-flop 60 is always reset before another pulse from pulser 8 can be present.

The "hi" pulses from the "hi" pulse generator 22 appear on lead 23 during dispensing, and are applied to the toggle input T of a flip-flop 66 one of whose outputs is connected to one of the two inputs of an AND circuit 67 with logic negation at its output. Keying pulses of the other phase (250 Hz, .PHI.1) are taken off from lead 59 by way of lead 68 and utilized as the other input for the AND 67. Each pulse coming in from the pulser 22 reverses the state of the flip-flop 66, and this reversal of state is transferred over to the OR circuit 63 at the time of occurrence of the next keying pulse appearing on lead 68. The 250 Hz pulses, .PHI.1, are applied to the input of a single shot (one shot) 69, which produces for each input pulse an output pulse of very short duration e.g., 2 microseconds); these latter pulses are applied by way of lead 70 to the clear (reset) input C of the flip-flop 66, to reset this latter flip-flop at the 250 Hz frequency. The flip-flop 66 is always reset before another pulse from pulser 22 can be present.

The result of the action described above is to produce in the OR output 71 a train or succession of pulses which is the sum of the pulses produced by the two pulse generators 8 and 22, this sum representing the combined flow of "lo" and "hi" gasolines through both meters 6 and 20. It may be here noted that since the keying pulses supplied at 62 and 68 to the AND circuits 61 and 67 are obtained from respective opposite phases of a two-phase source, the AND circuits 61 and 67 will never emit simultaneously any pulses to the OR 63. There is thus no necessity for the provision of any "anti-coincidence" arrangement of the type frequently used in other apparatus to avoid improper counting when pulses may be emitted simultaneously.

The pulse train output at 71, representing the sum total from the "hi" and "lo" pulsers 22 and 8, respectively, is passed through an inverter 72 and is then applied to the input of a single shot 73, which produces for each input pulse an output pulse of rather short duration (e.g., about 1 millisecond), and thus acts as a pulse shaper. The narrow-pulse output from the one shot 73 is fed into the divide-by-ten circuit 31 (FIGS. 1 and 2), and thence into the cost and quantity calculating units.

Refer now to FIG. 4, which is a logic diagram, in somewhat simplified form, of the gallons counters 32, the associated BCD (Binary Coded Decimal) decoders, and the gallons display 39. The train of narrow (short-duration) pulses from the pulse adder 10, which represents the summed pulses from the two pulsers 8 and 22, is applied to the input (CL) of an IC 31, which can function as a counter (divide by ten) and seven-segment decode. The output terminals of unit 31 are connected to the OR-AND logic arrangement enclosed by the dotted-line box 74, which functions as a BCD non-coincidental decoder, producing from the summed, divided-by-ten pulse output of unit 31, 1-2-4-8 binary coded signals, which appear at the correspondingly-labeled leads 75, 76, 77, and 78, respectively. These latter leads are cabled at 128 to supply such coded signals to the most significant digit (of the two digits) of all three of the % "hi" selector switches 40. The line (lead) 79 provides the decode carry-out (i.e., the zero) for the decoder 74, and also provides pulse width control.

Refer now to FIG. 5, the upper portion of which is a timing diagram illustrating the coding arrangement of the 1-2-4-8 pulses appearing on the leads 75-78, referred to a timing wave denoted as "clock". This illustrates the non-coincidental arrangement of the pulses. For the numeral "1", one pulse would be selected by using lead 75 alone. For numeral "2", lead 76 would be used alone; although the pulses on this lead occur at the same time as some of the pulses on lead 78, these two leads are never used simultaneously. For numeral "3", leads 75 and 76 are used together; the respective pulses are non-coincidental. For numeral "4", lead 77 would be used alone; it may be noted that leads 77 and 78 are never used simultaneously. For numeral "5", leads 75 and 77 are used together; the respective pulses are non-coincidental. For numeral "6", leads 76 and 77 are used together; the respective pulses are non-coincidental. For numeral "7" , leads 75, 76, and 77 are used together; the respective pulses are non-coincidental. For numeral "8", lead 78 is used alone. For numeral "9", leads 75 and 78 are used together; the respective pulses are non-coincidental.

The 1-2-4-8 coding arrangement just described in connection with FIG. 5, is used for both the price selector switches 30 and the percent "hi" selector switches 40. This will be further explained hereinafter.

From the carry-out terminal of unit 31, a lead extends through a carry-out circuit 81 (not detailed) to the input (CL) of a second IC 32.sub.1, which functions as a counter (divide by ten) and a seven-segment decode and is preferably of the same construction as IC 31. The output terminals of unit 32.sub.1 are connected to the BCD non-coincidental decoder 74.sub.1, which is exactly similar to unit 74. The 1-2-4-8 coded signals produced from the decade-divided output of unit 32.sub.1 (a description similar to that of FIG. 5 would apply here also) are cabled at 33.sub.1 to supply such coded signals to the least significant digit of all three of the % "hi" selector switches 40, and also to the most significant digit (of the three digits) of all five of the cents per gallon (price) selector switches 30.

The seven segment decode connections of the IC 32.sub.1 are coupled through an EXCLUSIVE OR display coupling circuit 80 to the seven segments of a so-called liquid crystal digit 39.sub.1 representing hundredths of gallons. The scheme for energizing these segments is illustrated in the lower portion of FIG. 5, taken in conjunction with the key in FIG. 6; the energization scheme is for the respective decimal digits given above the "clock" wave at the top of FIG. 5 and a segment waveform extending above the base line for that waveform indicating that the corresponding segment is energized.

From the carry-out terminal of unit 32.sub.1, a lead 82 extends to the input (CL) of a third IC 32.sub.2, which functions as a counter (divide by ten) and seven-segment decode and is preferably of the same construction as IC 31. The output terminals of unit 32.sub.2 are connected to the BCD non-coincidental decoder 74.sub.2, which is exactly similar to unit 74. The 1-2-4-8 coded signals produced from the decade-divided output of unit 32.sub.2 are cabled at 33.sub.2 to supply such coded signals to the middle digit of all five of the price selector switches 30.

The seven segment decode connections of the IC 32.sub.2 are coupled through a display coupling circuit 80.sub.1 (similar to circuit 80) to the seven segments of a liquid crystal digit 39.sub.2 representing tenths of gallons. The digit display 39.sub.2 operates in the same manner as digit display 39.sub.1, previously described.

From the carry-out terminal of unit 32.sub.2, a lead 83 extends to the input (CL) of a fourth IC 32.sub.3, which functions as a counter (divide by ten) and seven-segment decode and is preferably of the same construction as IC 31. The output terminals of unit 32.sub.3 are connected to the BCD non-coincidental decoder 74.sub.3, which is exactly similar to unit 74. The 1-2-4-8 coded signals produced from the decade-divided output of unit 32.sub.3 are cabled at 33.sub.3 to supply such coded signals to the least significant digit of all five of the price selector switches 30.

The seven segment decode connections of the IC 32.sub.3 are coupled through a display circuit 80.sub.2 (similar to circuit 80) to the seven segments of a liquid crystal digit 39.sub.3 representing gallons. The digit display 39.sub.3 operates in the same manner as digit display 39.sub.1, previously described.

From the carry-out terminal of unit 32.sub.3, a lead 84 extends to the input (CL) of a fifth IC 32.sub.4, which functions as a counter (divide by ten) and seven-segment decode and is preferably of the same construction as IC 31. The seven segment decode connections of the IC 32.sub.4 are coupled through a display coupling circuit (similar to circuit 80) to the seven segments of a liquid crystal digit 39.sub.4 representing tens of gallons. The digit display 39.sub.4 operates in the same manner as digit display 39.sub.1, previously described.

The net result of all the foregoing is that, during dispensing, the summed pulse output of the two flowmeters 6 and 20 (representing the total volume of fuel delivered) is counted, and displayed in four digits (to hundredths of gallons) by the display devices 39.sub.1 - 39.sub.4. A fixed decimal point is provided between the digits of 39.sub.3 and 39.sub.2 ; this decimal point may be painted on the outside of the housing. (In this connection, it is pointed out that the digits of the liquid crystal display 39.sub.1 -39.sub.4 are located so as to be visible through suitable openings provided in the dispensing apparatus housing.) Also, it may be noted that the total-flow pulses are coded in binary fashion for supply (by cables 128 and 33.sub.1-3) to the selector switches 30 and 40.

Refer now to FIG. 7, which is a circuit schematic of the blend select, % "hi" select, and price select portions of the system. The five "blend select" pushbuttons 29.sub.1, 29.sub.2, 29.sub.3, 29.sub.4, and 29.sub.5 (one for each of the five grades which may be dispensed) are located at the right-hand side of this figure. In this connection, it is noted that the term "blend select" is used herein for these pushbuttons because this term has become more familiar in the art; actually, the term "grade select" would be more appropriate since two of the grades which may be selected (to wit, solely "hi" gasoline, and solely "lo" gasoline) are of course not "blends".

The blend select pushbuttons 29.sub.1 -29.sub.5 are preferably individual single-pole, single-throw switches, normally open but manually operated to a closed position when a blend selection is made by the operator of the apparatus. They are mounted for operation from outside the apparatus housing, and are associated with the various grades, as follows: pushbutton 29.sub.1, "hi" or "super premium"; pushbutton 29.sub.2, "Blend A" or "premium"; pushbutton 29.sub.3, "Blend B" or "super regular"; pushbutton 29.sub.4, "Blend C" or "regular"; pushbutton 29.sub.5, "lo" or "economy regular".

Blend select flip-flops 85.sub.1 -85.sub.5 (actually, each may be a so-called flip-flop complementary) are individually associated with the pushbuttons 29.sub.1 -29.sub.5, respectively. When one of the pushbuttons 29.sub.1 -29.sub.5 is operated, a strobe voltage (denoted by STB 2, and derived as described hereinafter) is supplied through the operated pushbutton to the toggle (or trigger) T of the corresponding flip-flop 85.sub.1 -85.sub.5, reversing the state of this flip-flop.

A plurality of transfer gates 86-93 (solid-state switches) are associated with the various flip-flops 85.sub.1 -85.sub.5, to be operated by the latter. The gates 86-93 operate as series on-off switches operated by the flip-flops 85.sub.1 -85.sub.5, each switch being closed or turned on (and then having a low series resistance between the gate input and the gate output) when the associated flip-flop is reversed in state, and being opened or turned off (and then having in effect a very high series resistance between the gate input and the gate output) at all other times.

When the flip-flop 85.sub.1 is reversed in response to the operation of pushbutton 29.sub.1, the "price" gate 86 is operated to connect its price pulse input 94 to a common price pulse output 36. When the flip-flop 85.sub.2 is reversed in response to the operation of pushbutton 29.sub.2, the "percent" gate 87 is operated to connect its % pulse input 96 to a common % "hi" pulse output 43; also, the "price" gate 88 is operated to connect its price pulse input 98 to the common price pulse output 36. When the flip-flop 85.sub.3 is reversed in response to the operation of pushbutton 29.sub.3, the "percent" gate 89 is operated to connect its % pulse input 99 to the common % output 43; also, the "price" gate 90 is operated to connect its price pulse input 100 to the common price pulse output 36. When the flip-flop 85.sub.4 is reversed in response to the operation of pushbutton 29.sub.4, the "percent" gate 91 is operated to connect its % pulse input 101 to the common % output 43; also, the "price" gate 92 is operated to connect its price pulse input 95 to the common price pulse output 36. Finally, when the flip-flop 85.sub.5 is reversed in response to the operation of pushbutton 29.sub.5, the "price" gate 93 is operated to connect its price pulse input 97 to the common price pulse output 36.

As previously mentioned, the cents per gallon (i.e., the price) selector switches 30 comprise five sets (one set for each of the grades or products which may be dispensed) of three switches each, one switch representing tens of cents, the second representing cents, and the third, tenths of cents. These switches are thumbwheel-operated switches (5 .times. 3, or 15 in all) which are individually operable and are so located as to be accessible to the service station operator (dealer). Each switch is provided with indicia consisting of the numerals zero through nine, inclusive, which indicia are visible (one numeral at a time, of course, for each wheel) through openings in the dispensing apparatus housing. The three price selector switches 30 for each particular grade of product are located, physically, adjacent the pushbutton 29 for that same product, so that, by looking at the visible indicia on the switches, the customer can easily determine what price (in cents per gallon) has been pre-established for each respective product.

Assume, for purposes of discussion, that pushbutton 29.sub.2 has been operated to select Blend A for dispensing, and that the price of this product is 27.9 cents per gallon (as previously stated, it may be priced anywhere within the range of 0.1 cents to 99.9 cents per gallon). When pushbutton 29.sub.2 is operated, the price pulse input lead 98 is connected to the common price pulse output 36.

Refer now to FIGS. 8 and 9, which illustrate the construction of the set of price selector switches 30.sub.1, 30.sub.2, and 30.sub.3 for Blend A. This set of switches may be considered typical of all five sets. Referring again to FIG. 7, the output sides of the three price selector switches for the "hi" gasoline are all coupled to the price pulse input lead 94 for "hi" gasoline; the output sides of the price selector switches 30.sub.1, 30.sub.2, and 30.sub.3 are all coupled to the price pulse input lead 98 for Blend A; the output sides of the three price selector switches for Blend B are all coupled to the price pulse input lead 100 for Blend B; the output sides of the three price selector switches for Blend C are all coupled to the price pulse input lead 95 for Blend C; the output sides of the three price selector switches for the "lo" gasoline are all coupled to the price pulse input lead 97 for the "lo" gasoline.

FIG. 8 is a plan view of the price selector switch arrangement 30.sub.1 - 30.sub.3 with the price wheels removed, while FIG. 9 is a front elevation, with certain portions in cross-section. The three thumbwheel switches 30.sub.1, 30.sub.2, and 30.sub.3 are mounted in side-by-side relationship on a printed circuit board denoted generally by numeral 102. The 1-2-4-8 binary pulses from decoder 74.sub.1 are fed to the first switch 30.sub.1 (in FIG. 8, these pulses are denoted as 10-20-40-80 to indicate that the selection made by this particular switch represents tens of cents). The "40" pulses (corresponding to the line labeled "lead 77" in FIG. 5) are fed through a diode D1, poled as indicated, to a conductive strip 104 of arcuate configuration with an arrangement or pattern of spaced radially-extending teeth or projections thereon; the conductive strip 104, like others to be described, is formed on one surface of the board 102. The "10" pulses (corresponding to the line labeled "lead 75" in FIG. 5) are fed through a diode D2 to a conductive strip 106 of arcuate configuration with an arrangement or pattern of spaced radially-extending teeth or projections thereon. The "20" pulses (corresponding to the line labeled "lead 76" in FIG. 5) are fed through a diode D3 to a conductive strip 108 of arcuate configuration with an arrangement or pattern of spaced radially-extending teeth or projections thereon. The "80" pulses (corresponding to the line labeled "lead 78" in FIG. 5) are fed through a diode D4 to a conductive strip 110 of arcuate configuration with an arrangement or pattern of spaced radially-extending teeth or projections thereon.

All of the conductive strips 104, 106, 108, and 110 are centered at the center of a hole 111 which is provided in the board 102 for mounting of the thumbwheel 112 (see FIG. 9), which latter cooperates with the said conductive strips. The thumbwheel (price wheel) 112, although omitted from FIG. 8, is mounted for rotation about an axis perpendicular to the plane of the paper in FIG. 8. The wheel 112 is made of an electrically insulating material, this wheel having attached thereto four spring contacts or fingers 113 (see FIG. 9) which are connected together electrically and which are arranged to slide over the board 102 and to make contact selectively with the conductive strips 104, 106, 108, and 110.

In addition to the conductive strips 104, 106, 108, and 110, there is provided on board 102 an additional conductive area 114 which provides a common output connection for all three selector switches 30.sub.1 -30.sub.3 of the set, and which has separate arcuate portions associated with each respective one of the three thumbwheels of the set. The spring contacts or fingers 113 also make contact selectively with the conductive area 114. At the terminal side of the board 102 (upper edge in FIG. 8), the conductive area 114 is connected to the price pulse input lead 98 for the gate/switch 88 (see FIG. 7). Also, it may be noted that the four diodes D1, D2, D3, and D4 (for switch 30.sub.1) are illustrated in FIG. 7.

The price wheel 112 carries the numerals 0 through 9 around its periphery (see FIG. 9 for the illustration of this on the similar wheels for switches 30.sub.2 and 30.sub.3), and is provided with a detenting means (schematically illustrated at 116 in FIG. 8) for indexing the wheel to any one of its ten positions, 36.degree. apart. In FIG. 8, the locations on the board 102 of the contacts 113 are indicated at 115, and the electrical interconnection thereof is illustrated by means of a dotted line. The locations of the contact points 115, as well as the layout of the conductive strips 104, 106, 108, 110, and 114, are made such that, as thumbwheel 112 is rotated to its various positions, the appropriate number of pulses is selected (from the 1-2-4-8 input binary pulses supplied thereto) in accordance with the scheme set forth hereinabove (in connection with FIG. 5), and is fed to the output (area 114, lead 98, gate 88).

In FIG. 8, the first thumbwheel 112 (described in detail) is illustrated in the "2" position, a setting corresponding to a digit 2 in the tens place of the price per gallon in cents. In this position, one of the contact points 115 engages the "20" pulse strip 108, and another engages the common output area 114, which means that of the pulses in the output of the decoder 74.sub.1, two pulses out of every ten will be delivered to the line 98.

The 1-2-4-8 binary pulses from decoder 74.sub.2 are fed to the second switch 30.sub.2 (in FIG. 8, these pulses are denoted as 1-2-4-8 to indicate that the selection made by this particular switch represents cents). The construction, connection, and mode of operation of the second switch 30.sub.2 are all very similar to those of the first switch 30.sub.1 previously described, so the same reference numerals are employed. In switch 30.sub.2, the " 4", "1", "2", and "8" connections correspond respectively to the "40", "10", "20", and "80" connections in switch 30.sub.1.

In FIGS. 8-9 the second thumbwheel (i.e., the one for the second switch 30.sub.2) is illustrated in the "7" position, corresponding to seven cents. In this position, one of the contact points 115 engages the "4" pulse strip 104, a second engages the "1" pulse strip 106, a third engages the "2" pulse strip 108, and the fourth engages the common output area 114, which means that of the pulses in the output of the decoder 74.sub.1, seven pulses out of every hundred will be delivered to the line 98 (since only every tenth pulse entering the unit 32.sub.2 will enter the unit 74.sub.2).

The 1-2-4-8 binary pulses from decoder 74.sub.3 are fed to the third switch 30.sub.3 (in FIG. 8, these pulses are denoted as 0.1-0.2-0.4-0.8 to indicate that the selection made by this particular switch represents tenths of cents). Again, the construction, connection, and mode of operation of the third switch 30.sub.3 are all very similar to those of the first switch 30.sub.1, so the same reference numerals are employed. In switch 30.sub.3, the "0.4", "0.1", "0.2", and "0.8" connections correspond respectively to the "40", "10", "20", and "80" connections in switch 30.sub.1.

In FIG. 8-9, the third thumbwheel (i.e., the one for the third switch 30.sub.3) is illustrated in the "9" position, corresponding to 0.9 cent. In this position, one of the contact points 115 engages the "0.8" pulse strip 110, another engages the "0.1" pulse strip 106, and a third engages the common output area 114, which means that of the pulses in the output of the decoder 74.sub.1, nine pulses out of every thousand will be delivered to the line 98 (since only every tenth pulse entering the unit 32.sub.3 will enter the unit 74.sub.3).

The above means (assuming that the switches 30.sub.1 -30.sub.3 are set to 27.9 cents per gallon) that for every 1000 pulses appearing in the output of the flow pulse adder 10, 279 pulses will be selected (by the selector switches 30) and passed (by way of lead 98 and switch 88, assuming Blend A has been selected for dispensing by actuation of pushbutton 29.sub.2) to the price pulse output lead 36. Speaking more generally, there will appear on the price pulse output lead 36, for each delivery of fuel, a total number of pulses representing the product of the quantity of gasoline (in gallons) delivered (which is proportional to the cumulative pulse output of the pulse adder 10) and the price of the gasoline (in cents per gallon, as preset on whichever set of selector switches is operative for the delivery). The theory of operation of this pulse selection-multiplication process is explained more fully in Livesay U.S. Pat. No. 3,081,031, Mar. 12, 1963.

As previously stated, there are provided five sets of price selector switches 30, one set for each of the five grades of gasoline which may be selected for dispensing. One set of such switches (to wit, that for Blend A) has been described in detail in connection with FIGS. 8 and 9. These sets of switches are all supplied with pulses similarly, and all are constructed and operate like switches 30.sub.1 -30.sub.3. In FIG. 7, the commoned outputs (that is, the output area corresponding to 114 in FIG. 8) of the uppermost set of price switches 30 are connected to price pulse input lead 94, and these switches are set manually to establish the price per gallon for the "hi" gasoline; the outputs of the next set of switches (switches 30.sub.1 -30.sub.3) are commoned to price pulse input lead 98, and these switches are set manually to establish the price per gallon for Blend A; the outputs of the next lower set of switches are commoned to price pulse input lead 100, and these switches are set manually to establish the price per gallon for Blend B; the outputs of the next lower set of switches are commoned to price pulse input lead 95, and these switches are set manually to establish the price per gallon for Blend C; the outputs of the next lower set of switches are commoned to price pulse input lead 97, and these switches are set manually to establish the price per gallon for the "lo" gasoline.

As previously explained, the total number of pulses which appear on the price pulse output lead 36 during dispensing represents the product of the total volume or quantity of gasoline delivered and the unit price (in cents per gallon), which product of course is the total cost of the gasoline dispensed. These pulses are counted and displayed by means of the circuit arrangement of FIG. 10, now to be described.

The pulses appearing on the price pulse output lead 36 are applied to the input (CL) of an IC 37.sub.1, which functions as a counter (divide by ten) and seven-segment decode. The seven segment decode connections of the IC 37.sub.1 are coupled through a display coupling circuit 130.sub.1 (similar to coupling circuit 80, previously described) to the seven segments of a liquid crystal digit 38.sub.1 representing hundredths of dollars. The scheme for energizing these segments is exactly similar to that previously described in connection with digit 39.sub.1.

From the carry-out (CO) terminal of unit 37.sub.1, a lead 131 extends to the input (CL) of a second IC 37.sub.2, which functions as a counter (divide by ten) and seven-segment decode, and is preferably of the same construction as IC 37.sub.1. The seven segment decode connections of the IC 37.sub.2 are coupled through a display coupling circuit 130.sub.2 (similar to circuit 130.sub.1) to the seven segments of a liquid crystal digit 38.sub.2 representing tenths of dollars. The digit display 38.sub.2 operates in the same manner as digit display 38.sub.1 previously described.

From the carry-out terminal of unit 37.sub.2, a lead 132 extends to the input of a third IC 37.sub.3, which functions as a counter (divide by ten) and seven-segment decode and is preferably of the same construction as IC 37.sub.1. The seven segment decode connections of the IC 37.sub.3 are coupled through a display circuit 130.sub.3 (similar to circuit 130.sub.1) to the seven segments of a liquid crystal digit 38.sub.3 representing dollars. The digit display 38.sub.3 operate in the same manner as digit display 38.sub.1, previously described.

From the carry-out terminal of unit 37.sub.3, a lead 133 extends to the input of a fourth IC 37.sub.4, which functions as a counter (divide by ten) and seven-segment decode and is preferably of the same construction as IC 37.sub.1. The seven segment decode connections of the IC 37.sub.4 are coupled through a display circuit 130.sub.4 (similar to circuit 130.sub.1) to the seven segments of a liquid crystal digit 38.sub.4 representing tens of dollars. The digit display 38.sub.4 operates in the same manner as digit display 38.sub.1, previously described.

Thus, during dispensing, the pulses appearing on the price pulse output lead 36 (which represent the total cost of the gasoline delivered or dispensed) are counted, and displayed in four digits (to hundredths of dollars, that is, cents) by the display devices 38.sub.1 -38.sub.4. A fixed decimal point is provided between the digits of 38.sub.2 and 38.sub.3 ; this decimal point may be painted on the outside of the dispensing apparatus housing. (In this connection, it is pointed out that the digits of the liquid crystal display 38.sub.1 -38.sub.4 are located so as to be visible through suitable openings provided in the housing.)

Refer again to FIG. 7. As mentioned hereinabove, the % "hi" selector switches 40 comprise three sets (one set for each of the three blends A, B, and C which may be dispensed) of two switches each, one switch representing tens of percent and the other, units of percent. These switches are manually-operable (rotatable) switches (3 .times. 2, or six in all) which are individually operable and are so located (for example, within a locked enclosure) as to be accessible only to authorized maintenance personnel (not to the service station operator or dealer). Each rotatable switch wafer is provided with indicia consisting of the numerals zero through nine, inclusive.

Again assume that pushbutton 29.sub.2 has been operated to select Blend A for dispensing, and that the percentage of "hi" gasoline in this blend is 63 (as previously stated, it may be set anywhere within the range of 1% to 99%, in steps of 1%). When pushbutton 29.sub.2 is operated, the % pulse input lead 96 is connected to the common % pulse output 43.

Refer now to FIG. 11, which illustrates the construction of the set of % switches 40.sub.1, 40.sub.2 for Blend A. This set of switches may be considered typical of all three sets. Referring again to FIG. 7, the output sides of the two % selector switches 40.sub.1, 40.sub.2 are both coupled to the % pulse input lead 96 for Blend A; the output sides of the two % selector switches for Blend B are both coupled to the % pulse input lead 99 for Blend B; the output sides of the two % selector switches for Blend C are both coupled to the % pulse input lead 101 for Blend C.

FIG. 11 is a plan view (somewhat schematic) of the % selector switch arrangement 40.sub.1 -40.sub.2 with the diode-carrying rotatable wafer removed. The two switches 40.sub.1 and 40.sub.2 are mounted in side-by-side relationship on a printed circuit board (not detailed in FIG. 11). The 1-2-4-8 binary pulses from decoder 74 are fed to the first switch 40.sub.1 (in FIG. 11, these coded binary pulses are denoted as 10-20-40-80 to indicate that the selection made by this particular switch represents decade percents). The "40" pulses (as represented on "lead 77" in FIG. 5) are fed (by lead 77) to a conductive strip 117 of arcuate configuration which, like others to be described, would be formed on one surface of the circuit board. The "10" pulses (as represented on "lead 75" in FIG. 5) are fed (by lead 75) to a conductive strip 118 of arcuate configuration with an arrangement or pattern of spaced radially-extending teeth or projections thereon. The "20" pulses (as represented on "lead 76" in FIG. 5) are fed (by lead 76) to a conductive strip 119 of arcuate configuration with an arrangement or pattern of spaced radially-extending teeth or projections thereon. The "80" pulses (as represented on "lead 78" in FIG. 5) are fed (by lead 78) to a conductive strip 120 of arcuate configuration.

All of the conductive strips 117-120 are centered at the center of a hole 130 which is provided in the aforesaid board for mounting of a rotatable switch wafer (not shown) which cooperates with the said conductive strips. This wafer is mounted for rotation about an axis perpendicular to the plane of the paper in FIG. 11. The said wafer has attached thereto four spring contacts or fingers (represented by the contact points 121, 122, 123, and 124) which are arranged to make contact selectively with the conductive strips 117-120 and also with another conductive strip 125 formed as a complete ring or annulus and providing a common output connection for both selector switches 40.sub.1 and 40.sub.2 of the set, the strip 125 having also a second complete ring or annulus for the second switch 40.sub.2. The contact 124 continuously engages the output strip 125; this output strip is connected to the % pulse input lead 96 for the gate/switch 87 (see FIG. 7). The contact 121 is connected through a diode D5 (poled as illustrated, and mounted on the rotatable switch wafer) to contact 124; the contact 122 is connected through a diode D6, similarly mounted, to contact 124; the contact 123 is connected through a diode D7, similarly mounted, to contact 124. The three diodes D5-D7 (for switch 40.sub.1) are illustrated in FIG. 7. The electrical interconnections of the four contacts 121-124 are illustrated by dotted lines.

The rotatable switch wafer for switch 40.sub.1 is provided with a detenting means (schematically illustrated at 129 in FIG. 11) for indexing the wafer to any one of its ten positions, 36.degree. apart. The locations of the contacts 121-123, as well as the layout of the conductive strips 117-120, are made such that, as the rotatable wafer is rotated to its various positions, the appropriate number of pulses is selected (from the 1-2-4-8 input binary pulses supplied thereto) in accordance with the scheme set forth hereinabove, and is fed to the output (strip 125, lead 96, gate 87).

In FIG. 11, the first switch wafer (the one just described in detail, for switch 40.sub.1) is illustrated in the "6" position, a setting corresponding to a digit 6 in the decades place of the percent. In this position, contact 121 engages the "40" pulse strip 117 and contact 123 engages the "20" pulse strip 119, which means that of the pulses in the output of the decoder 74, six pulses out of every ten will be delivered to the line 96.

The 1-2-4-8 coded binary pulses from decoder 74.sub.1 are fed to the second switch 40.sub.2 (in FIG. 11, these pulses are denoted as 1-2-4-8 to indicate that the selection made by this particular switch represents units of percent). The construction, connection, and mode of operation of the second switch 40.sub.2 are all very similar to those of the first switch 40.sub.1 previously described, so the same reference numerals are employed. In switch 40.sub.2, the "4", "1", "2", and "8" connections correspond respectively to the "40", "10", "20", and "80" connections in switch 40.sub.1.

In FIG. 11, the second switch wafer is illustrated in the "3" position, corresponding to 3%. In this position, contact 122 engages the "2" pulse strip 119 and contact 123 engages the "1" pulse strip 118, which means that of the pulses in the output of the decoder 74, three pulses out of every hundred will be delivered to the line 96 (since only every tenth pulse entering the unit 32.sub.1 will enter the unit 74.sub.1).

The above means (if the switches 40.sub.1, 40.sub.2 are set to 63%) that for every 100 pulses appearing in the output of the flow pulse adder 10, 63 pulses will be selected (by the selector switches 40) and passed (by way of lead 96 and switch 87, assuming Blend A has been selected for dispensing by actuation of pushbutton 29.sub.2) to the % pulse output lead 43.

As previously stated, there are provided three sets of % selector switches 40, one set for each of the three blended products which may be selected for dispensing. One set of such switches (to wit, that for Blend A) has been described in detail in connection with FIG. 11. These sets of switches are all supplied with pulses similarly, and all are constructed and operate like switches 40.sub.1 -40.sub.2. The outputs of the % switches 40.sub.1 -40.sub.2 are commoned to % pulse input lead 96, and these switches may be preset manually to establish the desired percentage of "hi" gasoline in Blend A; the outputs of the next lower set of % switches (see FIG. 7) are commoned to % input pulse lead 99, and these switches may be preset manually to establish the desired percentage of "hi" gasoline in Blend B; the outputs of the next lower set of % switches are commoned to % input pulse lead 101, and these switches may be preset manually to establish the desired percentage of "hi" gasoline in Blend C.

Refer now to FIG. 12, which is a logic diagram of the motor control portion of the dispensing apparatus. First, the automatic control of the stepping motor 45 during dispensing of a blend will be described. As will be explained more in detail hereinafter, this motor functions, under blend-dispensing conditions, to automatically control (i.e., adjust) the "hi" and "lo" proportioning valves 13 and 27, respectively, in opposite senses, which is to say that as the "hi" valve 27 is moved toward its fully open position, the "lo" valve 13 is moved toward its fully closed position, and vice versa.

Assume, as before, that Blend A ("premium") has been selected for dispensing, by operation of the pushbutton 29.sub.2 (FIG. 7); however, the same description will apply to the dispensing of any other of the three possible blended products. During dispensing of a blend, as should be apparent, the pulses from the two flowmeter pulsers (pulse generators) are summed or added in adder 10, and the fraction (percentage) of these summed pulses selected for utilization by the % switches 40.sub.1, 40.sub.2 (e.g., 63%) appears on output line 43 (see FIG. 7). These % "hi" (reference) pulses are fed through a pair of NOR gates 134 and 135 (assumed for the present to be open; how this is brought about will be explained hereinafter) to the input T of a single shot (one shot) 136, which produces for each input pulse an output pulse of very short duration (e.g., 2 microseconds). Thus, the device 136 functions as a pulse shaper. The pulse output of 136 is fed as one of the two inputs to a logic unit 137 (enclosed by a dot-dash line) which operates as a level triggered flip-flop whose output (of one sense or the other, depending on which way the flip-flop has been operated) appears at point 138.

During dispensing of a blend, the pulses produced by the "hi" pulse generator 22 ("hi" flowmeter pulser) are fed by way of lead 24 through a NOR gate 139 (assumed for the present to be open; how this is brought about will be explained hereinafter) to the input T of a single shot (one shot) 140, exactly similar to the IC 136 and also operating as a pulse shaper. The pulse output of 140 is fed as the other input to the flip-flop unit 137.

As previously described in connection with FIG. 1, the stepping motor 45, through a mechanical coupling 46, drives a cam 47, which in turn operates the blend control valves (proportioning valves) 13 and 27. The constructional details of this cam and the valves will be set forth hereinafter. Loocking at the face of the cam, clockwise rotation thereof may be termed the "ON" direction, or rotation away from the "OFF" direction. The single shot 136 may be termed the "clockwise" or "ON" device, since pulses appearing in its output will result in a clockwise rotation of the valve drive cam; the single shot 140 may be termed the "counterclockwise" or "OFF" device, since pulses appearing in its output will result in a counterclockwise rotation of the valve drive cam.

Pulses from the "on" device 136, applied to flip-flop 137, drive the latter to one state; pulses from the "off" device 140, applied to the flip-flop, reverse the state of the latter.

The flip-flop output point 138 is connected to the P/S input of a shift register 141 which in effect differentially compares the pulses from the two sources 136 and 140. Adjacent output terminals Q2 and Q3 of the register 141 are connected by way of the paired leads 142 and 143, respectively, to separate corresponding power transistors connected in a bidirectional motor drive circuit and included in block 144. The power transistors provide drive for the stepping motor 45 (included for illustrative purposes in block 144).

As long as the individual pulses are received by the flip-flop 137 in strict alternation from the two sources 136 and 140, the state of this flip-flop is reversed back and forth in a regular manner, there is no net pulse count, and no net shift occurs in the shift register 141. However, if two (or more) pulses are received from one source before one is received from the other, there will be an excess count and the flip-flop operation will change to produce a net shift in register 141, resulting in a change in the order in which the signals appear at Q2 and Q3. This causes the stepping motor 45 to step in one direction or the other (the direction depending upon the order in which the signals appear at Q2 and Q3), the degree of rotation of the motor depending on the number of pulses which are in excess. The motor, by adjusting the blend control valves 13 and 27, will eliminate the excess pulse count, by adjusting the actual