Liquid delivery system with vapour and liquid recovering means

Abstract: A system for recovering vapor and liquid emerging from a tank as it is being filled, in which the volumetric flow of a recovery pump that withdraws the vapor through a recovery tube is made equal to the volumetric flow of a fuel delivery pump with a microprocessor. The microprocessor can also modify the volumetric flow of the recovery pump in response to variations in the hydraulic pressure at the inlet side of the recovery pump.

Description: The field of the present invention relates generally to liquid dispensers, and more particularly to fuel dispensers incorporating vapour recovery systems. With reference to DE-A-3903603 (pub. 9-8-90) and DE-A-4000165 (pub. 5-7-90), the applicant has voluntarily limited the scope of the present application, and submitted separate claims for Germany. Similarly with reference to FR-A-2641267 (pub. 5-7-90), GB-A-2226812 (pub. 11-7-90) and SE 8904389 (pub. 5-7-90), the applicant has also voluntarily limited the scope of the present application and submitted separate claims for France, Great Britain and Sweden. In fuel dispensing systems, such as those used for delivering fuel to the tank of a vehicle, environmental protection laws may require that vapours emitted from the tank during the fuel dispensing process be recovered. Fuel is customarily delivered through a nozzle via a fuel hose and vapours are recovered from the nozzle via a vapour hose that conveys the vapour to the main supply tank from whence the fuel came. In what is referred to as a balanced system, the vapours are forced through the vapour hose by the positive pressure created in the vehicle tank as the fuel enters it. In other systems the vapour is sucked from the vehicle tank by a vapour recovery means connected to the vapour hose and forced into the supply tank. In some systems, such as that described in the U.S. Patent No. 4,223,706 to McGahey, mechanical means are used for controlling the relative volumetric flows of the fuel delivered to a nozzle by a fuel delivery means and of the vapour recovered by the suction of a vapour recovery means. In McGahey, the liquid fuel flow itself is used to drive a vapour pump. This usually causes a reduction in the fuel delivery rate which is inconvenient for the user. In U.S. Patent No. 3,826,291 to Steffens, the vapour pump is calibrated so as to move a volume of vapour essentially equal to the volume of liquid flowing through the meter which measures the flow of fuel. Unfortunately, these and other systems using mechanical controls generally cannot be adjusted so as to adapt to changing environmental conditions such as changes in temperature and/or to changes in operation. German utility model number 8717378 discloses a liquid delivery system comprising: liquid delivery means having a volumetric flow; flow measuring means for generating an electrical signal representative of the volumetric flow of the liquid delivery means; vapour recovery means for sucking vapour at a first end and ejecting it at a second end; and control means for controlling the vapour recovery means in response to the electrical signal. The system disclosed in DE-U-8717378 enables independent control of the vapour recovery means relative to the fuel delivery means, thereby enabling vapour recovery to commence prior to the dispensing of fuel and an initial surge of vapours to be evacuated. The system disclosed however requires that the nozzle be of a bulky design such that it seals to the tank. This results in a vacuum being generated which prevents air being returned to the storage tank which could result in a potentially explosive vapour/air mixture in the storage tank. In one embodiment the establishment of a vacuum enables vapours to be collected for a short period after dispensing of fuel has terminated. According to the present invention there is provided a liquid delivery system comprising means for deriving the volumetric flow of the vapour recovery means, the volumetric flow of the vapour recovery means being controlled by the control means such that the vapour recovery means has a desired volumetric flow. By deriving the quantity of vapour recovered it is possible to recover a desired quantity of vapour by control of the vapour recovery means. The control means, normally in the form of a microprocessor, can determine on the basis of information stored therein the parameters of an electrical signal that can be applied to the vapour recovery pump means so as to make it have a desired volumetric flow. The volumetric vapour flow can be controlled by adjusting the speed of a motor for a recovery pump of the vapour recovery pump means, or by changing the displacement of the pump such that the volumetric flow of the vapour recovery means is accurately controlled, and is preferably controlled such that the volumetric flow of the vapour recovery is substantially proportional to the volumetric flow of the liquid delivery means. If a stepping motor drives the pump of the vapour recovery pump means, then preferably the microprocessor controls the repetition rate of the drive pulses supplied to the stepping motor so as to case the recovery pump to have the desired volumetric flow. If a different recovery pump or motor is used that requires drive pulses having a different repetition frequency to produce the desired volumetric flow, it is only necessary to make a slight change in the program controlling the microprocessor. Where the vapour recovery pump is a positive displacement pump the volumetric flow of the vapour recovery means can be derived by determining the operation of the motor driving the pump. Whereas the volumetric flow of the vapour recovery means may be set equal to the volumetric flow of the fuel delivery means, there are some conditions such as a difference in the temperature of the fuel in the vehicle tank and fuel from the supply tank under which it is desirable to use a volumetric vapour flow that is different from the volumetric fuel flow. In accordance with another aspect of the invention, therefore, an indication is derived as to the volumetric vapour flow, and the microprocessor compares this indication with a value of vapour flow that is normally expected and makes the required adjustment. In one embodiment, a transducer generates an electrical signal corresponding to the hydraulic pressure at the inlet side of the pump for the vapour recovery means. Under average conditions, the pressure will have a desired nominal value. When it is less than this value, the nominal pressure is restored by decreasing the volumetric flow of the vapour recovery means. The microprocessor is programmed to respond to the signal representing the pressure and provide signals for controlling the volumetric flow of the vapour recovery means. This is particularly easy to do if, in accordance with this invention, the motor driving the recovery pump is of the stepping type because it is driven at a speed determined by the repetition rate of drive pulses, and this can be easily changed. Vapour recovery systems m accordance with the invention permit the attainment of faster fuel delivery and greater efficiency, and make it easier to handle the hose. Furthermore, expensive vapour processing units, which are required when the vapour and liquid volumetric flow rates are not the same are not required. Various preferred embodiments of the present invention will be described below with reference to the accompanying drawings in which like items are indicated by the same reference designations, and in which: Fig. 1 is a cutaway view of one embodiment of the present invention. Fig. 2 is a cutaway view of another embodiment of this invention. Fig. 3 shows the metering pulses used to indicate the volumetric flow of liquid being dispensed or delivered. Fig. 4 shows drive pulses used to drive the motor for the recovery pump. Fig. 5 is a flow chart illustrating the operation of the embodiments of Fig. 1 and Fig. 2. In the embodiment of the invention shown in Fig. 1, a hose 2 extends from a fuel dispensing pump housing 4 to a nozzle 6. Although not shown, the nozzle 6 has an outlet tube that is inserted in the inlet pipe for the gas tank of the automobile 8, and an accordion-like hose 10 that is coaxial with the inlet pipe forms a seal with the pipe so that any liquid and vapour that emanate from the pipe during the dispensing procedure will be conducted to a chamber or space 12 formed between a liquid delivery hose 14 and an outer hose 16 coaxial therewith. A liquid and vapour recovery tube 18 is inserted to an expected low point in the chamber or space 12 formed between the delivery hose 14 and the associated outer hose 16. The tube 18 has such a small internal diameter that vapour passes through it with enough velocity to entrain liquid fuel. The end of the hose 16 that is remote from the nozzle 6 is scaled at a coupler 20. The liquid or fuel delivery hose 14 and the vapour recovery tube 18 pass into the pump housing 4 through a wall 22 that seals the end of the hose 16, that is joined to the coupler 20. Inside the pump housing 4 the liquid delivery hose 14 is connected to a flow meter 24 that is connected via a mechanical connection indicated by a dashed line 26 to a pulser 28. The speed of the flow meter 24 causes the pulser 28 to deliver pulses proportional to the volume of liquid flowing through inner hose 14 to microprocessor 34. The volumetric flow of a fuel delivery pump 32 that pumps fuel from a main supply tank, not shown, via a pipe 30 to the meter 24, is changed as the operator manually changes the opening in the nozzle 6. The pump 32, a motor 33 that drives it, and the manual control just described, constitutes a fuel delivery means. The vapour recovery tube 18 is coupled to the inlet side of a vapour recovery pump 36, and a transducer 38 produces an electrical signal indicative of hydraulic pressure at that point that is conveyed to the microprocessor 34. Vapour and liquid withdrawn from the chamber 12 via the recovery tube 18 and the recovery pump 36 are conveyed to the underground supply tank, not shown, via a tube 40. The vapour recovery pump 36 is of the displacement type in which volumetric flow is directly proportional to the speed of operation. The pump 36 is mechanically driven via a shaft 42 by an electrical stepper motor 44. The pump 36 and the motor 44 constitute a vapour recovery means. A drive pulse source 46 supplies drive pulses to the motor 44 at a repetition rate controlled by the microprocessor 34. The housing 4 is divided into upper and lower sections by a vapour barrier panel 48, and the only electrical component below it is the pressure transducer 38 that may easily be made explosion proof. Before discussing how the embodiment of Fig. 1 operates, reference is made to the differences of a very similar embodiment shown in Fig. 2. The principal differences are that the coaxial hose 16 is eliminated so as to make handling easier and that both the liquid delivery hose 14 and the vapour recovery tube 18 extend to the nozzle 6. As seen from the patents referred to, the nozzle 6 contains a chamber, corresponding in function to the chamber 12 of Fig. 1. The recovery tube 18 extends into the low point of the chamber, however formed, and sucks up any vapour or liquid therein. The operation of Figs. 1 and 2 is as follows. Assume that the signal supplied by the pulser 28 is a series of pulses 47 as shown in Fig. 3, and that they have a repetition rate F proportional to the volumetric flow in the delivery hose 14. Also, assume that a series of pulses 49 shown in Fig. 4 have a repetition rate V that is equal to the repetition rate F. Pulses 49 are applied to the motor 44 for the recovery pump 36 so as to cause the latter to have the same volumetric flow for vapour and entrained liquid as occurs for fuel in the delivery hose 14. The pulses 47 and 49 could have different repetition rates for the same volumetric flow, in which case means for changing the repetition rate of the pulses 49 could be used or the microprocessor 34 could be suitably programmed. Reference is now made to the flow chart of Fig. 5 for an explanation of operation. The input fuel pulses 47, step 45, are fed to a decision block 50. If the decision block 50 finds that the repetition rate F is 0, no fuel is being delivered so that no vapour pulses 49 are generated and no vapour is recovered. The procedure then loops back to the beginning of the chart as shown by the feedback. But, if the decision block 50 finds that F>0, the microprocessor 34 causes the drive pulse source 46 to supply drive pulses 49 having a repetition rate V=F (see step 54) to the motor 44 that drives the recovery pump 36. At this point in the process, the volumetric flow of vapour drawn through the recovery tube 18 by the recovery pump 36 is the same as the volumetric flow of liquid fuel via the delivery tube 14 to the nozzle 6. Under some conditions this is satisfactory so that the process reverts to the starting point as indicated by the dashed line 55. Whereas the system thus far described works well under some conditions, improved operation is obtained under other conditions by making the volumetric vapour flow greater or less than the volumetric fuel flow. If the temperature of the fuel delivered to the vehicle tank is the same as the temperature of the fuel in the vehicle tank, satisfactory operation may be attained by making the volumetric flow of the vapour recovery means equal to the volumetric fuel flow, but, if for example, the fuel in the vehicle tank is cooler, it will be warmed up as the delivery continues so as to produce more vapour than it would if the temperatures were the same so that the volumetric flow of the vapour recovery means 36, 44 should be increased. The inverse of this situation occurs if the temperature of the fuel in the vehicle tank is warmer than the fuel being delivered. In the embodiments of the invention shown in Figs. 1 and 2, a pressure transducer 38 provides a signal P corresponding to the pressure at the inlet of the vapour recovery pump 36. With any given design, P would have a known nominal value X if the volume of vapours emitted from the tank equalled the volume of fuel being delivered, as might be the case if the temperature of the fuel in the vehicle tank and the fuel being delivered were the same. But, if the volume of vapour is greater than the volume of fuel being delivered, the pressure P would be greater than X, and conversely, if the volume of the vapour is less than the volume of the fuel being delivered, P would be less than X. Referring again to Fig. 3, we find the following. If P=X , as determined by a decision block 58, the recovery pump 38 is considered to be operating at the correct speed and the repetition rate V is not changed, i.e. V is the output with V=F as in step 60. If, however, P < X, the recovery pump 36 is running too fast, and the repetition rate V of the drive pulses is reduced, for example, by one pulse a second, step 62, i.e. to (V - 1). In the event that P ≦ X, the pressure P is compared with an excess pressure Y, as indicated in a decision block 64. If P ≦ Y, the repetition rate V is increased, for example, by one pulse a second, i.e. to (V + 1), step 66, but if P > Y, the dispenser is shut down, via step 52. Thus if P > Y, the dispenser is shut down. Means other than those illustrated in Figs. 1 and 2 could be used to carry out the various functions. The recovery pump could be driven by a D.C. motor rather than a stepping motor in which case the microprocessor 34 could be programmed to provide a signal that would select an appropriate one of a number of different D.C. voltages for application to the motor. Although various embodiments of the invention have been illustrated and described herein, these are not exhaustive and other embodiments may become apparent which fall within the scope of the appended claims.

Claims: Claims for the following Contracting States : ES, DK A liquid delivery system comprising: liquid delivery means (32, 30, 14, 6) having a volumetric flow; flow measuring means (24, 28) for generating an electrical signal representative of the volumetric flow of the liquid delivery means; vapour recovery means (36, 44) for sucking vapour at a first end and ejecting it at a second end; and control means (34) for controlling the vapour recovery means in response to the electrical signal, characterised in that the liquid delivery system comprises means for deriving the volumetric flow of the vapour recovery means, the volumetric flow of the vapour recovery means being controlled by the control means such that the vapour recovery means has a desired volumetric flow. A system as claimed in claim 1 characterised in that the control means determines on the basis of information stored therein the parameters of an electrical signal that can be applied to the vapour recovery means so as to make it have a desired volumetric flow. A system as claimed in claim 1 characterised in that the volumetric flow of the vapour recovery means is substantially proportional to the volumetric flow of the liquid delivery means. A system as claimed in claim 1, 2 or 3 for delivering fuel to a vehicle fuel tank and recovering the vapour emanating therefrom without drawing in excess air. A system as claimed in any preceding claim characterised in that the control means makes the volumetric flow of the vapour recovery means the same as the volumetric flow of the liquid delivery means. A system as claimed in any preceding claim characterised in that the means for deriving the volumetric flow of the vapour recovery means comprises means for determining the operation of a positive displacement pump of the vapour recovery means. A system as claimed in claim 6 characterised in that the operation of the positive displacement pump is determined by the control means determining the speed of a motor which drives the pump. A system as claimed in claim 7 characterised in that the volumetric flow of the vapour recovery means is derived from signals of the control means which control the operation of the motor. A system as claimed in claim 7 or 8 characterised in that the electrical signal representative of the volumetric flow of the liquid delivery means is in the form of indicator pulses having a repetition rate corresponding to the volumetric flow of the liquid delivery means, and wherein the control means is responsive to the indicator pulses to provide drive pulses at a desired repetition rate to the motor, the speed of which is dependent on the repetition rate of drive pulses. A system as claimed in claim 6 characterised in that the operation of the vapour recovery pump is controlled by varying the displacement of the positive displacement pump. A system as claimed in any preceding claim characterised in that in addition to receiving a first electrical signal indicative of the volumetric flow of the liquid delivery means, the control means receives from the means for determining the volumetric flow of the vapour recovery means a second electrical signal indicative of the volumetric flow of the vapour recovery means. A system as claimed in claim 11 further comprising means for providing a third electrical signal indicative of the volumetric flow of the vapour recovery means under given conditions, wherein the control means compares the second and third signals and increases the volumetric flow of the vapour recovery means if the comparison indicates that the volumetric flow of the vapour recovery means is less than the flow under the given conditions, and decreases the volumetric flow of said vapour recovery means if the comparison indicates that the volumetric flow of the vapour recovery means is greater than the flow under the given conditions. A system as claimed in any preceding claim characterised in that the vapour recovery means comprises a vapour recovery pump driven by a stepper motor. A system as claimed in any preceding claim characterised in that the control means is a microprocessor. Claims for the following Contracting States : FR, GB, SE A liquid delivery system for dispensing liquid into a closed tank, the system comprising: liquid delivery means (32, 30, 14, 6) having a volumetric flow; flow measuring means (24, 28) for generating an electrical signal representative of the volumetric flow of the liquid delivery means; vapour recovery means (10, 18, 36, 44, 40) for sucking vapour at a first end arranged to be placed in the region of an opening in the tank and ejecting it at a second end, the vapour recovery means including pump means (36, 44); and control means (34) for controlling the vapour recovery means in response to the electrical signal, characterised in that the liquid delivery system comprises means for deriving the volumetric flow of the vapour recovery means and in that the control means (34) controls the vapour recovery means (36, 44) in response to the electrical signal to cause the rate at which vapour is recovered by the vapour recovery means to be substantially equal to the rate at which it is expected that vapour will be emanating from the tank thereby enabling substantially all the vapour to be recovered. A liquid delivery system as claimed in claim 1 wherein the volumetric flow rate of the vapour recovery means is substantially proportional to the volumetric flow of the liquid delivery means. A liquid delivery system as claimed in claim 1 or 2 for delivery of fuel to a vehicle fuel tank and recovering the vapour emanating therefrom without drawing in excess air. A system as claimed in claim 1, 2 or 3 wherein the control means makes the volumetric flow of the vapour recovery means the same as the volumetric flow of the fuel delivery means. A system as claimed in any preceding claim wherein the pump means comprises a motor (44) and a positive displacement pump (36), and wherein the control means (34) controls the speed of the motor. A system as claimed in claim 5 wherein the electrical signal is in the form of indicator pulses having a repetition rate corresponding the volumetric flow of the fuel delivery means, and wherein the control means is responsive to said indicator pulses to provide drive pulses at a desired repetition rate to the motor of the pump means the speed of which is dependent on the repetition rate of the drive pulses. A system as claimed in claim 6 wherein the desired repetition rate is the same as the repetition rate of the indicator pulses. A system as claimed in claim 1, 2, 3 or 4 wherein the pump means comprises a motor and a pump, and wherein the control means varies the displacement of the pump. A system as claimed in any preceding claim wherein the flow measuring means generates a first electrical signal indicative of the volumetric flow of the fuel delivery means, the system further comprising means for deriving a second electrical signal indicative of the volumetric flow of vapour in the vapour recovery means. A system as claimed in claim 9 further comprising means for providing a third electrical signal indicative of the volumetric flow of the vapour recovery means under given conditions, wherein the control means compares the second and third signals and increases the volumetric flow of the vapour recovery means if the comparison indicates that the volumetric flow of the vapour recovery means is less than the flow under the given conditions, id decreases the volumetric flow of said vapour recovery means if the comparison indicates that the volumetric flow of the vapour recovery means is greater than the flow under the given conditions. A system as claimed in claim 9 or 10 wherein the second electrical signal is representative of the pressure at the first end of said vapour recovery means. A system as claimed in claim 9, 10 or 11 wherein the control means is responsive to the first electrical signal for initially making the volumetric flow of the vapour recovery means substantially equal to the volumetric flow of the fuel delivery means, and responsive to the second electrical signal for modifying the volumetric flow of the vapour recovery means as required to maintain the pressure in the recovery hose within a given range of values. A system as claimed in claim 12 comprising means for maintaining the volumetric flow of the vapour recovery system at the same value if the pressure equals a nominal value. A system as claimed in claim 12 or 13 comprising means for reducing the volumetric flow of the vapour recovery means if the signal corresponding to pressure indicates a pressure less than a nominal value. A system as claimed in claims 8, 13 or 14 comprising mess for increasing the volumetric flow of the vapour recovery means if the signal corresponding to pressure indicates a pressure greater than a nominal value and less than an excessive value. A system as claimed in any one of claims 11 to 15 further comprising means for preventing delivery of liquid if the signal corresponding to pressure indicates a pressure greater than a certain value. A system as claimed in any preceding claim for delivering vaporizable fuel into an opening of a tank in such manner as to recover fuel and vapour that escapes from the opening. A system as claimed in any preceding claim in which the control mess is a microprocessor. Claims for the following Contracting State : DE A liquid delivery system comprising: liquid delivery means (32, 30, 14, 6) having a volumetric flow; flow measuring means (24, 28) for generating a first electrical signal representative of the volumetric flow of the liquid delivery means; vapour recovery means (10, 18, 36, 44, 40) for sucking vapour at a first end and ejecting it at a second end; the vapour recovery means including pump means (36, 44) and control means for controlling the vapour recovery means in response to the first electrical signal; characterised in that the system further comprises: means for deriving a second electrical signal indicative of the volumetric flow of vapour in the vapour recovery means; means for deriving from the first electrical signal a third electrical signal indicative of the volumetric flow of the vapour recovery means under given conditions; and control means for comparing the second and third signals and controlling the pump means such as to increase the volumetric flow of the vapour recovery means if the comparison indicates that the volumetric flow of the vapour recovery means is less than the flow under the given conditions, and to decrease the volumetric flow of said vapour recovery means if the comparison indicates that the volumetric flow of the vapour recovery means is greater than the flow under the given conditions. A system as claimed in claim 1 wherein the volumetric flow of the vapour recovery means is substantially proportional to the volumetric flow of the liquid delivery means. A system as claimed in claim 1 or 2 wherein the pump means comprises a motor (44) and a pump (36), and wherein the control means (34) varies the speed of the motor. A system as claimed in claim 2 or 3 wherein the pump means comprises a motor and a pump, and wherein the control means varies the displacement of the pump. A system as claimed in any preceding claim wherein the first electrical signal is in the form of indicator pulses having a repetition rate corresponding to the volumetric flow of the liquid delivery means, and wherein the control means is responsive to said indicator pulses to provide drive pulses at a desired repetition rate to the motor of the pump means. A system as claimed in any preceding claim wherein the second electrical signal is representative of the pressure at the first end of said vapour recovery means. A system as claimed in any preceding claim wherein the control means is responsive to the first electrical signal for initially making the volumetric flow of the vapour recovery means substantially equal to the volumetric flow of the fuel delivery means, and responsive to the second electrical signal for modifying the volumetric flow of the vapour recovery means as required to maintain the pressure in the recovery hose within a given range of values. A system as claimed in any one of claims 6 or 7 further comprising means for preventing delivery of liquid if the signal corresponding to pressure indicates a pressure greater than a certain value. A system as claimed in any preceding claim for delivering vaporizable fuel into an opening of a tank in such manner as to recover fuel and vapour that escapes from the opening. A system as claimed in any preceding claim in which the control means is a microprocessor.

Inventors: POPE KENNETH L, POPE, KENNETH L.
Applicants: GILBARCO INC, GILBARCO INC.
Application year: 1991
Main classification: B67D5
IPC codes: B67D7