Fuel dispensing system with shut off device upon detection of fuel flow in vapour recovery line

Abstract: A fuel dispensing system (200) comprises means (100) for detecting fuel flowing in a vapour recovery line (102) and means (100) for preventing flow of the fuel detected, possibly by accumulated fuel closing a valve in the vapour recovery line, generation of an appropriate signal to the dispenser control, or some such other means. The invention prevents fraud (intentional or otherwise) which may occur if fuel metered by the dispenser, and charged to a customer, is subsequently returned via the vapour recovery line which may occur, for example, if the vapour recovery line is coaxial with the fuel delivery line and a seal fails in the couplings between the dispenser and nozzle.

Description: This invention relates to a fuel dispensing system, particularly but not exclusively for use on a forecourt for refuelling road vehicles, which system aims to prevent the return, fraudulently or otherwise, through the vapour recovery pipe of the dispenser of fuel which has already been registered as having been dispensed to a customer. Fuel dispensers for refuelling road vehicles may be required, due to regulations for environmental protection and health reasons, to employ a system for recovering the vapours released from a vehicle's fuel tank during refuelling. This system forms part of a more extensive process for the recovery of fuel vapour which may be released throughout all stages of fuel movement from the refinery depots to the tanks of the roadside stations and from these to the vehicle fuel tanks. This process is intended to limit the vapour emissions by providing a closed loop during the transportation and delivery of the fuel, such that each time fuel is dispensed from one tank to another, the vapours displaced from the tank being filled are returned to the other tank replacing the fuel removed. In the particular aspect relating to fuel delivery to a vehicle, a vapour recovery system usually comprises a fuel delivery nozzle fitted with a suitable vapour collector, a coaxial delivery hose in which the centre pipe carries the collected vapour to be returned and the outer pipe carries the fuel to be delivered, a union isolating the fuel from the vapour, a suction pump for the vapour, connecting pipework between the isolator and the pump, preferably means for controlling the return of vapours in dependence on the quantity of fuel dispensed, and optionally an arrangement for indicating irregularities in the system. The output of the vapour collecting pump is connected by underground pipework to the top of the fuel delivery tank. The pipe work for conveying the vapour, together with the pipe carrying the fuel, provides the closed loop between the service station tank and the fuel tank of the vehicle. Within the fuel dispenser, the vapour and the fuel are conveyed through independent and separate pipes. Within the nozzle and within the connectors between the handgrip, the union and coaxial hose, isolation is achieved by means of O-ring seals. Unfortunately, any damage or leakage at these seals leads to a loss of fuel from the fuel line to the vapour return line. This fuel, which has already been metered by the dispenser indicator and will be charged to the customer, flows back via the vapour return line to the fuel storage tank and therefore could constitute fraud. Such prior art devices are known from e.g. EP-A-0 486 910 or DE-A-4 139 844. According to the present invention there is provided a fuel dispensing system comprising a fuel delivery line and vapour recovery line connected between a delivery nozzle of the dispenser and a fuel storage tank, characterised in comprising means for detecting the flow of fuel along the vapour recovery line and means for preventing the flow of fuel detected through the vapour line back to the fuel storage tank. Detection as used in the context of the present specification is to be interpreted to include detection within the detection device itself even if this detection is not communicated externally of the device. Detection may be by a device fitted with a magnetic switch which operates when a magnet, integral with a float, rises with the latter and thereby allows suitable sensors to control the stopping of the vapour recovery pump or the fuel dispenser, while providing a fault indication. Alternatively detection may be by the means for preventing the flow of fuel blocking the flow of fuel. Employing the present invention prevents the transfer of liquid to the main tank and thereby prevents fraud. A further advantage of the invention is that it can be inserted into dispensers fitted with a vapour recovery system either of the mechanical type, that is in which the control system operates on the pressure which the fuel applies to a suitable mechanism, or of the electronic type, that is in which the control system operates on the electrical signal of the dispenser pulse generator. Another advantage of the invention is that it ensures that fuel cannot flow through the vapour line when the vapour recovery system is deactivated. Even if inoperative, the suction pump does not impede the passage of liquid and therefore does not prevent fuel flow in the vapour lines. Preferably the means for detecting the flow of fuel along the vapour recovery line comprises a chamber in the vapour recovery line in which chamber fuel returning along the vapour recovery line accumulates, said flow of fuel being prevented when the fuel in said chamber reaches a predetermined level.. This has the advantage that a small (acceptable) quantity of fuel will not immediately trigger detection. Low flow in this context means at a rate which fuel accumulation would be acceptable. Advantageously the means for detecting the flow of fuel and means for preventing the flow of fuel comprises a float which rises on fuel accumulating in the chamber until it blocks an outlet to the vapour recovery line from the chamber to the fuel storage tank. This arrangement will automatically close the vapour recovery line and is tamper resistant, not relying on any electrical inputs, and is capable of being a sealed unit. It is particularly advantageous if said chamber has a drain outlet to drain any fuel accumulated in the chamber as this can provide a reset function. This drain may be connected to the system in a number of ways. One particularly advantageous implementation has the drain outlet connected to a low flow Venturi device in the fuel delivery line downstream of a fuel delivery meter. This permits fuel at low flow rates to be accepted into the chamber without triggering a detection, whilst returning that metered fuel back to the fuel delivery line downstream of the meter such that no fraud can occur. However fuel must be being delivered to provide a reset once a detection has occurred. In an alternative arrangement the drain outlet may be connected to a high flow drain line connected to the vapour return inlet of the suction pump or a high flow Venturi device in the vapour return line or fuel delivery line, the drain line having a valve arranged to be normally closed and opened in order to provide a reset when fuel flow in the vapour recovery line has been detected. In this manner the detection means can be quickly reset on application of a control signal to the valve in the drain line, and where the drain is connected to the inlet of a suction pump can be cleared without fuel being dispensed or vapour collected at the delivery nozzle. High flow in this context means at a rate greater than that at which fuel accumulation would be acceptable. One embodiment of the present invention will now be described by way of example only, with reference to the accompanying figures of which: Figure 1 is a schematic view of a valve in accordance with the invention; Figure 2 illustrates a possible location of the valve shown in Figure 1 within a fuel dispenser. Referring to Figure 1, this shows a preferred form of implementation of a valve (100) in accordance with the invention which, as shown in Figure 2, is connected by means of primary pipework (102) to the vapour recovery line of the hose (104) of a delivery nozzle (107) and through secondary pipework (106) to a suction pump (105) which returns vapours to tank (110). The nozzle (107) is also connected to a fuel line (103), within and coaxial with the line (102) in the common section within the hose (104) up to the union (109). Referring again to Figure 1 the valve (100) comprises a cylindrical cup (1) fitted with guides (2) within which slides a float (3). The cup has a cover (4) in which are the input aperture (5) (to be connected to the vapour line (102) coming from the delivery nozzle), the output aperture (6) (to be connected to the vapour line (106) which goes to the suction pump) and the mounting point (7) for fixing to the dispenser framework. A third aperture (14) is provided connected to loop pipe (13), the aperture when connected to a low pressure drain line removes any fuel accumulating in cup 1 via loop pipe (13). The cover is screwed on to the cup and sealing is implemented by means of the O-ring seal (8). Fitted to the top of the float (3) is a needle stop-valve (9), complete with O-ring seal (10), which acts to close off the output aperture (6) when the float rises as a result of a flow of fuel from the vapour recovery line collecting in the cup 1 at a rate faster than it can be removed via drain aperture (14). The float rising and sealing output aperture (6), prevents the fuel from making its way towards the suction pump and thus blocks the flow preventing possible fraud. However any small accumulation of fuel, due to condensation or accumulated as a result of successive "topping off" of a tank at the nozzle for example, will be removed via drain aperture (14) preventing any false alarms. The float (3) can be of differing height relative to the cup (1), depending on the sensitivity required of the device. The greater the sensitivity required, the greater the height of the float so that a very small flow of fuel in excess of that removed via the drain aperture may be enough to close the valve. In the bottom of the float is inserted a magnet (11) which is associated with a magnetic proximity sensor (12) attached to the bottom of the cup. The sensor (12) allows the rise of the float to create an electrical signal which can be utilised to shut off the dispenser or the suction pump, or again to show that shut-off has occurred. With reference to Figure 2, the valve (100) is located immediately upstream from the suction pump (105), and the wire from the magnetic switch is taken to the distribution box (not shown in the diagram), from which the signal can be passed to the indicator panel or to the electrical control board of the dispenser to shut down the dispenser or to indicate the potential fraud. Figure 2 also illustrates drain line (150) connecting the drain aperture (14) of valve (100) to a low flow Venturi device (151) in the fuel delivery line such that the flow of fuel there through causes small quantities of fuel accumulating in valve (100) to be removed and returned to the delivery pipe downstream of the meter (152) any fuel so accumulated only being metered once before being dispensed. The Venturi device may be of any suitable design such as for example that disclosed in US 4,687,033. As may be seen from the above description of the device, the valve normally allows free flow of the vapour drawn in by the pump, since in these conditions the float remains at the bottom of the cup. If instead the vapour line is subjected to a flow of fuel, the valve closes off its outlet towards the suction pump by means of its shut-off valve as a result of the raising of the float. The magnet fixed to the float closes or opens the circuit which provides for stopping delivery, shutting off the suction pump, or simply indicating that the device has operated. This invention has been described with reference to a preferred form of implementation, but changes may be effected by any person competent in this field without going beyond the range of the protection afforded by the claims.

Claims: A fuel dispensing system (200) comprising a fuel delivery line (103) and vapour recovery line (102) connected between a delivery nozzle (107) of dispenser (200) and a fuel storage tank (110), characterised in comprising means (100) for detecting the flow of fuel along the vapour recovery line (102) and means (100) for preventing the flow of fuel detected through the vapour line back to the fuel storage tank. A system as claimed in Claim 1 wherein the detecting means (100) is connected between the delivery nozzle (107) and a suction pump (105). A system as claimed in Claim 1 or Claim 2 wherein the means for preventing the flow of fuel comprises means (3, 9, 10) for blocking the flow of fuel. A system as claimed in Claim 1 or 2 wherein the means (100) for detecting the flow of fuel along the vapour recovery line (102) comprises a chamber (1) in the vapour recovery line (102) in which chamber (1) fuel returning along the vapour recovery line (102) accumulates, said flow of fuel being prevented when the fuel in said chamber (1) reaches a predetermined level. A system as claimed in Claim 4 wherein the means for detecting (100) the flow of fuel and means for preventing the flow of fuel comprises a float (3) which rises on fuel accumulating in the chamber (1) until it blocks an outlet (6) to the vapour recovery line (106) from the chamber (1) to the fuel storage tank (110). A system as claimed in Claim 4 or Claim 5 wherein said chamber (1) has a drain outlet (13, 14) to drain any fuel accumulated in the chamber (1). A system as claimed in Claim 6 wherein said drain outlet (13, 14) is connected to a low flow Venturi device (151) in the fuel delivery line (103) downstream of a fuel delivery meter (152). A system as claimed in Claim 6 wherein the drain outlet (13, 14) is connected to a high flow drain line connected to the vapour return inlet of the suction pump or a high flow Venturi device in the vapour return line or fuel delivery line, the drain line having a valve arranged to be normally closed and opened in order to provide a reset when fuel flow in the vapour recovery line has been detected. A system in accordance with any preceding claims comprising means (11, 12) of indicating the occurrence of such fuel flow. A system in accordance with any preceding claim wherein the detection means comprise a valve (100), consisting of a vertical cylindrical chamber (1) equipped with guides (2) within which guides slides a float (3) the chamber being fitted with a sealed cover (4) on which are located an input aperture (5) connected to a primary section (102) of the vapour line and an outlet aperture connected to the vapour line (106) which leads to the suction pump (105), the float (3) being fitted with a needle closure-valve (9), with seal (10), which closes the output aperture (6) as a result of the float (3) lifting due to any fuel from the vapour recovery line (102) collecting in the chamber (1). A system in accordance with Claims 9 and 10, wherein the means of indicating comprise a magnet (11) located on the bottom of the float (3) in association with a magnetic proximity sensor (12) attached to the base of the chamber (1). A system in accordance with any preceding claim wherein an output signal of the detecting means is connected to the indicating head or to the electrical control board of the fuel dispensing system to shut off delivery of fuel in response to the detection of fuel flow in the vapour recovery line. A fuel dispenser including a system in accordance with one or more of Claims 1 to 12.

Inventors: BARUCCI ALESSANDRO, FIORAVANTI LUCIANO, BARUCCI, ALESSANDRO, FIORAVANTI, LUCIANO
Applicants: GILBARCO S P A, GILBARCO S.P.A.
Application year: 2000
Main classification: B67D5
IPC codes: B67D7