EP1061038A1

EP1061038A1 - Device for preventing the backflow of fuel through a fuel vapour return line

Info

Publication number: EP1061038A1
Application number: EP00304876A
Authority: EP
Inventors: Stefano Olcese; Edoardo Motti
Original assignee: Nuovo Pignone Holding SpA; Nuovo Pignone SpA
Current assignee: DEG ITALIA S.P.A.
Priority date: 1999-06-10
Filing date: 2000-06-08
Publication date: 2000-12-20
Also published as: ITMI991293A1; ITMI991293A0

Abstract

A device (35) for preventing the backflow of fuel through a fuel vapour return line comprises a body (36) which defines a cavity (37) and has at least one inlet through-hole (38) which leads into the cavity (37) and through which at least one gas or vapour which may contain at least one liquid can enter and at least one outlet through-hole (39) which emerges from the cavity (37) and through which the gas or vapour can flow out, said cavity (37) housing internally at least one sensor element (42, 43, 54) designed to detect the presence of at least one liquid which has accumulated in the device (35).

Description

The present invention relates to petrol station pumps, in particular pumps provided with a system for recovery of the vapours emitted during motor-vehicle refuelling operations. In petrol stations, and in particular roadside petrol stations for the refuelling of motor-vehicles, the safety and environmental protection regulations stipulate that the vapour phase, or more precisely the air/vapour phase, which is emitted from the tanks of motor-vehicles during refuelling, must not be dispersed into the environment. This emission is due essentially to the displacement effect of the liquid fuel introduced into the tank, which reduces the volume above the surface of the fuel and expels an equal volume of gaseous phase consisting of a mixture of air and fuel vapours.
In the known art this air/vapour phase is drawn off by providing the fuel supply guns with fuel supply nozzles combined with suction nozzles by means of which this air/vapour phase is removed. The supply gun is connected to the pump by means of a liquid-fuel supply pipe which is supplied by a variable-delivery pumping unit and by means of a suction pipe connected to a volumetric pump for suction of the vapours which is controlled so that the delivery is strictly related, at each instant, to the fuel supply flow.
In the known art various systems for recovery of the vapours, or rather the air/vapour phase, emitted from the tanks of motor-vehicles during refuelling have been proposed, as described, for example, in US patent No. 5,038,838 in the name of the same applicants or in the patent EP-B-461,770 in the name of Gilbarco Inc.
In order to clarify the technical problems connected with recovery of the vapours in fuel pumps, reference will be made to the diagram shown in Figure 1 relating to a petrol station pump provided with a single supply gun.
The pump 10 has a box-shaped support structure 11 which contains and supports its component parts. The fuel is contained in an underground cistern - not shown in the figure - from where the fuel is supplied by means of the suction line which comprises the duct 12, the pumping unit 13 which is operated by the supply gun, the measuring unit 14 which measures the quantity of fuel supplied, before conveying it, via the duct 15, to the separator 16 from where the flexible pipe 17 of the supply gun 18 extends. The measuring unit 14 has, connected to it, a pulse generator 19 which generates an electric pulse for each unit of fuel supplied, for example for each centilitre. This pulse-type signal has a frequency proportional to the flowrate and is transmitted to the display block 20 which, depending on the number of pulses, calculates and displays the quantity supplied and the corresponding price of the refuelling operation. The same signal is transmitted to the electronic control unit 21 which controls and operates the vapour recovery system.
The pipe 17 of the supply gun 18 contains both a fuel supply duct 22, which is the continuation of the supply duct 15 leading to the supply nozzle, and a pipe which defines a return duct 23 connected to a suction nozzle located in the vicinity of the supply nozzle. The vapours expelled from the tank being filled are drawn off by means of the nozzle. This return pipe is connected, inside the separator 16, to a suction duct 24 which is connected to a volumetric pump 25 for suction of the vapours. This volumetric pump 25 is actuated by a motor 26 which is driven by the electronic control unit 21 at a number of revolutions which corresponds, at each instant, to the frequency of the pulse signal of the generator 19 so as to correlate the revolutions of the pump 25, and hence the volumetric suction rate, to the fuel supply flow. The delivery side of the volumetric pump 25 is re-connected by means of a duct 27 to the underground cistern of the petrol station from where the fuel is removed.
Generally the volumetric ratio between the fuel supplied and the gaseous phase drawn off is preset and kept at the value of about unity depending on the type of fuel and the environmental conditions.
In more modern petrol stations each pump is equipped with a plurality of supply guns which are connected to different underground fuel cisterns, containing, for example, 4-star leaded petrol, lead-free petrol of varying octanes, diesel fuel, etc. Generally these pumps are formed with two flanks or sides and each of these is provided with a series of supply guns for the different types of fuel available. Depending on the number of supply guns in each pump and depending on the number of different types of fuel which each pump is able to supply, the pipes 17 and the associated suction ducts 24 are multiplied.
The flexible pipe 17, which contains the fuel supply duct 22 and the return duct 23, has at each of its ends a generally metallic connection piece 28 for connecting it, on the one hand, to the supply gun 18 or the separator 16 and, on the other hand, to the pipe 17.
The connection piece 28 (Figure 2) is substantially formed by means of two concentric sleeves 29, 30 which are joined to two pipes (not shown) which are also concentric and located inside the pipe 17.
The sleeve 29 is threaded externally and is screwed into a threaded seat of the supply gun 18 or the separator 16 with the arrangement, in between, of a seal 31.
The sleeve 30, which is located inside the abovementioned sleeve, has a portion which emerges from the sleeve 29 so as to be inserted into a second seat of the supply gun 18 or the separator 16 coaxial with the former, with the arrangement, in between, of a pair of sealing rings 32 which prevent the backflow of the liquid fuel from the supply duct 22 to the return duct 23.
Conventional pumps and in particular the pipe 17 and fittings associated with it have numerous drawbacks, mainly due to the fact that the liquid fuel could pass from the supply duct 22 into the return duct 23. This possibility may arise should even only one of the sealing rings 32 be removed or break or if the pipe forming the duct 23 should be torn or perforated. In this situation there would be a twofold drawback since the consumer would have to pay for a quantity of fuel which was not supplied and problems could affect the suction pump 25 which is usually of the reciprocating type, for example of the membrane or piston type or vane or roller type.
The present invention seeks to eliminate the technical drawbacks mentioned by providing a device for preventing the backflow of fuel through a fuel vapour return line, which allows the presence of liquid inside recovered gases or vapours to be detected.
The invention further seeks to provide a device for preventing the backflow of fuel through a fuel vapour return line, which allows the flow of recovered gases or vapours to be interrupted when a liquid together with the vapours is detected.
The invention still further to provides a device for preventing the backflow of fuel through a fuel vapour return line, which is able to ensure a high degree of reliability and extremely safe operation of petrol station pumps.
The invention also seeks to provide a device for preventing the backflow of fuel through a fuel vapour return line which is substantially simple, safe and reliable.
These and other objects are achieved, according to the present invention, by providing a device for preventing the backflow of fuel through a fuel vapour return line according to Claim 1.
Other characteristic features of the present invention are also described in the claims below.
Advantageously, as a result of the device according to the present invention, it is possible to provide petrol supply pumps which are particularly reliable and safe since their operation may be interrupted when defects in correct operation thereof are detected.
The invention will now be described in greater detail, by way of example, with reference to the drawings, in which:
Figure 1 shows a schematic view of a supply pump which has a single fuel supply gun;
Figure 2 shows a view of a partially sectioned detail of a device for connection between a fuel supply gun and a flexible fuel supply pipe;
Figure 3 shows a longitudinal section through a device for preventing the backflow of fuel through a fuel vapour return line, provided with one inlet and one outlet, according to a first embodiment;
Figure 4 shows a longitudinal section through a device according to the invention, provided with one inlet and one outlet, according to a second embodiment;
Figure 5 shows a longitudinal section through a device according to the invention, provided with one inlet and one outlet, according to a third embodiment;
Figure 6 shows a schematic view of a device according to the invention, provided with two inlets and one outlet;
Figure 7 shows a schematic view of a device according to the invention, provided with two inlets arid two outlets;
Figure 8 shows a schematic view of a device according to the invention, provided with one inlet and two outlets;
Figure 9 shows a schematic view of a device for preventing the backflow of fuel through a fuel vapour return line according to the invention, provided with an electronic probe;
Figure 10 shows a schematic view of a further embodiment of the device according to the invention, provided with an inlet on a side wall.
With reference to the said figures, a device for preventing the backflow of fuel through a fuel vapour return line, denoted in its entirety by the reference number 35, is shown.
In a first embodiment, the device 35 has a body 36 consisting of two parts associated with each other so as to define a cavity 37. The body 36 has an inlet through-hole 38 through which the fuel vapours enter inside it and a second outlet through-hole 39 through which, instead, the vapours leave the body 36. The two holes 38, 39 are formed on opposite walls of the body 36 and are aligned with each other. The body 36 has, in the region of the inlet hole 38 and the outlet hole 39, respectively, internally threaded extensions allowing connection of the threaded pipes of the suction duct 24 forming the vapour recovery line.
Moreover, an additional bleeder through-hole 40, which is closed by means of a cap 41, is formed on a bottom portion of the body 36 (with respect to the device 1 when correctly mounted).
The body 36 houses internally a sensor element which is able to detect the presence of liquid which has accumulated inside the device 35.
The sensor element comprises a cup-shaped element 42 which is housed inside the body 36 in a position facing the outlet through-hole 39 and, therefore, aligned with the inlet through-hole 38. The cup-shaped element 42 acts as a guiding means for a floating obturator 43 contained inside it. The floating obturator 43 can be displaced, when liquid accumulates in the bottom portion of the element 42, from a working position, where an aperture of the outlet through-hole 39 is free to allow the gas or vapour to pass through and flow out from the device 35, and a position where the aperture of the outlet through-hole 39 is at least partially closed by the floating obturator 43 so as to hinder or prevent the gas or vapour from passing through and therefore from flowing out of the device 35.
A side wall of the cup-shaped element 42 extends beyond the bottom thereof so as to define a compartment 44 into which the inlet through-hole 38 leads. This extended portion is provided with a series of openings 45 which connect the compartment 44 to the cavity 37 of the body 36 inside which the obturator 43 is housed.
A free end of the extension of the element 42 has a flange 46 for connection to the body 36. The flange 46 is fixed between a shoulder 47 of one part of the body 36 and the other part.
The cup-shaped element 42 is provided with several openings which allow the liquid to enter inside it. In this embodiment the bottom of the cup-shaped element 42 is provided with an opening 48 and additional openings 49 are formed along its side wall.
The obturator 43 is cylinder-shaped with a coneshaped end directed towards the outlet hole 39. Moreover, a sealing ring 50 is arranged in special seats on one edge of the outlet hole 39 facing the obturator 43 so as to ensure always an optimum connection with the obturator 43 and good tightness of the connection.
The operating principle of a device for preventing the backflow of fuel through a fuel vapour return line according to the invention is substantially as described below.
The device 35 is mounted on the suction duct 24 of the vapour recovery line in a vertical position, i.e. with the outlet hole 39 directed upwards.
The pump 25 actuated by the motor 26 causes suction of the fuel vapours and conveys them into the cistern via the duct 27.
In a normal situation, the vapour passes from the compartment 44 to the cavity 37 through the openings 45 and then flows out from the cavity 37 through the outlet hole 39. The quantity of vapour which passes through the opening 48 is minimal owing to the throttling of the vapour by the latter and therefore the floating obturator 43 remains against the bottom of the cup-shaped element 42.
When a problem resulting in backflow of the liquid from the supply duct 22 to the return duct 23 of the pipe 17 occurs, both vapour and liquid enter the device 35.
The liquid passes through the openings 45 and accumulates inside the cavity 37. When its level reaches the opening 48 and then the opening 49, the liquid enters inside the cup-shaped element 42. At this point the floating obturator 43 is raised and closes the outlet hole 39 of the device 35. The closing action produces a vacuum inside the duct 24 which causes an increase in the power consumed by the motor 26 of the (suction) pump 25 which is disabled.
The activation times of the device 35 (for closing the outlet through-hole 39) are limited and adjustable and, in any case, the quantity of incoming liquid when a problem arises is such as to fill the cavity 37 very quickly.
Following a breakage and/or a problem which results in activation of the device 35, the duct portion 24 upstream of the device 35 could be entirely filled with liquid fuel; this would prevent any fluctuations in delivery which could cause a flow of liquid which is not detected through the device 35.
Even if fluctuations in the delivery should occur, however, activation of the device 35 and consequent disabling of the motor 26 of the pump 25 at a maximum power consumption peak would be sufficient. At this point manual intervention would be required in order to restore normal operation of the petrol pump 10. The device 35 described hitherto may be advantageously used by mounting a check valve (not shown) on the portion of the duct 24 upstream of the said device 35. The check valve, by preventing backflow of the liquid, prevents fluctuations in delivery and keeps the duct portion 24 between the check valve itself and the device 35 completely full of liquid.
A different embodiment of the device according to the invention is shown in Figure 4, the same reference numbers being used for identical or similar parts.
The device 35 shown in Figure 4 is similar to that shown in Figure 3 and differs from the latter in that the floating obturator 43 has a spherical shape and, moreover, a sleeve 51 facing the obturator 43 is inserted inside the outlet hole 39 so as to facilitate closing of the flow aperture of the outlet through-hole 39 by the said floating obturator 43.
The device 35, according to the present embodiment, has an inspection element designed to allow verification of the quantity of liquid contained inside the cavity 37.
The inspection element consists of a transparent panel 52 which closes an opening 53 in a part of the body 36. The panel 52 is curved (so as to follow the profile of the body 36), is inserted in three perimetral grooves formed on three edges of the opening 53 and is fixed by the second part of the body 36.
The operating principle of the device according to the invention in this embodiment is similar to that already described further above, with the additional feature that it is possible to inspect the cavity 37 of the body 36 through the transparent panel 52.
A further embodiment of the device according to the invention, which is similar to the preceding embodiments, is shown in Figure 5 in which the same numbers are used to indicate identical or similar parts.
In this embodiment the inlet hole 38 and the outlet hole 39 are formed on opposite walls of the body 36, but are not aligned. The inlet hole 38 is formed on a side portion of the bottom wall and opens out directly inside the cavity 37 of the body. The bleeder hole 40 opens out on the same bottom wall and is closed by means of the cap 41. The outlet hole 39 is formed on the wall opposite to the bottom and supports the sleeve 51. Facing the sleeve 51 and integral with the bottom wall of the body 36, the device 35 supports the cup-shaped element 42 which is provided with lateral openings 49 and which contains internally the floating obturator 43 which, for example, has a spherical shape.
The operating principle of the device in the present embodiment is similar to that already described above in connection with the first and the second embodiment. In particular, owing to the configuration and the geometrical form of the device, with this embodiment of the device 35 the liquid may be separated from the vapour in a particularly effective manner.
Moreover, in various embodiments, the device 35 has a different number of inlet through-holes 38 and/or outlet through-holes 39.
Figure 6 shows an example of embodiment of a device with two inlet holes 38 and a single outlet hole 39 which has, facing it, a single sensor element consisting of the cup-shaped element 42 and the obturator 43.
The operating principle is similar to that already described; it should be noted that the device 35 closes when the liquid enters through at least one of the inlet through-holes 38.
The device 35 in this embodiment may be useful for the recovery of vapours from a petrol pump 10 having, for example, two supply guns 18 which are able to supply a single type of fuel contained in a single storage tank. -
Figure 7 shows an example of a device with two inlet holes 38 and two outlet holes 39, each of which has, facing it, a sensor element consisting of the cup-shaped element 42 and the obturator 43.
In this case the device 35 closes all the outlet holes 39 when liquid arrives from at least one of the inlet through-holes 38.
The device 35 in this embodiment may be useful for the recovery of vapours from a petrol pump 10 having, for example, two supply guns 18 able to supply two different types of fuel, as required, contained in two different storage tanks.
Figure 8 shows an example of a device with one inlet hole 38 and two outlet holes 39, each of which has, facing it, a sensor element consisting of the cup-shaped element 42 and the obturator 43.
In this case, the device 35 closes all the outlet holes 39 when liquid arrives from the inlet through-hole 38.
The device 35 in this embodiment may be useful for the recovery of vapours from a petrol pump 10 having, for example, a single supply gun 18 able to supply two different types of fuel contained in two different storage tanks.
Moreover, the sensor element may consist of an electrical and/or electronic sensor 54. In this case, the liquid accumulated inside the cavity 37 is detected by the sensor 54 which generates a signal which causes, via the electronic control unit 21 of the petrol pump 10, disabling of the pump 25.
In addition to those already described, modifications and variations are obviously possible such that, for example, the inlet through-hole 38 may be formed at any point in the body 36, depending on requirements. For example, Figure 10 shows an embodiment of a device 35 according to the invention in which the inlet through-hole 38 is formed on a side wall of the body.
It has basically been shown how a device for preventing the backflow of fuel through a fuel vapour return line according to the invention is particularly advantageous because it allows the detection of a liquid which may have penetrated into the vapour recovery line and interruption of the latter, so as to increase the safety and reliability of the petrol pump.
For the sake of good order, various features of the invention are set out in the following clauses:-
1. A device (35) for preventing the backflow of fuel through a fuel vapour return line, characterized in that it comprises a body (36) which defines a cavity (37) and has at least one inlet through-hole (38) which leads into said cavity (37) and through which at least one gas or vapour which may contain at least one liquid can enter and at least one outlet through-hole (39) which emerges from said chamber (37) and through which said at least one gas or vapour can flow out, said cavity (37) housing internally at least one sensor element (42, 43, 54) designed to detect the presence of at least one liquid which has accumulated in said device 35) .
2. A device (35) according to Clause 1, characterized in that said at least one sensor element (42, 43, 54) comprises at least one floating obturator (43) associated with guide means (42) and housed in a position facing said outlet through-hole (39), said floating obturator (42) being designed to be displaced, when said liquid accumulates in a bottom portion of said cavity (37), from a working position, where an aperture of said outlet through-hole (39) is free to allow said at least one gas or vapour to pass through and flow out from said cavity (37), and a position where said aperture of said outlet through-hole (39) is at least partially closed by said floating obturator (43) so as to hinder or prevent said at least one gas or vapour from passing through and therefore flowing out from said cavity (37).
3. A device (35) according to Clause 2, characterized in that said body (36) has at least one additional bleeder through-hole (40), said bleeder hole 40) being able to be closed by means of a cap (41).
4. A device (35) according to Clause 2, characterized in that said guide means (43) comprise at least one cup-shaped element (43) housed inside said cavity (37) in a position
facing said outlet through hole (39), said cup-shaped element (42) containing said floating obturator (43).
5. A device (35) according to Clause 4, characterized in that said cup-shaped element (42) comprises openings (49) which are formed on one of its, side walls and which allow said liquid to enter inside said cup-shaped element (42).
6. A device (35) according to Clause 4, characterized in that said inlet through-hole (38) and said outlet through-hole (39) are formed on two opposite walls of said body (36) and are aligned with each other, said cup-shaped element (42) also having an extension of one of its side walls which extends beyond its bottom so as-to define a compartment (44) inside which said inlet through-opening (38) opens out, said extension having openings (45) through which said gas or vapour which may contain said liquid can pass so as to be introduced into said cavity (37).
7. A device (35) according to Clause 6, characterized in that said bottom of said cup-shaped element has one or more openings (48) which allow said liquid to enter inside it.
8. A device (35) according to Clause 6, characterized in that, at a free end of said extension, said cup-shaped element (42) has a flange (46) for connection to said body (36), said flange (46) being fixed between a shoulder (47) of a first part of said body (36) and a second part of said body (36) of said device (35).
9. A device (35) according to Clause 2, characterized in that said floating obturator (43) has a substantially spherical shape.
10. A device (35) according to Clause 2, characterized in that said floating obturator (43) has a substantially cylindrical shape with a closing end which is substantially cone-shaped.
11. A device (35) according to Clause 2, characterized in that a sleeve (51) facing said floating obturator (43) is inserted in said outlet through-hole (39) so as to facilitate closing of said flow aperture of said outlet through-hole (39) by said floating obturator (43).
12. A device (35) according to Clause 1, characterized in that it comprises an inspection element (52) .
13. A device (35) according to Clause 12, characterized in that said inspection element (52) consists of a transparent panel (52) which closes an opening (53) in a part of the body (36).
14. A device (35) according to Clause 1, characterized in that said at least one sensor element (42, 43, 54) comprises at least one electrical or electronic sensor (54).

Claims

A device (35) for preventing the backflow of fuel through a fuel vapour return line, characterized in that it comprises a body (36) which defines a cavity (37) and has at least one inlet through-hole (38) which leads into said cavity (37) and through which at least one gas or vapour which may contain at least one liquid can enter and at least one outlet through-hole (39) which emerges from said chamber (37) and through which said at least one gas or vapour can flow out, said cavity (37) housing internally at least one sensor element (42, 43, 54) designed to detect the presence of at least one liquid which has accumulated in said device 35) .
A device (35) according to Claim 1, characterized in that said at least one sensor element (42, 43, 54) comprises at least one floating obturator (43) associated with guide means (42) and housed in a position facing said outlet through-hole (39), said floating obturator (42) being designed to be displaced, when said liquid accumulates in a bottom portion of said cavity (37), from a working position, where an aperture of said outlet through-hole (39) is free to allow said at least one gas or vapour to pass through and flow out from said cavity (37), and a position where said aperture of said outlet through-hole (39) is at least partially closed by said floating obturator (43) so as to hinder or prevent said at least one gas or vapour from passing through and therefore flowing out from said cavity (37).
A device (35) according to Claim 2, characterized in that said body (36) has at least one additional bleeder through-hole (40), said bleeder hole 40) being able to be closed by means of a cap (41).
A device (35) according to Claim 2, characterized in that said guide means (43) comprise at least one cup-shaped element (43) housed inside said cavity (37) in a position facing said outlet through hole (39), said cup-shaped element (42) containing said floating obturator (43).
A device (35) according to Claim 2, characterized in that said floating obturator (43) has a substantially spherical shape.
A device (35) according to Claim 2, characterized in that said floating obturator (43) has a substantially cylindrical shape with a closing end which is substantially cone-shaped.
A device (35) according to Claim 2, characterized in that a sleeve (51) facing said floating obturator (43) is inserted in said outlet through-hole (39) so as to facilitate closing of said flow aperture of said outlet through-hole (39) by said floating obturator (43).
A device (35) according to Claim 1, characterized in that it comprises an inspection element (52) .
A device (35) according to Claim 12, characterized in that said inspection element (52) consists of a transparent panel (52) which closes an opening (53) in a part of the body (36).
A device (35) according to Claim 1, characterized in that said at least one sensor element (42, 43, 54) comprises at least one electrical or electronic sensor (54).