EP1302439B1

EP1302439B1 - Device and methods for facilitating maintenance of a fuel delivery unit

Info

Publication number: EP1302439B1
Application number: EP20020445129
Authority: EP
Inventors: Bengt I. Larsson
Original assignee: Dresser Wayne AB
Current assignee: Wayne Fueling Systems Sweden AB
Priority date: 2001-10-12
Filing date: 2002-10-11
Publication date: 2004-12-08
Anticipated expiration: 2022-10-11
Also published as: DE60202182T2; SE0103431L; DE60202182D1; SE0103431D0; EP1302439A1; SE523217C2

Description

Field of the Invention

The present invention relates to a filter and non-return valve device for use in a fuel delivery unit. The invention further relates to a fuel delivery unit comprising such a device, and methods for installation and maintenance of the device.

Background of the Invention

A fuel delivery unit typically comprises one or more storage tanks and a pump unit which generally comprises a housing that holds a pump, a pump motor, metering equipment and one or more delivery nozzles. The storage tanks are often located under ground and thus need to be connected to the pump unit by means of conduits.
The conduits connecting the pump unit and the storage tanks are generally provided with non-return valves which prevent fuel that has been pumped up from the storage tank from pouring back into the storage tank when the pump is inactive. It is important to have liquid, in this case fuel, in the system at all times for the pump to function properly. Introduction of air in the upper part of the system could cause the pump to cease functioning, especially if the vertical distance between the pump and the storage tank is large. The preservation of fuel in the conduit also decreases the delivery time when filling up a vehicle, since the fuel will not have to be pumped all the way from the storage tank each time a delivery is initiated.
As shown in Fig 1, the non-return valve was originally arranged near the storage tank, under ground, thus effectively preventing the fuel in the conduit from returning to the storage tank. However, this arrangement was prohibited for environmental reasons, since the non-return valve would, in case there was a leak in the conduit, allow the fuel in the conduit to leak out into the ground instead of pouring back into the storage tank. This is also the reason why the pump is often placed above ground.
US 2 922 288 A, according to the preamble of claim 1, discloses a fuel delivery device having a filter, a first non-return valve downstream the filter, and a second non-return valve upstream the filter.
Instead today, as shown in Fig 2, the non-return valve is placed just upstream from the pump, above ground level, inside the housing. Upstream from the non-return valve, a filter is generally arranged, in order to filter the fuel so as to remove e.g. solid particles which may damage the pump, the metering equipment or the vehicle being fueled. Such filters need regular maintenance or replacement.
In order to access the filter, the fuel in the conduit between the non-return valve and the filter needs to be removed in order to prevent fuel from spilling out and polluting the environment or causing a risk of explosion. This can be done by e.g. opening or removing the non-return valve and thus eliminating the vacuum that keeps the fuel from returning to the storage tank. The fuel then flows back to the storage tank. After the filter maintenance is completed, the fuel has to be pumped back all the way from the storage tank. This operation is time consuming and works against minimizing the maintenance downtime of a fuel delivery unit.
Hence there is a need for a device and method which enable more efficient filter maintenance in a fuel delivery unit.

Summary of the Invention

It is therefore an objective of the present invention to provide devices and methods for enabling e.g. maintenance access to a filter in a fuel delivery unit, without losing or releasing all of the fuel that has already been pumped up into the conduit.
This and other objectives are achieved wholly or partially by a device comprising the features of any one of the enclosed independent claims 1, 22 or 27, and by a method comprising the steps of any one of independent claims 28 or 29. Preferred embodiments are set forth in the enclosed dependent claims and in the following description.
According to the invention, a device for a fuel delivery unit is provided. The device comprises a channel for conducting a fuel flow, a filter unit arranged for filtering the fuel flow and a first non-return valve arranged downstream of the filter unit, said first non-return valve allowing the fuel to flow freely in a first direction but preventing the fuel from flowing in a second direction. The device further comprises a second non-return valve arranged upstream of said filter unit, allowing the fuel to flow freely at a first flow rate in the first direction but substantially preventing the fuel from flowing in the second direction. The device further comprises leakage means for allowing the fuel to flow at a second flow rate in the second direction, from a downstream side to an upstream side of the second non-return valve.
The channel is typically a conduit, pipe, hose or other type of tubular structure or hollow body that is suitable for conducting a fuel flow. The second direction is essentially opposite to the first direction. The "downstream side" of a non-return valve is to be understood as the downstream side of the main (first) flow direction. Analogously, the "upstream side" is to be understood as the upstream side in the main flow direction.
While it is known to arrange the first non-return valve downstream of the filter, the arrangement of the second non-return valve provides advantages in that fuel is allowed to flow backwards, past or through the second non-return valve at a rate which is low enough to allow an operator to e.g. replace the filter unit before all of the fuel remaining in the channel has flowed back towards the storage tank. Thus, some fuel is removed from the channel, so that the filter may be replaced essentially without spillage, but not so much as to introduce an amount of air in the conduits that could hamper the function of the pump.
Preferably, the channel may comprise an essentially tubular, flexible structure. Such a flexible structure makes assembly and disassembly more convenient.
The device may further comprise coupling means, adapted for detachably interconnecting any two of: an end of said channel, the filter unit, the first non-return valve and the second non-return valve. Such coupling means also provide for easy assembly and disassembly for e.g. maintenance purposes.
The coupling means may be integrated with at least one of the channel, the first non-return valve, the filter unit and the second non-return valve. This may provide for a compact design and a reduced amounts of parts to keep in storage and to assemble/disassemble. Preferably, the coupling means are adapted for detachably coupling one of the first non-return valve and the filter unit to a downstream element, such as a pump, conduit or other component within the fuel delivery unit.
The first non-return valve and the filter unit are advantageously detachably arranged, adjacent each other, at a first end of the channel. The first non-return valve and the filter unit may even be integrated or detachably integrated with each other. The first non-return valve may also be provided with means for regulating it between an open and a closed state. This would allow an operator to open the first non-return valve in order to let some fuel flow back through the second non-return valve before the channel is disconnected, so as to minimize the risk of spillage when disconnecting the channel.
The second non-return valve is advantageously arranged at a second end of the channel, so that the channel may lead a flow from the second non-return valve to the filter unit and the first non-return valve. The first non-return valve is preferably arranged at a vertically higher level than the second non-return valve, so as to prevent fuel from spilling from the channel when disconnecting the channel from the first non-return valve.
By arranging the channel between the first and second non-return valves, the channel may be disconnected from the first non-return valve while replacing the filter so that the fuel remaining in the channel slowly flows back through the second non-return valve, while the filter is replaced. By providing the channel with a flexible section that is arranged between said first and second non-return valves, the channel may be easily displaced during maintenance operations.
Preferably, the second flow rate is substantially lower than the first flow rate. This may be achieved by adapting the leakage means for allowing a predetermined amount of fuel to flow in the second direction during a predetermined time period. For example, the second non-return valve may be at least partly permeable, the leakage means may be formed by a hole in the second non-return valve, or the leakage means may comprise a by-pass channel leading the fuel past the second non-return valve.
In a preferred embodiment, the device is arranged in a fuel delivery unit comprising a pump for providing the fuel flow and a fuel source from which the fuel is drawn. The pump may be arranged downstream of the first non-return valve, while the fuel source may be arranged upstream of the second non-return valve.
The present invention also comprises a kit of parts for providing a device for a fuel delivery unit. This kit of parts may comprise a channel adapted for conducting a fuel flow, a filter unit adapted to be arranged for filtering the fuel flow and a first non-return valve adapted to be arranged downstream of said filter unit, so that the first non-return valve will allow the fuel to flow freely in a first direction but prevent the fuel from flowing in a second direction. The kit may further comprise a second non-return valve adapted to be arranged upstream of said filter unit, in order to allow the fuel to flow freely at a first flow rate in the first direction but to substantially prevent the fuel from flowing in the second direction. Finally, the kit may comprise leakage means adapted for allowing the fuel to flow at a second flow rate in the second direction, from a downstream side to an upstream side of the second non-return valve. The kit of parts may be assembled into a device such as the one described above.
The present invention further comprises a method for providing a filter unit in a fuel delivery unit. The method comprises a number of steps, one of which is to connect a second non-return valve to a fuel source in order to allow fuel to flow freely at a first flow rate in a first direction, while the fuel is substantially prevented from flowing in a second direction. Another step is to provide leakage means for allowing the fuel to flow at a second flow rate in the second direction, from a downstream side to an upstream side of the second non-return valve. Yet another step is to connect a channel to a downstream side of said second non-return valve, in order to conduct the fuel from the fuel source. A further step is to arrange a filter unit in the channel, in order to filter the fuel conducted in the channel. A first non-return valve is connected on a downstream side of said filter, in order to allow the fuel to flow freely in the first direction but prevent the fuel from flowing in the second direction. A downstream side of said first non-return valve is connected to a fuel drain. The fuel drain may be a conduit or a pipe that serves as a continuation of the conduit from the storage tank to the delivery nozzles. It may also be a pump or any other type of equipment which is connected downstream of the first non-return valve.
This method provides a structure in a fuel delivery unit, which allows for easy and spillage-free replacement of a filter unit. The above described steps do not need to be performed in the order recited.
Furthermore, a method for replacing a filter or filter unit that is positioned to filter a fuel flow conducted in a channel of a fuel delivery unit is provided. The method comprises the steps of disconnecting a first end of a channel from one of a fuel drain, a filter unit and a first non-return valve, and allowing fuel remaining in the channel to flow through a leakage means, in a second direction, from a downstream side to an upstream side of a second non-return valve.
While the fuel is flowing in the second direction, the steps of removing the filter or filter unit, inserting a new or restored filter or filter unit, and connecting the first end of the channel to said one of a fuel drain, a filter unit and a first non-return valve are performed. Through this method, the filter or filter unit may be replaced without total loss of all the fuel present in the channel or in a conduit from a storage tank. The method may also comprise a step of opening the first non-return valve prior to disconnecting the first end. This would further reduce the risk of spillage when disconnecting the channel.
A non-return valve for use in a fuel delivery unit, for example as the second return valve of the invention, may comprise a passage for conducting a fluid in a first direction and closure means for substantially closing said passage from conducting fuel in a second direction. The closure means may be moveable between a closed and an open position based on the direction of the flow through the non-return valve. The non-return valve further comprises leakage means for providing a flow in the second direction, from a downstream side to an upstream side of the closure means. Such leakage means enables the non-return valve to be used as the second non-return valve described above. The leakage means may comprise for example a permeable element or a hole in the closure means for allowing fuel to flow in the second direction through the non-return valve. The leakage means may also comprise a by-pass channel for allowing the flow in the second direction to flow past said closure means.
The non-return valve may be of may different types, as is described below. One appropriate non-return valve may be a dual flap check valve, but other types of non-return valves may also be used.
A filter unit for use in a fuel delivery unit such as the one described above may comprise a filter and a non-return valve, which is arranged at the downstream side of the filter or the filter unit and which allows fuel to flow freely in a first direction but which prevents the fuel from flowing in a second direction through the filter. From an assembly/disassembly point-of-view, it is advantageous to integrate the filter and the non-return valve into one housing.
The non-return valve may be of different types, as is described below. One appropriate non-return valve is a dual flap check valve, but other types of non-return valves may also be used. Finally, the filter unit may comprise means for regulating the non-return valve between an open and a closed state, so that fuel present in the channel may be removed prior to replacing the filter.

Brief Description of the Drawings

The invention will be described in more detail with reference to the appended schematic drawings, which show examples of presently preferred embodiments of the invention and its constituents.
Fig 1 is a schematic view of a first prior art fuel delivery system.
Fig 2 is a schematic view of a second prior art fuel delivery system.
Fig 3 is a schematic view of a fuel delivery system according to the invention.
Fig 4 is a schematic view of a an enlarged part of the fuel delivery unit in Fig 3.
Fig 5 is a perspective view of an embodiment of a device for a fuel delivery unit.
Fig 6 is a perspective view of a filter unit and a first non-return valve of the embodiment shown in Fig 5.
Fig 7 is a perspective side view of the filter unit and first non-return valve of the embodiment shown in Fig 5.
Fig 8 is a perspective view of a second non-return valve.
Fig 9 is a perspective top view of the second non-return valve.
Fig 10 is a detailed perspective view of a device according to an embodiment of the invention.
Fig 11 is a side view of the device shown in Fig 10.
Fig 12a-e are schematic views of examples of a filter unit and a first non-return valve to be used in the invention.
Fig 13a-c are schematic views of examples of a non-return valve with leakage means which may be used as the second non-return valve.

Description of Preferred Embodiments

Fig 1 and 2 show schematic diagrams of prior art fuel delivery systems, which have been discussed above.
Fig 3 is a schematic diagram of a fuel delivery system according to the invention. The fuel delivery system operates to transport fuel from a storage tank 2 to a delivery nozzle 18, for delivering fuel to vehicles such as e.g. automobiles, motorcycles, boats or aircraft. The storage tank 2 can typically be placed below the ground level 0 on which the fuel delivery unit 1 is arranged, e.g. buried or just placed on a lower level or story.
The storage tank 2 can be connected to the fuel delivery unit 1 via at least one conduit. The fuel can be caused to flow from the storage tank 2 through the conduit by means of a pump 5, which can be arranged within the fuel delivery unit 1. Such a pump can be e.g. a vacuum pump, that generates a negative pressure, which draws the fuel from the storage tank 2 and causes it to move in the flow direction F as indicated in Fig 3. The delivery nozzle 18 can be arranged downstream of the pump 5.
In the conduit, a second non-return valve 7 is arranged, which operates to allow the fuel to move in the flow direction F, but which prevents the fuel from moving against the flow direction F. The second non-return valve 7 may be any type of non-return or check valve, such as e.g. of ball type, flap type, disk type, ring type, membrane type. The non-return valve may also be a swing check valve, a piston or lift check valve or, as in the embodiment described herein, a dual flap check valve. The non-return valve may or may not be spring loaded. However, at this second non-return valve 7 a leakage means 13, such as e.g. a hole, a by-pass channel or a membrane is arranged, so that fuel may flow at a low rate, against the flow direction F, past or through the second non-return valve.
Downstream of the second non-return valve, a filter unit 6 is arranged for filtering the fuel flow so as to remove particles or solids that may damage the pump 5, the vehicle or any other parts of the fuel delivery unit 1. The filter unit comprises a filter 8 (Fig 4), which may be removable from the filter unit 6, e.g. so that it can be replaced or maintained. The filter 8 may be any type of filter or membrane that is suitable for filtering fuel of the type delivered by the system. Such filters may be made from e.g. fabric, non-woven, paper, polymers or other suitable filter materials.
Downstream of the filter unit and upstream of the pump 5 a first non-return valve 4 is arranged, which allows the fuel to move in the flow direction F but which prevents the fuel from moving against the flow direction F. The first non-return valve 4 may be of essentially the same type as the second non-return valve 7, or of a different type or size.
In addition to the above mentioned equipment, further equipment such as fuel blending means, metering equipment and payment equipment can be arranged in the fuel delivery unit.
The leakage means 13 operates to facilitate maintenance of the filter unit 6 by allowing fuel to flow back into the storage tank, past or through the second non-return valve, at a low enough rate, so that the filter unit may be maintained and the filter 8 replaced, before all the fuel present in the conduit 3 has flowed back to the storage tank 2. Thus, it will take less time to refill the conduit, and thereby the maintenance downtime of the fuel delivery unit 1 will be reduced.
Fig 4 is a schematic diagram of a device for a fuel delivery unit according to the invention. The device forms a part or a continuation of the conduit 3 from the storage tank 2 to the pump 5. The device comprises the two non-return valves 4, 7, the leakage means 13 and the filter unit 6 as described above. Between the filter unit 6 and the second non-return valve 7 a channel 9 is arranged.
The channel 9 may be any suitable conduit, pipe, hose, tubular structure or other hollow body that is capable of conveying a fluid such as fuel. The channel 9 can have a first end and a second end, at which first and second openings are provided. Generally, the first end of the channel 9 is situated on a vertically higher level than the second end of the channel, so that fluid present in the channel 9 needs to be propelled in order to move in a first direction, but may flow by means of gravity in the second direction.
The second non-return valve 7 is arranged at the second end of the channel 9, which is connected to the fuel source 11, e.g. the incoming part of the fuel conduit 3. The first non-return valve 4 is arranged at the first end of the channel 9, which is connected to a fuel drain 10, i.e. for example a conduit or a pump to which the fuel goes after having passed the first non-return valve.
The channel 9 and/or the non-return valves 4, 7 is coupled to the fuel source 11 and fuel drain 10 by coupling means 12 (Fig 6). These coupling means may be any sort of coupling or connection device that is suitable for providing a sealed and preferably detachable connection between the channel 9, its non-return valves 4, 7, filter unit 6 and the rest of the conduit 3 via the fuel source 11 and fuel drain 10. Thus, the coupling means 12 can be provided on the channel, the non-return valves as well as the filter unit, for coupling these components together and for coupling with the surrounding equipment such as the fuel source 11 and fuel drain 10. The coupling means comprise, but are not limited to, threaded fittings, bolted fittings, flange couplings, bayonet couplings, cam action couplers, bulkhead fittings, clamp fittings etc.
Fig 5 is a schematic view of an embodiment of a device for a fuel delivery unit according to the invention. In this embodiment, the channel 9 is a flexible pipe or hose. This can be advantageous since it will be easy to disconnect one end of the channel in order to remove the filter unit 6 for maintenance, while the other end near the second non-return valve 7 remains connected to the fuel source 11.
Fig 6 is a schematic perspective view of a filter unit and a first non-return valve of the embodiment shown in Fig 5. In this embodiment, the filter unit and the first non-return valve are integrated into one housing 20, which in turn is connected to an end flange 22 of the channel 9. Fig 6 shows the first non-return valve 4 with its closure means 14 in a closed state. The filter 8 is seen as a protrusion on the opposite, upstream side of the non-return valve 4. The filter according to this embodiment protrudes into the channel 9. The filter could also remain completely outside the channel or more or less be housed in the filter unit 6 or an extension thereof (not shown), so that the filter does not protrude into the channel 9. Fig 6 shows coupling means 12, of a slightly different type than those used in connection with the second non-return valve shown in Fig 8 and 9. Fig 6 also shows a turning device 23, which operates to open the first non-return valve 4, as will be explained below. This turning device 23 provides a means for regulating, controlling or switching the non-return valve between an open and a closed state. The means 23 may take on any form which enables the valve to be regulated between its two states.
Preferably, the coupling means 12 of the first non-return valve are of a type which is easily detachable, so that this end of the channel may be easily disconnected from the fuel drain 10 in order to enable filter maintenance.
Fig 7 is a schematic side view of the filter unit and first non-return valve shown in Fig 6. The housing 20 which incorporates the filter unit 6 and the first non-return valve is shown more clearly.
The filter unit/non-return valve 4 shown in Fig 6 and 7 is adapted for being permanently connected to the fuel drain 10, while the channel 9 with its flange 22 is detachably connected to the filter unit/non-return valve.
Fig 8 is a schematic perspective view of the second non-return valve 7. The non-return valve shown in Fig 8 is also a dual flap check valve, having a housing 19 in which the non-return valve itself, including its closure means 14, is located. In Fig 8, the closure means are in their open state. The housing 19 also comprises coupling means 12, which in Fig 8 are shown as holes or bolt fittings on the housing 19 of the non-return valve.
Fig 9 is a schematic top view of the second non-return valve 7. The housing 19 is shown having six holes 12c for bolts by which the valve is fitted to the fuel source 11 and/or the channel 9. In Fig 9, the closure means 14 are shown in their closed position. Leakage means 13 are shown as holes in the flaps.
Fig 10 and 11 show a detailed view of the device according to another embodiment of the invention. In the embodiment shown, the first non-return valve 4 is integrated with the filter unit 6 in a housing 20, and the filter 8 is removable from the housing 20. Coupling means are shown as bolts 12a which are to be arranged in holes 12c and fixated with nuts 12b. Plates 12d operate as to fixate the channel end flange 22 at the first en d 9a of the channel 9 to the housing 20. The channel 9 of Fig 10 is provided as a flexible pipe having end flanges 22 at both ends. The end flange 22 at the second end 9b is fastened to the housing 19 in a similar manner as the end flange at the first end 9a. Fig 10 and 11 also show a valve socket 21 and the closure means 14 of the second non-return valve 7. Gaskets 24 are provided between the first channel end 9a and the filter 8 as well as between the housing 20 and the fuel drain 11 and between the second channel end 9b and the valve 7.
Fig 12a-e are schematic diagrams of examples of a filter unit 6 and a first non-return valve 4 to be used in the invention.
In Fig 12a there is shown a filter unit with a first non-return valve which principally resembles the one shown in Fig 8 and 9, in that the filter unit 6 and the first non-return valve 4 are integrated into one housing. The channel with its coupling means 12 in the form of a flange 22 is also schematically shown, as well as the fuel drain 10 with its coupling means 12. The filter/ non-return valve unit 4, 6 has two separate sets of coupling means for coupling with the channel 9 and the fuel drain 10, respectively. It is however possible to provide coupling means on the filter/ non-return valve unit 4, 6, which connects with both the channel 9 and the fuel drain 10 simultaneously.
Fig 12b discloses a variant, in which the filter unit 6 and the non return valve 4 are provided as separate elements but are joined together by the coupling means. Here, just like in Fig 12a above, it is possible to use one coupling mechanism to lock all four parts 4, 6, 9, 10 together simultaneously.
Fig 12c shows another variant, where the filter unit 6 constitutes a housing having the coupling means, and where the non-return valve 4 is fitted in an appropriate manner and held in place by coupling means for coupling it with the filter unit 6. The valve in this embodiment may also be held in place by virtue of the fuel drain 10 (not shown) being coupled to the filter unit 6, thereby squeezing or fixating the valve as well.
Fig 12d shows yet another variant, where the relationship between the filter unit 6 and the non-return valve 4 is reversed: the filter unit is fitted into the housing of the valve and held in place when the valve housing is connected to the channel 9.
Finally, Fig 12e illustrates still another variant where both the filter unit 6 and the non-return valve 4 are fitted into a space in the joint between the channel 9 and the fuel drain 10. The filter unit 6 and the non-return valve 4 are thus held in place by e.g. flanges, protrusions, indentations or recesses in the joint between the channel 9 and fuel drain 10.
From Fig 12a-e it is clear that there are several different ways of connecting the channel, the filter unit, the first non-return valve and the fuel drain.
It can be advantageous to connect the first non-return valve 4 to the fuel drain 10 in a more permanent way, while making the connection between on one hand the channel 9 or the filter unit 6 and, on the other hand, the non-return valve 4, more easily detachable. The reason why this may be advantageous is that the non-return valve may prevent fuel remaining in the fuel drain 10 from flowing back causing spillage when the channel 9 and/or the filter unit 6 is removed.
Fig 13a-c are schematic diagrams of examples of non-return valves to be used as the second non-return valve in the invention.
Fig 13a shows how the leakage means 13 are provided as holes in the flaps 14 of the dual flap check valve. The leakage means may also be provided as an intentional "imperfection" or "misfit" in the edge of a flap 14, which enables fluid to pass the valve at a lower rate when it is closed.
As is shown in Fig 13b, the leakage means 13 may also be e.g. a by-pass channel, which is arranged so as to lead fluid past the closure means 14. Such a by-pass channel may e.g. be arranged in the housing 19 or in the valve socket 21.
Fig 13c shows another option, in which leakage means are provided by making the flap 14 or part thereof permeable, e.g. by providing pores or small holes in its surface.
In any case, the leakage means should be dimensioned so that they allow a reverse flow rate past or through the second non-return valve 7, that is low enough so that the channel may be disconnected from the fuel drain 10, the filter replaced and the channel reconnected in less time than it takes for the fuel that is present in the channel when the channel is disconnected to flow back past or through the second non-return valve 7. The dimensioning of the leakage means is believed to be within the capability of the skilled person.
Finally the leakage means can also comprise means for manually opening the closure means 14 of the non-return valve 7, such as e.g. those described in connection with Fig 6 and Fig 7 above and referred to as 23.
The channel 9, second and first non-return valves 7, 4 and filter unit 6 may advantageously be fitted into a fuel delivery unit, especially between the incoming conduit 3 from the storage tank and the pump 5 which provides the vacuum for generating the fuel flow.
A method of installing a detachable filter unit in a fuel delivery unit comprises a first step of arranging a second non-return valve 7 at a conduit of a fuel source 11, in order to allow fuel to flow freely at a first flow rate in a first direction, while the fuel is substantially prevented from flowing in a second direction. The valve 7 may be coupled to the fuel source 11 by means of complementary coupling means 12 provided on the fuel source 11 and on the valve 7.
The step of providing the second non-return valve may comprise the step of providing a leakage means for allowing the fuel to flow at a second flow rate in the second direction, past or through the second non-return valve. The leakage means may also be provided in a separate step.
A further step comprises connecting a second opening of a channel 9 to a downstream side of said second non-return valve 7, in order to conduct the fuel from the conduit of the fuel source 11. The channel 9 can be coupled to the valve using coupling means 12 on the valve and on the channel. It is also possible to couple the valve 7 and the channel 9 to the fuel source 11 in one step, using e.g. a set of locking means which couples all three components in a single step.
Yet another step comprises detachably arranging a filter unit 6 in, or at a first end of, the channel in order to filter the fuel conducted in the channel. The filter may e.g. be arranged according to any of the arrangements suggested above.
Another step comprises arranging a first non-return valve 4 on a downstream side of said filter, in order to allow the fuel to flow freely in the first direction but prevent the fuel from flowing in the second direction. The valve 4 may be arranged according to any of the arrangements suggested above.
A final step comprises connecting a downstream side of the first non-return valve 4 to a fuel drain conduit 10.
It is obvious that the steps do not need to be performed in the order set forth above. For example, it is possible to install the device in the fuel delivery unit 1 in the reverse order or to assemble the device comprising the two valves, the filter and the channel second and then install it in the fuel delivery unit 1.
The device provided herein enables a method for replacing a filter unit in a fuel delivery unit according to the following.
As a first step, a channel 9 is disconnected from its connection to a fuel drain 10. The disconnecting of the channel may comprise disconnecting the coupling means of any component which is arranged at that end of the channel, such as a valve 4 or a filter unit 6.
When the channel 9 is disconnected, fuel remaining in the channel is allowed to slowly flow in a direction opposite the normal flow direction F through a leaking means, past or through a second non-return valve 7.
While the fuel is flowing past or through the non-return valve 7, the filter unit is removed from the channel and a new or restored filter unit is inserted, after which the channel 9 is again connected to the fuel drain 10. The operations of removing and replacing the filter and reconnecting the channel 9 should take less time than it takes for the fuel present in the channel to drain completely back past or through the second non-return valve 7 through the leakage means 13. This is made possible by providing the appropriate dimensions of the leakage means 13.
The turning device 23 provided on the first non-return valve may advantageously be used to open the first non-return valve prior to disconnecting the channel for filter maintenance. When the valve is opened, fuel may flow back through the first non-return valve and through the leakage means at the second non-return valve, so that fuel remaining above the filter is removed, thereby further reducing the risk of spillage.
It is apparent to the skilled person that the embodiments described above may be combined and varied within the scope of the invention. For example, it is possible to combine different valve types with the different types of leakage means described above. The coupling means and their arrangement on the different parts are other aspects which provide for endless possibilities of variation.

It should furthermore be understood that the invention can also be applied to systems comprising a plurality of storage tanks, conduits, fuel delivery units etc.

Reference numbers
F	Flow direction
P	Pump

0	Ground level
1	Fuel delivery unit
2	Storage tank
3	Fuel conduit
4	First non-return valve
5	Pump
6	Filter unit
7	Second non-return valve
8	Filter
9	Channel
10	Fuel drain
11	Fuel source
12	Coupling means
13	Leakage means
14	Closure means
15
16
17	Pores
18	Delivery nozzle
19	Second non-return valve housing
20	First non-return valve housing
21	Valve socket
22	Channel end flange
23	Turning device

Claims

A device for a fuel delivery unit (1), said device comprising
a channel (9) for conducting a fuel flow;
a filter unit (6) arranged for filtering the fuel flow;
a first non-return valve (4) arranged downstream of the filter unit (6), said first non-return valve (4) allowing the fuel to flow freely in a first direction (F) but preventing the fuel from flowing in a second direction; and
a second non-return valve (7) arranged upstream of said filter unit (6), allowing the fuel to flow freely at a first flow rate in the first direction (F) but substantially preventing the fuel from flowing in the second direction;
characterized by
leakage means (13) for allowing the fuel to flow at a second flow rate in the second direction, from a downstream side to an upstream side of the second non-return valve (7).
A device as claimed in claim 1, wherein the channel (9) comprises an essentially tubular structure.
A device as claimed in claim 1 or 2, further comprising coupling means (12), adapted for detachably interconnecting any two of: an end (9a, 9b) of said channel (9), the filter unit (6), the first non-return valve (4) and the second non-return valve (7).
A device as claimed in claim 3, wherein the coupling means (12) are integrated with at least one of the channel (9), the first non-return valve (4), the filter unit (6) and the second non-return valve (7).
A device as claimed in claim 3, wherein the coupling means (12) are adapted for detachably coupling one of the first non-return valve (4) and the filter unit (6) to a downstream element (5, 10) within the fuel delivery unit (1).
A device as claimed in any of claims 1-5, wherein the first non-return valve (4) is arranged at a first end (9a) of the channel (9).
A device as claimed in any of claims 1-6, wherein the filter unit (6) is arranged at a first end (9a) of the channel (9).
A device as claimed in any of the preceding claims, wherein the filter unit (6) is detachably arranged in said channel (9).
A device as claimed in any of the preceding claims, wherein the first non-return valve (4) is arranged adjacent the filter unit (6).
A device as claimed in any of claims 1-8, wherein the first non-return valve (4) is integrated with the filter unit (6).
A device as claimed in claim 10, wherein the first non-return valve (4) is detachably integrated with the filter unit (6).
A device as claimed in any of the preceding claims, wherein the second non-return valve (7) is arranged at a second end (9b) of the channel (9).
A device as claimed in any of the preceding claims, wherein the second flow rate is substantially lower than the first flow rate.
A device as claimed in any of the preceding claims, wherein the leakage means (13) is adapted for allowing a predetermined amount of fuel to flow in the second direction during a predetermined time period.
A device as claimed in any of the preceding claims, wherein the second non-return valve (7) is at least partly permeable.
A device as claimed in any of the preceding claims, wherein said leakage means (13) comprises a hole in the second non-return valve (7).
A device as claimed in any of the preceding claims, wherein said leakage means (13) comprises a by-pass channel leading the fuel past the second non-return valve (7).
A device as claimed in any of the preceding claims, wherein the channel (9) comprises a flexible section that is arranged between said first and second non-return valves (4, 7).
A device as claimed in any of the preceding claims, wherein the first non-return valve (4) is arranged at a vertically higher level than the second non-return valve (7).
A device as claimed in any of the preceding claims, further comprising means (23) for regulating the first non-return valve (4) between an open and a closed state.
A device as claimed in any of the preceding claims, wherein the second direction is essentially opposite to the first direction (F).
A fuel delivery unit (1) comprising a device according to any of the preceding claims.
A fuel delivery unit (1) as claimed in claim 22, further comprising a pump (5) for providing the fuel flow.
A fuel delivery unit (1) as claimed in claim 22 or 23, further comprising a fuel source (11) from which the fuel is drawn.
A fuel delivery unit (1) as claimed in any of claims 23-24, wherein the pump (5) is arranged downstream of the first non-return valve (4).
A fuel delivery unit (1) as claimed in any of claims 24-25, wherein the fuel source (11) is arranged upstream of the second non-return valve (7).
A kit of parts for providing a device for a fuel delivery unit, said kit of parts comprising
a channel (9) adapted for conducting a fuel flow;
a filter unit (6) adapted to be arranged for filtering the fuel flow;
a first non-return valve (4) adapted to be arranged downstream of said filter unit (6), so that the first non-return valve (4) will allow the fuel to flow freely in a first direction (F) but prevent the fuel from flowing in a second direction;
a second non-return valve (7) adapted to be arranged upstream of said filter unit (6), in order to allow the fuel to flow freely at a first flow rate in the first direction (F) but to substantially prevent the fuel from flowing in the second direction; and
leakage means (13) adapted for allowing the fuel to flow at a second flow rate in the second direction, from a downstream side to an upstream side of the second non-return valve (7).
A method for providing a detachable filter unit in a fuel delivery unit (1), the method comprising the steps of
connecting a second non-return valve (7) to a fuel source (11), in order to allow fuel to flow freely at a first flow rate in a first direction (F), while the fuel is substantially prevented from flowing in a second direction;
providing leakage means (13) for allowing the fuel to flow at a second flow rate in the second direction, from a downstream side to an upstream side of the second non-return valve (7);
connecting a channel (9) to the downstream side of said second non-return valve (7), in order to conduct the fuel from the fuel source (11);
arranging a filter unit (6) in the channel (9) in order to filter the fuel conducted in the channel (9);
connecting a first non-return valve on a downstream side of said filter (6), in order to allow the fuel to flow freely in the first direction (F) but prevent the fuel from flowing in the second direction; and
connecting a downstream side of said first non-return valve (4) to a fuel drain (10).
A method for replacing a filter unit that is positioned to filter a fuel flow conducted in a channel of a fuel delivery unit (1), the method comprising the steps of:

disconnecting a first end (9a) of a channel (9) from one of a fuel drain (10), a filter unit (6) and a first non-return valve (4);

allowing fuel remaining in the channel (9) to flow through a leakage means (13), in a second direction, from a downstream side to an upstream side of a second non-return valve (7), while performing the steps of:

removing one of the filter unit (6) and the filter (8);

inserting a new or restored filter (8) or filter unit (6); and

connecting the first end (9a) of the channel (9) to said one of the fuel drain (10), the filter unit (6) and the first non-return valve (4).
The method of claim 29, further comprising the step of opening the first non-return valve (4) prior to disconnecting the first end (9a).