GB2511281A - Fuel tank - Google Patents

Abstract

A vent tube assembly 212 for use with a vehicle fuel tank 200 comprises a gas outlet vent (114 see fig 1, 414 see fig 4a) for allowing displaced gas to egress a fuel tank 200 as it is filled. At least one vent tube 230, 232 is provided in fluid communication with the gas vent (114) and extends into an internal volume of the tank 200. The assembly 212 is configured to close the gas vent (114) when fuel reaches a predetermined point within the vent tube 230,232. This may be achieved using a valve (116 see fig 1). The effective length may be configured by blocking vent tube sidewall apertures (440a-c see fig 4b). This may be achieved by rotation relative to the vent tube 230 of an inner tube having apertures on its outer wall. Differing effective lengths may be provided. The fuel tank and assembly are usable for a passenger bus. The invention prevents excess carriage of fuel weight by effectively adjusting tank capacity.

Description

Intellectual Property Office Application No. GB1221890.5 RTM Date:30 June 20t4 The following terms are registered trade marks and should be read as such wherever they occur in this document: Enviro Alexander Dennis Intellectual Property Office is an operating name of the Patent Office www.ipo.govuk

FUEL TANK

Field of the invention

The invention relates to a fuel tank and a method for restricting the capacity of a fuel tank. In particular, the invention relates to, but is not limited to, a fuel tank and a method for restricting the capacity of a fuel tank for use in passenger service vehicles.

Background

As used herein, the term passenger service vehicle" encompasses vehicles for transporting passengers and, in particular, road vehicles for transporting passengers.

Exemplary passenger service vehicles may be buses, coaches or the like.

Significant innovation and technology development has occurred in recent years in relation to the design of passenger service vehicles. In particular, there has been a continued drive towards providing vehicles that allow for improved fuel efficiency and ease of maintenance.

In addition, the weight of a passenger service vehicle has a direct correlation to its fuel efficiency and therefore its operating costs. It is therefore desirable to optimise the weight of a passenger service vehicle based on the vehicle operation during any given day.

Summary

According to the invention in a first aspect, there is provided a vent tube assembly for use with a vehicle fuel tank. The vent tube assembly comprises a gas vent configured to allow displaced gas to egress a fuel tank as the fuel tank is tilled with fuel. The vent tube assembly comprises a vent tube in fluid communication with the gas vent and configured to extend into an internal volume of a fuel tank when the vent tube assembly is fitted thereto. The vent tube assembly is configured to close the gas vent when fuel reaches a predetermined point within the vent tube, Optionally, the vent tube assembly comprises at least one aperture in a sidewall thereof, wherein the at least one aperture is selectively blockable to configure the vent tube assembly between a plurality of effective lengths for limiting a capacity of a fuel tank to which the vent tube assembly is fitted. In such exemplary fuel tanks, the effective length of the vent tube assembly may be defined as the distance from the outer wall of the fuel tank to the first of the plurality of apertures.

Optionally, the vent tube assembly is configured to be extractable from a fuel tank to which it is fitted to permit selective blocking of the at least one aperture.

Optionally, the at least one aperture is selectively blockable by one or more from the group comprising: a screw, a bolt and a plug. The effective length of the vent tube may thereby be configurable between a plurality of effective lengths.

Optionally, the vent tube assembly further comprises an inner tube located within and rotatable with respect to the vent tube, wherein the inner tube is configured to selectively block the at least one aperture when at a specific rotational position with respect to the vent tube.

Optionally, the vent tube assembly comprises a plurality of vent tubes each having a different effective length, and arranged such that the vent tube assembly may be configured between a plurality of effective lengths by selectively arranging one of the plurality of vent tubes in fluid communication with the gas vent for limiting a capacity of a fuel tank to which the vent tube assembly is fitted.

Optionally, the vent tube assembly further comprises a valve for closing the gas vent when fuel reaches a predetermined point within the vent tube, Optionally, the vent tube assembly further comprises a sensor configured to detect the presence of fuel at the predetermined point within the vent tube for closing the gas vent.

According to the invention in a second aspect, there is provided a fuel tank comprising a vent tube assembly as described above.

Optionally, the vent tube assembly is fitted to an upper region of the fuel tank, and the vent tube extends substantially downwards into an internal volume of the fuel tank.

According to the invention in a third aspect, there is provided a fuel tank. The fuel tank comprises an outer wall defining an internal volume of the fuel tank. The fuel tank comprises a filling tube configured to permit fuel to flow into the internal volume. The fuel tank comprises a vent tube assembly. The vent tube assembly comprises a gas vent configured to allow displaced gas to egress the fuel tank as the fuel tank is filled with fuel. The vent tube assembly comprises a vent tube in fluid communication with the gas vent and extending into the internal volume of the fuel tank. The vent tube assembly is configured to selectively close the gas vent when fuel reaches a predetermined point within the vent tube.

According to the invention in a third aspect, there is provided a fuel tank. The fuel tank comprises at least one outer wall defining an internal volume of the fuel tank. The fuel tank comprises a filling tube configured to permit fluid flow into the internal volume of the fuel tank. The fuel tank comprises a vent tube assembly. The vent tube assembly comprises a vent tube extending into the internal volume of the fuel tank. The vent tube assembly is configured to selectively allow gas to egress the internal volume of the fuel tank as the fuel tank is filled, based on whether fuel has reached a predetermined point within the vent tube. The vent tube assembly is configurable between a plurality of effective lengths to limit the amount of the internal volume of the fuel tank that may be filled with fuel.

In exemplary fuel tanks, the effective length of the vent tube assembly may refer to the length of a vent tube of the vent tube assembly between a valve configured to close the vent tube assembly and a point at which there is fluid communication between the vent tube assembly and the internal volume of the fuel tank. The effective length of the vent tube assembly may be the distance between the valve and the first point along the physical length of the tube at which there is fluid communication between the vent tube assembly and the internal volume of the fuel tank. It may be that the shorter the effective length of the vent tube assembly, the larger the amount of the internal volume of the fuel tank that may be filled with fuel.

The fuel tank may be an under stairs fuel tank on a bus. The fuel tank may be a behind the driver fuel tank on a bus.

A passenger service vehicle may comprise the variable capacity fuel tank described above.

The passenger service vehicle may be a bus.

According to the invention in a fourth aspect, there is provided a method for restricting the capacity of a fuel tank for a passenger service vehicle. The method comprises providing a fuel tank having a vent tube assembly fitted thereto. The vent tube assembly comprises a gas vent configured to allow displaced gas to egress a fuel tank as the fuel tank is filled with fuel. The vent tube comprises a vent tube in fluid communication with the gas vent and configured to extend into an internal volume of a fuel tank when the vent tube assembly is fitted thereto. The vent tube assembly is configured to close the gas vent when fuel reaches a predetermined point within the vent tube, thereby restricting the capacity of the fuel tank, Optionally, the method further comprises configuring the effective length of the vent tube assembly between a plurality of effective lengths.

Optionally, the vent tube assembly comprises a vent tube having a plurality of apertures in a sidewall thereof, and configuring the effective length of the vent tube assembly comprises selectively blocking one or more of the plurality of apertures.

Optionally, the method further comprises extracting the vent tube from the fuel tank for selectively blocking one or more of the plurality of apertures.

Optionally, the vent tube assembly comprises a plurality of vent tubes each of a different length, and wherein configuring the effective length of the vent tube assembly comprises selectively arranging one or more of the plurality of vent tubes in fluid communication with the gas vent.

Brief description of the drawings

Figure 1 is a schematic representation of a fuel tank for a passenger service vehicle with an outer wall removed; Figure 2 is a schematic representation of a fuel tank for a passenger service vehicle with an outer wall removed; Figure 3 is a schematic representation of a vent tube assembly and a filler tube; Figure 4a is a schematic representation of a fuel tank for a passenger service vehicle with an outer wall removed; Figure 4b is a schematic representation of a fuel tank for a passenger service vehicle with an outer wall removed and showing a vent lube assembly extracted from the fuel tank.

Description

Typically, a vehicle fuel tank has a single maximum capacity. If an alternative maximum capacity is required then a replacement tank may be fitted to the vehicle. In the case of passenger service vehicles, this can be costly for operators and may result in the vehicle being out of use while the replacement tank is filled. In fixed fuel tank designs, a passenger service vehicle will typically be refuelled to capacity at the start of a day in operation. This commonly results in the passenger service vehicle having a considerable amount of fuel left in the fuel tank at the end of a day in operation.

It is noted that the variable capacity fuel tanks disclosed herein may be fitted to any type of vehicle, not just passenger service vehicles. In particular, the fuel tanks may be fitted to freight movement vehicles, such as light goods vehicles and heavy goods vehicles, and to fleet delivery vehicles.

The inventors have appreciated that a reduction to the amount of excess fuel is a reduction in unnecessary weight and can influence the vehicle fuel consumption. This in turn has an effect on the efficiency of the passenger service vehicle for the vehicle operator.

For example, the Enviro 400 bus, manufactured by Alexander Dennis Limited, has a fuel tank capacity of approximately 270 litres and the operators refill the fuel tank to the maximum capacity for every day in operation. However, the bus very rarely uses the full capacity of the fuel tank during a day in operation and will normally use less than litres per day.

In addition, the inventors have appreciated that the introduction of a number of fuel saving ideas reduced further the amount of fuel used each day. In addition, if further fuel saving ideas are implemented in existing passenger service vehicles, the amount of fuel used each day may alter over time and according to different requirements and local environments. As a consequence, a passenger vehicle is typically regularly carrying a significant volume of fuel that is not required and, the inventors have appreciated that by reducing this, the vehicle weight can be reduced and the overall vehicle efficiency improved. For example, 170 litres of unused fuel is approximately kilograms carried for no reason (close to the equivalent of 2 passengers).

Different sized tanks can be made to suit different capacities. However, these can have packaging issues and operators may want one capacity for a period, then an alternative capacity for a period, followed by another capacity for a further period. This can be expensive as replacement sized tanks would be required and a passenger service vehicle may be out of use while the replacement fuel tanks are fitted. The purchase cost and storage required for multiple tanks can be expensive and time is required to remove the original and replace it with a different capacity tank.

Figure 1 shows a fuel tank 100. External walls of the fuel tank 100 are not shown so as to make the internal features of the fuel tank 100 clear. The exemplary fuel tank of Figure 1 is an under stairs" fuel tank for use in an Enviro 400 passenger service vehicle. However, exemplary fuel tanks may comprise other types of fuel tank, such as a "behind the driver" fuel tank. Exemplary fuel tanks may be suitable for use in any type of passenger service vehicle.

The fuel tank 100 comprises a top plate 102. The top plate 102 forms one of the outer walls of the fuel tank 100 and is configured to allow the fitment of various features of the fuel tank 100 thereto. Specifically, the top plate 102 comprises two apertures 104, 106. The apertures 104, 106 are rectangular in shape and are configured to allow one or more port plates 108, 110 to be fitted thereto. The port plates 108, 110 are detachably fitted to the top plate 102 to provide an air tight seal therebetween. In exemplary fuel tanks 100, the port plates 108, 110 may be fixed to the top plate 102 by screws.

The pod plate 108 comprises a vent tube assembly 112. The vent tube assembly is configured to allow gas in the internal volume of the fuel tank 100 to egress the fuel tank 100 as it is filled with fuel. That is, as the vent tube assembly 112 is configured to allow gas that is displaced by fuel entering the fuel tank 100 to escape the fuel tank 100. The gas will typically be a mix of air and fuel vapour.

The vent tube assembly comprises a gas outlet 114 and a valve 116. The valve 116 is configured to block of the gas outlet 114 when fuel contacts the underside of the valve 116. The underside of the valve 116 being exposed to the inside of the fuel tank 100.

The port plate 110 comprises a fill tube 118. The fill tube 118 is configured to allow fluid communication between the exterior and interior of the fuel tank 100. Moreover, the fill tube 118 is configured to allow fuel to pass from a fuel pump (not shown) into the internal volume of the fuel tank 100. The filler tube 118 is fitted with a filler cap 120.

The filler cap 120 is configured to selectively block the filler tube 118 and, in the case of the exemplary fuel tank of Figure 1, this is done with a hinge 122 and spring arrangement that biases the filler cap 120 in a closed position.

Figure 2 shows a fuel tank 200. Again, external walls of the fuel tank 200 are not shown so as to make the internal features of the fuel tank 200 clear. Features of the fuel tank 200 are similar to those of the fuel tank 100 and are therefore not explained again here.

The filler tube 218 extends into the internal volume of the fuel tank 200. The filler tube 218 is fitted to a pod plate 210 in an arrangement to the filler tube 118 and the port plate 110 of Figure 1.

The vent tube assembly 212 comprises a first vent tube 230 and a second vent tube 232 extending into the internal volume of the fuel tank 200 downward from the top plate. It is noted that the terms downward" and top' are used herein to help explain the configuration of the fuel tanks disclosed and are not to be construed as limiting.

However, when the fuel tanks disclosed are fitted to a passenger service vehicle, at least part of the vent tubes may extend generally downwards into the fuel tanks to achieve the desired variable capacity of the fuel tanks. The first vent tube 230 is longer than the second vent tube 232 and extends further into the internal volume of the fuel tank.

The first and second vent tubes 230, 232 are each connected to an aperture in the top plate 202. In the exemplary fuel tank 200 of Figure 2, the first vent tube 230 is in fluid communication with a first aperture 204a, and the second vent tube 232 is in fluid communication with a second aperture 204b. In addition, a third aperture 204c is formed in the top plate 202 and is not in fluid communication with a vent tube. In addition, the first and second vent tubes 230, 232 are each open at an end distal to the top plate 202. The first and second vent tubes 230, 232 therefore define a fluid path from the internal volume of the fuel tank 200 to an aperture 204a-c.

First, second and third port plates 208a-c are located on the top plate 202 to cover the first, second and third apertures 204a-c respectively. The effective length of the vent tube assembly 212 is configurable by fitting a port plate comprising a gas outlet to one or more of the apertures 204a-c. In the exemplary fuel tank 200, the port plate 208a comprises a gas outlet and a valve as described in Figure 1. The second and third apertures 204b, 204c are each fitted with a blanking plate that seals the respective aperture. Therefore, the effective length of the vent tube assembly 212 is configured to be the length of the first vent tube 230.

In an alternative configuration, the port plate 208b may comprise a gas outlet and a valve and the apertures 204a and 204c may be sealed by a blanking plate. In such configurations, the effective length of the vent tube assembly is configured to be the length of the second vent tube 232. In another alternative configuration, the port plate 208c may comprise a gas outlet and a valve and the apertures 204a and 204b may be sealed with a blanking plate. In such configurations, the vent tube assembly has an effective length of zero, as the aperture 204c opens directly into the internal volume of the fuel tank 200.

Taking the configuration of figure 2 as an example, the capacity of the fuel tank 200 is limited to a level slightly above the distal end of the first vent tube 230. As the fuel tank is filled through the filler tube 218, the tank fills normally until the fuel reaches the bottom (i.e. the distal end) of the first vent tube 230. At this point, as fuel continues to enter the fuel tank, it will fill the first vent tube 230 more quickly than it will fill the remainder of the fuel tank 200. Therefore, fuel will travel up the first vent tube toward the valve and the gas outlet more quickly than the fuel will fill the remainder of the fuel tank 200. As the fuel contacts the valve, it will operate to block the gas outlet prevent further egress of gas and/or fuel from the outlet. When the gas outlet is blocked, fuel then begins to travel up the filler tube 218 until it makes contact with the nozzle of a fuel pump, which then operates to stop fuel flowing into the fuel tank 200.

This limits the capacity of the fuel tank 200 to a level slightly above the end of the first vent tube 230. The capacity is just above the level of the end of the first vent tube 230, as some fuel (largely equivalent to the volume of the vent tube 230 itself) will till the remainder of the fuel tank while the fuel travels up the first vent tube 230.

In the configuration in which the port plate 208b comprises a gas outlet and a valve and the apertures 204a and 204c are sealed, the capacity of the fuel tank is limited to a level slightly above the level of the end of the second vent tube 232. In the configuration in which the port plate 208c comprises a gas outlet and a valve and the apertures 204a and 204b are sealed, the capacity of the fuel tank 200 is equivalent to the total internal volume of the fuel tank 200.

It is therefore possible to vary the capacity of the fuel tank 200 by varying the effective length of the vent tube assembly 212. In the case of the fuel tank 200, this is achieved by sealing one or more apertures 204a-c in the fuel tank 200, and allowing gas to egress the fuel tank 200 from one aperture 204a-c. The effective length of the vent tube assembly is the length of the longest unsealed vent tube 230, 232.

Accordingly, the fuel tank 200 has three (or more in other exemplary tanks) fill capacities that can easily be obtained by the changing of port plates 208a-c of the fuel tank 200. No new tank is required to alter the capacity of the fuel tank 200.

It is noted that other exemplary fuel tanks may comprise vent tube assemblies having any number of vent tubes.

Figure 3 shows a schematic representation of the filler tube 218 and the first and second vent tubes 230, 232, which more clearly shows the relative lengths of each tube.

Figures 4a and 4b show a fuel tank 400. External walls of the fuel tank 400 have been removed so as to make the internal features of the fuel tank 400 clear. The exemplary fuel tank 400 is a behind the driver" fuel tank for use in an Enviro 400 passenger service vehicle. The fuel tank 400 comprises a filler tube 418, which is arranged in a similar configuration to the filler tubes 118, 218 of Figures 1 and 2. The fuel tank 400 also comprises vent tube assembly 412. The vent tube assembly 412 comprises a vent tube 430, a gas outlet and a valve. The vent tube assembly is detachably connected to a top plate 402 of the fuel tank 400. In the exemplary fuel tank 400 of figure 4, the vent tube assembly 412 may be detached from the top plate 402 by removal of a plurality of screws, which secure the vent tube assembly 412 to the top plate 402. Once the screws have been removed, the vent tube assembly 412 may be pulled out of the fuel tank 400 to expose the vent tube 430. Therefore, the vent tube assembly 412 is extractable from the fuel tank 400.

The vent tube 430 comprises a cylindrical tube, open at each end. An open end of the vent tube 230 positioned at or near the top plate 402 is in fluid communication with the gas outlet 414. The gas outlet 414 is selectively blockable by the valve. The open end of the vent tube 430 distal to the top plate 402 is in fluid communication with the internal volume of the fuel tank. The vent tube 430 therefore provides a fluid path from the internal volume of the fuel tank 400, through the vent tube 430 and out through the gas outlet 414. The wall of the vent tube 430 has two apertures 440a-c formed therein, which are best seen in Figure 4b. The apertures 440a-c are selectively blockable. The apertures 440a-c may be blocked by any suitable means, such as, for example, bolts, screws, plugs. Alternatively, the apertures 440a-c may be selectively blocked by way of an inner tube located within the vent tube 430. The inner tube may be configured to rotate within the vent tube and may have a number of apertures on its outer wall. The apertures on the outer wall of the inner tube may be configured to align with the apertures 440a-c in the vent tube at specific relative rotations of the inner tube and the vent tube 430. For example, if the inner tube is rotated by a specific amount with respect to the vent tube 430, the aperture 440c may be unblocked and the apertures 440a and 44b may be blocked. At other relative rotational positions of the inner tube, other of the apertures 440a-c may be blocked or unblocked to achieve at least the configurations discussed above.

When the vent tube 430 is removed from the fuel tank 400, the apertures 440a-c are exposed. When the vent tube assembly 412 is fitted to the fuel tank, the apertures 440a-c are located within the internal volume of the fuel tank 400.

In the configuration shown in Figures 4a and 4b, aperture 440c is unblocked and apertures 440a and 440b are blocked with bolts or screws. It is noted that any other configurations of blocked and unblocked apertures may be used. In a particular configuration, the aperture 440b may be unblocked and the aperture 440a may be blocked. In another particular configuration, the aperture 440a may be unblocked.

Referring to the exemplary aperture configuration of Figures 4a and 4b, the effective length of the vent tube assembly 412 is the length of the vent tube 430 to the aperture 440c. When the fuel tank 400 is being filled, the fuel fills the tank in a normal fashion until the level of the fuel is such that it covers the aperture 440c. At this point, all the apertures 440a, 440b above the fuel level are blocked by the bolts or screws, and there is therefore no fluid (gas) path between the inside of the vent tube 430 and the internal volume of the fuel tank 400. Therefore, as fuel continues to enter the fuel tank 400, it rises up through the vent lube more quickly than it fills the remainder of the fuel tank 400. As a result, the fuel level within the vent tube 430 rises more quickly than the fuel level in the remainder of the fuel tank 400 and fuel rises up the vent tube 430. When the fuel contacts the valve, it operates to close the gas outlet. As fuel continues to enter the fuel tank, it must travel up the filler tube 418 where it makes contact with a nozzle of the fuel pump, preventing any more fuel from being pumped into the fuel tank 400. The maximum capacity of the fuel tank is thereby limited to a level slightly above the level of the aperture 440c when the vent tube assembly 412 is fitted to the fuel tank 400, as explained above in relation to Figure 2.

If the aperture 440b is unblocked and the aperture 440a is blocked, the effective length of the vent tube assembly 412 is the length of the vent tube 430 to the aperture 44Db.

The capacity of the fuel tank 400 is therefore to level slightly above the aperture 440b.

It is noted that, in such a configuration, it is not important whether the aperture 440c is blocked or unblocked. If the aperture 440a is unblocked, the effective length of the vent tube assembly 412 is the length of the vent tube 430 to the aperture 440a. The capacity of the fuel tank 400 is therefore to level slightly above the aperture 440a. II is noted that, in such a configuration, it is not important whether the apertures 440b and 440c are blocked or unblocked.

The effective length of the vent tube assembly may therefore be configured to limit the capacity of the fuel tank. The effective length of the vent tube assembly is configurable by selectively blocking and/or blocking one or more of the apertures 440a-c in the vent tube 430.

The skilled person will be able to envisage other embodiments without departing from the scope of the appended claims.