WO1998041415A1

WO1998041415A1 - Arrangement for venting of fuel tanks in a vehicle

Info

Publication number: WO1998041415A1
Application number: PCT/SE1998/000466
Authority: WO
Inventors: Jan MALMSTRÖM; Karl-Gustav Davidsson; Dennis Jonsson
Original assignee: Scania Cv Aktiebolag (Publ)
Priority date: 1997-03-18
Filing date: 1998-03-16
Publication date: 1998-09-24
Also published as: SE9701023L; SE506883C2; SE9701023D0

Abstract

An arrangement for venting of fuel tanks in buses whereby at least two fuel tanks are arranged on either side of the vehicle's centreline (5) includes a vent line between the tanks. This involves the vent line (30) being accommodated in a supporting tube (6) which extends through the vehicle's passenger space. This makes it possible for the vent line (30) to be in a protected location and for the tanks to be arranged at relatively high positions in the bus, e.g. in its wheel housings.

Description

Arrangement for venting of fuel tanks in a vehicle

Technical area

The invention relates to an arrangement for venting of fuel tanks in a vehicle in accordance with the preamble to patent claim 1.

State of the art

It is necessary for motor vehicle fuel tanks to be provided with some form of conduit by means of which they can be vented (ventilated) to the surrounding air. This is required not only to facilitate refuelling by allowing the evacuation of air confined in the tank but also to allow air to enter the tank while the vehicle is operating and thereby to prevent the formation in the tank of a vacuum which would make it difficult for fuel to be drawn from the tank.

In the case of fuel tanks for passenger cars and other vehicles with relatively narrow long filler pipes, it is usual to provide a separate vent line leading into the filler pipe. This is advantageous in that the location is protected from external influences and contamination. It also ensures that any fuel which might for any reason leak out through the vent line will drain to the tank.

Fuel tanks for heavy-duty vehicles such as buses and trucks usually require no separate vent line, since their filler pipe is not only relatively short but also sufficiently large to allow direct venting via the filler pipe.

However, heavy-duty vehicles usually have two or more fuel tanks to make it possible for them to travel considerable distances without having to refuel. The respective tanks are connected together so that refuelling can be effected via a single filler pipe leading to only one of the tanks and the other tank needs no filler pipe of its own. In such cases the tanks are connected via a vent line which allows the tank which has no filler pipe to be vented initially to the tank which has the filler pipe, via which conventional venting can then take place. For this reason, the tanks are mutually connected via a vent line which links the tops of the respective tanks and runs between them at a level higher than the tanks in order to prevent fuel from blocking the vent line. In addition, the respective bottoms of the tanks are mutually connected so that fuel can move between the tanks in order to equalise differences in level.

The possibilities of providing a vehicle with a vent line between two tanks which are arranged on either side of the vehicle's centreline are limited by the fact that the space available is limited. For example, in heavy-duty buses, particularly those which have their floor situated low, practical problems arise in running a vent line outside the passenger space. Difficulties in finding space for the tanks and/or a desire to increase the total tank volume have resulted in solutions involving several tanks, sometimes up to four in number. There are solutions for buses whereby two tanks are conventionally arranged on the vehicle's frame on either side of the bus centreline but with two further tanks arranged in the front wheel housings. In this type of vehicle the tanks are placed at such a high level that it is impossible to arrange vent lines outside or below the passenger space. The vent lines have instead to be arranged to run along and inside the two sidewalls of the bus and across the inner roof of the passenger space. This requires special measures not only to fasten the vent line but also to protect it from external influences.

Objects of the invention

One object of the invention is to provide an arrangement for simple and protected placing of a vent line in a vehicle with fuel tanks arranged on either side of the vehicle's centreline. Further objects are to allow great flexibility with regard to the possibilities of using various different numbers of tanks and to enable vehicles to be manufactured as standardised units which can be adapted individually to the relevant number of tanks.

Brief description of the invention

These objects are achieved by means of an arrangement in accordance with the characterising part of patent claim 1. Using a supporting tube for the vent line affords the possibility of a simple and inexpensive solution for installing the vent line. The supporting tube provides the vent line with a protected location and obviates the need which would otherwise arise to adapt walls and panels of the passenger space.

According to one advantageous embodiment, the supporting tube takes the form of a single bent tube. This not only makes it easy to fit the vent line but also means that the supporting tube forms an enclosed space. Should the vent line leak, there is no risk of fuel or fuel vapour leaking into the passenger space.

Further features and advantages of the invention are indicated in the patent claims and the embodiment described below.

List of drawings

The attached drawings are as follows:

Fig.1 shows part of a passenger space in a bus and a supporting tube which is arranged within the passenger space, Fig.2 shows schematically the bus's fuel tanks, and Fig.3 shows on a larger scale an upper fastening of the supporting tube to the vehicle's roof.

Description of an embodiment

Fig.1 shows a horizontal view of part of a passenger space in a vehicle, exemplified here by a heavy-duty bus. The bus conventionally incorporates a number of seats and the diagram shows four seats 2 arranged on either side of a central gangway 3. In the region of the bus's front wheels there are wheel housings 4 which extend into the passenger space on either side of the bus centreline 5. These wheel housings 4 accommodate not only the vehicle's front wheels but also two fuel tanks 22,23, which are thus arranged on each side of the vehicle's centreline 5. To enable passengers to steady themselves, a number of supporting tubes are arranged conventionally between the floor and roof of the passenger space. Fig.1 shows a supporting tube 6 arranged to extend between the bus's wheel housings 4. In this case the supporting tube 6 consists of a single tube bent into an inverted "U" shape. Passengers who do not see the upper central horizontal section 7 of the tube 6 will regard the tube as two separate vertical supporting tubes.

Fig.1 also shows a cross-section of the bus roof in the region of the upper horizontal section 7 of the supporting tube 6. The bus has an outer roof 8 and an inner roof 9. The outer roof 8 forms part of the bus's external body structure and consists of sheetmetal panels which are fastened to and held together by a latticework of beams. The inner roof 9 is made of porous material, e.g. pressed fibre material, and is supported by brackets fastened to the inside of the outer roof. Between the inner roof 9 and the outer roof 8 there is a space 10 which is at least to some extent filled with damping insulating material and is also used to accommodate pipe systems, wiring etc. in the bus.

Fig.3 shows a fastening 17 by means of which the supporting tube 6 is fastened to the roof. An angle bracket 12 is fastened to one of the beams 11 of the outer roof by means of a bolted connection 18 and has fastened under its angled section a clamp 13 which surrounds the supporting tube. The clamp 13 consists of two halves 14,15 with semicircular inside surfaces which grip the supporting tube 6 on the section 7 which extends horizontally across the bus. The halves 14,15 are clamped together by two bolted connections 16 on either side of the supporting tube 7, which thereby also clamp the supporting tube firmly between them. These bolted connections 16 are also used for fastening the halves 14,15 to the bracket 12. In this example two identically similar fastenings 17 are arranged for fastening the supporting tube 6 to the roof, as depicted in Fig.1.

Fig.2 shows a schematic diagram of the bus's fuel tank system. As previously mentioned, the bus has two fuel tanks 22,23, each of them accommodated in one of the wheel housings 4. In addition, there are two lower fuel tanks 20,21 at the level of the bus's two longitudinal frame members. The two lower tanks 20,21 are arranged at a lower level than the upper tanks 22,23 accommodated in the wheel housings 4. In the example depicted, the righthand upper tank 22 is provided with a filler pipe 25. The mouth of the filler pipe 25 is arranged at such a level that the tank cannot be filled right up without fuel beginning to run out via the filler pipe 25, provided that the bus is standing on a relatively 5 level surface. This means that there is in the tank 22 a certain spare volume which cannot be filled with fuel and is intended to cater for possible expansion of fuel due to temperature variation. Fig.2 shows a level 26 in the two upper tanks 22,23 which corresponds to the highest level to which they can be filled.

10 The upper righthand tank 22 is connected to the lower righthand tank 20 via a fuel line 28 which extends between the bottom of the upper tank 22 and the top of the lower tank 20.

The upper tank 23 and a lower tank 21 are arranged analogously on the other side of the bus, on the lefthand side in the diagram, and communicate with one another via a fuel line 15 29. The lefthand upper tank 23, however, is not provided with a filler pipe.

A vent line 30 extends between the two upper tanks 22,23 arranged in the wheel housings and has its two ends connected to connections on the respective tanks 22,23. These connections are arranged at the same level as the level 26 to which the tanks can be filled.

20 An equalising line 31 links the bottoms of the respective lower tanks 20,21. In the bottom of the righthand lower tank 20 there is also a connection (not depicted) for a fuel line via which the bus's fuel injection pump and engine can be supplied with fuel. The vent and fuel lines described are made of conventional materials suitable for the purpose, such as rubber and similar elastic materials. The tanks 20-23 are made of injection moulded

25 plastic material to form shapes suitable for incorporation in buses. In alternative embodiments these lines and tanks may be made of other materials such as steel, aluminium or sheetmetal.

Fig.2 is a schematic diagram intended to show how the various components are connected 30 to one another. In practical embodiments these components may differ in form from what has been described and depicted. For example, the tanks may be shaped differently, they may be arranged so that the bottoms of the upper tanks are at a lower level than the tops of the lower tanks, the connections may be at other points and what has been described as lines may in practice consist of a number of lines connected to one another. The upper tanks 22,23 are in practice arranged not as depicted in Fig.2, directly above the lower tanks 20,21, but are displaced relative to the lower tanks in the longitudinal direction of the bus. In addition to what has been described, the bus's fuel tank system includes conventional fuel return lines, fuel gauges and other units and lines which are described in no greater detail here because they are not essential for understanding the invention. For the same reason, the functioning of this fuel tank system is described only schematically below.

Refuelling is effected via the filler pipe 25, which first leads the fuel to the righthand upper tank 22. During refuelling, air is evacuated from the tank 22 to the surrounding air via the filler pipe 25. During refuelling, the fuel fills first the two lower tanks 20,21 and thereafter the two upper tanks 22,23. It runs through the lines 28,29,31 connected to the tanks so that the level rises substantially equally in the tanks on both sides as refuelling proceeds. Evacuation of air from the two lefthand tanks 21,23 takes place via the vent line 30 so that the air is first ventilated to the righthand upper tank 22 from which, as indicated in the foregoing, it is then ventilated via the filler pipe to the surrounding air. Just before the upper tanks 22,23 are completely full to their maximum levels 26, the fuel level reaches the connections for the vent line 30, thereby preventing further venting. If any further fuel is introduced, the filler pipe 25 will be filled with fuel until it overflows unless refuelling is halted.

When the bus is in operation, fuel will be supplied to the engine via the connection (not depicted) in the bottom of the righthand tank 20. As during refuelling, equalisation of the level of the fuel in the right and left tanks takes place via the equalising line 31. The tanks need ventilating progressively as fuel is consumed. The righthand upper tank 22 is ventilated via a valve (not depicted) arranged in a tank lid 32 covering the filler pipe 25.

This valve is arranged as a check valve which opens at a certain relatively low negative pressure in the tank 22 so that air can be drawn in and equalise the pressure in the tank 22.

The lefthand tanks 21,23 are ventilated in the same way as during refuelling, via the vent line 30 connected to the tanks. A particular feature of the embodiment described is that the vent line 30 is accommodated in the previously described supporting tube 6. In this example the vent line takes the form of a separate line accommodated in the supporting tube. This makes it easy to install the vent line 30 while at the same time providing it with a protected location. The supporting tube, which is designed to provide passengers with good support, is not only fastened robustly in the bus but also made of robust material. This means that the vent line is in a protected location. If the supporting tube 6 connects to the wheel housings 4 as described and the bus is provided with upper tanks 22,23, the result is a short distance between the respective tanks and the supporting tube, thereby facilitating line installation. In alternative embodiments the supporting tube may be more or less bent, which causes no problems if the vent line 30 is made of flexible material.

To facilitate and standardise bus manufacture, all buses may be provided with a supporting tube which accommodates a prefitted vent line which is provided with connection nipples at both ends in the vicinity of the ends of the supporting tube. In cases where the bus is equipped with tanks on either side of its centreline, vent lines from the respective tanks may be connected to connections at the ends of the supporting tube by means of relatively short lines. This also makes it easy for a bus which originally had only one tank to have a tank added on the other side of the bus.

In alternative embodiments the bus may be provided with other numbers of tanks. In cases where only one upper tank is arranged on one side of the bus, the vent line on the other side is connected analogously to the top of the tank concerned. In cases where the bus has only lower tanks, these may be connected analogously, even if somewhat longer lines are required before the vent line is led into the supporting tube or is connected to the connections at the respective ends of the supporting tube. It is also possible to arrange a supporting tube which extends between two points on the bus floor instead of between the wheel housings, to accommodate a vent line. Another possible solution is to use the supporting tube itself as part of the vent line and thus connect vent lines directly from respective tanks to the ends of the supporting tube. This poses somewhat more exacting requirements for the supporting tube, however, so in the majority of cases it would represent a less advantageous overall solution.

It is possible to use combinations with other numbers of tanks, e.g. there need not be two upper tanks but possibly only one or none at all. Venting of the two lower tanks can be achieved either by means of a supporting tube which may be arranged on the wheel housings or via a supporting tube which is otherwise analogous in form and extends between the bus floor and roof.

An advantage of the invention is that a bus which at the time of manufacture is only provided with one tank can easily have a further tank added on the opposite side and that it is easy to fit a vent line in a supporting tube. The potential for standardised manufacture of a bus in combination with the possibility of using various different numbers of tanks is obvious.

In the example described, the supporting tube is intended as a tube which a passenger can hold on to or otherwise use to steady him/herself while the bus is in motion and/or while he/she is moving about in the bus. The supporting tube is usually circular in cross- section, but it is obvious that other cross-sectional shapes are also conceivable. The supporting tube may also be to a lesser or greater extent combined with walls and panels in the passenger space of the bus and there is no need for it to take the form of a totally exposed tube accessible along its entire extent. All that is required for it to be a supporting tube according to the invention is that some part of it can in some way be used as support for a passenger.

Claims

Patent claims

1. Arrangement for venting of fuel tanks in a vehicle, preferably a bus, whereby at least two fuel tanks are arranged on either side of the vehicle's centreline (5) and are connected to one another via a vent line (30), characterised in that the vent line (30) is accommodated in a tube (6) with extent in the passenger space of the vehicle, which tube also constitutes a supporting tube for passengers to steady themselves against.

2. Arrangement according to claim 1 , characterised in that the supporting tube takes the form of a bent tube (6) with its ends arranged on either side of the vehicle's centreline (5) and that an upper central horizontal section (7) of the supporting tube is accommodated in a space (10) in the vehicle's roof, with the end sections of the supporting tube extending vertically in the passenger space.

3. Arrangement according to claim 1, characterised in that the vent line takes the form of a separate line (30) which is accommodated in the supporting tube (6).

4. Arrangement according to claim 2, characterised in that the ends of the supporting tube (6) are fastened to the vehicle's wheel housings (4).

5. Arrangement according to claim 2, characterised in that the ends of the supporting tube (6) are fastened to the vehicle's floor.

6. Arrangement according to claim 4, characterised in that at least one of the fuel tanks (22,23) is arranged in one of the vehicle's front wheel housings (4).

7. Arrangement according to any one of claims 1-6, characterised in that only one of the tanks (20-23) is provided with a fuel filler pipe (25).

8. Arrangement according to any one of claims 1-7, characterised in that the vehicle takes the form of a bus.