SE540795C2

SE540795C2 - A gas fuel storage assembly

Info

Publication number: SE540795C2
Application number: SE1650865A
Authority: SE
Inventors: Pasic Anel; BÖRJES Markus
Original assignee: Scania Cv Ab
Priority date: 2016-06-20
Filing date: 2016-06-20
Publication date: 2018-11-13
Also published as: DE102017005448A1; SE1650865A1

Abstract

A gas fuel storage assembly for a heavy motor vehicle comprises at least two elongated gas storage tanks (3) with a circular crosssection arranged in parallel with each other, a spacer arrangement for keeping the tanks apart and at least one strap (1 1) secured to a vehicle chassis fixed part (9) and tightened around the tanks so as to press them together to form a tank package (4). The spacer arrangement has at least one spring member (7) arranged in a space (8) formed between the tanks prior to the tightening of the strap (11) and to be compressed by this tightening so as to store potential energy urging the tanks apart.

Description

A gas fuel storage assembly TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas fuel storage assembly for a heavy motor vehicle, for example a truck or a bus, comprising • at least two elongated gas storage tanks with a circular cross-section arranged in parallel with each other, • a spacer arrangement configured to keep said tanks apart, and • at least one strap configured to be secured to a vehicle chassis fixed part and tightened around said tanks so as to press them together to form a tank package, said spacer arrangement comprising at least one member configured to be compressed by said tightening of the strap.

“Heavy motor vehicle” is here defined as a motor vehicle with a service weight above 3.5 tons and is mostly, but not exclusively, a truck, a lorry or a bus.

When providing such a motor vehicle with a gas fuel storage assembly it is for keeping production costs of the vehicle mostly desired to arrange said tank package where for other vehicles produced in the same production line the fuel tank, for instance for containing diesel, is to be mounted so as to be able to mount said tank package in a similar way as such other fuel tanks. This means normally that said gas storage tanks, normally four to the number, with spacer arrangement are pre-mounted in a tank package when lifted in place on vehicle chassis fixed parts in the form of brackets secured to the chassis and then secured to these parts by tightening one or more said straps. The spacer arrangement has normally a plurality of spacer pieces and said members of rubber being compressed by the tightening of the strap for forming the tank package and protecting the gas storage tanks against chafing.

High jamming forces in a said strap, well in the order of 30-45 kN, are required for firmly securing said tank package in such a heavy motor vehicle, such as in a truck. However, in spite of that, the firm stability of the arrangement of the tank package may be partly lost, since the tank package includes spacers and rubber members having properties making them deformed and hardened after some time, and also since the pressure in the gas storage tanks will vary a lot, such as from 15 to 200 bars during a driving cycle causing a variation of the perimeter on the gas storage tanks by extension and compression thereof. Gas storage tanks of steel may have the perimeter varying by as much as 0.5 % during a driving cycle and this variation may be even larger for tanks of composite. A solution to this problem would be to provide the strap with a very strong spring, but that solution would not be attractive, since it would compromise the volume available for the gas storage tanks, and it is desired to keep this volume at a maximum so as to optimize the reach of the vehicle by the fuel contained in the gas storage tanks of the gas fuel storage assembly.

BACKGROUND ART US 2006/0033322 A1 discloses a gas fuel storage assembly for a motor vehicle of a similar type to that defined in the introduction not able to address the problems mentioned above.

SUMMARY OF THE INVENTION The object of the present invention is to provide a gas fuel storage assembly of the type defined in the introduction being improved in at least some aspect with respect to such gas fuel storage assemblies already known.

This object is according to the invention obtained by providing such an assembly with the features listed in the characterizing part of appended patent claim 1.

Thus, the spacer arrangement is provided with at least one spring member configured to be arranged in a space formed between the gas storage tanks prior to the tightening of the strap and to be compressed by this tightening so as to store potential energy urging the tanks apart. The potential energy stored in said at least one spring member will ensure that the tank package will be firmly secured with respect to the chassis of the vehicle without any risk of movements, such as vibrations, of the gas storage tanks with respect to each other irrespectively of variations of the gas pressures in the tanks and any deformations and hardening of spacer members. Furthermore, this is obtained without compromising the total volume of gas possible to be stored in the tank package, since the space between the tanks anyway free is used to provide means in the form of said at least one spring member for keeping the gas storage tank package as one rigid unit. Another advantage of arranging said at least one spring member in said space between the tanks instead of in said at least one strap is to get rid of the dependence of friction occurring when the strap otherwise has to be sliding against the tank package during action of the spring member.

According to an embodiment of the invention said at least one spring member is configured to be prestressed when put into said space prior to said tightening of the strap. The effective spring action distance may by this be optimized.

According to another embodiment of the invention said at least one spring member is a mechanical spring. This choice of spring member results in a high reliability to a competitive cost.

According to another embodiment of the invention said at least one spring member is a cup spring. The use of one or more cup springs as spring members makes it possible to provide a high spring stiffness with a short spring action distance making such spring members especially preferred considering the restricted space available therefor.

According to another embodiment of the invention the spacer arrangement comprises at least two sets of at least one spring member acting in planes being perpendicular to the longitudinal extension of the tanks and mutually displaced along said longitudinal extension of the tanks. A provision of a plurality of such sets of spring members will increase the total spring force acting to stabilize the gas storage tank package in place.

According to another embodiment of the invention the gas fuel storage assembly comprises four said gas storage tanks configured to form a said package by said tightening of the at least one strap. The use of four gas storage tanks in a said package results in an efficient utilization of the volume available for the package and provide a said space between the tanks suitable to be used for the arrangement of said at least one spring member, and according to a further development of this embodiment the gas storage tanks are arranged to form a corner each of a substantially square cross-section of said package, and the spacer arrangement comprises four said spring members acting in a plane being perpendicular to the longitudinal extension of the tanks and so that each gas storage tank is associated with two spring members acting to urge it apart from each of the two gas storage tanks adjacent thereto. By having such a set of four spring members acting in a plane the total force urging the tanks apart is distributed among these spring members resulting in a possibility to a large spring acting distance, i.e. elastic deflection.

According to another embodiment of the invention said at least one strap is configured to be secured to a bracket secured to the chassis of the vehicle to together with said bracket embrace said package of gas storage tanks.

According to another embodiment of the invention said the gas storage tanks are made of steel or a composite, which are suitable materials for such tanks.

The invention also relates to a heavy motor vehicle, especially a truck or a bus, provided with a gas fuel storage assembly according to the invention, in which said motor vehicle may also be provided with two or more such gas fuel storage assemblies so as to be able to store a larger amount of gas fuel for increasing the possible reach of the vehicle.

Other advantageous features as well as advantages of the present invention appear from the description following below.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a specific description of an embodiment of the invention cited as an example.

In the drawings: Fig 1 is a schematic view illustrating how a gas fuel storage assembly according to the present invention may be arranged in a heavy motor vehicle in the form of a truck, Fig 2 is a perspective view of a pre-mounted tank package being a part of a gas fuel storage assembly according to an embodiment of the invention and ready to be lifted onto brackets secured to the chassis of a motor vehicle, and Fig 3 is a view illustrating the gas fuel storage assembly with the tank package secured to said brackets by tightening of a strap secured thereto.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION Fig 1 illustrates very schematically a possible position of a gas fuel storage assembly 1 according to the present invention in a heavy motor vehicle 2 in the form of a truck at a place where normally a liquid fuel tank, such as containing diesel, is placed for such a vehicle. It is pointed out that a number of components of the vehicle have been omitted, since they have nothing to do with the present invention directed to the design of a gas fuel storage assembly for such a vehicle.

A gas fuel storage assembly according to an embodiment of the present invention will now be described while simultaneously making reference to figs 2 and 3. This gas fuel storage assembly has four elongated gas storage tanks 3 with a circular cross-section arranged in parallel with each other so as to form a tank package 4 with a substantially square cross-section. Each gas tank has typically a volume in the order of 100 litres, for instance by having a length of 1500 mm and a diameter of 320 mm, but any other size of this volume is conceivable. The tanks may contain any type of gas suitable to be used for the propulsion of a vehicle, for example biogas. Fig 2 shows the tank package 4 in a pre-mounted state in which the gas storage tanks 3 are kept in place by any form of strips or the like and in which state a spacer arrangement is a part of the tank package to keep the tanks 3 apart.

The spacer arrangement comprises spacers 5 wedged in between adjacent tanks as well as at least one set 6 of four spring members 7 in the form of cup rings arranged in a space 8 delimited by and between the gas storage tanks. These spring members 7 are acting in a plane being perpendicular to the longitudinal extension of the tanks and so that each gas storage tank is associated with two spring members acting to urge it apart from each of the two storage tanks adjacent thereto. Support pieces 12 with a surface designed to follow and bear upon the circumferential surface of a tank 3 form supports for the spring members and onto which these are acting.

Fig 3 shows a gas fuel storage assembly according to an embodiment of the invention, in which the pre-mounted tank package 4 of fig 2 has been put on one or more brackets 9 secured to the chassis 10 of the vehicle and one or more straps 11 secured to the bracket 9 has been tightened around the tank package 4 for pressing the gas storage tanks 3 together, i.e. towards each other without entering into contact with each other, while compressing the spring members 7 to store potential energy urging the tanks apart, which will result in a very firm and stable tank package unit. Would the perimeter of the gas tanks be reduced owing to a lower gas pressure therein the spring members 7 will expand and press the gas tanks apart to bear tightly against the strap 11. Would the perimeter of the gas storage tanks instead increase owing to a higher gas pressure therein the spring members 7 will instead be compressed and urge the gas tanks to be biased against the strap 11. If we consider the gas tank 3’ in fig 3 this is associated with two spring members 7’, 7” acting to urge it apart from each of the two gas storage tanks 3 and 3” adjacent thereto.

The spacer arrangement may thanks to the longitudinal extension of the gas tanks 3 comprise several sets 6 of spring members 7 acting in planes being perpendicular to the longitudinal extension of the tanks and mutually displaced along this longitudinal extension, such as a plane of each place of the spacers 5 shown in fig 2, which will then mean three such sets.

The invention is of course in no way restricted to the embodiment described above, since many possibilities for modifications thereof are likely to be obvious to one skilled in the art without having to deviate from the scope of invention defined in the appended claims.

The number of gas tanks in said gas fuel storage assembly may be another than 4 in each tank package, and the assembly may include more than one said tank package or the vehicle may be considered to then have more than one gas fuel storage assembly.

Other spring members than cup springs may be used, even nonmechanical springs, but cup springs are particularly advantageous thanks to the possibility to obtain a high spring stiffness with a short spring acting distance. The spring stiffness may be varied by varying the number of the cups used to form each spring and the design of each such cup.

Claims

1. A gas fuel storage assembly for a heavy motor vehicle (2), for example a truck or a bus, comprising • at least two elongated gas storage tanks (3) with a circular cross-section arranged in parallel with each other, • a spacer arrangement configured to keep said tanks apart, and • at least one strap (1 1) configured to be secured to a vehicle chassis fixed part (9) and tightened around said tanks so as to press them together to form a tank package (4), said spacer arrangement comprising at least one member (7) configured to be compressed by said tightening of the strap, said spacer arrangement comprising at least one spring member (7) configured to be arranged in a space (8) formed between said tanks prior to said tightening of the strap (11), characterized in that said at least one spring member (7) is configured to be compressed by said tightening so as to store potential energy urging the tanks (3) apart.

2. A gas fuel storage assembly according to claim 1, characterized in that said at least one spring member (7) is configured to be prestressed when put into said space (8) prior to said tightening of the strap (11).

3. A gas fuel storage assembly according to claim 1 or 2, characterized in that said at least one spring member (7) is a mechanical spring.

4. A gas fuel storage assembly according to claim 3, characterized in that said at least one spring member (7) is a cup spring.

5. A gas fuel storage assembly according to any of the preceding claims, characterized in that the spacer arrangement comprises at least two sets (6) of at least one said spring member (7) acting in planes being perpendicular to the longitudinal extension of the tanks (3) and mutually displaced along said longitudinal extension of the tanks.

6. A gas fuel storage assembly according to any of the preceding claims, characterized in that it comprises four said gas storage tanks (3) configured to form a said package (4) by said tightening of the at least one strap (11).

7. A gas fuel storage assembly according to claim 6, characterized in that the gas storage tanks (3) are arranged to form a corner each of a substantially square cross-section of said package, and that said spacer arrangement comprises four said spring members (7) acting in a plane being perpendicular to the longitudinal extension of the tanks and so that each gas storage tank is associated with two spring members (7) acting to urge it apart from each of the two gas storage tanks adjacent thereto.

8. A gas fuel storage assembly according to any of the preceding claims, characterized in that said at least one strap (11) is configured to be secured to a bracket (9) secured to the chassis (10) of the vehicle (2) to together with said bracket embrace said package (4) of gas storage tanks (3).

9. A gas fuel storage assembly according to any of the preceding claims, characterized in that said gas storage tanks (3) are made of steel or a composite.

10. A heavy motor vehicle, especially a truck or a bus, characterized in that it is provided with a gas fuel storage assembly (1) according to any of the preceding claims.

11. A motor vehicle according to claim 10, characterized in that it is provided with two or more said gas fuel storage assemblies (1).