DE102014003586A1 - Fuel tank, motor vehicle - Google Patents

Abstract

The invention relates to a gas tank (2, 2 ') for gaseous fuel under normal conditions, comprising a tank housing (4, 4') which serves to receive the fuel, and at least one safety valve (6) arranged on the tank housing (4, 4 ') , 8, 6 '), via which fuel from the fuel tank (2, 2') can be released, wherein the safety valve (6, 8, 6 ') by means of an actuator medium (38) is hydraulically actuated, wherein the actuator medium (38) for the safety valve (6, 8; 6 ') is a positive thermal expansion coefficient fluid, the safety valve (6, 8; 6') being evidenced by expansion of the actuator medium (38).

Description

The invention relates to a gas tank for a motor vehicle. The invention further relates to a motor vehicle.

Fuel tanks and motor vehicles of the type mentioned are known in the art. The majority of road vehicles are fueled by liquid fuels. These liquid fuels include, for example, diesel and gasoline. Furthermore, battery-powered motor vehicles are known. A third type of vehicle relates to motor vehicles which are operated under normal conditions gaseous fuels. Normal conditions in this and in the following sense are normal physical conditions, ie a pressure of 1013 HPa and 273 K.

Such under normal conditions gaseous fuels include, for example, natural gas, LPG and hydrogen. Such under normal conditions gaseous fuels must be stored in fuel tanks under pressure, otherwise the energy density is too low. The entrainment of gaseous fuels in motor vehicles requires the provision of various safety measures. Thus, the tank is to be protected by suitable constructions against explosion and against uncontrolled burning. In the prior art, therefore, dense and explosion-resistant gas tanks are known, the z. B. are multi-layered and on the one hand represent a gas barrier, on the other hand are resistant to deformation and moreover have a protective layer against other damage. In addition, gas tanks are usually equipped with pressure relief valves, pressure sensors and temperature sensors.

However, circumstances are conceivable in which the known security systems do not work. These include u. a. Local heat effects on the fuel tank from the outside. Such local heat effects do not lead to a significant increase in the temperature of the fluid in the fuel tank and thus not to an activation of the safety valves via known pressure or temperature sensors.

The EP 2 361 797 A1 discloses a gas tank with a relief valve thermally connected to a shell. The energy absorbed by the sheath is led to the valve, whereby this is triggered. The heat causes a metal element with a low melting point to melt. Relative to a valve piston, the metal element is arranged on the outside.

The prior art requires that the amount of heat supplied to the metal element must be sufficient to melt the metal element to cause the safety valve to trip.

This raises the task of developing a gas tank of the type mentioned in such a way that a safety valve can be reliably triggered even at a small local heating, which generates a total of a small amount of heat.

The object is achieved by a motor vehicle according to the independent claim 15. Further embodiments are the subject of the dependent claims.

The below-described gas tank for under normal conditions gaseous fuel has a tank housing, which serves to receive the relevant fuel. The fuel can be stored in the tank liquefied under pressure. At least one safety valve is arranged on the tank housing, via which fuel can be released from the fuel tank. The safety valve is hydraulically actuated by means of an actuator medium. The actuator medium for the safety valve is a liquid with a positive thermal expansion coefficient.

The positive thermal expansion coefficient is necessary at relevant temperature ranges, ie at least at temperatures greater than 300 K. Liquids may also behave differently below this temperature.

It is provided that the safety valve can be opened by an expansion of the actuator medium. Such an expansion of the actuator medium can be spatially very limited, since liquids are substantially incompressible and therefore, if they arise in places other than the safety valve, can exert an effect on the safety valve. Thus, a very local, possibly remote heat exposure to the actuator medium is sufficient to allow triggering of the safety valve.

The thermally induced increase in volume of the actuator medium according to one embodiment can be> 0.02% vol / K, in particular> 0.05% vol / K. If the temperature reaches a threshold value, the volume of a corresponding actuator medium has increased greatly. A stroke in the safety valve required for actuation can be achieved by the appropriate volume in the reservoirs of the acute medium. They represent in comparison to the volume in the pipes a much larger volume and accordingly the hydraulic stroke acts on the safety valve.

For actuator media with a larger coefficient of expansion, the reservoirs may be correspondingly smaller in volume. The volume expansion of the actuator medium, the switching temperature and the reservoir size are manipulated variables to set the system to the desired situation.

According to a further aspect, an oil can be used as the actuator medium. Such an oil can be flame retardant and, moreover, liquid even at low outside temperatures.

According to a further aspect it can be provided that at least one reservoir for the actuator medium is present, which is in fluid communication with the safety valve. Such a reservoir facilitates the filling of the actuator-medium-carrying components and can also be used in some embodiments for venting.

A further aspect of the gas tank may provide that the at least one reservoir is connected to at least one heat conductor so that heat conducted via the heat conductor can be delivered to the actuator medium in the reservoir. The heat conductor and reservoir are thus thermally coupled, so that heat conducted via the heat conductor leads to an expansion of the actuator medium in the reservoir, which in turn can open the safety valve by means of the fluid connection.

A possible further embodiment provides that the at least one heat conductor at least partially surrounds an outer surface of the tank housing. In this way, locally occurring heat rises on the tank housing, which are triggered for example by a fire, give their heat to the heat conductor and thus cause a triggering of the safety valve.

In this case, the heat conductor can be designed according to an embodiment as a shell that surrounds the tank housing completely or at least partially. Such a shell encloses the tank housing over a large area and thereby causes a large-area cover of the tank housing and thus a high reliability of the triggering of the safety valve in the event of fires occurring anywhere in the tank.

In addition, the at least one heat conductor can be formed as one or more thermally conductive strands. Such strands can conduct the heat energy well and can be attached where the risk of a fire occurring is greatest.

Sheath and strands can be combined according to an embodiment, z. B. guided by means of a sheath strands.

According to a further aspect it can be provided that the at least one reservoir is arranged on the outer surface of the tank housing. By arranging the reservoir directly on the outer surface of the tank housing, heat can be applied to the reservoir directly at the site of the action of heat and thus directly cause an expansion of the actuator medium there. This expansion affects the entire hydraulic system, so that the arrangement of the reservoir on the tank housing also a direct triggering of the safety valve can be achieved.

In one aspect, the reservoir disposed on the outer surface of the tank housing may be connected to the safety valve with a fluid line. The use of fluid lines allows easy mounting of the reservoirs on the tank. In addition, the fluid lines can be bundled well and can be arranged on the tank housing to save space.

According to a further embodiment, it can be provided that a plurality of reservoirs are arranged on the outer surface of the tank housing. In this way, the reservoirs can form a matrix that spans the outer surface of the tank housing in a sensible arrangement and mesh size. The matrix can be rectangular, for example.

Another aspect of the gas tank concerns the design of the safety valve. The safety valve may have at least one main valve, wherein the main valve has at least one auxiliary valve which can be actuated by the actuator medium. In this case, the main valve can be opened by an actuation of the auxiliary valve. By using an auxiliary valve to operate the main valve, the main valve itself can be made simpler, as the use of the auxiliary valve allows for a change in actuator force, making it easier to open a preloaded main valve. Such an opening may then depend on the overpressure in the fuel tank.

A possible embodiment of the use of an arrangement of main and at least one auxiliary valve is to equip the main valve with a spring-loaded valve body, wherein a spring has a hydraulically loaded support. The supporting medium of the hydraulically loaded support can then be discharged by means of the auxiliary valve. The support of the spring thus falls away and a valve body is against with less force pressed a valve seat, so that the safety valve is opened at a lower pressure from the inside of the tank.

According to a further aspect it can be provided that a plurality of auxiliary valves are arranged on the main valve. With a plurality of auxiliary valves, a plurality of fluid lines can be provided in parallel, which is particularly useful when using a plurality of reservoirs, since a merger of the fluid lines can be omitted in this case.

According to a further aspect, it can be provided that the main valve can be opened by a single auxiliary valve. In this way, in an arrangement of a plurality of reservoirs on the outer surface of the tank housing, an opening of the main valve of the safety valve can then take place when a local heating acts on a single reservoir.

According to a first independent aspect, a motor vehicle is described which has at least one gas tank previously described.

Further features and details will become apparent from the following description, in which - where appropriate, with reference to the drawings - at least one embodiment is described in detail. Described and / or illustrated features form the subject matter, or independently of the claims, either alone or in any meaningful combination, and in particular may additionally be the subject of one or more separate applications. The same, similar and / or functionally identical parts are provided with the same reference numerals. Here are shown schematically:

1 a perspective view of a gas tank according to a first embodiment;

2 a longitudinal section through a safety valve, as can be used in the first embodiment;

3 a cross section through the safety valve 2 with open valve;

4 a perspective view of a gas tank according to a second embodiment;

5 an enlarged view of a reservoir of the gas tank according to 4 ;

6 a sectional view of a safety valve, as it can be used according to the second embodiment, as well as

7 a further sectional view of the safety valve along the section line AA 6 ,

1 shows a gas tank 2 in a schematic perspective view.

The gas tank 2 is used to store under normal conditions gaseous fuels, such as natural gas, LPG or hydrogen.

The gas tank 2 has a tank housing 4 on. The tank housing 4 is substantially cylindrical in a central region and tapered in its end regions, in order to be as pressure-stable as possible. The rejuvenation can for example be continuous, z. B. by a hemispherical configuration of the taper.

The tank housing 4 can be constructed in multiple layers, for example, with an inner layer of a gas-tight material, a composite layer applied thereto and possible other layers.

At the front ends of the tank housing are safety valves 6 . 8th arranged. The safety valves 6 . 8th can be designed as automatic valves (OTAV).

The tank housing 4 is made of two half-shell-shaped cases 10 . 12 surround. The sheath shells 10 . 12 can be over fasteners 14 connect together and surround the tank housing 4 then more or less completely.

In the sheath shells 10 . 12 are thermally conductive pipes 16 arranged, leading to thermal contacts 18 . 20 . 22 . 24 to lead. The thermally conductive pipes 16 can transfer the heat according to different principles. For example, the heat-conducting tubes can be configured as metal tubes, since some metals are very good heat conductors. The thermally conductive pipes 16 can also be filled with a liquid through which the heat is passed. Other concepts are also conceivable.

The to the thermal contacts 18 to 24 Heat given off is applied to one or both of the safety valves 6 . 8th so that the safety valves whose operation according to the first embodiment in the 2 and 3 is explained in more detail, trigger. A local fire 26 can be reliably detected in this way, even if by the fire 26 amount of energy is not sufficient to heat the tank contents such that a pressure or temperature sensor could lead to an opening of a safety valve.

2 shows a longitudinal section through the safety valve 6 ,

The safety valve 6 has a valve body 28 on, the one valve head 30 possesses, which by the pressure inside the boiler (on the right side) against a valve seat 32 is pressed and thus closes the valve.

The valve body 28 has a valve mandrel 34 up in a reservoir 36 dips. The reservoir 36 is with an oil 38 with high thermal expansion coefficient, in particular> 0.05% vol / K filled. The reservoir 36 is through a cartouche 40 limited to the outside and the valve mandrel 34 is from a seal 42 surrounded to the reservoir 36 seal. The cartouche 40 is with the thermal contact 18 surrounded, so that heat of the thermal contact 18 over the cartridge 40 to the oil 38 is deliverable.

3 shows a longitudinal section through the safety valve 6 in open condition. An expansion of the oil 38 causes a force on the seal 42 and thus a force on the valve mandrel 34 , The force acting on the valve body 28 on the part of the valve mandrel 34 Acts through expansion at some point so great that it releases the drag on the valve head 30 acts, overcomes, so the valve head 30 from the valve seat 32 is lifted. The valve body thus provides a fluid connection between an interior space 44 and a drain line 46 free. By releasing the pressure, the back pressure on the valve head drops 30 so that the safety valve remains open until the tank has been emptied as far as possible and there is no danger of detonation.

4 shows a second embodiment of a fuel tank 2 ' , The fuel tank 2 ' has a tank housing 4 ' on, in a central region cylindrical and tapering in one end spherical. At both ends of the tank housing 4 ' are safety valves 6 ' arranged. The rear safety valve is not visible through the perspective.

On an outer surface 50 of the tank housing 4 ' are a plurality of reservoirs 52 to 66 arranged. The reservoirs 52 to 66 may be arranged in common rows as shown. Other structures are also conceivable. The reservoirs 52 to 66 are with fluid lines 68 to 82 with the safety valves 6 ' connected. The fluid lines 68 to 82 are arranged in a group to the safety valves 6 ' guided.

The construction of a reservoir is in 5 shown.

The reservoir 52 is on a sign 84 arranged. The shield 84 Can be used as a mounting unit for fixing the reservoir 52 on the tank housing 4 ' serve. On the sign 84 is the fluid line 68 guided.

6 shows a cross section through a safety valve 6 ' how it can be used according to the second embodiment.

The safety valve 6 ' has a main valve 86 on. The main valve 86 is an auxiliary valve 88 assigned.

The main valve 86 has a valve body 90 on which of a spring 92 against a valve seat 94 is pressed. This seals the valve body 90 with the valve seat 94 against an interior of the boiler. The feather 92 is hydraulically supported on the other side. This is in a valve chamber 96 a stopper 98 provided, leading to the walls of the valve chamber 96 seals off.

On the pen 92 opposite side of the plug 98 is an oil 100 provided, which in fluid communication with the auxiliary valve 88 stands. The auxiliary valve 88 has a valve body 102 on, the one valve head 104 own that by the oil 100 against a valve seat 106 is pressed.

From the opposite side is the valve body 102 from the oil 38 subjected to high thermal expansion coefficient. An expansion of the oil 38 leads to a force on the valve body 90 so that the valve body 90 from a certain limit force in the direction of the valve head 104 moves, causing the auxiliary valve 88 opens and the oil 100 about a drain 108 can be drained. By draining the oil 100 becomes the spring 92 taken the support, since the plug 98 is now movable. The overpressure in the tank housing 4 ' can the main valve 86 open so valve over a drain line 110 can be drained.

7 shows a section along the section line AA 6 ,

The main valve 86 is star-shaped by a plurality of auxiliary valves 88 . 112 to 124 surround. main valve 86 and auxiliary valves 88 . 112 to 124 are coordinated so that opening an auxiliary valve is sufficient to open the main valve. This is done by draining the oil 100 Although the object has been illustrated and explained in detail by embodiments, the invention is not limited by the disclosed examples, and other variations can be deduced therefrom by those skilled in the art. It is therefore clear that a multitude of possible variations exists. It will also be understood that exemplary embodiments are examples only which are not to be construed in any way as limiting the scope, applicability, or configuration of the invention. Rather, the foregoing description and description of the figures enable one skilled in the art to practice the exemplary embodiments, and those of skill in the knowledge of the disclosed inventive concept may make various changes, for example as to the function or arrangement of particular elements recited in an exemplary embodiment, without Protected area, which is defined by the claims and their legal equivalents, such as further explanation in the description.

LIST OF REFERENCE NUMBERS

2, 2 '

gas tank

4, 4 '

tank housing

6, 6 '

safety valve

8th

safety valve

10

Cover half shell

12

Cover half shell

14

fastener

16

thermally conductive pipes

18-24

Thermal contacts

26

Local fire

28

valve body

30

valve head

32

valve seat

34

valve mandrel

36

reservoir

38

oil

40

cartridge

42

poetry

44

inner space

46

drain line

50

outer surface

52-66

reservoir

68-82

fluid line

84

sign

86

main valve

88

auxiliary valve

90

valve body

92

feather

94

valve seat

96

valve chamber

98

Plug

100

oil

102

valve body

104

valve head

106

valve seat

108

drainage

110

drain line

112-124

auxiliary valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2361797 A1 [0005]

Claims (15)

Gas tank for motor vehicles, with a tank housing ( 4 . 4 ' ), which serves to receive the fuel, and at least one of the tank housing ( 4 . 4 ' ) arranged safety valve ( 6 . 8th ; 6 ' ), about the fuel from the fuel tank ( 2 . 2 ' ) is releasable, the safety valve ( 6 . 8th ; 6 ' ) by means of an actuator medium ( 38 ) is hydraulically actuated, wherein the Aktuatormedium ( 38 ) for the safety valve ( 6 . 8th ; 6 ' ) is a liquid with a positive thermal expansion coefficient, the safety valve ( 6 . 8th ; 6 ' ) by an expansion of the actuator medium ( 38 ) is apparent. A gas tank according to claim 1, wherein the actuator medium is an oil ( 38 ). Gas tank according to claim 1 or 2, wherein at least one reservoir ( 36 ; 52 . 54 . 56 . 58 . 60 . 62 . 64 . 66 ) for the actuator medium ( 38 ) which is in fluid communication with the safety valve ( 6 . 8th ) stands. A gas tank according to claim 3, wherein the at least one reservoir ( 36 ) with at least one heat conductor ( 16 ), so that via the heat conductor ( 16 ) conducted heat to the Aktuatormedium ( 38 ) is deliverable. Gas tank according to one of the preceding claims, wherein the at least one heat conductor ( 16 ) an outer surface of the tank housing ( 4 ) at least partially surrounds. Gas tank according to claim 3 or 4, wherein the at least one heat conductor ( 16 ) as a shell ( 10 . 12 ) is trained. Gas tank according to one of claims 3 to 5, wherein the at least one heat conductor ( 16 ) as one or more thermally conductive strands ( 16 ) are formed. Gas tank according to one of claims 3 to 7, wherein the at least one reservoir ( 52 . 54 . 56 . 58 . 60 . 62 . 64 . 66 ) on the outer surface ( 50 ) of the tank housing ( 4 ' ) is arranged. Gas tank according to claim 8, wherein the at least one reservoir ( 52 . 54 . 56 . 58 . 60 . 62 . 64 . 66 ) with a fluid line with the safety valve ( 6 ' ) connected is. A gas tank according to claim 8 or 9, wherein a plurality of reservoirs ( 52 . 54 . 56 . 58 . 60 . 62 . 64 . 66 ) on the outer surface ( 50 ) of the tank housing ( 4 ' ) are arranged. Gas tank according to one of the preceding claims, wherein the safety valve ( 6 ' ) at least one main valve ( 86 ), wherein the main valve ( 86 ) at least one auxiliary valve ( 88 . 112 . 114 . 116 . 118 . 120 . 122 . 124 ), which depends on the actuator medium ( 38 ), the main valve ( 86 ) by an actuation of the auxiliary valve ( 88 . 112 . 114 . 116 . 118 . 120 . 122 . 124 ) is openable. Gas tank according to claim 11, wherein the main valve ( 86 ) a spring-loaded valve body ( 90 ), wherein a spring ( 92 ) a hydraulically loaded support ( 98 . 100 ), wherein the supporting medium ( 100 ) by means of the auxiliary valve ( 88 . 112 . 114 . 116 . 118 . 120 . 122 . 124 ) is drainable. Gas tank according to claim 11 or 12, wherein at the main valve ( 86 ) a plurality of auxiliary valves ( 88 . 112 . 114 . 116 . 118 . 120 . 122 . 124 ) are arranged. Gas tank according to claim 13, wherein the main valve ( 86 ) from a single auxiliary valve ( 88 . 112 . 114 . 116 . 118 . 120 . 122 . 124 ) is openable. Motor vehicle, with at least one gas tank ( 2 . 2 ' ) according to any one of the preceding claims.

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