Tank Assembly

Abstract

A tank assembly includes a tank, at least one pressure relief valve, at least one heat transmission path, and at least one heat transmission element. The at least one pressure relief valve is configured to allow a pressure relief of the tank when a temperature threshold value at the pressure relief valve is exceeded. The heat transmission path and the pressure relief valve are connected via the at least one heat transmission element. The heat transmission element is changeable with respect to the heat transmission between the heat transmission path and the pressure relief valve.

Claims

1.-15. (canceled)

16. A tank assembly comprising: a tank; at least one pressure relief valve which is configured to allow a pressure relief of the tank when a temperature threshold value at the pressure relief valve is exceeded; at least one heat transmission path; and at least one heat transmission element, by means of which the heat transmission path and the pressure relief valve are connected, wherein the heat transmission element is changeable with respect to the heat transmission between the heat transmission path and the pressure relief valve.

17. The tank assembly according to claim 16, further comprising: a number of further pressure relief valves which are each configured to allow a pressure relief of the tank when a respective temperature threshold value at the respective pressure relief valve is exceeded.

18. The tank assembly according to claim 17, further comprising: a number of further heat transmission paths; and a number of further heat transmission elements, by means of which a respective further heat transmission path and a pressure relief valve are connected, wherein the further heat transmission elements are changeable with respect to heat transmission between the respective further heat transmission paths and the respective pressure relief valve.

19. The tank assembly according to claim 18, wherein a number of the pressure relief valves are each connected to a plurality of heat transmission paths.

20. The tank assembly according to claim 19 wherein a number of the pressure relief valves are each connected to only one heat transmission path.

21. The tank assembly according to claim 20 wherein a number of the heat transmission paths each have a number of additional heat transmission elements, and the additional heat transmission elements are changeable with respect to heat transmission within the respective heat transmission path.

22. The tank assembly according to claim 21, wherein the heat transmission elements are configured to be changeable in response to a temperature difference present over the elements, the heat transmission is allowed in response to a temperature difference which is falling towards the pressure relief valve, and the heat transmission is interrupted in response to a temperature difference which is rising towards a pressure relief valve.

23. The tank assembly according to claim 22, wherein a respective heat transmission element has a respective protrusion and a respective recess, and the protrusion engages in the recess, and the dimensions of the protrusion and/or recess change depending on the temperature difference present over the heat transmission element, such that the protrusion comes or does not come into contact with the recess.

24. The tank assembly according to claim 23, wherein a respective heat transmission element comprises a respective bimetal element, and the bimetal element changes depending on the temperature difference present over the heat transmission element, such that it allows or interrupts a heat transmission.

25. The tank assembly according to claim 24, wherein the heat transmission elements are configured to be changeable in response to a physical position.

26. The tank assembly according to claim 25, wherein a respective heat transmission element has a respective movable heat transmission medium, and the heat transmission medium allows or interrupts a heat transmission depending on the physical position.

27. The tank assembly according to claim 26, wherein the heat transmission medium is a fluid or a solid body.

28. The tank assembly according to claim 27, wherein a respective heat transmission element is configured to interrupt a heat conduction if the heat transmission path leads upward from the pressure relief valve, and/or to allow a heat conduction if the heat transmission path leads downward from the pressure relief valve.

29. The tank assembly according to claim 28, wherein a respective heat transmission path is configured as a heat pipe or a succession of heat pipes.

30. The tank assembly according to claim 29, wherein the tank is a gas tank and/or a fuel tank for a motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1: a tank assembly;

[0039] FIGS. 2 and 3: a heat transmission element;

[0040] FIGS. 4 and 5: a heat transmission element; and

[0041] FIG. 6: an arrangement of a pressure relief valve and three heat transmission paths.

DETAILED DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 shows a tank assembly 5 according to an exemplary embodiment of the disclosure. It is understood that this is purely a diagrammatic depiction.

[0043] The tank assembly 5 has a tank 10. In the present case, this is a pressurized tank for pressurized gaseous fuel. For example, hydrogen may be stored therein.

[0044] The tank assembly 5 has two pressure relief valves 20 which are each arranged on the side of the tank 10. The pressure relief valves 20 are each configured to relieve the pressure in the interior of the tank 10, i.e. to allow a defined outflow of gas from the tank 10, when a respective temperature threshold value at the respective pressure relief valve 20 is exceeded.

[0045] The tank assembly 5 furthermore has two heat transmission paths 30 which in the present case are configured as respective heat pipes. Furthermore, the tank assembly 5 has two heat transmission elements 40, wherein as shown a heat transmission element 40 is in each case arranged between a respective heat transmission path 30 and a respective pressure relief valve 20.

[0046] The heat transmission paths 30 are routed along the tank 10 as shown, and thus absorb heat which is produced at the side of the tank 10. This heat is initially conducted in the direction of the respective connected pressure relief valve 20.

[0047] The heat transmission elements 40 are changeable with respect to their heat transmission between the respective pressure relief valve 20 and the respective pressure transmission path 30. It may therefore be selected whether heat transmission takes place or not.

[0048] For this, the designs of heat transmission elements described below with reference to FIGS. 2 to 5 may be used. However, other designs may be used.

[0049] FIGS. 2 and 3 show a heat transmission element 40 according to an exemplary embodiment. The heat transmission element 40 has a protrusion 42 and a recess 44, wherein the protrusion 42 engages in the recess 44. The protrusion 42 has a temperature T.sub.1, wherein a material 45 surrounding the recess 44 has a second temperature T.sub.2.

[0050] FIG. 2 shows a state in which the first temperature T.sub.1 is lower than the second temperature T.sub.2. Because of thermal expansion, the protrusion 42 contracts radially and thus does not touch the wall surrounding the recess 44. This hinders heat transport between the protrusion 42 and the material 45 surrounding the recess 44.

[0051] FIG. 3 shows a state in which the first temperature T.sub.1 is higher than the second temperature T.sub.2. Because of thermal expansion, the radial dimension of the protrusion 42 is increased so that it contacts the material surrounding the recess 44. This allows a good heat flow through the heat transmission element 40.

[0052] The state shown in FIG. 3 may also be described as a thermal press fit which allows intensive mechanical contact and hence also direct heat conduction.

[0053] The design described may for example be applied such that the protrusion 42 is connected to a heat transmission path 30 or formed by a heat transmission path 30, and the recess 44 or the material 45 surrounding the recess 44 is directly connected to the respective pressure relief valve 20. Thus in the case that the heat transmission path has a higher temperature than the pressure relief valve, the corresponding heat is conducted to the pressure relief valve 20 and thus a deployment may be initiated. This corresponds to the state shown in FIG. 3. At the same time however, in the reverse case in which the heat transmission path 30 is colder than the pressure relief valve 20, the transport of heat away from the pressure relief valve 20 is prevented. This corresponds to the state shown in FIG. 2.

[0054] The protrusion 42 and the material 45 surrounding the recess 44 may be made of the same material or also of materials with different thermal expansion coefficients.

[0055] FIGS. 4 and 5 show a heat transmission element 40 according to an exemplary embodiment. This is not controlled by temperature difference like the exemplary embodiment, but rather by gravity.

[0056] The heat transmission element 40 according to the exemplary embodiment comprises a first part 46 and a second part 48 which have only a weak interconnection by material bonding. A heat transmission medium 50, in the form of a fluid and a gas 52 lying above this, is present between the two parts 46, 48. A vacuum may also be used instead of the gas. The heat transmission medium 50 and the gas 52 are situated in a hermetically sealed cavity 54.

[0057] In the state shown in FIG. 4, the first part 46 is at least partially above the second part 48. In this state, the heat transmission medium only provides a very poorly heat-conductive connection between the two parts 46, 48. The heat transmission is thus largely interrupted.

[0058] In the state shown in FIG. 5, the first part 46 is at least partially below the second part 48, and in particular the first part 46 is further down than in the state shown in FIG. 4, in comparison with the rest of the heat transmission element 40. As shown, thus a substantially larger area inside the cavity 54 adjoining the first part 46 is covered by the heat transmission medium 50, so that a substantially better heat transmission occurs between the two parts 46, 48. In effect, in this way, a heat transmission is controlled position-dependently.

[0059] By means of the heat transmission element 40 according to the exemplary embodiment, a position-controlled heat transmission can be achieved. Thus in particular it may be prevented that, in an unfavorable position such as for example following a vehicle rollover in an accident, heat is transported vertically upward away from the pressure relief valve 20. For example, the first part 46 may be connected to a heat pipe or formed by heat pipe, and the second part 48 may be connected for example to the pressure relief valve 20. In this case, if the heat transmission path 30 extends upward away from the pressure relief valve 20, heat conduction is suppressed. This corresponds to the state shown in FIG. 4. In the other case, i.e. if the heat transmission path 30 extends downward, heat conduction may however be allowed. This corresponds to the state shown in FIG. 5. The safety of deployment of the pressure relief valves 20 is thereby significantly increased, since an undesirable transport of heat away is prevented and heat is rather conducted in targeted fashion to the pressure relief valves 20.

[0060] Instead of a liquid heat transmission medium 50, which may for example be or contain mercury, indium or a sufficiently liquid heat conduction paste, in principle a solid body, such as for example a metal piece, or a plurality of solid bodies, such as example a metal powder, may be used. Typically, the heat transmission medium 50 varies its position because of gravity, which is either favorable or unfavorable for heat transmission.

[0061] FIG. 6 shows diagrammatically a configuration of a pressure relief valve 20 and a total of three heat transmission paths 30. Each of the heat transmission paths 30 is connected to a respective heat transmission element 40 at the pressure relief valve 20, but within its respective course comprises two additional heat transmission elements 40. These are also changeable with respect to their heat transmission, like the heat transmission elements 40 which create the contact to the pressure relief valve 20. In this way, already within a respective heat transmission path, it can be ensured that heat is transmitted only in a specific direction, in particular towards a pressure relief valve 20.

[0062] FIG. 6 shows purely diagrammatically a respective protrusion and a respective recess on each heat transmission element 40, corresponding schematically to the configuration described with reference to FIGS. 2 and 3. This clarifies the function.

[0063] It is understood that any arbitrary other number of heat conduction paths may be used for a connection with a pressure relief valve 20.

[0064] As FIG. 6 shows, thus a heat transmission path 30 may be segmented into several portions which are each connected via a changeable heat transition. Depending on the location of the heat source, only heat transitions or heat transmission elements 40 which conduct heat in the direction of the respective pressure relief valve 20 will provide good thermal conduction. Heat conduction in the opposite direction is thereby effectively suppressed.

[0065] It is understood that in principle heat pipes situated between the heat transmission elements 40 or heat transitions may also be completely omitted.

[0066] With respect to the fundamental problem, it is pointed out that within a heat pipe as may typically be used for a heat transmission path 30, the upward heat transmission is stronger because of gravity than the downward heat transmission. A pressure relief valve 20 should therefore preferably be arranged at the upper end of a respective heat pipe or heat transmission path 30. Since however according to statistics, around 3% of all vehicle fires occur following collisions and rollovers, it is typically necessary to take into account all possible vehicle orientations. Thus it is sensible to use several heat transmission paths 30, some of which in the normal position of the vehicle run downward from the pressure relief valve 20 while others run upward.

[0067] By means of the design of a heat transmission element 40 shown in FIGS. 4 and 5, it is possible to thermally decouple those heat transmission paths 30 which, in the case of fire, lead upward in the present position of the vehicle and thus with good thermal conduction could dissipate heat away from the pressure relief valve 20.