Patent ID: 12214655

DETAILED DESCRIPTION OF THE DRAWINGS

FIG.1shows a tank assembly5according to an exemplary embodiment of the disclosure. It is understood that this is purely a diagrammatic depiction.

The tank assembly5has a tank10. In the present case, this is a pressurized tank for pressurized gaseous fuel. For example, hydrogen may be stored therein.

The tank assembly5has two pressure relief valves20which are each arranged on the side of the tank10. The pressure relief valves20are each configured to relieve the pressure in the interior of the tank10, i.e. to allow a defined outflow of gas from the tank10, when a respective temperature threshold value at the respective pressure relief valve20is exceeded.

The tank assembly5furthermore has two heat transmission paths30which in the present case are configured as respective heat pipes. Furthermore, the tank assembly5has two heat transmission elements40, wherein as shown a heat transmission element40is in each case arranged between a respective heat transmission path30and a respective pressure relief valve20.

The heat transmission paths30are routed along the tank10as shown, and thus absorb heat which is produced at the side of the tank10. This heat is initially conducted in the direction of the respective connected pressure relief valve20.

The heat transmission elements40are changeable with respect to their heat transmission between the respective pressure relief valve20and the respective pressure transmission path30. It may therefore be selected whether heat transmission takes place or not. For this, the designs of heat transmission elements described below with reference toFIGS.2to5may be used. However, other designs may be used.

FIGS.2and3show a heat transmission element40according to an exemplary embodiment. The heat transmission element40has a protrusion42and a recess44, wherein the protrusion42engages in the recess44. The protrusion42has a temperature T1, wherein a material45surrounding the recess44has a second temperature T2.

FIG.2shows a state in which the first temperature T1is lower than the second temperature T2. Because of thermal expansion, the protrusion42contracts radially and thus does not touch the wall surrounding the recess44. This hinders heat transport between the protrusion42and the material45surrounding the recess44.

FIG.3shows a state in which the first temperature T1is higher than the second temperature T2. Because of thermal expansion, the radial dimension of the protrusion42is increased so that it contacts the material surrounding the recess44. This allows a good heat flow through the heat transmission element40.

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

The design described may for example be applied such that the protrusion42is connected to a heat transmission path30or formed by a heat transmission path30, and the recess44or the material45surrounding the recess44is directly connected to the respective pressure relief valve20. 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 valve20and thus a deployment may be initiated. This corresponds to the state shown inFIG.3. At the same time however, in the reverse case in which the heat transmission path30is colder than the pressure relief valve20, the transport of heat away from the pressure relief valve20is prevented. This corresponds to the state shown inFIG.2.

The protrusion42and the material45surrounding the recess44may be made of the same material or also of materials with different thermal expansion coefficients.

FIGS.4and5show a heat transmission element40according to an exemplary embodiment. This is not controlled by temperature difference like the exemplary embodiment, but rather by gravity.

The heat transmission element40according to the exemplary embodiment comprises a first part46and a second part48which have only a weak interconnection by material bonding. A heat transmission medium50, in the form of a fluid and a gas52lying above this, is present between the two parts46,48. A vacuum may also be used instead of the gas. The heat transmission medium50and the gas52are situated in a hermetically sealed cavity54.

In the state shown inFIG.4, the first part46is at least partially above the second part48. In this state, the heat transmission medium only provides a very poorly heat-conductive connection between the two parts46,48. The heat transmission is thus largely interrupted.

In the state shown inFIG.5, the first part46is at least partially below the second part48, and in particular the first part46is further down than in the state shown inFIG.4, in comparison with the rest of the heat transmission element40. As shown, thus a substantially larger area inside the cavity54adjoining the first part46is covered by the heat transmission medium50, so that a substantially better heat transmission occurs between the two parts46,48. In effect, in this way, a heat transmission is controlled position-dependently.

By means of the heat transmission element40according 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 valve20. For example, the first part46may be connected to a heat pipe or formed by heat pipe, and the second part48may be connected for example to the pressure relief valve20. In this case, if the heat transmission path30extends upward away from the pressure relief valve20, heat conduction is suppressed. This corresponds to the state shown inFIG.4. In the other case, i.e. if the heat transmission path30extends downward, heat conduction may however be allowed. This corresponds to the state shown inFIG.5. The safety of deployment of the pressure relief valves20is thereby significantly increased, since an undesirable transport of heat away is prevented and heat is rather conducted in targeted fashion to the pressure relief valves20.

Instead of a liquid heat transmission medium50, 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 medium50varies its position because of gravity, which is either favorable or unfavorable for heat transmission.

FIG.6shows diagrammatically a configuration of a pressure relief valve20and a total of three heat transmission paths30. Each of the heat transmission paths30is connected to a respective heat transmission element40at the pressure relief valve20, but within its respective course comprises two additional heat transmission elements40. These are also changeable with respect to their heat transmission, like the heat transmission elements40which create the contact to the pressure relief valve20. 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 valve20.

FIG.6shows purely diagrammatically a respective protrusion and a respective recess on each heat transmission element40, corresponding schematically to the configuration described with reference toFIGS.2and3. This clarifies the function.

It is understood that any arbitrary other number of heat conduction paths may be used for a connection with a pressure relief valve20.

AsFIG.6shows, thus a heat transmission path30may 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 elements40which conduct heat in the direction of the respective pressure relief valve20will provide good thermal conduction. Heat conduction in the opposite direction is thereby effectively suppressed.

It is understood that in principle heat pipes situated between the heat transmission elements40or heat transitions may also be completely omitted.

With respect to the fundamental problem, it is pointed out that within a heat pipe as may typically be used for a heat transmission path30, the upward heat transmission is stronger because of gravity than the downward heat transmission. A pressure relief valve20should therefore preferably be arranged at the upper end of a respective heat pipe or heat transmission path30. 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 paths30, some of which in the normal position of the vehicle run downward from the pressure relief valve20while others run upward.

By means of the design of a heat transmission element40shown inFIGS.4and5, it is possible to thermally decouple those heat transmission paths30which, 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 valve20.