DE102015206823A1 - Method for operating a motor vehicle with a cryogenic pressure vessel - Google Patents

Abstract

The technology disclosed herein relates to a method of operating a motor vehicle having a cryogenic pressure vessel for fuel storage. It comprises the steps of: 1) determining whether the motor vehicle is traveling or is entering a room in which the rate of air exchange is above an air exchange limit and / or the oxygen supply is above an oxygen storage limit; and 2) generating a feedback if the air exchange rate and / or the oxygen supply is not above the air exchange limit and / or the oxygen storage limit.

Description

The technology disclosed herein relates to a method of operating a motor vehicle having a cryogenic pressure vessel. Cryogenic pressure vessels are known in the art. Such a pressure vessel comprises an inner container as well as an outer container surrounding it to form a super-isolated (eg evacuated) (intermediate) space. Cryogenic pressure vessels are used, for example, for motor vehicles, in which a gaseous fuel under ambient conditions is cryogenically stored and thus essentially in the liquid or supercritical state of aggregation with respect to the ambient conditions of significantly higher density. Such fuels are stored cryogenic in the cryogenic pressure vessels. Therefore, highly effective insulation sheaths (eg vacuum envelopes) are provided. For example, the EP 1 546 601 B1 such a pressure vessel.

If the stored fuel warms up slowly, the pressure in the pressure vessel slowly rises at the same time. If a limit pressure is exceeded, the fuel must escape via suitable safety devices in order to avoid bursting of the cryogenic pressure vessel. For example, a so-called blow-off management system or boil-off management system (hereinafter BMS) is used. These systems allow fuel to escape, with the vented fuel being reacted, for example, in a catalyst. The chemical reaction between hydrogen and oxygen leads to oxygen depletion in enclosed spaces (eg garage). The depletion of oxygen in closed rooms represents a potential hazard for humans.

Furthermore, additional mechanical safety valves (SVT) or pressure relief valves and rupture disks are used, which can release the fuel downstream of the BMS. Unless the deflated fuel can be reacted by the BMS, the fuel is released into the environment unused. It could then be an explosive or at least a combustible mixture.

It is an object of the technology disclosed herein to reduce or eliminate the disadvantages of the prior art pressure vessels. In particular, it is a concern of the technology disclosed here to reduce the risk potential in enclosed parking spaces. Other objects arise from the beneficial effects of the technology disclosed herein. The object (s) is / are solved by the subject matter of claim 1. The dependent claims are preferred embodiments.

The technology disclosed herein relates to a cryogenic pressure vessel for storing fuel for a motor vehicle. The pressure vessel can be used in a motor vehicle, for example, with compressed natural gas, often referred to as compressed natural gas (CNG), or operated with hydrogen (fuel cell electrical vehicle). The cryogenic pressure vessel may store fuel preferably in the liquid or supercritical state. The fuel can be stored, for example. At temperatures of about 30 K to 360 K in the cryogenic pressure vessel. The pressure vessel is preferably designed to permanently store fuel at a pressure of above approximately 200 bar, furthermore preferably above approximately 350 bar and especially preferably above approximately 500 bar.

The technology disclosed herein preferably relates to a motor vehicle having at least one cryogenic pressure vessel as disclosed herein and having at least one fuel cell system having at least one fuel cell, preferably a proton exchange membrane (PEM).

The technology disclosed herein relates to a method of operating a motor vehicle having a cryogenic pressure vessel for fuel storage.

The method includes the step of determining whether the motor vehicle is traveling in or in a room where the rate of air exchange is above an air exchange threshold and / or the oxygen supply is above an oxygen storage limit.

Thus, there are two parameters that are determined. The air exchange rate is a measure of the circulation of air in the room in which the motor vehicle drives. It indicates how much fresh air from the environment gets into the room. The oxygen supply indicates what amount of oxygen is present in the room. The oxygen supply may be an absolute oxygen amount, an oxygen concentration, or preferably a combination of oxygen amount and oxygen concentration. The oxygen storage limit value therefore preferably consists of a combination of minimum oxygen quantity and minimum oxygen concentration. For example, if the vehicle is traveling in a large hall with few parking spaces, a comparatively low oxygen concentration can be compensated for by a large absolute amount of oxygen. The risk of oxygen depletion can then be ruled out. If, however, the vehicle drives into a closed single garage, a higher oxygen content compared to the large hall could possibly still be critical.

To determine whether the air exchange rate is above an air exchange limit and / or the oxygen supply above an oxygen storage limit, these values need not necessarily be measured. Furthermore, it is also possible for the measured values of the air exchange rate and / or the oxygen supply to be transmitted to the motor vehicle, and / or for the motor vehicle to receive a signal representing the air exchange rate and / or the oxygen supply from at least one transmitter. Here, all wireless transmission paths are conceivable (radio, WLAN, etc.) Also, at least one geographic information signal representing the air exchange rate and / or the oxygen supply. For example, it can be deposited in the map material of the navigation system that the garage does not have a sufficient rate of air exchange. Furthermore, it can be assumed in one embodiment that it is a closed space with a low air exchange rate if in the room no GPS signal (Global Positioning System), Galileo signal, GLONASS signal, o. Ä. Receive can.

The technology disclosed herein assumes that there are sufficient values for the air exchange rate and / or for the oxygen supply that directly or indirectly indicate that they are above any limit values for the air exchange rate and / or for the oxygen supply.

The method disclosed herein further includes the step of: generating feedback to the driver or to a driver assistance system when the air exchange rate and / or the oxygen supply is not above the air exchange limit and / or the oxygen storage limit. For example, the driver assistance system may at least be able to assist in parking. But it can also include fully autonomous driving in addition to semi-autonomous driving.

The feedback may be a request to connect the motor vehicle to an external fuel line or to park the vehicle at a location other than the room. In the case of an active driver assistance system, the feedback may include the instruction to the driver assistance system or the vehicle occupants to search or select a different parking location for the motor vehicle.

If the motor vehicle is connected to an external fuel line, and if the BMS is able to discharge the fuel safely via this external fuel line, there is at no time the risk of oxygen depletion and / or combustible mixture formation. If the vehicle is parked in a place other than the room, the aforementioned dangers are also banned. The discharged into the external fuel line fuel can then be used otherwise meaningful.

Preferably, the feedback may include a visual and / or audible signal, which may further preferably be perceived from outside the vehicle. Thus, the driver can be reminded and additionally motivated to take measures to reduce the risk potential (eg: connection of a fuel line or re-parking). Preferably, the externally perceptible signal is activated only with some time delay, so that the driver has time to connect the fuel line.

The determination of the air exchange rate and / or the oxygen supply may include the step of: determining whether the vehicle is in a closed space. In this case, the closed space can be determined, for example, by at least one environmental sensor. The oxygen supply could be determined for example by an oxygen sensor in combination with an environmental sensor.

• – Bestimmen, ob ein Abblasen von Brennstoff notwendig ist; und
• – Generieren der Rückmeldung, wenn das Abblasen von Brennstoff notwendig ist.

The method may further comprise the steps of:

• - determining whether a blow-off of fuel is necessary; and
• - Generate the feedback when the blowing off of fuel is necessary.

The term "blow off" here includes the conversion by the BMS and an actual untreated venting of the fuel by the SVT.

Determining whether fuel bleed is necessary may be determined, for example, based on the pressure vessel condition values (inner vessel pressure, density and / or temperature of the fuel in the inner vessel, parking duration, etc.). In addition to the parameters air exchange rate and oxygen supply so also the need for blowing is taken into account. For example, the density of the fuel can be determined within the pressure vessel and the feedback is generated only if in addition to the air exchange rate and oxygen supply and the density of the fuel is above a lower limit density. For example, the lower limit density can be the density that the cryogenic pressure vessel can withstand even just at elevated design temperatures (eg 360 K) just without damage. If the density is below the limit, there will be no release of fuel. Thus, the motor vehicle can be parked in closed rooms with low oxygen concentration and without exchange of oxygen.

The lower limit value of the density can also be determined in a further embodiment on the basis of the predicted parking duration. Methods for determining the limit value or internal pressure limit value are known from the patent application with the application number going back to the applicant DE 10 2015 206 782.3 known. The content of the patent application DE 10 2015 206 782.3 is hereby incorporated by reference.

• – Bestimmen der Isolationsgüte; und
• – Generieren der Rückmeldung, wenn die Isolation nicht intakt ist.

Verfahren zur Bestimmung der Isolationsgüte sind beispielsweise aus der auf die Anmelderin zurückgehende Patentanmeldungen mit der Anmeldenummern DE 10 2015 203 702 und DE 10 2014 226 545 bekannt. Der Inhalt der Patentanmeldung DE 10 2015 203 702 bezüglich der Bestimmung der Isolationsgüte wird hiermit durch Verweis mit in diese Patentanmeldung aufgenommen.The method disclosed herein may further include the step of:

• - determining the insulation quality; and
• - Generate the feedback if the isolation is not intact.

Methods for determining the insulation quality are, for example, from the applicant's patent applications with the application numbers DE 10 2015 203 702 and DE 10 2014 226 545 known. The content of the patent application DE 10 2015 203 702 with regard to the determination of the insulation quality is hereby incorporated by reference into this patent application.

In addition to the air exchange rate and / or the oxygen supply, it is also preferably determined on the basis of further pressure vessel parameters whether a hazard can occur at all.

The technology disclosed herein will now be explained with reference to the figures. Show it:

1 a schematic flow diagram of the method;

2 a schematic flow diagram with respect to the air exchange; and

3 a schematic flow diagram with respect to the blow-off.

1 shows the general procedure of the procedure. With the step 100 the procedure begins. For example, the vehicle driver may choose a parking space or a driver assistance system selects a parking location for the motor vehicle.

In step S200, the air exchange or the air exchange rate (both terms are used synonymously here) and / or the oxygen supply is determined (cf. 2 ). On the basis of the result of this determination, a query is made in step S300 as to whether the room has sufficient air exchange and / or a sufficient oxygen supply.

If the air exchange and / or oxygen supply is sufficient, then the motor vehicle in the room, for. As a garage or a parking garage or a free storage area, parked or parked (step S700).

If the air exchange and / or oxygen supply is insufficient, then optionally further queries can be provided. For example, it may be provided that in a step S400 (cf. 3 ) determines whether a blow-off of fuel is necessary or is. If it is not necessary to blow off fuel, the motor vehicle can also be parked directly in the room (step S700). However, if it has been recognized that a bleeding of fuel is or becomes necessary (compare steps S400, S500), then the motor vehicle or its control system gives a feedback to the vehicle driver or to the driver assistance system (see step S610). This feedback can vary in content as well as in the type of feedback:
Initially, the feedback may consist, for example, after the motor vehicle has been brought into the state and the engine was turned off by the motor vehicle driver, that the motor vehicle to be connected to a fuel line, such as a hydrogen line. If the driver of this request within a certain time, for. After 30 seconds, for example, the display goes out and the motor vehicle allows the parking or parking, ie the complete rest of the motor vehicle without acoustic or visual feedback (step S700). However, if the driver does not connect the motor vehicle to the fuel line within the predetermined time, then a clear, audible and / or visual signal perceptible outside the motor vehicle can indicate that the motor vehicle is to be connected to a fuel line or has to be parked. The period of time until the clearly perceptible signal can vary and possibly adapt to the motor vehicle driver. It is preferably sized so that the motor vehicle driver has enough time to connect the line. On the other hand, it is so dimensioned that the driver is so far in the vicinity of the motor vehicle that he can also perceive the signal. It may be provided for reasons of safety that immediately after the engine is stopped, the clearly perceptible signal is initiated.

Is already detected before switching off the engine, for example, during the entrance to the motor vehicle in the closed space, that the room is not suitable for parking the motor vehicle (eg. Can the motor vehicle of a transmitter of a parking garage receive such information), so For example, a feedback (see step S610) to the driver or to a driver assistance system during the entry or during the search for a parking space can be made by a corresponding signal. The feedback will be different then in the first case. Instead of the Instruction to connect the fuel line, the driver is prompted in this case to park his car in another garage.

In the case of an active driver assistance system, the feedback to the driver assistance system or the vehicle occupants may be to search for another parking location for the motor vehicle. In this case, step S620 would not be checked, but step S610 would directly refer back to step S300 for the new room / storage location. Furthermore, it can be provided that the driver assistance system parks only after reconfirmation of the vehicle occupant at another location.

In 1 For example, the loop may be looped through steps S300, S400, S500, S610 and S620 until the motor vehicle is connected to a fuel line (see step S620) or until step S700 is reached via the abort criteria of steps S300 or S500.

The steps relating to determining whether blow-off is necessary, ie steps S400, S500, are part of a preferred embodiment. Likewise, these steps could be omitted. For this reason, these steps are shown in dashed lines.

• – Mindestens ein empfangenes Signal, welches indiziert, dass ausreichend Luftaustausch und/oder ein ausreichender Sauerstoffvorrat vorliegt. Ein solches Signal können beispielsweise übertragene Messwerte sein. Ferner kann das Signal eine generelle Information sein, die lediglich indiziert, dass dieser Raum für das Parken von Kraftfahrzeugen mit kryogenen Druckbehältern zugelassen ist. Das Signal kann von einem Sender im Parkhaus ausgesandt werden. Ferner könnten nicht zertifizierte Parkhäuser zusätzlich in Geoinformationssystemen hinterlegt sein.
• – Mindestens einem Messwert, bevorzugt zwei Messwerten, die das Kraftfahrzeug selbst ermittelt. Die Messwerte können direkt oder indirekt zur Bestimmung des Luftaustausches und/oder des Sauerstoffvorrates herangezogen werden.

In 1 further shown in dashed lines is a further preferred embodiment, which, however, need not be realized. If it is determined in step S300 that there is a space with sufficient air exchange and / or oxygen supply, steps S400 (cf. 3 ) and S500. In this case, since the space for parking the vehicle is generally suitable, another feedback may be output in step S612. For example, the driver could only be encouraged to connect the motor vehicle to an external fuel line or to a power grid, so that the fuel is not blown off unused. This feedback can be displayed, for example, until the non-connection is confirmed by the driver (can also be a default) or the vehicle is connected. Thereafter, the controller may allow the parking (step S700) 2 shows the method steps, which may include the determination of the air exchange and the oxygen supply. Here, steps S210, S220 and S230 are shown as a sequential order. It is also conceivable that only one or two of these steps will be followed sequentially. It is also conceivable that at least two of the steps S210, S220 and S230 are queried in parallel. In other words, a lack of positive information or a closed space or an insufficient oxygen supply would then lead to the fact that in step S300 always sufficient air exchange is not assumed. Preferably, these steps will be sequential, as explained below:
In step S210 it is checked whether a pos. Information regarding the air exchange and / or regarding the oxygen supply is present. The positive information may result from:

• - At least one received signal indicating that there is sufficient air exchange and / or sufficient oxygen supply. Such a signal can be, for example, transmitted measured values. Further, the signal may be general information merely indicating that this space is permitted for parking cars with cryogenic pressure vessels. The signal can be sent by a transmitter in the parking garage. Furthermore, non-certified parking garages could additionally be deposited in geoinformation systems.
• At least one measured value, preferably two measured values, which the motor vehicle itself determines. The measured values can be used directly or indirectly for determining the air exchange and / or the oxygen supply.

In particular, it may be provided that in a step S210 it is detected whether there is a closed space. For example, for this purpose, sensors of the motor vehicle, such as environment sensors or the GPS receiver can be used. If it is safely ruled out that the motor vehicle is located in a closed space, sufficient air exchange can be assumed in step S300. If, however, a closed room is detected, it can not be assumed that there is sufficient air exchange in a preferred embodiment. It should be noted that a ventilation system with sufficient air exchange would have already led to a positive result in step S210, if the information is available to the motor vehicle. Preferably, step S210 is run through if no positive information has previously been obtained in step S210.

After step S220, step S230 may be followed, in which the vehicle determines whether there is a minimum amount of oxygen in the space. For this purpose, the motor vehicle can have, for example, an oxygen sensor and approximate the size of the room via environmental sensors.

In particular, steps S220 and S230 can also be provided as redundant protection of step S210. In other words, they can also be traversed with a positive information in step S200 to secure this information.

In the 3 are the optional procedural steps that could be run to determine the blow-off. In step S410, it is first determined whether the fuel density in the container is below a first limit density (see above). If this is the case, the container would still be able to safely store the fuel even in the fully heated state without the fuel having to be blown off. If the fuel density is above the first limit density, the isolation quality of the cryogenic pressure vessel can be determined (step S420). For this purpose, for example, the last determined and stored insulation quality value can be used. If it is determined that the insulation quality is below a threshold value, it can be assumed that the insulation quality is not intact. In this case, for reasons of safety, it can always be assumed that bleeding is necessary. If the insulation is intact, it can be determined on the basis of the pressure vessel parameters and the insulation quality, whether blow-off is necessary. If so, it is assumed in step S500 that blow-off is necessary. Does not need to be blown off in the predetermined life, it is assumed in step S500 that no blow-off is necessary.

The foregoing description of the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

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 1546601 B1 [0001]
• DE 102015206782 [0020, 0020]
• DE 102015203702 [0021, 0021]
• DE 102014226545 [0021]

Claims (10)

Method for operating a motor vehicle with a cryogenic pressure vessel for fuel storage, comprising the steps: - Determine whether the motor vehicle is driving or in a room in which the air exchange rate is above an air exchange limit and / or the oxygen supply is over a Sauerstoffvorratsgrenzwert; and Generating a feedback if the air exchange rate and / or the oxygen supply is not above the air exchange limit and / or the oxygen storage limit. The method of claim 1, wherein the feedback is a request to connect the motor vehicle to an external fuel line or to park the motor vehicle at a location other than the space. The method of claim 1 or 2, wherein the feedback comprises a visual and / or acoustic signal that can be perceived from outside the vehicle. Method according to one of the preceding claims, further comprising the steps: - determining whether a blow-off of fuel is necessary; and - Generate the feedback when the blowing off of fuel is necessary. The method of claim 4, further comprising the step of: Determining the density of the fuel within the pressure vessel; and - Generate the feedback if the density of the fuel is above a lower limit density. Method according to claim 4 or 5, further comprising the step: - determining the insulation quality; and - Generate the feedback if the isolation is not intact. Method according to one of the preceding claims, further comprising the step: - Receiving the air exchange rate and / or the oxygen supply or a signal representing this (s) of at least one external transmitter. Method according to one of the preceding claims, wherein at least one geographic information signal representing the air exchange rate and / or the oxygen supply. The method of claim 1, wherein determining the rate of air exchange comprises the step of: determining whether the vehicle is in a closed space. The method of claim 8 or 9, wherein the closed space is determined by at least one environmental sensor; and / or wherein the at least one geographic information signal is a GPS signal.

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