Ascertaining the starting capability of a vehicle

Abstract

A method for ascertaining the re-starting capability of a vehicle, in particular when parking the vehicle, includes detecting the pressure and the temperature of fuel in a pressurized container, determining a final pressure value of the fuel in the pressurized container, where the final pressure value is an expected pressure of the fuel in the pressurized container after a period of parking of the vehicle, comparing the final pressure value with a minimum pressure value in order to ascertain whether the vehicle is capable of re-starting after the parking period, and generating a warning signal when the final pressure value is lower than the minimum pressure value.

Claims

1. A method for ascertaining a restarting capability of a vehicle, wherein the vehicle has a pressure vessel system comprising a pressure vessel for storing a fuel, and comprising the acts of: detecting a pressure and a temperature of the fuel in the pressure vessel; determining a final pressure value of the fuel in the pressure vessel, wherein the final pressure value is an expected pressure of the fuel in the pressure vessel after a parking period of the vehicle; comparing the determined final pressure value with a minimum pressure value for ascertaining whether the vehicle is capable of restarting after the parking period; and generating a notification signal when the determined final pressure value is lower than the minimum pressure value.

2. The method according to claim 1, wherein the method is performed during parking of the vehicle or before parking of the vehicle.

3. The method according to claim 1, wherein an ambient temperature is taken into account when determining the final pressure value.

4. The method according to claim 3, wherein an expected temperature development of the ambient temperature during the parking period is taken into account when determining the final pressure value.

5. The method according to claim 4, wherein the expected temperature development is based on weather forecast data.

6. The method according to claim 1 further comprising the act of providing a notification to a driver of the vehicle on a basis of the notification signal.

7. The method according to claim 6, wherein the notification to the driver is a warning notification to the driver of the vehicle that the vehicle should not be parked and that the pressure vessel of the vehicle should be filled before parking the vehicle.

8. The method according to claim 1, wherein, in response to the notification signal being generated, the fuel in the pressure vessel is heated and the final pressure value is determined again until the final pressure value has reached or undershot the minimum pressure value if it is possible to reach the minimum pressure value without exceeding a maximum temperature of the fuel in the pressure vessel and without exceeding a maximum pressure of the pressure vessel solely by heating.

9. The method according to claim 1, wherein the minimum pressure value is determined depending on a range of the vehicle which is required until a filling station for filling the pressure vessel is reached.

10. The method according to claim 1, wherein a temperature of the pressure vessel is taken into account when determining the final pressure value.

11. The method according to claim 1, wherein the act of determining the final pressure value of the fuel in the pressure vessel is carried out on a basis of a characteristic map.

12. The method according to claim 1 further comprising the act of heating the fuel in the pressure vessel when the pressure of the fuel in the pressure vessel lies below the minimum pressure value when restarting the vehicle after parking.

13. A pressure vessel system for a vehicle, comprising: a pressure vessel, wherein a fuel is stored in the pressure vessel; a first temperature measuring apparatus, wherein a temperature of the fuel in the pressure vessel is measurable by the first temperature measuring apparatus; a pressure measuring apparatus, wherein a pressure of the fuel in the pressure vessel is measurable by the pressure measuring apparatus; and a control device, wherein the control device is configured to: determine a final pressure value of the fuel in the pressure vessel, wherein the final pressure value is an expected pressure of the fuel in the pressure vessel after a parking period of the vehicle; compare the determined final pressure value with a minimum pressure value for ascertaining whether the vehicle is capable of restarting after the parking period; and generate a notification signal when the determined final pressure value is lower than the minimum pressure value.

14. The pressure vessel system according to claim 13, wherein the control device is configured to determine, compare, and generate when the vehicle is being parked.

15. The pressure vessel system according to claim 13, further comprising: a heating apparatus, wherein the fuel in the pressure vessel is heatable by the heating apparatus in response to the notification signal if it is possible to reach the minimum pressure value without exceeding a maximum temperature of the fuel in the pressure vessel and without exceeding a maximum pressure of the pressure vessel solely by heating; wherein the control device is configured to determine the final pressure value again until the final pressure value has reached or exceeded the minimum pressure value.

16. The pressure vessel system according to claim 15, wherein the heating apparatus is a heat exchanger.

17. The pressure vessel system according to claim 13 further comprising: a fuel consuming apparatus, wherein the vehicle is drivable by the fuel consuming apparatus and wherein the fuel consuming apparatus is supplyable with fuel from the pressure vessel via a fluid line; and a buffer store, wherein fuel from the pressure vessel is storable by the buffer store and wherein fuel is supplyable to the fuel consuming apparatus by the buffer store when the fluid line is blocked.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The FIGURE shows a schematic view of the pressure vessel system of the present invention.

DETAILED DESCRIPTION OF THE DRAWING

(2) The FIGURE shows a schematic view of the pressure vessel system 10 disclosed here. The pressure vessel system 10 comprises a pressure vessel 20, a fuel consuming apparatus 60 and a control device 30. The pressure vessel 20 serves to store fuel, in particular hydrogen. The fuel can be CcH2, CGH.sub.2 or CNG.

(3) The pressure vessel system 10 is arranged in a vehicle. The pressure vessel 20 is connected to the fuel consuming apparatus 60 via a fluid line 65 and a tank shut-off valve 70 in the fluid line 65. The fuel consuming apparatus 60 serves to drive the vehicle. The fuel consuming apparatus 60 can be a fuel cell.

(4) The control device 30 is connected via measuring lines 32, 33, 34, 35 to a first temperature measuring apparatus 45 for measuring the temperature of the fuel in the pressure vessel 20, to a pressure measuring apparatus 50 for measuring the pressure of the fuel in the pressure vessel 20, to a second temperature measuring apparatus 55 for measuring the temperature of the pressure vessel 20 and/or the installation space temperature (the installation space temperature is the temperature which prevails in the installation space of the pressure vessel 20) and to an ambient temperature measuring apparatus 40 for measuring the ambient temperature or the outside temperature.

(5) When parking the vehicle, that is to say when the control device 30 identifies that a parking process is being carried out or is immediately imminent, it is ascertained whether the vehicle is capable of restarting after a parking period, that is to say whether a sufficiently high pressure of the fuel (corresponding at least to the minimum pressure value) will be present, so that further extraction of fuel can be carried out without possible damage to the pressure vessel 20.

(6) The parking period (for example 30 minutes, 1 hour or 8 hours) can be entered by the user or can be a parking duration which is calculated based on experience or historical data or comprise other customer data (appointment planning, navigation data, ConnectedDrive or similar systems from other manufacturers).

(7) Ascertaining whether parking (and therefore turning off of the vehicle and consequently stoppage of fuel extraction) is immediately imminent or is currently taking place (for example entering a parking spot and/or driving into a parking garage) can be carried out on the basis of navigation data, position data, historical data and/or by a parking button which the driver operates.

(8) It is also conceivable that the starting point is a parking period which is so long that (thermodynamic) equalization between the temperature of the fuel and the ambient temperature has taken place, that is to say the fuel is at the temperature of the surrounding area (which is determined by means of weather forecast services or, when parking in parking garages, by means of the ambient temperature of the parking garage) at the end of the parking period.

(9) The control device 30 detects the temperature and the pressure of the fuel in the pressure vessel 20. The temperature of the pressure vessel 20 and the ambient temperature are likewise detected. In addition, weather forecast data (for example from the Internet or World Wide Web) can be taken into account by the control device 30. In addition, historical temperature developments of the ambient temperature (for example in the last 24 hours) can be taken into account. The quantity of fuel in the pressure vessel 20 can also be detected and taken into account in the determination operation.

(10) A final pressure value is determined by the control device 30 on the basis of this data, wherein the final pressure value is the pressure of the fuel in the pressure vessel 20 after a (prespecified or calculated) parking period of the vehicle. The final pressure value can be calculated by the control device 30. By way of example, the final pressure value can be calculated as follows:

(11) pressure of the fuel in the pressure vessel when parking the vehicle is 26 bar at a temperature of the fuel in the pressure vessel of 55 C. (density approximately 1.89 g/l);

(12) pressure of the fuel in the pressure vessel when restarting the vehicle is 20 bar at a temperature of the fuel in the pressure vessel of 20 C. (density approximately 1.89 g/l).

(13) The (expected) parking period is calculated with reference to historical data. As an alternative or in addition, the driver can enter the length of the (expected) parking period into the control device 30.

(14) The cooling down of the fuel in the pressure vessel 20 can be calculated by means of mathematical or physical models. Historical data from previous parking processes can also be employed here. The calculated or determined final pressure value indicates the magnitude of the pressure of the fuel in the pressure vessel 20 at the end of the parking period, that is to say when the vehicle is next started.

(15) When the determined final pressure value corresponds to the minimum pressure value (for example 20 bar) or is greater than the minimum pressure value, restarting of the vehicle and extraction of fuel from the pressure vessel 20 is possible during or after restarting of the vehicle since there is no risk of damage to the pressure vessel 20 in the event of a further reduction in pressure due to the extraction of the fuel.

(16) The control device 30 can make the decision as to whether the vehicle is capable of restarting after the parking period by way of comparing the final pressure value with the minimum pressure value.

(17) If the control device 30 ascertains that the final pressure value lies below the minimum pressure value and/or it is ascertained that the closest filling station will no longer be reached, the control device 30 generates a notification signal. The notification signal can be used to display an item of information or a warning signal to the driver that restarting of the vehicle after the (planned or expected) parking period will not be possible. The display or the warning signal can acoustically and/or optically prompt the driver to fill the pressure vessel 20 with fuel before parking or turning off the vehicle (and the resulting cooling down of the fuel in the pressure vessel 20). The display or the warning signal can read, for example, Do not park the vehicle! Fill the vehicle with fuel before parking! An acoustic signal to the driver (warning sound) can also be generated on the basis of the notification signal here.

(18) It is also conceivable, in response to the notification signal being generated, for the control device 30 to heat the fuel in the pressure vessel 20 using a heating apparatus, so that the pressure of the fuel corresponds at least to the minimum pressure value after the (planned) parking period. The final pressure value is repeatedly determined during heating. This heating is carried out by the control device 30 only when it is ascertained by the control device 30 that a pressure of this kind or a temperature of this kind of the fuel can be reached without exceeding a maximum temperature of the fuel in the pressure vessel 20 or a maximum temperature of the pressure vessel 20 and without exceeding a maximum pressure of the pressure vessel 20. If it is ascertained that this is not possible, the fuel in the pressure vessel 20 is not heated.

(19) Since the vehicle and, respectively, the pressure vessel system 10 can (usually) be filled after restarting of the vehicle and further extraction of fuel from the pressure vessel 20 after parking the vehicle only when the vehicle has been moved to a filling station, the remaining range of the vehicle can be taken into account when determining the final pressure value. Therefore, the distance from the next filling station and the amount of fuel required to reach the filling station are calculated. The cooling down of the fuel in the pressure vessel 20 and the drop in pressure due to the extraction of fuel after parking are taken into account or included in the determination operation or calculation operation. When the fuel is extracted after parking on the way to the filling station, the pressure of the fuel must likewise not fall below the minimum pressure value. Therefore, a minimum pressure value is determined by the control device 30 and takes into account the extraction of fuel on the way from the parking location or the parking position of the vehicle to the filling station.

(20) A notification signal is generated when the fuel or the pressure of the fuel after parking is (expected to be) insufficient to reach a filling station (without allowing the pressure of the fuel to fall below the minimum pressure value).

(21) The minimum pressure value can be determined again at intervals or continuously during driving (and therefore before parking the vehicle). In this case, it is possible to start, for example, from a parking period which is of such a length that the temperature of the fuel has reached the temperature of the surrounding area (in particular the ambient temperature after the parking period) (thermodynamic equalization). As an alternative, the parking period can be estimated, for example, with reference to historical data. During driving of the vehicle, a warning can be issued to the driver on the basis of the notification signal or in response to the notification signal when he/she is so far away from the next filling station for filling the pressure vessel 20 with fuel, or shortly before this time, to do so that, when the temperature of the fuel is matched to the ambient temperature (either the current ambient temperature or the expected ambient temperature at a later time, wherein this is determined, for example, with reference to weather forecast data), the pressure of the fuel in the pressure vessel 20 lies below the minimum pressure value. This means that a check is made during driving as to whether the vehicle is capable of restarting, that is to say there is a sufficiently high pressure of the fuel after the parking period to move the vehicle, and the vehicle can be driven into the next filling station without falling below a minimum pressure in the pressure vessel 20 in the event of the vehicle being immediately parked and a parking period (which is so long that complete equalization of the fuel temperature and the ambient temperature has taken place or the duration of which is estimated on the basis of historical data). The driver can be warned by way of an acoustic and/or optical and/or haptic warning (for example If you park the vehicle now, it is likely that you will no longer be able to reach a filling station after restarting the vehicle after parking!) if he/she is too far away from the filling station.

(22) The consumption, the quantity of fuel in the pressure vessel 20 and/or the state (state of charge; SOC) of a high-voltage store can be taken into account when determining the remaining range.

(23) The information about the location and/or the distance of the vehicle from the parking position to the filling station can be transmitted from a navigation system to the control device 30.

(24) If the parking period is longer than planned or determined and/or the development of the ambient temperature differs from the weather forecast data, it may be the case that, under certain circumstances, the pressure of the fuel at the end of parking is nevertheless below the minimum pressure value. In this case, the fuel can be heated at the end of parking in order to raise the pressure of the fuel in the pressure vessel 20 to a value which corresponds at least to the minimum pressure value. This heating process is carried out only when the minimum pressure value can be reached without exceeding a maximum temperature of the fuel in the pressure vessel 20 and without exceeding a maximum pressure of the pressure vessel 20.

(25) Characteristic maps can be used in order to determine the final pressure value. In this way, the final pressure value can be determined with a low level of computational expenditure. The characteristic maps can take into account, inter alia, the temperature of the fuel, the remaining range, the ambient temperature, the installation space temperature, the pressure of the fuel.

(26) A buffer store for buffer-storing fuel can be arranged between the tank shut-off valve 70 and the fuel cell 60 (not shown), the buffer store supplying the fuel cell 60 with fuel when the tank shut-off valve 70 is closed (for example during parking). Therefore, the fuel cell 60 can be supplied with fuel at the end of the parking period or parking, so that the waste heat from the fuel cell heats the fuel in the pressure vessel 20 and/or the fuel cell supplies energy to a tank heat exchanger which is designed to heat the fuel in the pressure vessel 20. The tank heat exchanger can also be supplied with energy from a high-voltage store. Therefore, it is possible to heat the fuel in the pressure vessel 20 at the end of the parking period or parking in order to increase the pressure of the fuel in the pressure vessel 20 to or above the minimum pressure value if it is possible to reach the minimum pressure value without exceeding a maximum temperature of the fuel in the pressure vessel 20 and without exceeding a maximum pressure of the pressure vessel 20 solely by heating.

(27) For the reasons of readability, the expression at least one has, in some instances, been omitted for the sake of simplicity. If a feature of the technology disclosed here is described in the singular or using the indefinite article (for example the/a pressure vessel, the/a control device etc.), the disclosure is simultaneously also intended to encompass the plural thereof (for example the at least one pressure vessel, the at least one control device etc.).

(28) The above description of the present invention serves merely for illustrative purposes and not for the purposes of limiting the invention. In the context of the invention, numerous changes and modifications are possible without departing from the scope of the invention and its equivalents.

LIST OF REFERENCE CHARACTERS

(29) 10 Pressure vessel system 20 Pressure vessel 30 Control device 32, 33, 34, 35 Measuring lines 40 Ambient temperature measuring apparatus 45 First temperature measuring apparatus 50 Pressure measuring apparatus 55 Second temperature measuring apparatus 60 Fuel consuming apparatus 65 Fluid line 70 Tank shut-off valve

(30) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.