Method for filling a hydrogen tank of a motor vehicle comprising a fuel cell drive and motor vehicle

Abstract

The invention relates to a method for filling a hydrogen tank (2) of a motor vehicle (1) comprising a fuel cell drive, wherein the method comprises the steps: (a) determining a first operating time at which the motor vehicle (1) is to be started up and an expected first operating location at which the motor vehicle (1) is to be started up, (b) ascertaining a predicted maximum ambient temperature (T.sub.U,max) at the first operating location at the first operating time, and (c) filling the hydrogen tank with hydrogen (3) until a tank pressure (p) in the hydrogen tank (2) reaches a maximum permissible tank pressure (p.sub.max) at a tank temperature (T), wherein the following applies for the tank temperature (T): tank temperature (T)=[maximum ambient temperature (T.sub.U,max); maximum ambient temperature (T.sub.U,max)+10 K]. The invention relates further to a motor vehicle (1) comprising a hydrogen tank (2), a fuel cell drive and a control system (5) for controlling filling of the hydrogen tank (2), wherein the control system (5) to carry out the method.

Claims

1. A method for filling a hydrogen tank of a motor vehicle having a fuel cell drive, the method comprising providing a control system configured to: (a) determine a first predicted future operating time at which the motor vehicle is to be started up and a first operating location at which the motor vehicle is to be started up, (b) ascertain a predicted maximum ambient temperature (TU,max) at the first operating location at the predicted future first operating time, and (c) fill the hydrogen tank with hydrogen until a tank pressure (p) in the hydrogen tank reaches a maximum permissible tank pressure (pmax) at a tank temperature (T), wherein the following applies for the tank temperature (T): the tank temperature (T) corresponds to the predicted maximum ambient temperature (TU,max) or corresponds substantially to the predicted maximum ambient temperature (TU,max).

2. The method as claimed in claim 1, wherein the control system is configured to relieve the pressure in the hydrogen tank when it is determined that the tank pressure (p) will exceed the maximum permissible tank pressure (pmax).

3. The method as claimed in claim 2, wherein the control system is configured to ascertain whether the ambient temperature (TU) will exceed the tank temperature before the motor vehicle is started up, in order to determine whether the tank pressure (p) will exceed the maximum permissible tank pressure (pmax).

4. The method as claimed in claim 2, wherein the control system is configured to relieve the pressure by starting up the fuel cell drive in order to charge a battery of the motor vehicle.

5. The method as claimed in claim 2, wherein the control system is configured to relieve the pressure by discharging hydrogen from the hydrogen tank.

6. The method as claimed in claim 2, wherein the motor vehicle is an autonomous motor vehicle and the pressure is relieved by driving the motor vehicle autonomously.

7. The method as claimed in claim 1, wherein the control system is configured to determine an expected second predicted future operating time at which the motor vehicle will be started up following the first predicted future operating time, wherein the predicted maximum ambient temperature (TU,max) at the second predicted future operating time is ascertained.

8. The method as claimed in claim 1, wherein the filling of the hydrogen tank with hydrogen takes place in two mutually alternating intervals, wherein in a first interval hydrogen flows into the hydrogen tank until a maximum permissible temperature (Tmax) of the hydrogen in the hydrogen tank is reached, and in a second interval no hydrogen flows into the hydrogen tank so that the hydrogen in the hydrogen tank with the maximum permissible temperature (Tmax) can cool down.

9. A motor vehicle comprising a hydrogen tank, a fuel cell drive and the control system that is adapted to carry out the method as claimed in claim 1.

10. The method as claimed in claim 1, wherein the first predicted future operating time is defined by a vehicle user providing a time value as in input.

11. The method as claimed in claim 1, wherein the first predicted future operating time is during a following day.

12. The method as claimed in claim 11, wherein the first predicted future operating time is defined by a vehicle user providing a time value as in input.

13. The method as claimed in claim 1, wherein the first predicted future operating time is ascertained by the motor vehicle on basis of a use profile of the motor vehicle.

14. The method as claimed in claim 13, wherein the operating location is determined by GPS.

15. The method as claimed in claim 1, wherein the first predicted future operating time is capable of being passed without starting of the motor vehicle.

16. The method as claimed in claim 15, wherein the operating location is determined by GPS.

17. The method as claimed in claim 1, wherein the first predicted future operating time is provided by a vehicle user entering a time value to an external device that interfaces with the control system of the motor vehicle.

18. The method as claimed in claim 17, wherein the external device is a smartphone.

19. A method for filling a hydrogen tank of a motor vehicle having a fuel cell drive, the method comprising providing a control system configured to: (a) determine a first predicted future operating time at which the motor vehicle is to be started up and a first operating location at which the motor vehicle is to be started up, (b) ascertain a predicted maximum ambient temperature (TU,max) at the first predicted future operating location at the first operating time, (c) fill the hydrogen tank with hydrogen until a tank pressure (p) in the hydrogen tank reaches a maximum permissible tank pressure (pmax) at a tank temperature (T), wherein the following applies for the tank temperature (T): tank temperature (T)=[maximum ambient temperature (TU,max); maximum ambient temperature (TU,max)+10 K], and (d) relieve the pressure in the hydrogen tank when it is determined that the tank pressure (p) will exceed the maximum permissible tank pressure (pmax), wherein the ambient temperature (TU) is the tank temperature before the start of operation of the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in greater detail hereinbelow with reference to the accompanying drawing. All the features which follow from the claims, the description or the figure, including structural details, can be essential to the invention both on their own and in any different combinations. In the drawing, in each case diagrammatically:

(2) FIG. 1 is a perspective side view of an exemplary embodiment of a motor vehicle according to the invention during refueling, and

(3) FIG. 2 is a graphical representation of a method according to the invention for refueling the motor vehicle from FIG. 1.

DETAILED DESCRIPTION

(4) Elements having the same function and effect are provided with the same reference signs in each of FIGS. 1 and 2.

(5) FIG. 1 is a perspective side view of an exemplary embodiment of a motor vehicle 1 according to the invention comprising a fuel cell drive (not shown) during refueling at a hydrogen dispenser 6.

(6) The hydrogen dispenser 6 is connected to the vehicle 1 by means of a hose and a dispenser nozzle. A hydrogen tank 2 of the motor vehicle 1 is filled with hydrogen 3 from the hydrogen dispenser 6.

(7) The motor vehicle 1 further has a battery 4 and a control system 5. The battery 4 can be charged by means of the fuel cell drive and the hydrogen 3 from the hydrogen tank 2. The control system 5 serves to control the refueling process.

(8) FIG. 2 is a graphical representation of a method according to the invention for refueling the motor vehicle 1 from FIG. 1.

(9) The graphical representation shows a graph in which a flow S of hydrogen 3 into the hydrogen tank 2, or filling of the hydrogen tank 2 with hydrogen 3, the temperature T of the hydrogen 3 in the hydrogen tank 2 and the tank pressure p of the hydrogen 3 in the hydrogen tank 2 are shown. The time t of the refueling process is plotted on the abscissa. The temperature T and the tank pressure p of the hydrogen are plotted on the ordinate.

(10) In a first interval I, hydrogen 3 is supplied to the hydrogen tank 2 by means of the flow S.1. The tank pressure p and the temperature T of the hydrogen 3 thereby increase. When or before the temperature T reaches a maximum permissible temperature T.sub.max, the flow S.1 is stopped and the refueling process is paused.

(11) There then follows a second interval II in which a time t is allowed to pass, during which the hydrogen 3 cools down. Cooling can actively be assisted.

(12) The second interval II is again followed by a further first interval I in which hydrogen 3 is supplied to the hydrogen tank 2 by means of the flow S.2 until the maximum permissible temperature T.sub.max is reached. A second interval II then again follows.

(13) This intermittent refueling process continues until a tank pressure p is reached that corresponds to a maximum permissible tank pressure p.sub.max at a predicted maximum ambient temperature T.sub.U,max. The predicted maximum ambient temperature T.sub.U,max is a temperature that will be present at an expected first operating time and at an expected first operating location.

(14) An exemplary application scenario will be explained in greater detail in the following text. The current ambient temperature (at about 1 o'clock at night) is TU=10? C. At this time, the motor vehicle 1 is to be refueled. The motor vehicle 1 is then predicted to be started up at 8 o'clock in the morning on the following day.

(15) In order to determine how much hydrogen 3 can be introduced into the hydrogen tank 2, the maximum ambient temperature TU,max is predicted by the control system 5 on the basis of a weather forecast for 8 o'clock in the morning for the location at which the motor vehicle 1 is predicted to be started up. In the present case, it is TU,max=20? C. Accordingly, the hydrogen tank 2 can be filled with hydrogen 3 under the control of the control system 5 until a maximum permissible tank pressure pmax of, for example, 875 bar and a tank temperature of 20? C. is reached.

(16) If, contrary to what was planned, the vehicle is then not started up at 8 o'clock in the morning as predicted and it is determined that the ambient temperature TU will rise above the predicted maximum ambient temperature TU,max=20? ? C., this would lead to an increase in the tank pressure above the maximum tank pressure pmax.

(17) In order to avoid the maximum tank pressure p.sub.max being exceeded, the motor vehicle 1 can, for example, be started up in order to charge the battery 4, in order to drive autonomously, or hydrogen 2 can be discharged from the hydrogen tank 3 by means of a purge valve.