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 (2) of a motor vehicle (1) having a fuel cell drive, the method comprising the steps of: (a) determining a first operating time at which the motor vehicle (1) is to be started up and a 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].

2. The method as claimed in claim 1, wherein the tank temperature (T) corresponds to the predicted maximum ambient temperature (T.sub.U,max) or corresponds substantially to the predicted maximum ambient temperature (T.sub.U,max).

3. The method as claimed in claim 1, wherein the method further comprises the step: relieving the pressure in the hydrogen tank (2) if it is determined that the tank pressure (p) will exceed the maximum permissible tank pressure (p.sub.max).

4. The method as claimed in claim 3, wherein it is ascertained whether the ambient temperature (T.sub.U) 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 (p.sub.max).

5. The method as claimed in claim 3, wherein the pressure is relieved by starting up the fuel cell drive in order to charge a battery (4) of the motor vehicle (1).

6. The method as claimed in claim 3, wherein the pressure is relieved by discharging hydrogen (3) from the hydrogen tank (2).

7. The method as claimed in claim 3, wherein the motor vehicle (1) is an autonomous motor vehicle (1) and the pressure is relieved by driving the motor vehicle (1) autonomously.

8. The method as claimed in claim 1, wherein an expected second operating time at which the motor vehicle (1) will be started up following the first operating time is determined, wherein the predicted maximum ambient temperature (T.sub.U,max) at the second operating time is ascertained.

9. The method as claimed in claim 1, wherein filling of the hydrogen tank (2) with hydrogen (3) takes place in two mutually alternating intervals, wherein in a first interval hydrogen (3) flows into the hydrogen tank (2) until a maximum permissible temperature (T.sub.max) of the hydrogen (3) in the hydrogen tank (2) is reached, and in a second interval no hydrogen (3) flows into the hydrogen tank (2) so that the hydrogen (3) in the hydrogen tank (2) with the maximum permissible temperature (T.sub.max) can cool down.

10. 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) is adapted to carry out a method as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] FIG. 1 is a perspective side view of an exemplary embodiment of a motor vehicle according to the invention during refueling, and

[0027] FIG. 2 is a graphical representation of a method according to the invention for refueling the motor vehicle from FIG. 1.

DETAILED DESCRIPTION

[0028] Elements having the same function and effect are provided with the same reference signs in each of FIGS. 1 and 2.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] FIG. 2 is a graphical representation of a method according to the invention for refueling the motor vehicle 1 from FIG. 1.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] An exemplary application scenario will be explained in greater detail in the following text. The ambient temperature at about 1 o'clock at night is T.sub.U=10° C. At this time, the motor vehicle 1 is to be refueled. The motor vehicle 1 is then to be started up at 8 o'clock in the morning on the following day.

[0039] In order to determine how much hydrogen 3 can be introduced into the hydrogen tank 2, the maximum ambient temperature T.sub.U,max is predicted on the basis of a weather forecast for 8 o'clock in the morning for the location at which the motor vehicle 1 is to be started up. In the present case, it is T.sub.U,max=20° C. Accordingly, the hydrogen tank 2 can be filled with hydrogen 3 until a maximum permissible tank pressure p.sub.max of, for example, 875 bar and a tank temperature of 20° C. is reached.

[0040] If, contrary to what was planned, the vehicle is then not started up at 8 o'clock in the morning and it is determined that the ambient temperature T.sub.U will rise above the predicted maximum ambient temperature T.sub.U,max=20° C., this would lead to an increase in the tank pressure above the maximum tank pressure p.sub.max.

[0041] 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.