Method for operating a valve of a pressure vessel system, and pressure vessel system

Abstract

A method for operating a valve of a pressure vessel system includes determining an actual pressure difference between an inlet pressure at an inlet of the valve and an outlet pressure at an outlet of the valve, and enabling the valve if the actual pressure difference is lower than or equal to a maximum admissible pressure difference of the valve.

Claims

1. A method for operating a valve of a pressure vessel system of a motor vehicle, wherein the pressure vessel system includes a pressure vessel that is a cryogenic pressure vessel or a high-pressure gas vessel, wherein the valve is fluidically connected to the pressure vessel, wherein the pressure vessel system includes a control unit, wherein a safety function is stored in the control unit, and wherein the safety function ensures that the valve can be actuated only if an actual pressure difference between an inlet pressure at an inlet of the valve and an outlet pressure at an outlet of the valve is in a range of 0% to 50% inclusive, comprising the steps: determining the actual pressure difference; and enabling the valve by the control unit when the actual pressure difference is in the range of 0% to 50% inclusive, wherein the range is a design limit of the valve that is not to be exceeded.

2. The method as claimed in claim 1, further comprising reducing, before opening of the valve, the actual pressure difference.

3. The method as claimed in claim 2, wherein reducing the actual pressure difference comprises at least one of: opening a pilot control seat of the valve; opening a bypass valve; relieving pressure in a fuel line upstream of the valve; and increasing pressure in the fuel line downstream of the valve.

4. A method for operating a valve of a pressure vessel system, comprising the steps: determining an actual pressure difference between an inlet pressure at an inlet of the valve and an outlet pressure at an outlet of the valve; opening the valve only if the actual pressure difference is lower than or equal to a maximum admissible pressure difference of the valve, wherein the maximum admissible pressure difference of the valve is a design limit of the valve that is not to be exceeded; and determining the inlet pressure at the inlet of the valve by: determining an inlet pressure of a fuel and a temperature of the fuel at the inlet at a first time, wherein the first time is a time at which the valve was most recently open; measuring a present actual inlet pressure at a second time at which the valve is closed; comparing the present actual inlet pressure at the second time with the inlet pressure at the first time.

5. The method as claimed in claim 2 further comprising the step of: determining the inlet pressure at the inlet of the valve by: determining an inlet pressure of a fuel and a temperature of the fuel at the inlet at a first time, wherein the first time is a time at which the valve was most recently open; measuring a present actual inlet pressure at a second time at which the valve is closed; comparing the present actual inlet pressure at the second time with the inlet pressure at the first time.

6. The method as claimed in claim 3 further comprising the step of: determining the inlet pressure at the inlet of the valve by: determining an inlet pressure of a fuel and a temperature of the fuel at the inlet at a first time, wherein the first time is a time at which the valve was most recently open; measuring a present actual inlet pressure at a second time at which the valve is closed; comparing the present actual inlet pressure at the second time with the inlet pressure at the first time.

7. A pressure vessel system of a motor vehicle, comprising: a pressure vessel that is a cryogenic pressure vessel or a high-pressure gas vessel configured to store fuel; a valve fluidically connected to the pressure vessel; and a control unit, wherein the control unit is configured to determine an actual pressure difference between an inlet pressure at an inlet of the valve and an outlet pressure at an outlet of the valve, and wherein a safety function is stored in the control unit and wherein the safety function ensures that the valve can be actuated only if the actual pressure difference is in a range of 0% to 50% inclusive, wherein the range is a design limit of the valve that is not to be exceeded.

8. The pressure vessel system as claimed in claim 7, wherein the valve is a pilot-controlled valve.

9. The pressure vessel system as claimed in claim 7, further comprising a bypass valve in relation to the valve.

10. The pressure vessel system as claimed in claim 8, further comprising a bypass valve in relation to the valve.

11. The pressure vessel system as claimed in claim 7, further comprising a pressure relief device arranged upstream of or fluidically in parallel with respect to the valve, wherein the pressure relief device is configured to discharge fuel to reduce the actual pressure difference.

12. The pressure vessel system as claimed in claim 8, further comprising a pressure relief device arranged upstream of or fluidically in parallel with respect to the valve, wherein the pressure relief device is configured to discharge fuel to reduce the actual pressure difference.

13. The pressure vessel system as claimed in claim 9, further comprising a pressure relief device arranged upstream of or fluidically in parallel with respect to the valve, wherein the pressure relief device is configured to discharge fuel to reduce the actual pressure difference.

14. The pressure vessel system as claimed in claim 7, further comprising at least one replenishment line fluidically connected to the outlet of the valve such that the pressure downstream of the valve can be increased.

15. The pressure vessel system as claimed in claim 8, further comprising at least one replenishment line fluidically connected to the outlet of the valve such that the pressure downstream of the valve can be increased.

16. The pressure vessel system as claimed in claim 11, further comprising at least one replenishment line fluidically connected to the outlet of the valve such that the pressure downstream of the valve can be increased.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically depicts one embodiment of a pressure vessel system configured in accordance with the principles of the invention.

(2) FIG. 2 depicts one embodiment of a process for operating the pressure vessel system of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) FIG. 1 schematically shows the pressure vessel system disclosed here. In the pressure vessel 100, fuel is stored, for example hydrogen at 700 bar. The pressure vessel 100 provides hydrogen for a fuel cell stack with a multiplicity of fuel cells 300, which are operated at a relatively low pressure level, for example 0 to 2 barg (positive pressure in relation to atmospheric pressure). At one end of the pressure vessel 100, there is provided a tank shut-off valve 210. Instead of only one pressure vessel 100 with a tank shut-off valve 210, it would likewise be possible for multiple pressure vessels 100 with multiple tank shut-off valves 210 to be provided. In the system illustrated here, there are furthermore provided two pressure stages which each operate with a pressure reducer 211, 212. The first pressure stage lowers the pressure from 700 bar to a medium pressure level of for example 11 to 13 bar (medium pressure region). The second pressure stage lowers the pressure from the medium pressure to the low pressure of the fuel cells. To prevent inadmissible loading of the pipelines in the event of a malfunction of the pressure reducers 211, 212, in each case one pressure relief valve 213, 214 is provided on the low-pressure side. During the replenishment of the pressure vessel system, fuel flows through the replenishment coupling 221 and the replenishment line 220 into the pressure vessel 100. The replenishment line 220 is connected to the outlet of the tank shut-off valve 210. If an excessively large actual pressure difference between inlet and outlet of the tank shut-off valve 210 has now been detected by the controller 400, then a user or trained service personnel can increase the pressure in the anode subsystem, for example by pressurizing the replenishment line 220 and/or the anode feed line 215. For this purpose, the replenishment coupling 221 or a service port (not shown here) may be utilized. Dashed lines are used to show a bleed port 219. Said bleed port 219 likewise opens out in the pressure vessel 100, and is thus arranged fluidically in parallel with respect to the tank shut-off valve 210. Here, the bleed port 219 may be manually actuated, such that the pressure in the pressure vessel 100 can be reduced by means of said bleed port 219. The pressure relief unit disclosed here however does not need to be designed as a bleed port 219.

(4) Alternatively or in addition to the bleed port 219, it is furthermore possible for a bypass valve 218 to be provided, which is in this case electrically actuated.

(5) The components shown here with the reference designations 100, 210, 211, 212, 213, 214, 215, 218, 219, 220, 221, 232, 234, 236, 238 (and in part) 300 are constituent parts of the anode subsystem A. The flow direction of the fuel is illustrated here by an arrow.

(6) The method disclosed here will now be discussed on the basis of FIG. 2. The method starts with the step S100. Firstly, the actual pressure difference between the inlet and the outlet of the valve is directly or indirectly determined. For this purpose, both pressure values may be measured. It is preferable for only pressure values downstream of the valves to be measured, from which the values at the inlet are then calculated. In the step 300, the actual pressure difference is then compared with the maximum admissible pressure difference of the valve 210. If the actual pressure difference is greater than the maximum admissible pressure difference, then in the step S400, the pressure difference is reduced, for example by virtue of the anode subsystem being pressurized downstream of the valve 210 and/or by virtue of fuel being discharged from the at least one pressure vessel 100. In the step S500, an output to a user of the motor vehicle or else to a servicing facility may be performed. Subsequently, the step S200 is performed again. If the actual pressure difference is lower than the maximum admissible pressure difference, then the valve 210 can be enabled. The valve 210 may then be opened or continue to be operated. The control unit 400 is designed to carry out the abovementioned steps.

(7) For the sake of legibility, the expression “at least one” has, in part, been omitted for the sake of simplicity. If a feature of the technology disclosed here is described in the singular or indeterminate (for example the/a pressure vessel, the/a valve, the/a bypass valve etc.), the disclosure is simultaneously also intended to encompass the plural thereof (for example the at least one pressure vessel, the at least one valve, the at least one bypass valve etc.).

(8) 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.

(9) 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.