FUEL CELL SYSTEM AS WELL AS A VEHICLE HAVING SUCH A FUEL CELL SYSTEM

Abstract

A fuel cell system (100) having a fuel cell stack (10) and a fuel cell cooling system (40) to cool the fuel cell stack (10), including a coolant path (4) into which the fuel cell stack (10) is integrated so as to transfer heat and in which at least one cooler (43) or heat exchanger is arranged. It is provided that the at least one cooler (43) or heat exchanger that does not have shock-hazard protection is interconnected so as to establish equipotential bonding (47), whereby at least one control element is arranged in the connection of the at least one cooler (43) or heat exchanger to equipotential bonding (47). Moreover, a vehicle having such a fuel cell system (100) is disclosed.

Claims

1. A fuel cell system comprising: a fuel cell stack; and a fuel cell cooling system to cool the fuel cell stack, the fuel cell cooling system including a coolant path, the fuel cell stack integrated into the coolant path so as to transfer heat, at least one cooler or heat exchanger being arranged in the coolant path, the at least one cooler being connected via a connection so as to establish equipotential bonding, at least one control element being arranged in the connection of the at least one cooler or heat exchanger to the equipotential bonding.

2. The fuel cell system as recited in claim 1 wherein the at least one control element is an electrical switch.

3. The fuel cell system as recited in claim 1 wherein the electrical switch is a relay.

4. The fuel cell system as recited in claim 1 further comprising a control unit configured to control the at least one control element.

5. The fuel cell system as recited in claim 4 wherein the control unit has a detector for detecting insulation faults in the fuel cell cooling system.

6. The fuel cell system as recited in claim 1 wherein the at least one cooler is arranged in the coolant path and connected to at least one sacrificial anode.

7. The fuel cell system as recited in claim 1 further comprising a deionization filter.

8. A vehicle comprising the fuel cell system as recited in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be described below by means of an embodiment on the basis of the accompanying drawings. The following is shown:

[0025] FIG. 1 a flow diagram of a fuel cell system.

DETAILED DESCRIPTION

[0026] FIG. 1 shows a fuel cell system designated in its entirety by the reference numeral 100. The fuel cell system 100 is part of a vehicle 1 (referenced schematically), especially an electric vehicle, which has an electric traction motor that is supplied with electric energy by the fuel cell system 100.

[0027] The fuel cell system 100 has, as its core component, a fuel cell stack 10 with a plurality of stacked cells 11, each of which comprises an anode space 12 as well as a cathode space 13, which are separated from each other by an ion-conductive polymer electrolyte membrane 14 (see detailed cutout view). Between two such membrane electrode units, there is also a bipolar plate that serves to feed the operating media into the anode and cathode spaces 12, 13 and that also establishes the electric connection between the individual fuel cells 11. In order for the fuel cell stack 10 to be supplied with the operating gases, the fuel cell system 100 has an anode supply system 20 on the one hand, and a cathode supply system 30 on the other hand.

[0028] The anode supply system 20 comprises an anode supply path 21 that serves to feed an anode operating gas (the fuel), for example, hydrogen, into the anode space 12 of the fuel cell stack 10. For this purpose, the anode supply path 21 connects a fuel reservoir 23 to an anode inlet of the fuel cell stack 10. The anode supply system 20 also comprises an anode exhaust gas path 22 that discharges the anode exhaust gas out of the anode spaces 12 via an anode outlet of the fuel cell stack 10. Moreover, the anode supply system 20 can have a fuel recirculation line that connects the anode exhaust gas path 22 to the anode supply path 21. The cathode supply system 30 comprises a cathode supply path 31 that feeds a cathode operating gas containing oxygen, especially air, into the cathode spaces 13 of the fuel cell stack 10.

[0029] The cathode supply system 30 also comprises a cathode exhaust gas path 32 that discharges the cathode exhaust gas (especially the exhaust air) out of the cathode spaces 12 of the fuel cell stack 10 and, if applicable, conveys it to an exhaust gas system.

[0030] Moreover, a fuel cell cooling system is being put forward, which is designated in its entirety by the reference numeral 40, which has a coolant path 41 in which the fuel cell stack 10 is integrated in a heat-exchanging manner. The coolant that is circulating in the coolant path 41 is conveyed by a coolant pump 42 driven by an electric motor. The temperature of the coolant, preferably water, a water-alcohol mixture or a water-ethylene glycol mixture, is controlled by a cooler 43 which, in case it is arranged in a vehicle, is normally a radiator equipped with an air fan. The cooler 43 has a sacrificial anode 44 and is connected to equipotential bonding 47 via a relay 45 that is controlled by a control unit 46. The relay 45 is controlled by means of the control unit 46 as a function of a detection of an insulation fault in the fuel cell cooling system 40. Thus, through the control of the relay 45, the connection of the cooler 43 to equipotential bonding 47 can be activated or deactivated. An insulation fault is detected, for example, by a conductivity measurement of the coolant or by an insulation resistance measurement in or on the fuel cell cooling system 40, for example, using a detection means 48. However, this information can also be provided by other suitable means in the fuel cell system 100, which are not shown here. The relay 45 is controlled based on the result of this measurement. Thus, for example, in case of an excessively high conductivity of the coolant, that is to say, if the measured value exceeds a prescribed value for the conductivity, the relay 45 establishes a connection between the cooler 43 and the equipotential bonding 47, as a result of which corrosion of the sacrificial anode 44 becomes possible, thereby protecting the cooler 43, which is made of less noble metals than the other components in the fuel cell cooling system 40. Moreover, in order to compensate for an ion input from the sacrificial anode 44 into the coolant, a deionization filter 49, for example, is arranged in the fuel cell cooling system 40. Once the fault that led to the elevated conductivity value has been remedied, the connection between the equipotential bonding 47 and the cooler 43 is once again deactivated, for example, by means of the control device 46. This can also be done manually in a repair shop. Control lines of the control unit 46 are not shown. Merely for the sake of illustration, an input 50 and an output 51 for the control lines on the control unit 46 are shown.

LIST OF REFERENCE NUMERALS

[0031] 100 fuel cell system [0032] 10 fuel cell stack [0033] 11 individual cell [0034] 12 anode space [0035] 13 cathode space [0036] 14 polymer electrolyte membrane [0037] 20 anode supply [0038] 21 anode supply path [0039] 22 anode exhaust gas path [0040] 23 fuel tank [0041] 30 cathode supply [0042] 31 cathode supply path [0043] 32 cathode exhaust gas path [0044] 40 fuel cell cooling system [0045] 41 coolant path [0046] 42 coolant pump [0047] 43 cooler [0048] 44 sacrificial anode [0049] 45 relay [0050] 46 control unit [0051] 47 equipotential bonding [0052] 48 detection means [0053] 49 deionization filter [0054] 50 input of the control unit [0055] 51 output of the control unit