DE102007003503A1 - Safety device for fuel cells - Google Patents

Abstract

The invention relates to devices for securing fuel cells in vehicles. For this purpose, there are sensors (2, 5) in / on the stack housing (1) which emit a signal when the stack housing (1) penetrates an object or other strong deformation which could also mechanically damage the stack (3) or interrupt a signal circuit (6), which then leads by means of monitoring device (7) to a shutdown of the media supply (8) to the fuel cell stack (3) or to an interruption of the power circuit (9) of the fuel cell system and possibly other aggregates.

Description

The The invention relates to devices for securing fuel cells. In particular, the invention relates to provisions for securing fuel cell stacks in vehicles.

fuel cell stacks are usually housed in housings. These enclosures protect the stack from dust, water (Short circuit) etc. These enclosures are usually only designed as a shell, the strong mechanical Influences from the outside can not resist. Becomes the housing and immediately afterwards the fuel cell stack of damaged outside and the BZ stack is located while in operation, the reaction media can exit the stack. Furthermore, they can be the stack damaging objects with current carrying Parts come into contact and form a short circuit, or derive the stack current uncontrolled.

Around to detect such stack damage will become common through the continuous measurement of single cell voltages, the Total stack voltage and other characteristics a monitoring the status realized. Damage to the stack However, the use of these parameters can in principle only be recognized if the damage has already occurred is and is already so advanced that malfunctions of the stack. That way, it's only at this stage be reacted and so i. a. only after the damage has occurred a shutdown of the media supply and an interruption of the circuit be brought about.

The publication US 2006/0137929 A1 describes a fuse system for vehicles with fuel cells in which via collision sensors in a vehicle accident, the fuel cells are switched off. Also the DE 10 2005 056 345 A1 describes such a device with acceleration sensors. These devices thus check the situation in which the vehicle is located and trigger, for example, in an accident safety measures. Damage to the fuel cell itself, in the normal operating situation of the vehicle (without collision), is not detected.

The patent DE 4341437 C1 describes a device for fuel cell-powered vehicles, in which gas sensors detect the escape of reaction media of the fuel cell and as a security measure close the valves of the gas supply and electrically disconnect the fuel cell. This arrangement thus reacts only when the fuel cell is damaged, which is so extensive that reaction media can escape and have already (depending on the position and sensitivity of the sensor) already already flowed out for a certain period of time.

The The invention is based on the aforementioned prior art. You are lying the object of a safety precaution for fuel cells develop early on damage to a fuel cell reacted with shutdown.

These Task is in a device with the features of the preamble of claim 1 solved by the characterizing features nenden of claim 1. Further details and advantageous embodiments the device according to the invention are the subject the dependent claims.

The Invention will be described below with reference to preferred embodiments with reference to the figures and the references therein explained in more detail.

there demonstrate:

1 Perspective view of a fuel cell housing with sensor wire as a security device

2 Section through the housing with safety device after 1

3 Sealing of the sensor wire

4 Fuse version with strain gauges

5 Interconnection of the sensor elements

6 Meandering arrangement of the sensor wire

7 Mesh-like arrangement of the sensor wire

8th Section through the housing with strain gauges

9 Section through the housing with securing device as a security device

The Invention proposes that in / on the stack housing Sensors are located, the housing at a penetration of the Stackge with an object or a strong deformation, which is also the Stack could mechanically damage a signal leave or interrupt a signal circuit, which then by means of monitoring device to a shutdown of the media supply to the fuel cell stack or to an interruption of the power circuit of the fuel cell system and possibly other aggregates.

This is realized by a corresponding sensor, which is mounted in or on the stack housing. As a sensor element may be a simple embodiment of a thin wire, which is mounted in or on the stack housing. 1 shows in perspective a fuel cell housing ( 1 ) with such a arranged on a housing surface sensor wire ( 2 ). 2 schematically shows a section through a fuel cell. Shown are two stacks ( 3 ) and the surrounding housing wall ( 1 ), which in this example on all surfaces with wire sensors ( 2 ) Is provided.

While of fuel cell operation (or from switching on a monitoring function) each sensor element is monitored for integrity, d. H. For example, the internal resistance of each sensor wire is measured or the wire is traversed by a very low current or is under tension.

To protect against accidental damage to a wire sensor, eg. B. during installation of the fuel cell, the wire by means of sealing ( 4 ), z. B. be protected in the form of a synthetic resin or lacquer layer. This is in 3 shown.

4 shows another embodiment of the device according to the invention. As an alternative to wire sensors, strain gauges ( 5 ) provided on the housing ( 1 ) are attached for example by means of adhesive and detect corresponding deformations on the housing and to the monitoring device ( 7 ) hand off. Critical deformation will in turn lead to shutdown of the media supply and interruption of the power circuit.

In 5 the external wiring of the sensor elements is shown schematically. For example, if an external mechanical damage causes a sensor wire ( 2 ), the corresponding sensor circuit ( 6 ) and it can be controlled by a control logic in the monitor ( 7 ) the shutdown of the media supply ( 8th ) to the fuel cell stack and / or an interruption of the power circuit ( 9 ) respectively.

The monitoring sensors are to be mounted on the stack in such a way that critical mechanical influences are detected as far as possible over the entire housing, which could (potentially only at a much later date) lead to potential damage to the stack. This can be z. B. by the meandering laying of a corresponding wire on a housing surface, as in 6 (or in 1 ). Other arrangements such as meshes, lattice shape, etc. are also suitable (cf. 7 ).

Strain gauges are preferably to be mounted so that they are located at the location where the design results in the largest strains. In 8th is an example of a distribution of strain gauges ( 5 ) on the edge areas and center areas of the housing ( 1 ). This is the most critical zones around the stacks ( 3 ) monitored by sensors.

In an extended embodiment of the invention Device can also be a combination of several types of sensors (eg break wire and strain gauges) or a combination from different arrangements (meander shape, network course) be used. The strain gauges and wire sensors are like that to dimension that not in case of shock or Vibrations already a (false) signal is delivered.

Next the already mentioned strain gauge and break wire Other types of sensors are conceivable that are similar can respond to the corresponding effects, for example thin metal foils with interlayer insulation, which in mechanical Impact is destroyed. Likewise, different can Combinations / arrangements of said sensors are used.

By the invention becomes ("imminent") damage a fuel cell already at the onset of damage the housing detected and the appropriate media supply to the fuel cell stack can be turned off before the fuel cell stack even by external mechanical influences is damaged and the reaction media contained therein get outside. By doing the shutdown of the media supply to the stack and the interruption of the power circuit in the fuel cell system is initiated before a direct mechanical damage of the Fuel cell stack occurs, it ensures that the shutdown done very early (considerable time savings) and thus the escape of reactants from the stack is prevented.

Next shutdown the media supply for the stack when the sensor is triggered, further actions take place. For example, other high voltage components (eg hybrid battery etc.) or near the fuel cell stack located aggregates and components are switched off with (Close the tank valves, etc.), if a threat of damage of the stack due to deformation or damage of the Stack housing was detected.

By equipping the stack housing with the sensor according to the invention can be dispensed with additional mechanical reinforcements to protect the housing. The connected with it dene saving in weight and space is therefore particularly when used in mobile systems advantage.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2006/0137929 A1 [0004]
• DE 102005056345 A1 [0004]
• - DE 4341437 C1 [0005]

Claims (3)

Device for securing fuel cells in which in a stack housing ( 1 ) one or more fuel cell stacks ( 3 ) are arranged, characterized in that in and / or on the stack housing ( 1 ) one or more sensor elements ( 2 . 5 ) are mounted, which in a deformation or penetration of the stack housing ( 1 ), which also the stack ( 3 ) could mechanically damage, give a signal or a signal circuit ( 6 ), which is then monitored by means of a monitoring device ( 7 ) to a shutdown of the media supply ( 8th ) to the fuel cell stack ( 3 ) or to an interruption of the power circuit ( 9 ) of the fuel cell system and possibly other aggregates. Apparatus according to claim 1, characterized in that as a sensor element, a wire ( 2 ) and / or strain gauges ( 5 ), wherein wire sensors ( 2 ) preferably meandering or net-shaped on the wall of the stack housing ( 1 ). Apparatus according to claim 1 or 2, characterized in that sensors ( 2 . 5 ) against accidental damage by means of sealing ( 4 ), z. B. in the form of a synthetic resin or paint layer protected.