DE102007038153A1 - Fuel cell, has conductive rubber layer extending from one end of stack to other end of stack and comprising conductive layers that contact bipolar plates for measuring voltage at respective bipolar plate - Google Patents

Abstract

The cell has a set of bipolar plates forming a stack and separated from each other by a membrane. A conductive rubber layer extends from one end of the stack to the other end of the stack. The conductive rubber layer has conductive layers that contact the bipolar plates for measuring the voltage at the respective bipolar plate. The conductive plate is attached to the conductive rubber layer by the conductive strips. The conductive strips of each conductive layer contact the conductive rubber layer and the bipolar plates for guiding the voltage to measure value detection. An independent claim is also included for a voltage tapping device.

Description

State of the art

Fuel cell technology

fuel cells put chemical energy directly, in conjunction with a high Efficiency, into electrical energy. They often consist of stacks of cells called stacks. The cells are made up with one bipolar plate (f) left and right and one membrane (g). The voltage generated by the chemical reaction falls over the Membrane off. This voltage can be measured on the bipolar plates and is a relevant one Size at Operating the fuel cell.

Einzelzellspannungsabgriff

Around To measure the cell voltages are often used spring contacts which are often mounted on a bracket. These contacts will be Positioned on each individual cell and by means of a printed circuit board fixed. This circuit board has traces which passes the voltage of the individual cells to a measuring point.

• • Hoher Aufbau des Abgriffs aufgrund relativ langer Federkontakte
• • Messspitzen verletzen die Oberfläche der Bipolarplatten
• • Rüttelempfindlich
• • Aufwendige Justierung
• • Temperaturempfindlichkeit
• • Anfällig gegenüber mechanischer Belastungen

This technique has the following disadvantages:

• • High construction of the tap due to relatively long spring contacts
• • Measuring tips injure the surface of the bipolar plates
• • sensitive to vibration
• • Extensive adjustment
• • Temperature sensitivity
• • Susceptible to mechanical loads

statement of the patent

task

• • Flach im Aufbau
• • Brennstoffzellenoberflächen sollen nicht beschädigt werden
• • Rüttelunempfindlichkeit
• • Wiederkehrende Montagefähigkeit
• • Temperaturbeständigkeit > 160°C

The aim is to develop a measuring tap which has the following properties:

• • Flat in construction
• • Fuel cell surfaces should not be damaged
• • Rüttelunempfindlichkeit
• • Recurring assembly capability
• • Temperature resistance> 160 ° C

solution the task with achieved advantages

to Contacting the bipolar plates (f) becomes a conductive rubber (b) in combination used with a printed circuit board (s).

Advantages:

• • flat under construction.
• • fuel cells will not be damaged.
• • Rüttelunempfindlich.

So-called Conductive rubbers usually exist alternating layers of conductive and non-conductive materials, For example, carbon rubber and silicone rubber. Other rubber materials or general materials with elastic properties (not only rubber materials) and with the mentioned electrical properties are of course also conceivable. Ie. that in the context of the present invention under the term "conductive rubber" in general materials or means should be understood, on the one hand flexible or elastic and conductive and non-conductive areas have, with the areas alternate.

In the 1 and 2 For example, an embodiment of a fuel cell having a voltage tapping device is shown having a conductive rubber layer and an overlying circuit board. The conductive rubber layer rests directly on the bipolar plates of the fuel cell, so that an electrical connection is formed between the bipolar plates and the adjacent conductive regions of the conductive rubber layer. If the grid (distance) of the conductive layers of the conductive rubber is smaller than the distance between the bipolar plates, it can be ensured that at least one conductive layer of the conductive rubber always bears against a bipolar plate.

Referring to the 1 and 2 For example, printed conductors are provided on the printed circuit board, which electrically contact respective conductive rubber layers and run to a measured value detection, which is not shown in the figures, however.

to Contacting the bipolar plates (f) becomes a conductive rubber (b) in combination used with a printed circuit board (s).

The Conductive rubber consists of alternating conductive and non-conductive Layers. The conductive layers are thinner than the membrane (g) or the gaps two bipolar plates (f) of the fuel cell. This will ensure that under no circumstances a short circuit between two cells is caused. An exact one Positioning is not necessary, because on the one hand always a contact the bipolar plates (f) touched and on the other hand no short circuit can be caused. The conductive rubber must be permanently exposed to a certain pressure, so that the contact between conductive rubber (b) and fuel cell is perfect. The conductive rubber (b) can be used up to 100,000 times be relieved and is therefore for a permanent operation and frequent Dismantling suitable.

To the individual voltages of the Zel To contact and pass on plugs or the like, which are conducted via the conductive rubbers (b), a printed circuit board (e) is contacted with the conductive rubber (b). On the circuit board (e) conductor tracks (c) are positioned, which are touched by the conductive layer of the conductive rubber (b). One or more tracks (c) are positioned on the circuit board (e) for each bipolar plate (f). A change in length of the stack due to thermal expansion can thus also be compensated. The conductive rubber can literally shift on the track and on the fuel cell and re-establishes contact with the track on the board and fuel cell with another conductive layer of the rubber.

With the printed circuit board (e) can also be the pressure on the above described Rubber can be made. The circuit board (s) can be on or between attached to the end plates (a) of the fuel cell, thereby a high structure is avoided.

Around the individual measured values can be evaluated on the printed circuit board u. a. a connector can be mounted, which is the interface of each Cells to the analyzers (eg Cell Voltage Monitoring).

Further technical details emerge from the figures and the annex, in the keywords the invention is shown again.

If in the context of the present invention of conductive or conductivity is always meant, the electrical conductivity is meant.

Cursive representation the invention

• • Main application area So far, the contacting of LC displays.
• • Of the Structure of the conductive rubber consists of conductive and non-conductive Layers.
• • temperature resistance depending on the material combination up to 250 ° C
• • The conductive layer is thinner as the insulating layer, causing short circuits through the contact be avoided.
• • The Conductive rubber provides the electrical contact between the bipolar plate and the tracks of the circuit board ago. The conductor leads the measuring signal for evaluation on.

Advantages of conductive rubbers:

• • Height temperature resistance
• • flat under construction
• • bipolar plates will not be damaged
• • vibration insensitivity
• • Variables Pitch: 0.1 mm to 0.25 mm
• • (Total from senior and non-executive level)

Required information for realization

• • Expansion coefficient of the stack
• • Exact dimensions (Thickness) of the bipolar plates and membranes
• • Dimensions of the end plate (Fastening possibility of PCB)
• • Cell voltage tap is for the use of conductive rubbers a pilot application

Claims (8)

Fuel cell with at least several a stack forming bipolar plates separated by membranes are characterized by a conductive rubber layer extending from extends one end of the stack to the other, wherein at least some the conductive one Layers of conductive rubber layer Contact the bipolar plates to check the voltage at each To tap bipolar plate. Fuel cell according to claim 1, characterized in that that the conductive rubber layer assigned to a printed circuit board with conductor tracks wherein tracks are those conductive layers of the conductive rubber layer Contact the bipolar plates to check the voltage to carry out a measured value acquisition. Fuel cell according to claim 1 or 2, characterized that the conductive rubber layer of conductive and non-conductive layers consists of two layers of one or more elastic Materials exist. Fuel cell according to claim 1, 2 or 3, characterized characterized in that the conductive rubber layer of conductive and non-conductive Layers, the conductive layers of carbon rubber and the non-conductive ones Layers of silicone rubber exist. Fuel cell according to claim 1, 2, 3 or 4, characterized characterized in that the conductive rubber layer is heat resistant at least up to 160 ° C. Spannungsabgriffs device for a fuel cell, characterized by a conductive rubber layer, which is formed to individual plates of the Contact fuel cell electrically. Spannungsabgriffs device according to claim 6, characterized characterized in that a printed circuit board provided with conductor tracks is, the conductive layers Contact the conductive rubber layer. Use of a conductive rubber, the conductive and non-conductive Has areas as electrical contactant to bipolar plates a fuel cell to tap the voltage across the bipolar plates to be able to.