ELECTRICAL DEVICE FOR USE IN A HYDROGEN SYSTEM

Description

State of the art

[0001] Hydrogen-powered systems, such as fuel cell systems or hydrogen combustion systems, use electrically operated devices that come into contact with a hydrogen-containing operating gas. If the operating gas is, for example, the anode gas of a fuel cell system, the hydrogen content can range from 50 to 100 percent by volume. The electrical devices may have operating components that are controlled by an electronic control circuit. Such operating components can be, for example, sensor elements in contact with the operating gas or electrically operated actuators, which may also contain assemblies that come into contact with the operating gas. The device's electronic control circuit is usually mounted on an electronic circuit board inside the device's housing and is electrically connected to the sensor element or actuator.connected to parts of the actuator.

[0002] From DE 10 2014 212 430 A1, an electrical device designed as a hydrogen concentration sensor for use in a hydrogen system is known. This device comprises a housing with an inlet channel for the operating gas formed on the housing, at least one housing interior in which an electronic circuit part is arranged, and an operating component arranged in the housing and electrically connected to the electronic circuit part. The inlet channel is connected to the operating component via a first sealing element arranged in the housing, and the operating component can be supplied with operating gas via the inlet channel. The first sealing element seals the inlet channel against the housing interior. Further sensors for determining the hydrogen concentration are known, for example, from DE 10 2005 058 832 A1, DE 10 2011 008 720 A1, and DE 10 2014 202 169 A1.Such sensor elements for detecting hydrogen can be used, for example, in hydrogen fuel cell vehicles to detect hydrogen escaping due to damage or a defect, and to trigger warning signals or protective measures.

[0003] Furthermore, it is also known to use electrically operated actuators in fuel cell systems. These can be, for example, electrically controlled valves that open or close flow paths within the fuel cell system.

[0004] An air-hydrogen mixture can become ignitable at a hydrogen content of approximately 4%. Therefore, direct contact between the operating gas and the electronic circuitry used to control the operating component is undesirable to prevent ignition of a potentially ignitable gas mixture inside the housing. Disclosure of the invention

[0005] The invention presents an electrical device for use in a system operated with a hydrogen-containing operating gas. The device comprises a housing with an inlet channel for the operating gas formed on the housing and with at least one internal chamber in which an electronic circuit element is arranged. An operating component arranged in the housing is electrically connected to the electronic circuit element. The inlet channel is connected to the operating component via a first sealing element arranged in the housing, so that the operating component can be supplied with operating gas via the inlet channel. The first sealing element seals the inlet channel against the internal chamber of the housing, except for a remaining hydrogen permeability.The invention now proposes that the housing further comprises at least one second sealing element sealing the housing interior to the outside, wherein the second sealing element has a hydrogen permeability that is equal to or greater than the hydrogen permeability of the first sealing element.

[0006] In the context of this application, permeation is understood as a process in which a solute penetrates or migrates through a solid. The solute penetrates the solid through pores and molecular spaces. Permeation consists of three steps: sorption of the solute at the interface of the solid, diffusion through the solid, and desorption on the other side of the solid. The driving force is a gradient of the chemical potential. Permeability is expressed as a measure of permeation in the unit µg cm⁻² / min⁻¹.

[0007] The thickness of a sealing element is understood to be the distance between two interfaces of the sealing element, wherein a first interface is located in a gas with a higher hydrogen concentration and the second interface is located on a side of the sealing element facing away from the first interface.

[0008] A hydrogen system is understood to be a system powered by hydrogen, in particular a fuel cell system or a system with hydrogen combustion. The hydrogen system specifically includes at least one flow line in which a hydrogen-containing operating gas flows. The flow line can, for example, be located in the anode path of a fuel cell. Advantages of the invention

[0009] To prevent physical contact between the electronic circuitry and the hydrogen, the operating component could, for example, be covered with a hydrogen-impermeable cap. However, this requires a very high degree of design effort to integrate the cap into the housing interior, particularly to seal the electrical contacts between the electronic circuitry and the operating component, as these contacts would have to pass through the cap. Selecting a hydrogen-impermeable material such as steel also increases costs.

[0010] The invention advantageously enables the interior of the housing of an electrical device, in which an electronic circuit component is arranged, to be sealed cost-effectively against the inlet channel using a simple first sealing element, whereby the first sealing element does not need to be hermetically sealed. For example, an elastomer can be used as the first sealing element. It could be, for instance, an inexpensive sealing ring or a sealant. Although a sealing element made of an elastomer or a similar material can be designed to be gas-tight, hydrogen can permeate the material over time. Therefore, hydrogen can penetrate from the inlet channel through the first sealing element and into the interior of the housing by permeation.Since the housing is generally made of a gas-tight material (for example, a thermoplastic) which has a lower permeability to hydrogen than the first sealing element, the hydrogen concentration inside the housing could slowly increase without countermeasures. This is unacceptable, however, because in the worst-case scenario, the electronic circuitry inside the housing could ignite the flammable mixture.

[0011] By having a second sealing element that seals the housing interior from the exterior, and where this second sealing element has a hydrogen permeability equal to or greater than that of the first sealing element, it is advantageously achieved that hydrogen entering the housing interior through permeation of the first sealing element escapes from the housing interior to the exterior through permeation of the second sealing element. Since the hydrogen permeability of the second sealing element is equal to or greater than that of the first, at least as much hydrogen escapes from the housing interior to the exterior through the second sealing element as enters the housing interior through the first sealing element. This advantageously prevents the formation of an ignitable mixture within the housing interior.Since the overall permeability remains very low, only a very small amount of hydrogen escapes from the housing into the outside space and disperses rapidly there, so that no ignitable mixture can accumulate outside the housing.

[0012] Advantageous embodiments and further developments of the invention are made possible by the features specified in the dependent claims.

[0013] Advantageously, the second sealing element can be embedded in a housing wall. In particular, the second sealing element can be designed as a membrane embedded in the housing wall. The membrane can have a hydrogen permeability that is equal to or greater than that of the first sealing element.

[0014] The hydrogen permeability of a sealing element is defined by its material and its spatial dimensions, which are determined by the diffusion cross-section and the thickness. If the sealing element is a membrane embedded in the housing wall, the hydrogen permeability is determined by the area of ​​the opening in the housing wall into which the membrane is embedded, the thickness of the membrane, and its material. Although it is generally possible to make the second sealing element from a different material than the first, it can also be made of the same material. An equal or higher hydrogen permeability of the second sealing element can then be easily achieved by appropriately selecting the size of the membrane.With the same thickness of the first sealing element and the second sealing element, for example, the cross-section of the membrane which seals an opening in the housing wall can be easily made sufficiently large to achieve a hydrogen permeability that is equal to or greater than the hydrogen permeability of the first sealing element.

[0015] It is particularly advantageous for the first and / or second sealing element to consist of an elastomer sealant. The elastomer provides a reliable seal against gas and moisture and is cost-effective. Alternatively, the first and / or second sealing element can be manufactured as an adhesive seal. The adhesive sealant can also incorporate an elastomer.

[0016] The electrical device can be connected to a flow channel carrying the operating gas via a nozzle surrounding the inlet channel. The device is then easily installed by inserting the nozzle into the flow channel.

[0017] Particularly preferably, the operating component can be designed as a sensor element for detecting at least one property of the operating gas.

[0018] The sensor element can be preferably selected from the following group of sensor elements: a sensor element for detecting the hydrogen concentration of hydrogen in the operating gas, a sensor element for detecting the pressure of the operating gas, a sensor element for detecting the temperature of the operating gas, a sensor element for detecting the humidity in the operating gas.

[0019] Furthermore, it is also possible to use an electrically operated actuator as an operating component. This actuator could, for example, be an electrically actuated valve, and in particular a metering valve, which is used for the inlet or outlet of gas components in the hydrogen system. Brief description of the drawings

[0020] Possible embodiments of the invention are explained below with reference to the accompanying drawing. Fig. 1 shows a flow channel of a hydrogen system with an embodiment of an attached electrical device, the operating component of which is designed as a sensor element. Embodiments of the invention

[0021] Fig. 1 Figure 1 shows an embodiment of an electrical device 1, which is configured as a sensor. The electrical device 1 has a housing 9 made of, for example, thermoplastic material, which contains an interior housing space 10. The housing 9 is provided with a nozzle 11 in which an inlet channel 2 is formed. The electrical device 1 can be connected to a flow channel 3 of a hydrogen system by means of the nozzle 11. In the flow channel 3 in Fig. 1 An operating gas flows in the direction of the arrow shown. The operating gas contains hydrogen. The operating gas flowing in the flow channel 3 reaches the housing 9 via the inlet channel 2. The housing 9 has an interior compartment 10 in which an operating component 4 is arranged, for example, a sensor element 4a. The sensor element 4a can be connected via electrical connections, for example, bond wire connections, to an electronic circuit part 5 arranged in the interior compartment 10, on which a control and evaluation circuit is arranged. The electronic circuit part 5 can be connected to an electrical counterpart via a housing connector (not shown). The sensor element 4a has one side facing the inlet channel 2 and an opposite side facing the interior compartment 10.Preferably, the sensor element 4a is a hydrogen concentration sensor that determines the hydrogen concentration in the inlet channel 2. The operating gas in the inlet channel 2 acts on the sensor element 4a on its side facing the inlet channel 2. The sensor element 4a is, for example, designed as a measuring chip as described in DE 10 2014 212 430 A1, and has a membrane that can be heated relative to the environment by means of a heating conductor. This generates a heat flow that depends on the mixing ratio of the operating gas. By evaluating the temperatures of the heating elements using the evaluation circuit arranged on the electronic circuit part 5, the hydrogen concentration or the humidity, for example, can then be measured. However, other configurations are also conceivable.

[0022] As in Fig. 1As can be seen further, a first sealing element 6 seals the area between the inlet channel 2 and the sensor element 4a. The first sealing element 6 can be, for example, an elastomer. Other materials are also possible. It can be a sealing ring or an adhesive seal. The first sealing element 6 surrounds the opening of the inlet channel 2 on the inside of the housing and rests with a first sealing surface on the inside of the housing wall 9 and with a second sealing surface on the sensor element 4a. This seals the area filled with the operating gas between the inlet channel 2 and the side of the sensor element 4a exposed to the operating gas from the housing interior 10. However, hydrogen can pass through the first sealing element 6 from the inlet channel 2 into the housing interior 10 by permeation. Therefore, the housing wall 9 of the housing 1 has an opening closed by a second sealing element 7.The second sealing element 7 can, for example, be designed as a membrane. Hydrogen penetrating the interior of the housing 10 can advantageously escape into the exterior space 12 through permeation of the second sealing element 7. It is important that the permeation of hydrogen through the second sealing element 7 is equal to or greater than the permeation of hydrogen through the first sealing element 6 into the interior of the housing 10. If this condition is met, the hydrogen concentration in the interior of the housing 10 does not increase.

[0023] The second sealing element 7 can be made of the same material or a very similar material to the first sealing element 6, for example, an elastomer. The second sealing element 7 can be designed as a sealing body or an adhesive seal. The permeability of the second sealing element 7 can be relatively easily adjusted by its surface area or cross-section in the opening of the housing wall 9. The larger the cross-section of the second sealing element 7, the greater the permeation of hydrogen into the external space 12. Furthermore, it is also possible to adjust the hydrogen permeation through the second sealing element 7 to a value equal to or greater than the hydrogen permeation through the first sealing element 6 by selecting the appropriate thickness or material.

[0024] The present embodiment has been explained using a sensor element 4a. However, it is understood that a similar structure, while retaining the essential features of the invention, can also be used for an operating component 4 that is not designed as a sensor but as an actuator, in particular as an electrically actuated valve.

Claims

1. Electrical apparatus (1) for use in a system which is operated with an operating gas containing hydrogen, comprising: a housing (9) with an inlet channel (2) for the operating gas, formed on the housing (9), and with at least one housing interior (10), in which an electronic circuit component (5) is arranged, and with an operating component (4), which is electrically connected to the electronic circuit component (5) and is arranged in the housing (9), wherein the inlet channel (2) is attached to the operating component (4) by way of a first sealing element (6) arranged in the housing (9) and operating gas can be applied to the operating component (4) by way of the inlet channel (2), wherein the first sealing element (6) seals off the inlet channel (2) from the housing interior (10) apart from a remaining hydrogen permeability, characterized in that the housing also has at least one second sealing element (7), sealing off the housing interior (10) with respect to the outside (12), wherein the second sealing element (7) has a hydrogen permeability which is equal to or greater than the hydrogen permeability of the first sealing element (6).

2. Electrical apparatus according to Claim 1, characterized in that the second sealing element (7) is let into a housing wall (19) of the housing (9).

3. Electrical apparatus according to Claim 1 or 2, characterized in that the second sealing element (7) takes the form of a membrane.

4. Electrical apparatus according to one of the preceding claims, characterized in that the second sealing element (7) consists of the same material as the first sealing element (6) or a different material.

5. Electrical apparatus according to one of the preceding claims, characterized in that the first sealing element (6) and / or the second sealing element (7) consist(s) of an elastomer sealing body or a sealing adhesive.

6. Electrical apparatus according to one of the preceding claims, characterized in that the electrical apparatus (1) can be connected by a connecting piece (11) surrounding the inlet channel (2) to a flow channel (3) carrying the operating gas, in particular to an anode path of a fuel cell system.

7. Electrical apparatus according to one of the preceding claims, characterized in that the operating component (4) takes the form of a sensor element (4a) for sensing at least one property of the operating gas.

8. Electrical apparatus according to Claim 7, characterized in that the sensor element (4a) is selected from the following group of sensor elements: - a sensor element for sensing the hydrogen concentration of hydrogen in the operating gas, - a sensor element for sensing the pressure of the operating gas, - a sensor element for sensing the temperature of the operating gas, - a sensor element for sensing the moisture in the operating gas.

9. Electrical apparatus according to one of Claims 1 to 6, characterized in that the operating component (4) is an electrically operated actuator, in particular an electrically operated metering valve.

10. Hydrogen system with an electrical apparatus (1) according to one of Claims 1 to 9.