Sensor, channel and fuel cell system

Abstract

Channel (3a) for a fuel cell system, comprising a sensor (4a) for determining a hydrogen concentration in a channel (3a) of a fuel cell system (2), comprising a sensor housing (6), a measuring chamber, wherein the measuring chamber is arranged in the sensor housing (6), and a measuring chamber channel, wherein the measuring chamber channel fluidically connects the measuring chamber to the environment of the sensor (4a), wherein the sensor (4a) is mountable such that the measuring chamber is located in the channel (3a), characterized in that the sensor is arranged in the channel, that the measuring chamber channel and / or the sensor is completely located in the channel, that the measuring chamber channel is closed by a membrane, that the membrane is gas-permeable and liquid-impermeable, and that the membrane is metallurgically bonded to the sensor housing by means of welding.

Description

Technical area

[0001] The invention relates to a channel with a sensor and a fuel cell system with such a channel. State of the art

[0002] Sensors for determining hydrogen concentration in a channel of a fuel cell system are typically located outside the channel to isolate them from the challenging measurement conditions within the channel. This usually requires a heating process before each sensor start-up to prevent moisture from influencing the measurement process.

[0003] The document US 6 668 616 B1 discloses a carbon monoxide sensor.

[0004] The documents DE 10 2015 121 298 A1, CN 1 05 492 898 A and US 8 815 161 B2 concern gas sensors for ducts.

[0005] A particular disadvantage of the state-of-the-art devices is the effort required before each commissioning to prevent moisture from influencing the measuring process. Description of the invention, task, solution, advantages

[0006] The object of the present invention is to provide an alternative channel with a sensor, which is characterized in particular by the fact that a heating process prior to starting a measurement process with the sensor can be dispensed with. Furthermore, a further object is to provide a fuel cell system with such a channel.

[0007] The first problem is solved by a channel having the features of claim 1.

[0008] By mounting the sensor in such a way that the measuring chamber is located within the duct, a separate heating process prior to commissioning the sensor is eliminated, as the flow in the duct can be used to heat the sensor. This prevents any negative influence of humidity on the measurement process, even without a separate heating process prior to commissioning the sensor.

[0009] It is particularly advantageous if the sensor is a thermal sensor. In other words, the sensor comprises a heating element and a temperature sensor, which are located particularly within the measurement chamber. Depending on the hydrogen concentration in the measurement chamber, a temperature profile can be determined using the temperature sensor during a heating process using the heating element, from which the hydrogen concentration in the measurement chamber can be determined. This measurement process is primarily based on the high heat capacity of hydrogen compared to the other components of the gas whose hydrogen concentration is to be determined.

[0010] It is also advantageous if the duct is an exhaust duct of a fuel cell system. Furthermore, it is advantageous if the fuel cell system is a fuel cell system for a motor vehicle.

[0011] It is particularly advantageous if the measuring chamber channel fluidically connects the measuring chamber with the environment of the sensor housing.

[0012] Furthermore, it is preferred if the sensor can be mounted in such a way that the measuring chamber channel and / or the sensor housing are arranged in the channel.

[0013] It is particularly advantageous if the sensor can be mounted in such a way that the measuring chamber channel fluidically connects the measuring chamber with the channel.

[0014] It is particularly preferred if the measuring chamber can be fluidically connected to the channel through the measuring chamber channel.

[0015] The measuring chamber channel is sealed by a membrane, which is gas-permeable and liquid-impermeable. This reliably prevents liquid from entering the measuring chamber from the channel, further reducing humidity within the measuring chamber.

[0016] The membrane is firmly bonded to the sensor housing by welding. In particular, the connection or attachment is designed in such a way that bypass flow past the membrane into the measuring chamber is prevented. This prevents fluid from entering the measuring chamber.

[0017] Furthermore, it is advantageous if the sensor can be mounted in such a way that the membrane is arranged in the channel.

[0018] A further preferred embodiment is characterized in that the measuring chamber channel opens into a measuring chamber opening and that the measuring chamber opening is arranged on the surface of the sensor housing.

[0019] A further preferred embodiment is characterized in that the measuring chamber opening is closed by the membrane. This prevents liquid from penetrating the measuring chamber channel. At the same time, the membrane is arranged on the surface of the sensor housing and, when the sensor is arranged in the channel, is positioned such that the flow within the channel cleans the membrane and blows away liquid droplets. Furthermore, mounting or fastening the membrane is particularly simple with this membrane arrangement.

[0020] A further preferred embodiment is characterized in that the sensor comprises a flow influencing geometry that influences the flow in the channel.

[0021] It is also preferable if the flow influencing geometry, viewed from the measuring chamber opening, is arranged against the flow direction of the flow in the duct when the sensor is mounted.

[0022] Furthermore, it is advantageous if the flow control geometry is formed integrally, particularly as a single piece, with the sensor housing. This represents an extremely cost-effective solution.

[0023] Furthermore, it is advantageous if the flow influencing geometry borders directly on the measuring chamber opening.

[0024] It is also advantageous if the flow control geometry is designed such that, when the sensor is mounted, the flow in the channel is directed toward the measuring chamber opening and / or the membrane. This keeps the measuring chamber opening and / or the membrane clean.

[0025] Furthermore, it is advantageous if the flow control geometry is designed such that, when the sensor is mounted, the flow control geometry generates a turbulent flow from the flow in the channel. This keeps the measuring chamber opening and / or the membrane clean.

[0026] A further preferred embodiment is characterized in that the measuring chamber channel is designed as a straight line, a curved line, or a labyrinth. While a straight line is particularly advantageous and simple, especially when manufactured using plastic injection molding, a curved line or a labyrinth-like design is particularly helpful for preventing fluid from entering the measuring chamber, especially in the case of a damaged or unintended membrane.

[0027] The sensor is located entirely within the duct. Alternatively, the measuring chamber duct is located entirely within the duct. Furthermore, it is preferred if the measuring chamber opening is located within the duct. It is particularly advantageous if the sensor housing is located partially or entirely within the duct. Furthermore, it is preferred if the duct is an exhaust duct. Furthermore, the duct is preferably circular or has a circular cross-section.

[0028] In addition, it is advantageous if the channel is made of a metal, especially stainless steel, or a plastic.

[0029] It is particularly preferred if the measuring chamber channel fluidically connects the measuring chamber with the channel.

[0030] A further preferred embodiment is characterized in that the sensor housing, the measuring chamber, the measuring chamber channel, the membrane, and / or the measuring chamber opening are intersected by a centroid vector, wherein the centroid vector runs through the centroid of a channel cross-section of the channel, wherein the channel cross-section lies in a plane that runs perpendicular to the longitudinal direction of the channel and intersects the sensor, and wherein the centroid vector intersects the plane perpendicularly. Furthermore, it is particularly preferred if the centroid vector intersects at least one, two, three, four, or five of the following components of the sensor: the sensor housing, the measuring chamber, the measuring chamber channel, the membrane, and the measuring chamber opening.

[0031] It is particularly preferred if the centroid vector runs at a distance from at least one, two, three, four, or five of the following components of the sensor: the sensor housing, the measuring chamber, the measuring chamber channel, the membrane, and the measuring chamber opening. In other words, the components of the sensor are either intersected by the vector or arranged at a distance from it. "Arranged at a distance" means that the component is not intersected by the vector. The longitudinal direction refers in particular to the flow direction of the gas within the channel, into which the gas can flow, or the extension direction of the channel.

[0032] It is also advantageous if the duct is an exhaust duct of a fuel cell system. Furthermore, it is advantageous if the fuel cell system is a fuel cell system for a motor vehicle.

[0033] A further preferred embodiment is characterized in that the sensor is arranged in the channel such that the area center of gravity vector intersects a further plane in which the membrane or the measuring chamber opening is arranged at an angle of 70° to 110°.

[0034] A further preferred embodiment is characterized in that the sensor is arranged such that the membrane is at least partially opposite to the flow direction. In other words, the sensor is arranged such that the membrane faces the flow in the channel. This arrangement makes it possible for the flow to clean the membrane or remove droplets on the membrane.

[0035] Another preferred embodiment is characterized in that the sensor is attached to a channel wall of the channel. It is particularly preferred if the sensor is attached by means of a thread pair comprising an external thread on the sensor housing and an internal thread in the channel wall. This makes mounting the sensor particularly simple and time-saving.

[0036] Furthermore, it is particularly preferred if the sensor housing has thermal insulation at the point where the sensor is attached to the channel wall. This prevents the sensor from cooling down due to the temperature of the channel wall. This helps prevent any droplets from accumulating on the sensor or the sensor housing.

[0037] One of the preceding embodiments or another preferred embodiment is characterized in that the sensor extends from outside the channel into the channel through an opening in the channel wall. This allows the sensor to be flange-mounted to the channel wall.

[0038] The problem regarding the fuel cell system is solved by a fuel cell system with a channel according to the invention. This creates a fuel cell system that eliminates the need for a separate process prior to commissioning the sensor.

[0039] Furthermore, it is advantageous if the fuel cell system is a fuel cell system for a motor vehicle.

[0040] Furthermore, it is particularly preferred to provide a motor vehicle with such a fuel cell system.

[0041] Advantageous further developments of the present invention are described in the subclaims and in the following description of the figures. Short description of the drawings

[0042] The invention is explained in detail below using exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 a motor vehicle with a fuel cell system, and Fig. 2 a channel with a sensor, and Fig. 3 one channel with one sensor. Preferred embodiment of the invention

[0043] The Fig. Figure 1 shows a motor vehicle 1 with a fuel cell system 2 according to the invention. This is a motor vehicle 1 with an electric drive. The fuel cell system 2 comprises a channel 3a according to the invention with a sensor 4a, which is designed as a thermal sensor 4a to determine the hydrogen concentration in the channel 3a.

[0044] The Fig. 2 shows a sectional view that runs perpendicular to the flow pattern within the channel 3a and perpendicular to the direction of extension of the channel. In other words, the channel cross-section is shown, which lies in a plane that runs perpendicular to the longitudinal direction of the channel 3a. This is the XY plane. The channel 3a has a circular cross-section, the centroid 3c of which is located in the center of the circular cross-section of the channel 3a. Furthermore, the channel 3a has a channel wall 3b made of stainless steel with a constant wall thickness. Furthermore, a sensor 4b known from the prior art for determining the hydrogen concentration is shown, which sensor is located outside the channel 3a and is attached to the channel wall 3b. The sensor 4b is fluidically coupled to the channel 3a through an opening in the channel wall 3b.Since the sensor 4b is located outside the channel 3a, the sensor 4b is largely decoupled from the temperature of the flow in the channel 3a.

[0045] The Fig. 3 shows the same circular channel 3a from Fig. 2, but with a sensor 4a that is attached to the channel wall 3b and extends from outside the channel 3a to the inside of the channel 3a through an opening in the channel wall 3b. The view is a longitudinal section through the channel 3a in the ZY plane. The channel 3a extends in the Z-direction, whereby the flow within the channel 3a also runs in the Z-direction. The sensor 4a shown here is the sensor 4a that is in the Fig. 1. The sensor 4a is attached to the channel wall 3b by means of a thread (not shown in detail here) and further comprises an elastomer seal to prevent the gas within the channel from escaping. The sensor 4a comprises a sensor housing 6 in which a measuring chamber is accommodated. A heating element and a temperature sensor are accommodated in the measuring chamber to measure the concentration of hydrogen in the measuring chamber. The measuring chamber is fluidically coupled to the channel by means of a measuring chamber channel that opens into a measuring chamber opening. The measuring chamber opening is arranged on the surface of the sensor housing 6 and covered by a membrane 5. The membrane 5 is gas-permeable and liquid-impermeable. The sensor housing 6 is made of a material that has high thermal conductivity.

[0046] The examples of the Fig. 1 and Fig.3 are not restrictive in nature and serve to clarify the inventive concept. List of reference symbols 1 motor vehicle 2 Fuel cell system 3a Canal 3b Canal wall 3c centroid 4a Sensor 4b Sensor 5 Membran 6 sensor housing

Claims

[1] Channel (3a) for a fuel cell system, with a sensor (4a) for determining a hydrogen concentration in a channel (3a) of a fuel cell system (2), comprising a sensor housing (6), a measuring chamber, wherein the measuring chamber is arranged in the sensor housing (6), and a measuring chamber channel, wherein the measuring chamber channel fluidically connects the measuring chamber to the environment of the sensor (4a), wherein the sensor (4a) can be mounted such that the measuring chamber is located in the channel (3a), characterized by that the sensor is arranged in the channel, that the measuring chamber channel and / or the sensor is completely located in the channel, that the measuring chamber channel is closed by a membrane, that the membrane is gas-permeable and liquid-impermeable, and that the membrane is integrally connected to the sensor housing by welding. [2] Channel (3a) according to claim 1, characterized bythat the measuring chamber channel opens into a measuring chamber opening and that the measuring chamber opening is arranged on the surface of the sensor housing. [3] Channel (3a) according to claim 1 or 2, characterized by that the measuring chamber opening is closed by the membrane. [4] Channel (3a) according to one of the preceding claims, characterized by that the sensor includes a flow control geometry that influences the flow in the channel. [5] Channel (3a) according to one of the preceding claims, characterized by that the measuring chamber channel is straight, angled or designed as a labyrinth. [6] Channel (3a) according to one of the preceding claims, characterized bythat the sensor housing (6), the measuring chamber, the membrane (5), the measuring chamber channel and / or the measuring chamber opening is cut by a center of gravity vector, wherein the center of gravity vector runs through the center of gravity (3c) of a channel cross-section of the channel (3a), wherein the channel cross-section lies in a plane which runs perpendicular to the longitudinal direction of the channel (3a) and intersects the sensor (4a), and that the center of gravity vector intersects the plane perpendicularly. [7] Channel (3a) according to claim 6, characterized by that the sensor (4a) is arranged in the channel (3a) in such a way that the area center of gravity vector intersects a further plane in which the membrane (5) or the measuring chamber opening is arranged, at an angle of 70° to 110°. [8] Channel (3a) according to one of the preceding claims, characterized by that the sensor (4a) is arranged such that the membrane (5) is at least partially opposite to the flow direction. [9] Channel (3a) according to one of the preceding claims, characterized by that the sensor (4a) is attached to a channel wall (3b) of the channel (3a). [10] Channel (3a) according to one of the preceding claims, characterized by that the sensor (4a) extends through an opening in a channel wall (3b) from outside the channel (3a) into the channel (3a). [11] Fuel cell system (2) with a channel (3a) according to one of the preceding claims.

Images