Patent Application
20180026281
The present disclosure relates to knock-out valves for fuel cell stacks for vehicles.
During fuel cell operation, byproducts such as product water and nitrogen, as well as unconsumed hydrogen, may form at the anode side of a fuel cell stack. In certain known systems, accumulation of product water and nitrogen accumulation is controlled in an attempt to avoid a reduction in fuel cell performance, and/or fuel cell system shut down. One known approach is to release the water and nitrogen via a passageway downstream of the fuel cell stack. Using such approach, the passageway is coupled with a valve for the controllable release of water and nitrogen from the fuel cell stack. This approach causes the potential for problems to occur during cold weather operation of the fuel cell when water may freeze in the passageway, or valve, or other regions of the fuel cell with small cross sectional areas. The resulting ice formation may cause blockage of at least a portion of the passageway and prevent fluid flow (e.g., water and nitrogen removal), which may inhibit fuel cell system function.
A knock-out assembly for a fuel cell purge line includes a separator, a valve and a tube. The separator has a drain fluidly coupled to a body attached to an anode. The valve has a first inlet attached to and in fluid communication with the drain. The tube is disposed within the drain and the first inlet, and is configured to extend into the body and away from the drain.
A fuel cell system includes a fuel cell stack and a knock-out assembly in fluid communication with the fuel cell stack. The fuel cell stack includes a separator having a body and first and second drains fluidly coupled to first and second inlets of a valve, respectively, wherein the first inlet and drain includes a tube disposed therein and configured to extend into the body and away from the first drain.
A knock-out assembly for a fuel cell purge line includes a separator, a first valve, a second valve and a tube. The separator has first and second drains fluidly coupled to a body attached to an anode. The first valve has a first inlet attached to and in fluid communication with the first drain. The second valve has a second inlet attached to and in fluid communication with the second drain. The tube extends between the drain and the first inlet such that, upon blockage of the third inlet, the tube defines a fluid passageway from the body through the drain into the first valve.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Referring to
To ensure efficient fuel cell system operation, the product water may be purged from the separator 18 via the valve 22. During cold weather operation, the product water may freeze in the separator 18 causing blockage of the valve 22 and preventing purging of the fuel cell system 12. Specifically, cold weather operation or freezing conditions may include subjecting the fuel cell system 12 to temperatures below the freezing point of product water, nitrogen, and residual hydrogen. Cold weather operation or freezing conditions may also include subjecting the fuel cell system 12 to temperatures below the freezing points of any other potential byproduct that gathers in the separator 18. For example, when described herein, cold weather operation and freezing conditions may include operation of the fuel cell system 12 in temperatures equal to or less than 32° F., 0° C. or 273° K.
Likewise, the vehicle 10 may operate on a variety of roadways 24 having a variety of pitch angles α. For example, the vehicle 10 may be on a roadway 24 having a pitch of ±19.5 degrees. Therefore, the fuel cell system 12 may also be disposed at the pitch angle α of the roadway 24 based on a position of the vehicle 10. When the fuel cell system 12 is disposed at the pitch angle α of the roadway 24 during freezing conditions, the knockout assembly 16 may be configured to account for blockage through the separator 18 into the valve 22 due to freezing product water. The knockout assembly 16, and specifically the separator 18 and valve 22 may be configured in a way such that the knockout assembly 16 can purge water and nitrogen from the fuel cell stack 14 accounting for an increase in depth of the product water due to the pitch angle α of the roadway 24.
Typically, the fuel cell system 12 in the knockout assembly 16 may use a scavenging reservoir (not shown) to account for the product water and the blockage between the separator 18 and the valve 22 during freezing conditions and an inclined pitch angle α that may occur due to accumulation of the product water. However, the scavenging reservoir may only account for a set volume of product water and accumulation of product water may result in complete blockage. Likewise, the scavenging reservoir may not completely account for the pitch angle α of the roadway 24, which may also lead to complete blockage. Lastly, the scavenging reservoir may not effectively purge the fuel cell system 12 due to the position and inherent nature of the reservoir within the fuel cell system 12 resulting in an accumulation of product water and therefore complete blockage of the fuel cell system. Therefore, a knockout assembly 16 that accounts for the pitch angle α of the roadway 24 and the freezing conditions described above that eliminates a scavenging reservoir may be advantageous.
The separator 18 defines a body 32 and a drain 34. The body 32 is fluidly connected to the drain 34. Specifically, the drain 34 is disposed at a bottom 36 of the body 32. The drain 34 may also be referred to as a first drain 34. The product water collects within the body 32 of the separator 18 and may create blockage of the drain 34 during freezing conditions. The valve 22 is fluidly coupled to the separator 18. Specifically, the valve 22 includes an inlet 38 that fluidly couples the valve 22 to the bottom 36 of the body 32 through the drain 34. The valve 22 may also include an outlet 40. When the valve 22 is in a closed position, there is no fluid flow between the separator 18, including the body 32 and the drain 34 and the valve 22 through the inlet 38 or the outlet 40. When the valve 22 is in an open position, as shown, fluid passage is defined between the outlet 40 and the inlet 38 of the valve 22, and the drain 34 and body 32 of the separator 18. Specifically, in order for the knockout assembly 16 to be effectively purged, coupling between the drain 34 and the inlet 38 should be open such that fluid flow from the body 32 of the separator 18 through the outlet 40 of the valve 22 is uninterrupted.
When the fuel cell system 12, and specifically the knockout assembly 16 is subject to conditions that may cause the product water to freeze, coupling between the inlet 38 of the valve 22 and the drain 34 of the separator 18 may be blocked. Blockage between the inlet 38 of the valve 22 and the drain 34 of the separator 18 results in an interrupted or stopped fluid passage between the outlet 40 of the valve 22 and the body 32 of the separator 18. Interrupted or stopped fluid passage between the outlet 40 of the valve 22 and the body 32 of the separator 18 causes purging failure of the fuel cell system 12 and specifically the knockout assembly 16. Moreover, sustained blockage of the drain 34 of the separator 18 and the inlet 38 of the valve 22 from ineffectual purging of the knockout assembly 16 may result in inefficiencies of the fuel cell system 12, making the fuel cell system 12 ineffective. Therefore, the knockout assembly 16, and specifically the coupling between the inlet 38 of the valve 22 and the drain 34 of the separator 18 may be configured to create a passageway 42 through the inlet 38 of the valve and the drain 34 of the separator 18 that extends above the first depth 28 and the second depth 30, as described above.
The knockout assembly 16 may further include a tube 44. The tube 44 may be an extension tube 44, which extends between the inlet 38 of the valve 22 and the drain 34 of the separator 18. The tube 44 may be configured to extend away from the drain 34 of the separator 18 and into the body 32 of the separator 18. The tube 44 may extend into the body 32 of the separator such that the tube 44 extends above the first depth 28 and the second that 30 to create the passageway 42 that fluidly couples the separator 18 and the valve 22. The passageway 42 is therefore defined through the tube 44 and interconnects the body 32 of the separator 18 and the outlet 40 of the valve 22. The tube 44 may be composed of a relatively insulative material such that heat transfer through the tube 44 during cold weather operation of the knockout assembly 16 does not result in a significant temperature difference inside the tube 44, preventing condensation formation within the tube 44. Therefore, when the valve 22 is open, the tube 44 allows the passageway 42 to be clear and unobstructed for purging.
As can be seen with reference to
The tube 44 therefore extends between and interconnects the drain 34 of the separator 18 and the inlet 38 of the valve 22. The tube 44 provides further coupling between the separator 18 and the valve 22 of the knockout assembly 16. By providing additional coupling between the body 32 of the separator 18 and the outlet 40 of the valve 22 specifically, the tube 44 allows the passageway 42 to be an additional passageway to promote purging during normal operational use of the fuel cell system 12. The tube 44 also allows the fuel cell system 12 to purge the knockout assembly 16 without requiring a scavenging reservoir (not shown), as discussed above. Stated differently, the tube 44 replaces the scavenging reservoir and allows the knockout assembly 16 to account for a greater volume of product water based on the significantly larger body 32 of the separator 18 compared to a scavenging reservoir. Therefore, the tube 44 reduces the complexity of the knockout assembly 16 and increases the efficiency of the fuel cell system 12.
The diameter 54 of the tube 44 may be based on the purging requirements of the knockout assembly 16. Likewise, the diameter 54 of the tube 44 may be less than the diameter 56 of the drain 34 to account for blockage between the drain 34 and the inlet 38 when the fuel cell system 12 is operated under freezing conditions. Further, the difference between the diameter 54 of the tube 44 and the diameter 56 of the drain 34 allows product water to be purged through the knockout assembly 16 when the fuel cell system 12 is operated in non-freezing conditions. Using the tube 44 having a diameter 54 less than the diameter 56 of the drain 34 and inlet 38 allows the knockout assembly 16 to maintain a consistent purging cycle under freezing conditions as well as purge the product water under non-freezing conditions. Again, the tube 44, via the smaller diameter 54, defines an additional passageway 42 between the body 32 of the separator 18 and the outlet 40 of the valve 22 to allow purging of the knockout assembly 16 during all operating conditions. The diameter 54 of the tube may be between 4 mm and 25 mm. Further, in at least one other embodiment, the passageway 42 defined between the tube 44 and the drain 34 and inlet 38 may be used solely for purging gaseous fluids.
Because the diameter 54 of the tube 44 is less than the diameter 56 of the drain 34 and the inlet 38, a plurality of supports 58 may be disposed between the tube 44 and the drain 34 and inlet 38. The supports 58 are configured to maintain the position of the tube 44 within the drain 34 and inlet 38. As depicted in
To effectively hold the tube 44 within the drain 34 and inlet 38, each of the supports 58 defines a length 62 equal to the difference between the diameter 54 of the tube 44 and the diameter 56 of the drain 34 and the inlet 38. By defining the length 62 of each of the supports 58 such that the length 62 is defined by the distance between the diameter 54 of the tube 44 and the diameter 56 of the drain 34 and the inlet 38, the supports 58 are in constant compression between the tube 44 and the drain 34 and inlet 38. Maintaining constant compression of the supports 58 allows the fuel cell system 12 to purge the knockout assembly 16 without displacing the tube 44. Therefore, the supports 58 prevent the tube 44 from collapsing into the valve 22. The supports 58 aid the tube 44 in maintaining the passageway 42 from the outlet 40 of the valve 22 and the body 32 of the separator 18.
The plurality of supports 58 may be configured to extend vertically with respect to a vertical axis 61 along the distance 52 between the coupling of the drain 34 and the inlet 38. The supports 58, therefore, extend with the tube 44 through the drain 34 and into the inlet 38. Extending the distance 52 allows the plurality of supports 58 to distribute compression between the tube 44 and the drain 34 and the inlet 38 throughout the distance 52. In at least one other embodiment, the plurality of supports 58 may be disposed within the drain 34 and the inlet 38 separately. For example, at least four supports 58 may maintain the position of the tube 44 within the drain 34 and at least four additional supports 58 disposed at a distance along the vertical axis 61 may maintain the position of the tube 44 within the inlet 38. Likewise, the plurality of supports 58 may extend the total length 50 of the tube 44.
In this embodiment, the supports 58 that extend into the body 32 of the separator 18 may define a length 62 greater than a length 62 of the supports 58 that extend into the drain 34 and the inlet 38. Each of the supports 58 extend the total length 50 of the tube 44 and each of the supports 58 may have a substantially tapered shape. Similarly, the supports 58 may be disposed vertically along the vertical axis 61 at regular intervals along the total length 50 of the tube 44. For example, at least four supports 58 may maintain the position of the tube 44 within the body 32, at least four additional supports 58 may maintain the position of the tube 44 within the drain 34 and at least four other supports 58 may maintain the position of the tube 44 within the inlet 38. The plurality of supports 58 may define any arrangement that allows the tube 44 to maintain a passageway 42 between the drain 34 and the inlet 38 to effectuate purging of the knockout assembly 16.
Referring to
In the embodiment depicted in
The second valve 68 may also be operational only if purging fails through the first valve 22. For example, the second valve 68 may be a normally closed valve and only be configured to open in the event purging fails through the first valve 22. For example, the second valve 68 may only be energized to provide a fluid passageway 42 between the second drain 66 and the second inlet 64 via the tube 44 if purging cannot be complete through the first valve 22. Again, addition of the second valve 68 ensures that the knockout assembly 16″ accomplishes purging regardless of vehicle use, as described above. In at least one other embodiment, the first valve 22 may be normally closed and include the tube 44 extending between the drain 34 and the inlet 38 to define a fluid passageway 42 between the body 32 of the separator 18 and the outlet 40 of the first valve 22 and only energize in the event that the second valve 68 is occluded or blocked causing the knockout assembly 16″ to fail to purge.
In each embodiment shown and described through
While exemplary to embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
