Integrated fuel cell injection unit using additive manufacturing

Abstract

The invention relates to an integrated fuel cell injection unit using additive manufacturing. Aspects of the integrated hydrogen fuel cell injection unit herein use additive manufacturing to form a single part. A space between the body and the injector nozzle / venturi system forms a damping volume. The heat exchanger is integrated within the attenuation volume, thereby saving space. An injector nozzle / venturi and a stack anode inlet to the fuel cell are arranged through the heat exchanger and allow an injector at the base of the body to selectively discharge hydrogen into the anode of the fuel cell. This architecture eliminates the need for many O-rings and bolts used in current fuel injection systems using existing manufacturing techniques, which may be too large and bulky and may lead to hydrogen leaks at different connection points.

Description

Background Art

[0001] The injection unit can be used to controllably inject a fuel such as hydrogen into a fuel cell of a vehicle in order to generate electricity and propel the vehicle via an electric motor. One advantage of hydrogen fueled vehicles is that, unlike gasoline controlled combustion engines which emit carbon monoxide, the main byproduct of a hydrogen system is water vapor, thereby eliminating most toxic emissions.

[0002] The injection unit typically works by injecting a fuel such as hydrogen into the anode portion of a hydrogen fuel cell (or stack), where the power-generating combustion reaction occurs. Before the hydrogen is actually injected into the fuel cell, various preparatory steps are taken using different connecting components. For example, a heat exchanger is used to heat the hydrogen. Noise is suppressed by an attenuator. Various nozzles and injection elements are also used to adjust the hydrogen to the appropriate pressure and velocity. These elements can help reconstruct unused hydrogen from previous cycles and help inject hydrogen into the fuel cell using a streamlined injector assembly.

[0003] Modern fuel cell injection units are large and bulky and prone to hydrogen leaks. Bolts and O-rings are required to connect the different parts of the injection unit together. The bulky noise attenuators are particularly prone to leaks, and complex forging techniques are often used to prevent this phenomenon. These injection units may still have several points where leakage is serious. Since the conventional isotope of the hydrogen atom consists of a single proton and a single electron (usually bonded to another such atom in molecular form), the fuel is physically very small and penetrates through the smallest of holes. Leaks are particularly serious in elastomeric seals such as O-rings that are commonly used in injection units and other connectors between different components. Such leaks can lead to fuel losses and an increase in undesirable hydrogen emissions. Summary of the invention

[0004] In one aspect of the present disclosure, an additively manufactured hydrogen fuel cell injection unit includes: a body including a noise attenuation volume, a first end of the body including a hole for mounting an injector; an injector assembly including an injector pipe and a stack anode inlet located at a second end of the body, the stack anode inlet configured to inject hydrogen into a fuel cell; a heat exchanger integrated within the noise attenuation volume and including a three-periodic minimal surface (TPMS) lattice structure of cells arranged therein, the TPMS lattice structure being configured to heat hydrogen flowing therethrough, each end surface of the heat exchanger being separated from the first end and the second end of the body by a corresponding volume; and an injector nozzle coupled to the interior of the body and aligned with the injector at the first end of the body, the injector nozzle being surrounded by a gap; the gap leading to a recirculation path inlet of the body for recapture of residual hydrogen near the recirculation path inlet; wherein the injector pipe protrudes through the heat exchanger and is aligned with the injector nozzle so that the injector pipe delivers hydrogen to the stack anode inlet.

[0005] In various aspects, hydrogen delivered to the stack anode inlet includes: (1) pressurized hydrogen originating from an injector nozzle; (2) residual hydrogen in the gap; and (3) hydrogen exiting the heat exchanger. The second end of the body includes an inlet for receiving hydrogen from a source. The volume between the first end surface of the heat exchanger and the first end of the body defines a first volume. The second end surface of the heat exchanger adjacent to the second volume is shaped with a geometrical gradient configured to enable residual hydrogen received at the inlet at the second end of the body to be evenly distributed across the second volume upon entering the heat exchanger to enable uniform heat addition of the hydrogen.

[0006] In various embodiments, the second end surface of the heat exchanger is proximate to the second volume into which the hydrogen flows. The first end surface of the heat exchanger defines a lower portion of the first volume and is shaped to form a gradient to more evenly distribute the heated hydrogen. In one embodiment, the gradient is shaped at least partially conical. The TPMS grid structure includes a plurality of cells having two channels, wherein the first channel passes hydrogen through the heat exchanger and the second channel passes a fluid to heat the hydrogen.

[0007] In various embodiments, one side of the body includes two holes for passing fluid through the second channel of the heat exchanger. The injector nozzle can be configured to be selectively activated to controllably cause hydrogen flowing from the heat exchanger surface near the first end of the body to pass through the injector tube for discharge into the fuel cell. Activation of the injector is configured to create a low pressure area in the gap to introduce residual hydrogen into the stack anode inlet through the injector nozzle and the injector tube.

[0008] In another aspect of the present disclosure, an additively manufactured fuel cell injection unit includes a body having a noise attenuation volume therein. The first end of the body includes a hole for mounting a hydrogen injector. The injector assembly includes an injector tube having a stack anode inlet positioned at the output of the injector tube for injecting hydrogen into the fuel cell. The heat exchanger includes a lattice structure of cells integrated within the noise attenuation volume. The lattice structure is configured to heat hydrogen flowing through it. Each end surface of the heat exchanger is separated from a corresponding volume by a corresponding first end and a second end of the body. The surface of the heat exchanger adjacent to each corresponding volume includes a gradient. The injector nozzle is coupled to the interior of the body and aligned with the injector at the first end of the body. The injector nozzle is surrounded by a gap. The gap leads to a recirculation path inlet of the body for recapturing residual hydrogen. The injector tube protrudes through the heat exchanger and is aligned with the injector nozzle so that the injector tube is configured to deliver hydrogen to the stack anode inlet.

[0009] In various embodiments, one or both of the surfaces of the heat exchanger adjacent the respective volumes are at least partially conical in shape. An injector is selectively activated to inject hydrogen from a source into the injector nozzle to create a low pressure region in the gap for recapture of unused hydrogen from a previous engine cycle.

[0010] The injector may also be configured to discharge heated hydrogen exiting the heat exchanger into a volume defined by a surface of the heat exchanger, into the injector nozzle, and thereafter into the injection tube.

[0011] In various embodiments, the fuel injection unit further comprises a plurality of pressure sensors co-printed within the outlet of the noise attenuation volume. When the pressure drops below a threshold, the injector may be activated cyclically to inject hydrogen. The additively manufactured body and the integrated noise attenuation volume and heat exchanger may be formed as a single integral unit to eliminate the use of elastomeric seals. The elements of the body are designed to avoid sharp corners and abruptly changing edges and use curved portions instead. The injection tube may be a venturi tube formed using additive manufacturing without a draft angle.

[0012] In yet another aspect of the present disclosure, a method for additively manufacturing a fuel injector unit includes forming a body having an at least partially cylindrical shape and defining an acoustic attenuation volume therein. The method also includes printing a venturi extending longitudinally from a first end to a second end along at least a portion of the body, and printing a stack anode inlet at the second end to inject hydrogen into the fuel cell. The method also includes printing an injector nozzle aligned with the venturi at the first end for selectively injecting hydrogen into the venturi, and enclosing the injector nozzle in a gap extending to a hole in the surface of the body. The gap is used to recover residual hydrogen for discharge into the stack anode inlet via the injector nozzle and the venturi.

[0013] The method also includes integrating a heat exchanger into the acoustic attenuation volume. The heat exchanger includes a lattice structure of cells arranged between the venturi tube and the periphery of the body, so that a first surface of the heat exchanger adjacent to the first end includes a gradient defining the first volume at the first end, and a second surface of the heat exchanger adjacent to the second end includes a gradient defining the second volume with the second end. Hydrogen entering the inlet hole in the second surface flows from the second volume to the first volume through the heat exchanger. The method also includes forming a hole in the first end for mounting an injector, which is configured to selectively discharge hydrogen from the gap, the first volume and the injector through an injector nozzle and into the venturi tube so as to enter the fuel cell at the stack anode inlet.

[0014] In various embodiments, the first surface or the second surface of the heat exchanger is at least partially conical in shape. The body may also include: a coolant input portion for injecting coolant into the channel of the heat exchanger; and a coolant output portion for receiving the coolant from the heat exchanger.

[0015] The present invention also includes the following technical solutions:

[0016] Solution 1. An additively manufactured hydrogen fuel cell injection unit, comprising:

[0017] a body including a noise attenuation volume integrated therein, a first end of the body including a hole for mounting a syringe;

[0018] an injector assembly including an injector tube and a stack anode inlet at the second end of the body, the stack anode inlet configured to inject hydrogen into the fuel cell;

[0019] a heat exchanger integrated within the noise attenuation volume and comprising a three-periodic minimal surface (TPMS) lattice structure of cells arranged therein, the TPMS lattice structure configured to heat hydrogen flowing through the TPMS lattice structure, each end surface of the heat exchanger being separated from the first end and the second end of the body by a respective volume; and

[0020] an injector nozzle coupled to the interior of the body and aligned with the injector near the first end of the body, the injector nozzle being surrounded by a gap that opens to a recirculation path inlet of the body for recapture of residual hydrogen proximate the recirculation path inlet,

[0021] wherein the injection tube protrudes through the heat exchanger and is aligned with the injector nozzle such that the injection tube passes hydrogen through the stack anode inlet.

[0022] Option 2. A fuel cell injection unit according to Option 1, wherein the hydrogen delivered to the fuel cell from the stack anode inlet includes: (1) pressurized hydrogen originating from the injector; (2) residual hydrogen near the recirculation path inlet; and (3) hydrogen leaving the heat exchanger.

[0023] Option 3. The fuel cell injection unit according to Option 1, wherein:

[0024] The second end of the body includes an inlet coupled to a hydrogen source;

[0025] A volume between a first end surface of the heat exchanger and the first end of the body is a first volume;

[0026] a volume between a second end surface of the heat exchanger and the second end of the body being a second volume; and

[0027] The second end surface of the heat exchanger is shaped with a geometric gradient configured to enable hydrogen received from the inlet at the second end of the body to be evenly distributed in the second volume as it enters and passes through the heat exchanger to enable uniform heat addition of the hydrogen.

[0028] Solution 4. The fuel cell injection unit according to Solution 1, wherein:

[0029] a first end surface of the heat exchanger and the first end of the body defining a first volume into which heated hydrogen exiting the heat exchanger flows; and

[0030] The first end surface of the heat exchanger is shaped to form a gradient so that the heated hydrogen is more evenly distributed as it exits the heat exchanger into the first volume.

[0031] Embodiment 5. A fuel cell injection unit according to Embodiment 4, wherein the gradient is shaped at least partially conically.

[0032] Embodiment 6. The fuel cell injection unit according to Embodiment 1, wherein the TPMS grid structure includes a plurality of cells forming two channels, wherein a first channel allows hydrogen to pass through the heat exchanger and a second channel transfers a fluid to heat the hydrogen.

[0033] Embodiment 7. The fuel cell injection unit according to embodiment 6, wherein one side of the body includes two holes for allowing the fluid to pass through the second channel of the heat exchanger.

[0034] Option 8. A fuel cell injection unit according to Option 1, wherein the injector is configured to be selectively activated to controllably cause hydrogen flowing from a volume proximate the first end of the body to pass through the injector nozzle and the injection tube for discharge into the fuel cell.

[0035] Option 9. A fuel cell injection unit according to Option 1, wherein the injection pipe includes a venturi tube, and the venturi tube and the injector are configured to generate a low pressure in the gap to introduce the residual hydrogen into the gap through the recirculation path inlet and enter the fuel cell through the injection pipe via the stack anode inlet.

[0036] Solution 10. An additively manufactured fuel cell injection unit, comprising:

[0037] a body having a noise attenuation volume therein; a first end of the body including a hole for mounting a hydrogen injector;

[0038] an injector assembly including an injector tube coupled to a stack anode inlet at the second end of the body for injecting hydrogen into the fuel cell;

[0039] a heat exchanger comprising a lattice structure of cells integrated within the noise attenuation volume, the lattice structure configured to heat hydrogen flowing therethrough, each end surface of the heat exchanger separating a respective volume from the first end and the second end of the body, a surface of the heat exchanger adjacent each respective volume comprising a gradient;

[0040] an ejector nozzle coupled to the output of the injector at the first end of the body, the ejector nozzle being surrounded by a gap leading to a recirculation path inlet of the body for recapture of excess hydrogen; and

[0041] An injection tube protrudes through the heat exchanger and is aligned with the injector nozzle such that the injection tube is configured to deliver hydrogen to the fuel cell via the stack anode inlet.

[0042] Embodiment 11. A fuel cell injection unit according to embodiment 10, wherein one or both of the surfaces of the heat exchanger adjacent to the respective volumes are at least partially conical in shape.

[0043] Option 12. A fuel cell injection unit according to Option 10, wherein the injector is selectively activated to inject hydrogen from a source into the injector nozzle, thereby injecting hydrogen from the stack anode inlet into the fuel cell via the injection pipe, and generating a low pressure area in the gap for recapture of excess hydrogen.

[0044] Embodiment 13. A fuel cell injection unit according to Embodiment 12, wherein the injector is further configured to direct heated hydrogen leaving the heat exchanger into a volume proximate the first end, into the injector nozzle, and subsequently into the injection tube.

[0045] Option 14. The fuel cell injection unit according to Option 12 further includes a plurality of pressure sensors printed together with the injector assembly, wherein when the pressure drops below a threshold, the injector is cyclically activated to inject the hydrogen.

[0046] Option 15. A fuel cell injection unit according to Option 10, wherein the body includes an additively manufactured (AM) body, and wherein the AM body and the integrated noise attenuation volume and heat exchanger are formed as a single integral unit to eliminate the use of elastomeric seals.

[0047] Aspect 16. A fuel cell injection unit according to aspect 10, wherein the elements of the body are designed to avoid sharp corners and abruptly changing edges, and instead form curved portions.

[0048] Embodiment 17. A fuel cell injection unit according to embodiment 10, wherein the injection pipe comprises a venturi tube formed using additive manufacturing without a draft angle.

[0049] Scheme 18. A method for additively manufacturing a fuel injector unit, comprising:

[0050] forming a body having an at least partially cylindrical shape and defining a sound attenuation volume therein;

[0051] printing a venturi extending longitudinally along at least a portion of the body from a first end to a second end at which a stack anode inlet is printed for injecting hydrogen into the fuel cell;

[0052] printing an injector nozzle at the first end aligned with the venturi tube for selectively injecting hydrogen into the venturi tube;

[0053] enclosing the injector nozzle within a gap extending to a hole in a surface of the body, the gap being used to recover unused hydrogen for discharge into the stack anode inlet via the injector nozzle and the venturi;

[0054] integrating a heat exchanger into the acoustic attenuation volume, the heat exchanger comprising a lattice structure of cells arranged between the venturi and a perimeter of the body, such that a first surface of the heat exchanger adjacent the first end comprises a gradient defining a first volume at the first end, and a second surface of the heat exchanger adjacent the second end comprises a gradient defining a second volume with the second end, wherein hydrogen entering an inlet hole in the second surface flows through the heat exchanger from the second volume to the first volume; and

[0055] A hole is formed in the first end for mounting an injector configured to selectively discharge hydrogen from the first volume and from the injector through the injector nozzle and into the venturi for entry into the fuel cell at the stack anode inlet.

[0056] Option 19. The method according to Option 18, wherein the first surface or the second surface of the heat exchanger is at least partially conical in shape.

[0057] Option 20. The method according to Option 18, wherein the main body further comprises: a coolant input portion for injecting coolant into the channel of the heat exchanger; and a coolant output portion for receiving the coolant from the heat exchanger.

[0058] The above summary is not intended to represent every embodiment or every aspect of the present disclosure. On the contrary, the above summary only provides examples of some novel concepts and features set forth herein. When combined with the accompanying drawings and the appended claims, the above-mentioned features and advantages of the present disclosure and other features and accompanying advantages will be apparent through the following detailed description of the illustrated examples and representative modes for implementing the present disclosure. Moreover, the present disclosure explicitly includes various combinations and sub-combinations of the elements and features presented above and below. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0060] Figure 1 is a mechanical diagram of a conventional fuel injection unit.

[0061] Figure 2 is a mechanical diagram of an additively manufactured integrated fuel injection unit according to one aspect of the present disclosure.

[0062] Figure 3 is taken along a vertical axis passing through the figure according to one aspect of the present disclosure Figure 2 Cross-sectional view of the fuel injection unit.

[0063] Figure 4 is a geometric representation of a dual-pass heat exchanger according to one aspect of the present disclosure.

[0064] Figure 5 is used in additive manufacturing, e.g. Figure 2 Conceptual diagram of a three-dimensional (3-D) printer for powder bed fusion of metal products (PDF).

[0065] Figure 6 is an exemplary flow chart of a method for additively manufacturing an integrated fuel injection unit according to one aspect of the present disclosure.

[0066] The drawings are not necessarily drawn to scale and may present simplified representations of various features of the present disclosure, including, for example, specific dimensions, orientations, positions, and shapes. In some cases, well-known features may be omitted from certain drawings to avoid overly obscuring the concepts of the present disclosure. Details associated with such features will be determined in part by the specific intended application and use case environment. DETAILED DESCRIPTION

[0067] The present disclosure allows for embodiments in many different forms. Representative examples of the present disclosure are shown in the accompanying drawings and described in detail herein as non-limiting examples of the disclosed principles. For this reason, elements and limitations described in the abstract, background, summary, and detailed description sections but not explicitly set forth in the claims should not be incorporated into the claims individually or collectively by implication, inference, or otherwise.

[0068] For the purposes of the present description, unless otherwise stated, the use of the singular includes the plural and vice versa, the terms "and" and "or" shall be both conjunctions and disjunctive conjunctions, and the terms "including," "comprising," "containing," "having," and the like shall mean "including but not limited to." In addition, approximate terms such as "approximately," "almost," "substantially," "roughly," "approximately," and the like may be used herein in the sense of "at, close to, or nearly at," or "within 0-5% of," or "within an acceptable manufacturing tolerance," or a logical combination thereof. As used herein, a component "configured to" perform a specified function is capable of performing the specified function without change, rather than merely having the potential to perform the specified function after further modification. In other words, when explicitly configured to perform a specified function, the hardware described is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the specified function.

[0069] Apparatus, systems and methods are disclosed for integrating elements of a fuel injection system using additive manufacturing (also known as 3-D printing). The result is a much smaller and more streamlined fuel injection system. Many types of 3-D printers exist. Printers specifically designed for printing metals, such as powder bed fusion (PDF) printers, may be particularly useful. For example, a CAD file described in detail using specialized computer-aided design ("CAD") software is initially created, which defines the shape, geometry, and properties of the device being printed, sometimes referred to as a "build." Increasingly advanced 3-D printers can use advanced technology to precisely print very small geometric metals and other designs, resulting in a single integrated unit as the final build.

[0070] In many 3-D printing applications, the CAD file is then "sliced" by a slicing application, which effectively divides the CAD designed part into many small geometric configurations that, when combined, recreate the part. Slicing can be used because, in PDF and related printers, the printed object is gradually built up from a substrate in individual slices. Each slice corresponds to a powder layer. As the 3-D printer scans each new layer, each scanned cross-sectional area of ​​the layers melts and subsequently solidifies. To print a slice of a build, a uniform layer of powder can first be deposited on a substrate by a depositor. Thereafter, a laser or electron beam in the printer can be used to selectively fuse or melt the areas of the slice that are considered part of the part, as determined by the coordinates found in each slice. The remaining unfused areas in the slice are not part of the part, and therefore the powder associated with these areas will not melt, allowing it to subsequently fall free or fall off the design. After the fusion process just described, a depositor can be used to deposit another layer of powder on top of the newly printed layer. The laser or electron beam can then scan the layer to form the next slice in sequence. The process continues until each layer has been deposited or scanned. The result is a build or printed object that can be cleaned of excess powder.

[0071] One advantage of 3-D printed parts is that multiple elements can be printed as a single, discrete, unified object. In various aspects of the present disclosure, the fuel injection unit and its various components are integrated together in a single design and then additively manufactured. The resulting fuel injection unit is significantly smaller than the existing unit. Equally important, a major problem with modern hydrogen fuel cells is hydrogen leakage. Existing fuel injection systems are constructed using typical subtractive manufacturing techniques, such as machining, molding, mold processing, extrusion, forging, die casting, etc. A problem with using only this method is that it tends to produce multiple discrete devices that need to be combined together by some kind of connecting device. As described in the background technology section above, hydrogen is a very small molecule and can easily leak out from many devices. Subtractive manufacturing techniques typically rely on the use of bolts, nuts, O-rings, brackets and other such elements to connect various objects together, but hydrogen may easily leak through these elements. The result is not only undesirable hydrogen emissions in the air, but also a significant decrease in the overall efficiency of the hydrogen vehicle due to the spontaneous loss of hydrogen by the hydrogen vehicle. Additionally, using molding, machining, and forging as primary manufacturing techniques tends to produce sharper corners and draft angles, which can undesirably alter the effective flow of hydrogen and produce unexpected emission phenomena. In contrast, the geometric nature of additive manufacturing makes it easier to form smooth, intended surfaces that are consistent with the actual geometric goals of the structure and minimize the undesirable phenomena caused by sharp corners, draft angles, and other defects caused by many implementations of existing manufacturing.

[0072] Figure 1is a mechanical diagram of an existing fuel injection unit. The pipe 15 of the device transmits the hydrogen to be input into the fuel cell from the inlet 20 to the inlet 17 via the injection assembly, which is the inlet of the heat exchanger 19. The function of the heat exchanger 19 is to increase the temperature of the hydrogen flowing through one of the channels by exchanging heat between the first channel and the second channel, the first channel including hydrogen, and the second channel may include a hotter "coolant" or other substance, and according to general thermodynamic principles, heat can flow from the hotter "coolant" or other substance to hydrogen, or cold can flow from hydrogen to the coolant. As shown in the figure, a typical heat exchanger 19 can be implemented as a plurality of stacked plates, the area of ​​which is maximized to thereby maximize the exposure area of ​​the channels to each other. The heat exchanger 19 can be mounted to the frame of the vehicle using holes 18a in bolts and brackets.

[0073] The heat exchanger 19 is typically attached to the bracket 18 by means of a series of bolts. The purpose of the bracket 18 is to enable the fuel injection unit to be fixedly mounted to a frame (not shown) on some portion of the interior vehicle assembly. The heat exchanger 19 may also include one or more pressure sensors 12b mounted on the heat exchanger 19 for sensing the pressure of the fluid entering the heat exchanger 19.

[0074] As the hydrogen fuel flows from the inlet 17, the hydrogen fuel is gradually heated by the heat exchanger 19 until it leaves the heat exchanger 19 and flows into the channel 16, which can be an elongated tube. The input and output of the channel 16 can include corresponding connectors 16a and 16b (e.g., connected using bolts, nuts or other fixings), which can also include additional pressure sensors. An example is the pressure sensor 12a near the connector 16b. The hydrogen can then flow into the fuel rail attenuation volume 14 (sometimes referred to as a "FRAV", acoustic attenuator volume or attenuator volume). Figure 1 The FRAV in is a complex assembly of components designed to reduce the acoustic noise generated by the hydrogen flow and the corresponding pressure differential. Figure 1 As shown in the figure, the FRAV 14 is a separate component from the components of the heat exchanger 19. Although the outer portion of the FRAV 14 is shown in the figure, the interior of the FRAV 14 includes an outer cylinder (e.g., defined by component 14b) and an inner cylinder (obscured from view). The inner cylinder includes heated hydrogen flowing out of the heat exchanger from the output portion 16a of the channel 16. The perimeter of the connector 16a may correspond to the perimeter of the inner cylinder of the FRAV 14. The outer cylinder defined by component 14b includes attenuated hydrogen (e.g., a portion of hydrogen used to suppress acoustic noise) located between the inner perimeter of the inner cylinder and the outer perimeter (component 14b) of the FRAV 14.

[0075] Existing FRAVs typically include a subset of discrete components that are sealed and bolted together. In the example shown, the FRAV 14 includes two aluminum components 14a and 14b. Currently, the aluminum components 14a and 14b are manufactured using forging, die casting and / or machining techniques. After they are formed, the aluminum components 14a and 14b are joined together and sealed. For example, during the manufacture of the aluminum components 14a and 14b, a ridge 27 may be formed. Half of the ridge 27 may be manufactured as a part of the aluminum component 14a, and the remaining half of the ridge 27 may be manufactured as a part of the aluminum component 14b. Then, the corresponding portions of the ridge 27 are aligned and fixed together using bolts 28 extending through the ridge.

[0076] To further seal the aluminum components 14a and 14b of the ridge 27 together, an O-ring is inserted between the ridge 27 to secure the seal. The O-ring is squeezed very thin when the two aluminum components 14a and 14b of the FRAV 14 are joined together; therefore, the O-ring is obscured from view. In addition, as described above, the FRAV 14 includes an inner cylinder (obscured from view) through which the heated hydrogen from the heat exchanger 19 is directed. Along with hardware similar to the ridge 27, a second O-ring is inserted into the FRAV 14 between the aluminum components 14a and 14b. Therefore, in addition to a plurality of bolts 28 for joining at least corresponding portions of the ridge 27 together, the FRAV 14 also includes at least two O-rings. These areas where bolts 28 and elastomeric materials (i.e., O-rings) are used are particularly susceptible to hydrogen leakage.

[0077] In addition, the FRAV 14 also includes two injectors 6 and 8. The injectors can be opened or closed in a manner that optimizes the flow of hydrogen through the inner barrel of the FRAV 14. The injectors 6 and 8 can be adjacent to an input 10 that allows pressurized hydrogen to flow to the injectors 6 and 8 and to be released into the FRAV 14 when the injectors 6 and 8 are activated. The FRAV 14 can also be close to a pressure sensor 12a for sensing the pressure inside the FRAV 14. In this example, the injectors 6 and 8 are side-feed injectors. The injectors 6 and 8 bridge the gap between the inner barrel and the outer barrel of the FRAV 14. That is, hydrogen is supplied to the FRAV 14 using the injectors 6 and 8 via the input 10. Then, the injectors 6 and 8 control the pressure and speed of the hydrogen flow to the inner barrel of the FRAV 14. Therefore, in addition to the hydrogen entering the FRAV 14 from the heat exchanger 19, hydrogen also originates from the injectors 6 and 8. When the injectors 6 and 8 are selectively or periodically activated, the FRAV 14 suppresses the sound generated.

[0078] Still refer to Figure 1, the FRAV 14 is connected to the injector assembly 13. Although including various components, the injector assembly 13 is characterized as the portion of the fuel injector unit from reference numeral 13 (and including reference numeral 13) to reference numeral 12 (and including reference numeral 12). The injector assembly 13 is terminated at the stack anode inlet 12, where the latter is the position where hydrogen is injected into the anode of the corresponding fuel cell. The injector assembly 13 may include three injection molded components welded into a single assembly. As a discrete device, the injector assembly 13 is connected to the FRAV 14. In this example, the cylindrical portion of the injector assembly 13 is coupled to the aluminum component 14a using three bolts, two of which are represented by small sections 32 protruding through the connecting plate 31, and one of the bolts is obscured from view on the opposite side of the assembly. During the use of the fuel injection unit, hydrogen from the inner barrel of the FRAV 14 is guided through the pipe 33 of the injector assembly 13 and leaves from the stack anode inlet 12 to enter the anode portion of the corresponding fuel cell. The injector assembly also includes pressure sensors 39 a and 39 b for sensing the pressure of the hydrogen as it passes through the region of conduit 33 .

[0079] The exemplary fuel injection unit described above is susceptible to hydrogen leakage in multiple areas. During manufacturing, the FRAV 14 is first divided into two discrete components, which are then connected using a combination of bolts and O-rings. As described above, hydrogen leakage occurs in the FRAV 14 due to defects in the elastomeric O-rings and the overall defective nature of the connection. In addition, the injector assembly 13 is separately connected to the FRAV using multiple bolts. Therefore, hydrogen may leak through the defective connection between the injector assembly 13 and the FRAV 14. As shown, the injection unit from the inlet 20 through the pipe 15 and ultimately to the stack anode inlet 12 is not only susceptible to excess hydrogen leakage, but also its irregular and large shape needs to be taken into account in the overall design of the vehicle's body. Each pressure sensor, including the pressure sensor 12a on the FRAV 14 and the pressure sensors 39a and 39b on the pipe 33 of the injector assembly, will suffer additional hydrogen leakage.

[0080] Thus, in one aspect of the present disclosure, additive manufacturing techniques are used to (1) reintegrate the fuel cell injection unit into a single, unified structure, and (2) reduce and streamline the shape and size of the structure, thereby making the vehicle's power system more compact and capable of producing more power in a smaller volume. As discussed further below, the streamlined internal shape of the FRAV's internal volume can also enable the integrated fuel injection unit to have significant performance benefits, such as, among other benefits, being able to produce a high-efficiency venturi tube in the FRAV without significant draft angles.

[0081] Figure 2is a mechanical diagram of an additively manufactured integrated fuel cell injection unit 200 according to one aspect of the present disclosure. Figure 1 and including several additional differences to be addressed herein, the integrated fuel cell injection unit 200 includes the presence of Figure 1 A high efficiency version of the feature between the inlet 20 in and the stack anode inlet 12.

[0082] Figure 2 The structure can be additively manufactured using one of a variety of suitable 3-D printers. In the initial stages of the additive manufacturing process, the designer typically creates a detailed CAD file that discloses a visual and digital representation of the features of the structure in question. In one example, a powder bed fusion (PBF) 3-D printer can be used. The CAD drawing is then formatted for use by the 3-D printer. For example, in one step, software compatible with the 3-D printer can be used to analyze the CAD file and divide the file into multiple slices. These slices physically and visually represent cross-sectional fragments of the structure to be printed. Therefore, these slices include the data required to recreate a physical version of the integrated hydrogen fuel injection unit in the 3-D printer.

[0083] In this embodiment, one slice is produced at a time. The PDF printer in this embodiment may include a substrate. During a first printing cycle, the printer may deposit a first layer of powder into a powder bed using a depositor. In an alternative printing design, a roller may alternatively be used to spread a predetermined amount of powder from a first powder source to the substrate. Depending on the printer and the design goals, the powder may represent a specific type of metal or alloy. However, it will be appreciated that different types of printers are capable of printing different materials. Referring back to the first printing cycle, after depositing the first layer, a laser beam source or an electron beam source may deflect the laser or electron beam via a movable mirror so that the laser or electron beam source can selectively melt or weld portions of the deposited powder slice defined by the data in the slice. The remaining unmelted portion of the deposited powder may then be removed, for example, when the final structure is removed from the printer.

[0084] After the first slice is deposited and selectively melted, the 3-D printer can deposit the next slice and selectively melt areas in the slice. This process can continue until the so-called build is complete. Unused residual powder can be removed and the build can be post-processed for cleaning purposes. Thereafter, the structure can be integrated with other structures and ultimately connected to an associated fuel cell in that portion of the vehicle.

[0085] Still reference Figure 2, the integrated fuel cell injection unit 200 includes a stack anode inlet 212, which provides an aperture for introducing heated hydrogen into the anode portion of an associated fuel cell or fuel cell stack (not shown) at an appropriate pressure and velocity. The integrated fuel cell injection unit 200 also includes a flange 202, which in this example includes two apertures for coupling the integrated fuel cell injection unit 200 to its associated location in the vehicle. The stack anode inlet 212 and the flange 202 are positioned at a top end 221 of the integrated fuel cell injection unit 200. (For purposes of this disclosure, the top end 221 is also referred to as the second end.)

[0086] As shown, the integrated fuel cell injection unit 200 also includes a generally cylindrical body 214. The upper portion of the body 214 adjacent the second end adopts a generally conical portion 222 of the body 214, but other shapes are also possible. Figure 3 As more clearly seen in the cross-sectional view of the integrated fuel cell injection unit 200 in FIG. 2 , the interior of at least a portion of the tapered portion 222 of the body 214 includes a volume between the surface of the internal heat exchanger and the top or second end of the integrated fuel cell injection unit 200. In this embodiment, the tapered portion 222 also includes an inlet 204. The inlet 204 is coupled to a channel for receiving fresh hydrogen from a hydrogen tank or other source. In some embodiments, the inlet 204 may be used additionally or alternatively to receive unused hydrogen previously injected into the corresponding fuel cell. In this embodiment, unused hydrogen that does not interact or explode in the fuel cell may be redirected back through the channel and into the inlet 214 of the tapered portion 222 of the body 214. In order to help ensure the efficiency and performance of the fuel cell or fuel cell stack, the integrated fuel cell injection unit 200 is configured to inject more hydrogen into the fuel cell than is required for subsequent chemical reactions. As a result, the unused hydrogen can be pumped back to the stack anode inlet 212 using a jet pump or a recirculation blower. With reference to Figure 3 By way of further explanation, residual hydrogen not used in previous reactions may be recycled using a dedicated recycle path inlet 220 .

[0087] Continue to refer Figure 2, the body 214 includes a bottom end 224, which is also referred to herein as the first end. In addition, the body 214 includes two holes 206 and 208. The hole 206 can be an inlet, and the other hole 208 is an outlet. As described below, the holes 206 and 208 can be used to pass fresh and used coolant through the second channel of the dual-channel heat exchanger accordingly. When the coolant enters the integrated fuel cell injection unit 200, the temperature of the coolant is higher than the temperature of the hydrogen. The body 214 also includes a partial view of the recirculation path inlet 220 leading to the body 214. Residual hydrogen from the surrounding area that may otherwise cause wasteful emissions can be sucked into the recirculation path inlet 220 and reused in the corresponding fuel cell.

[0088] In the integrated fuel cell injection unit 200, the interior of the body 214 may include a volume that acts as a decay volume (eg, Figure 3 That is, as will be seen, the inner barrel within the body 214 may include passages for traveling heated hydrogen injected into the fuel cell, while the outer volume of the body 214 may operate to suppress sound, much like Figure 1 FRAV-14.

[0089] Figure 3 is taken along a vertical axis passing through the integrated fuel cell injection unit 200 according to one aspect of the present disclosure Figure 2 324 of the integrated fuel cell injection unit 200 includes a hole 356 incorporated into the body 314 of the integrated fuel cell injection unit 200. Although there may be more than one such hole, in this embodiment, one hole 356 is shown. Vertically aligned with the hole 356 in the body 314 is a nozzle socket 360. The nozzle socket 360 can be mounted to the inner surface of the body 314. The function of the hole 356 and the nozzle socket 360 is to enable the manufacturer to vertically insert a selectively activated hydrogen injector 391 into the body 314 near the bottom (first) end 324. The injector 391 is similar in function to Figure 1 Injector 391 is used to control the flow of heated hydrogen in volume 340 in addition to the hydrogen discharged from the ejector. Figure 1 Different in Figure 3 In the embodiment of the present invention, the syringe can be vertically mounted in the hole 356 so that the end of the syringe can be securely coupled with the nozzle socket 360.

[0090] The pressure sensor may be integrated into the nozzle socket 360 or the injector itself, or both, as well as other areas within the body 314 of the integrated fuel cell injection unit 200. In the prior art, the pressure sensor is a discrete component that may cause leakage. Figure 3In an embodiment of the present invention, one or more pressure sensors may be integrated into the additively manufactured body 314 to avoid leakage. From a manufacturing perspective, during 3-D printing, printing may be temporarily paused at a designated point to add a pressure sensor, after which printing may continue. In other examples, the 3-D printer itself may be used to construct the pressure sensor or a portion thereof. In either case, the pressure sensor may be integrated into the body 314, effectively eliminating the leakage problem.

[0091] The syringe may be installed at a strategic point during the additive manufacturing process, or it may be inserted after the 3-D printing job is completed. The nozzle socket 360 is not only designed to stabilize and fix the inserted syringe, but also includes an output portion that guides the hydrogen discharged from the syringe through an appropriate path 361. Path 361 allows the syringe output to be effectively aligned with the input 344a of the injector nozzle 344. Although shown in section here, the injector nozzle 344 can be a cylindrical or tubular nozzle that receives hydrogen from the syringe output (via channel 361) and other hydrogen sources described herein, and injects hydrogen into the injection tube 390. In some embodiments, the injection tube 390 is a venturi tube. The pressure change caused by the selective activation of the syringe causes the injector nozzle 344 to output hydrogen into the injection tube 390. This mechanism of action includes a pressure difference that occurs in the gap 342 due to the selective injection of hydrogen from the syringe as described herein. The gap 342 is coupled externally through the body 314 via the recirculation path inlet 320 (shown in section). In other words, the gap 342 is a recirculation path for residual hydrogen and includes a wide-mouthed cross-sectional opening (i.e., the recirculation path inlet 320) that bends upward to the injection tube 390. The gap allows residual hydrogen outside the integrated fuel cell injection unit 200 to flow into the body 314 through the inlet 320 for use in the fuel injection process. Similar to the unused hydrogen entering the inlet 304, the recirculation path can be used to recirculate residual hydrogen that has been injected into the fuel cell but not used. The residual hydrogen may originate from the outlet of the fuel cell stack in use.

[0092] The injection tube 390 extends at least partially longitudinally upward along the body 314 to the stack anode inlet 312 at the top end 321, where hydrogen is supplied to the anode of the fuel cell. When an interaction occurs in the fuel cell, unused hydrogen can be redirected to the input portion 304 through a channel (not shown). Therefore, the input portion 304 receives unused hydrogen from the fuel cell (or fuel cell stack), which receives hydrogen from the stack anode inlet 312. Therefore, hydrogen that is not used in the interaction enters the tapered portion 322 of the body 314 via the input portion 304. Unused hydrogen may initially enter the tapered portion 322 as a liquid, for example when a large amount of heat is released during the most recent fuel cell reaction. In various embodiments, the input portion 304 may alternatively or additionally be used to supply hydrogen to the integrated fuel cell injection unit 200 from another source such as a tank.

[0093] The unused hydrogen from the reaction, after passing through the inlet 304, first enters the volume region 338 located near the top surface 321 and surrounding the injection tube (e.g., venturi) 390. Since the unused hydrogen at this stage is at a lower temperature than the temperature required for injection into the fuel cell, the unused hydrogen should be reheated in a relatively fast and efficient manner. Therefore, in one aspect of the present disclosure, a heat exchanger 336 is positioned within the body 314 of the integrated fuel cell injection unit 200. The heat exchanger 336 constitutes a set of wavy lines on either side of the injection tube 390 and the blank area between them. Although Figure 3 390 is a cross-sectional view, but the heat exchanger 336 may extend around the entire circumference of the injection tube 390 in various embodiments.

[0094] The strategic placement of the heat exchanger 336 within the body 314 significantly simplifies the design and significantly reduces the space required for the heat exchanger. In another aspect of the present disclosure, the top surface 350 of the heat exchanger 336 is formed around the body 314 of the integrated fuel cell injection unit 200 in the shape of a gradient. For example, the surface 350 at the top of the heat exchanger 336 gradually increases in height. Like a cone (whether symmetrical or not), the opposite sides of the heat exchanger surface 350 gradually decrease in height. The distributed gradient of the heat exchanger 336 defined by its conical surface 350 provides significant advantages. For example, the gradient of the surface 350 allows the hydrogen input from the inlet 304 to be evenly distributed over a much larger area. In addition, compared to Figure 1Unlike stacked plate heat exchangers, heat exchanger 336 uses a gyroid pattern or a similar pattern using a triply periodic minimal surface (TPMS) grid structure of cells. As a result, hydrogen can be heated to a desired temperature in a much faster and more efficient manner. For clarity, it should be noted that although a cross-sectional view is shown, the gradient has a surface area that can extend around the perimeter of the gap 342 / injector nozzle 344 / injector tube 390 assembly (collectively referred to as "injector assembly 388") on the inside of the body 314 and is defined by the perimeter of the body 314 on the outside of the body 314.

[0095] To more clearly understand the fluid flow in the embodiment of the dual-pass heat exchanger 336, Figure 4 A non-sectional view of a heat exchanger is provided in . In general, reference Figure 3 , the exemplary heat exchanger 336 is a dual-channel heat exchanger. In the first channel 336a (wherein one of the multiple sections is referenced), hydrogen can flow freely. For clarity, reference numeral 332 also shows the first channel to the right of the injection tube 390. The heat exchanger 336 is optimized to facilitate hydrogen flow through the first channel 336a, starting from the surface 350 of the heat exchanger 336, and then downward through the various branches of the first channel 336a to the second tapered gradient 350 near the bottom end 324 of the body 314 of the integrated fuel cell injection unit 200. Although from Figure 3 It is not clear in , but paths similar to 336a are arranged in a topologically optimized three-dimensional shape that is configured to facilitate hydrogen flow through heat exchanger 336 and into volume 340 at the bottom (“first”) end of body 314 .

[0096] Similarly, adjacent to the first channel 336a, there is a second channel 336b. The second channel 336b is mainly shown as an empty space area within the heat exchanger 336. The second channel 336b carries a "coolant" material from which hydrogen absorbs heat. The second channel 336b is designed so that the molecules of the coolant cannot leave the second channel. Like the first channel 336a, the second channel 336b is locally optimized in three dimensions. In various embodiments, the second channel 336b is usually directly adjacent to the first channel 336a to facilitate heat exchange between the hydrogen in the first channel 336a and the coolant in the second channel 336b.

[0097] Because the coolant entering the heat exchanger through the input portion 206 is at a higher temperature than the hydrogen passing through the heat exchanger, the coolant can be used to heat the hydrogen. The hydrogen absorbs heat from the coolant until the former is vaporized by exchanging heat with the coolant. A thermally conductive metal or alloy can be used to define the corresponding channels 336a-b and physically separate the two materials. For example, in this cross-sectional view, fresh coolant can be injected into the inlet 362 closer to the top end 321 of the integrated fuel cell injection unit 200, and the cold (used) coolant can leave the body 314 via certain outlets 372 near the first end 324. In various embodiments, Figure 3 The inlet 362 may correspond to the input portion 206 ( Figure 2 ),and Figure 3 The outlet 372 may correspond to the output portion 208 ( Figure 2 ).

[0098] After the heated hydrogen reaches the bottom of the heat exchanger 336 , the hydrogen passes through the tapered wall 352 and fills the volume 340 below the heat exchanger 336 .

[0099] When the injector is activated, hydrogen is discharged from an external source (e.g., a tank). One consequence of this discharge is that the unused hydrogen in the volume 340 heated by the heat exchanger 336 is actuated upwards by the path 361 that the injector is aligned with the injector nozzle 344, through the input portion 344a of the injector nozzle 344, upwards through the injection pipe 390, and enters the fuel cell via the stack anode inlet 312 at the top 321 of the integrated fuel cell injection unit 200. In addition, the activation of the injector produces hydrogen with a selected pressure and speed. These characteristics of the discharged hydrogen produce a low-pressure area in the gap 342. This mechanism allows the residual hydrogen outside the main body 314 of the integrated fuel cell injection unit 200 to enter the recirculation path inlet 320 into the gap. The residual hydrogen in the gap can enter the injection pipe 390 together with the hydrogen discharged from the injector and the unused hydrogen by the heat exchanger. Hydrogen can then enter the fuel cell via the stack anode inlet 312. In short, the integrated fuel cell injection unit 200 can use hydrogen activated from the injector to create a low pressure area in the gap 342 and thereby draw residual hydrogen back into the stack anode inlet.

[0100] Another significant benefit of the described subject matter is that Figure 1 The injector assembly 13 in is now integrated into the body 314 of the integrated fuel cell injection unit 200. In this example, the injector assembly may include the injection tube 390 and the stack anode inlet 312. Therefore, the connecting plate 31 and the bolts represented by the cylindrical section 32 are no longer required. In this way, this area where hydrogen leakage exists is effectively eliminated.

[0101] In a related aspect of the present disclosure, a heat exchanger 336 is integrated within the decay volume (FRAV volume). When hydrogen is flowing, activation of the injector results in a reduction in fluid pressure. When the activated injector is closed, the gap 342 between the body 314 and the recirculation path inlet 320 can be used to suppress sound. In the example shown, the volume inside the body 314 to the boundary created by the injector assembly 388 constitutes the FRAV volume. Including the heat exchanger 336 within the FRAV volume potentially saves a significant amount of space and reduces the overall size of the integrated fuel cell injection unit 200. The injector nozzle 344 and the injection pipe 390 correspond to Figure 1 The inner barrel of the FRAV 14.

[0102] Continue to refer Figure 3 , high pressure, high speed hydrogen from the injector travels through the nozzle 344 and the injection pipe 390, wherein the latter can be a venturi tube. In some cases, the inlet 304 receives fresh hydrogen from one or more fuel sources such as a hydrogen tank. The hydrogen that has just passed through the inlet 304, the volume 338, the heat exchanger 336 and the volume 340 is guided to the injection pipe 390 via the injector nozzle 344, as described herein. In addition to the hydrogen from this fresh source, the residual hydrogen in the area near the identified integrated fuel cell injection unit 200 is usually a byproduct of early interaction or combustion in the fuel cell stack, and the byproduct includes hydrogen, some other gaseous reagents and water. The geometric configuration of the injection pipe 390 can produce a low pressure area in the gap 342 so that the residual hydrogen can flow into the gap 342. Then, the hydrogen in the gap 342 is ejected upward through the injection pipe 390. The overall pressure control system allows the injector 391 to be activated when the pressure of the hydrogen flow toward the stack anode inlet 312 drops below the threshold value, so that the hydrogen fuel is injected. This injection of hydrogen raises the pressure in the system, after which injector 391 is closed and the flow of hydrogen from injector 391 is stopped.

[0103] According to the power demand of the fuel cell to which the integrated fuel cell injection unit 200 is coupled, the cyclic injection from the injector 391 can occur at a higher or lower frequency. The venturi behaves like a jet pump or a vacuum pump. In certain embodiments, the anode stack inlet can reach a point where it is under a higher pressure than the injected contents from the integrated fuel cell injection unit 200. Of course, the pressure difference will form a backward hydrogen flow. This action can be avoided by using a venturi as the injection pipe 390. For example, when hydrogen is injected into the fuel cell, a low pressure region is created as described herein. In the case of receiving residual or excess hydrogen from the recirculation path inlet 320, the gap 342 can overcome the pressure difference.

[0104] The venturi tube increases the velocity of hydrogen flowing therein by confining the hydrogen in a tube having a cone, such as Figure 3The cone 396 near the base of the venturi 390 in FIG. The remainder of the venturi is constrained to cylindrical dimensions as it extends upward toward the stack anode inlet 312. Due to this geometric constraint, the hydrogen flow must accelerate, which reduces its pressure and creates a partial vacuum at the gap 342. In the venturi, the pressure of the hydrogen increases as it leaves the constriction. Figure 3 The integrated fuel cell injection unit 200 in FIG. 1 effectively utilizes the velocity of the hydrogen and the sonic flow exiting the injector nozzle so that the geometric relationship between the venturi and the injector nozzle 344 maintains sufficient pressure that prevents backflow of the hydrogen.

[0105] In contrast, using prior art, the venturi tube could not be ideal because it is constructed of injection molded plastic. This in turn creates an undesirable draft angle that compromises the effectiveness of the venturi tube. However, in this embodiment, injection molding is not required and the venturi tube can be additively manufactured without having a compromised draft angle.

[0106] Another benefit of the present disclosure is the elimination of pressure sensors 39a and 39b located on the conduit 33 of the injector assembly 13. Instead, pressure sensors may be integrated at strategic points within the body 314 of the FRAV during the additive manufacturing process. Thus, hydrogen leakage due to sensors 39a and 39b may be substantially eliminated.

[0107] Another disadvantage of existing fuel injection units relates to the fact that FRAVs or acoustic noise attenuators typically require forging to close the molecular structure of the aluminum to prevent excess hydrogen from diffusing through the aluminum. Additive manufacturing can be used to eliminate the disadvantages associated with the cumbersome forging process, and integrating the various fuel injection components within the body substantially minimizes hydrogen diffusion.

[0108] Figure 4 is a geometric representation of a dual-pass heat exchanger 436 according to one aspect of the present disclosure. The heat exchanger 436 and Figure 2 and Figure 3 The upper portion 450 of the semi-cylindrical structure is shown for increasing the volume 338 ( Figure 3 ) The surface area of ​​incident hydrogen gas entering the heat exchanger is a gradient. The spherical appearance element is part of a first channel, and hydrogen is configured to flow from the upper gradient 450 and downward through the first channel. Therefore, the first channel 436 transports hydrogen. The TPMS cell grid structure can be used to form a channel and restrict fluid flow. For example, the metal portion 463 of the first channel 436a can be used to restrict the flow of hydrogen within the first channel, which can be distributed throughout the heat exchanger 436. The hydrogen itself includes substances such as hydrogen 465 between the channels.

[0109] The second channel for conveying coolant material is represented by each empty space between the first channels 436a, including channel 436b. Since a large amount of hot coolant is required to heat the hydrogen, the second channel is larger. It should also be noted that the simple external illustration of the heat exchanger 436 does not seem to show how hydrogen can flow from the upper part 450 to the lower part 424. However, it should be remembered that the internal part of the heat exchanger 436 can connect the various branches of the first channel together. In addition, as pointed out, the TPMS grid structure can be designed to topologically optimize the flow of hydrogen from the upper part 450 to the lower part 424. For example, the two channels 436a and 436b can be aligned so that hydrogen is exposed to the maximum amount of coolant (although separated by the channels), but it flows from the upper part 450 to the lower part 424 quickly enough to provide a sufficient amount of hydrogen fuel to the fuel cell stack.

[0110] The heat exchanger 436 may also have a dedicated location for injecting coolant, such as the input 462in of the second channel, and a dedicated location for recovering the used (cold) coolant, such as at the output 462out. In this way, the heat exchanger 436 using channels 426in and 462out can be continuously supplied with a sufficient volume of heated coolant.

[0111] The lower portion 424 may correspond to the bottom end 324 ( Figure 3 ) edge. It should be noted that in some embodiments, for example Figure 3 , the gradient is an upward cone. Therefore, only the edge of the bottom surface 424 is visible, making the object appear flat at the bottom.

[0112] Although a heat exchanger is typically included with other components in a practical integrated fuel cell injection unit 200, Figure 4 Only the heat exchanger is shown in order to avoid overly obscuring the concepts of the present disclosure. Moreover, although the heat exchanger 436 adopts a semi-cylindrical shape with a gradient at the respective upper portion 450 and lower portion 424, the principles of the present disclosure are not limited to this shape. A variety of geometric configurations can be used and integrated into the acoustic volume attenuator. In some examples, additional channels can be used. Different materials and different architectures can also be used to form the channels.

[0113] Figure 5 It is used for additive manufacturing such as Figure 21 is a conceptual diagram of a powder bed fusion (PDF) three-dimensional (3-D) printer 500 for metal products. Although a powder bed fusion (PBF) printer is described for illustrative purposes, many different types of 3-D printers may be used to form the integrated fuel cell injection unit 200 without departing from the principles of the present disclosure. Additionally, 3-D printers may be complex devices and may be controlled using integrated electronics, a separate computer, or some combination thereof, the present disclosure focuses on the basic elements.

[0114] As described above, after generating the computer-aided design (CAD) file of the integrated fuel cell injection unit 200, the software dedicated to the 3-D printer in question can be executed to geometrically divide the structure and its details into a large number of discrete slices. Each slice corresponds to a powder layer. The powder can be one of a variety of metals or alloys thereof, such as but not limited to aluminum or aluminum alloys. After depositing each layer and depositing the relevant cross-sectional area of ​​the structure, the integrated fuel cell injection unit 200 can be post-processed and completed.

[0115] refer to Figure 5 502 can be a large tank for holding powder to be used during printing. An output device such as channel 504 can retrieve a selected amount of powder from the tank and send it to the depositor 510. The depositor 510 is a mobile device, and at least for this reason, the use of channel 504 to retrieve the powder is a simplification. In fact, the depositor can rest on the platform 523 or hover above the platform 523 while the scanning process is in progress. In some embodiments, the depositor may include a smaller tank to store enough powder for a few cycles. In some embodiments, when the depositor 510 is stationary, the powder is deposited from the tank using a vertical channel.

[0116] After the controller managing the printing process receives the slice code and the hopper supplies powder to the depositor, the depositor can deposit the first layer onto the substrate 518. At the beginning of printing, the substrate 518 can be approximately flush with the platform 523. The depositor 510 then slides across the surface of the substrate and deposits the first layer representing the first slice or bottom of the integrated fuel cell injection unit 200. The depositor can then return to the platform 523 to avoid becoming an obstacle to the next process, which is a scanning cycle. In this scanning cycle, under the control of the code and / or electronic hardware, a Cartesian coordinate system can be used as a reference to implement the scanning cycle. The laser beam source 506 (which may alternatively include an electron beam source in other printers) irradiates the laser beam at a mirror 508 or other reflective movable lens. The laser 507 is turned to hit and effectively melt the selected area of ​​the powder corresponding to the first slice. The powder area that does not represent the cross-sectional area of ​​the structure is not scanned. The scanned area melts after being hit by the laser and then quickly fuses together to form the cross section of the first slice.

[0117] Before the depositor deposits another layer corresponding to the second slice, the controller can use piston 520 to move the substrate downward slightly. After each deposition and scanning cycle, the substrate moves downward a small but equal amount. This movement enables the object being printed, also referred to as a build 516, to become larger as more slices are used. This movement also creates a powder reservoir 512, which is included in the area between the top of the powder bed 512 and one side of the 3-D printer wall 514 (which is sliced ​​for illustrative purposes). In some cases, the controller and extensive electronic circuitry may also be integrated into the 3-D printer 500, below the platform and within the body of the 3-D printer defined by the wall 514, integrated into the internal rectangular area. In other embodiments, the platform 523 may alternatively include a second powder bed that uses rollers to roll each layer of powder evenly onto the powder bed 512. However, Figure 5 The embodiments focus on depositor embodiments.

[0118] After retrieving excess powder from hopper 502 via channel 504, depositor 510 deposits another layer and moves back to platform 523. The controller then uses the position data from the second slice to scan the area of ​​powder that will become part of build 516 with laser beam 507. Mirror 508 is precisely controlled by the controller as it is responsible for directing the laser beam to the correct location on the powder layer.

[0119] This process is repeated slice by slice and identically layer by layer until the build 516 (here the integrated fuel cell injection unit 200) is completed. In some embodiments, the printing process may be paused. For example, if the manufacturer wishes to insert a customized syringe into the integrated fuel cell injection unit 200, or insert a customized pressure sensor into the integrated fuel cell injection unit 200 along with accompanying electronic devices (e.g., semiconductors, low resistance metal traces, etc.), such a pause may be desired. In some embodiments, printing is paused multiple times to enable various components to be inserted into the integrated fuel cell injection unit 200, including non-metallic or other materials. In some printer designs, a variety of printing materials may be used. In addition, in some 3-D printers, certain other substances, such as gels or liquids, may be used instead of metal powders.

[0120] like Figure 5As shown in , the 3-D printing (also known as additive manufacturing) process is very beneficial because the printer 500 can integrate different features of the integrated fuel cell injection unit 200 into a single body. For example, the 3-D printer is able to build TPMS lattice structures, nozzles, tubes of different selected geometric configurations, and many other structures. 3-D printers are highly geometrically diverse. In this case, the 3-D printer does not require many (if not most) subtractive manufacturing techniques, such as machining, molding, extrusion, forging, die casting, etc. These techniques are not only expensive, but also inflexible. For example, a mold can produce a single shape. In contrast, the geometry using the 3-D printer 500 is mainly limited by the imagination of the manufacturer.

[0121] Figure 6 is an exemplary flow chart 600 of a method for additively manufacturing an integrated fuel injection unit according to one aspect of the present disclosure. Figure 6 The steps can be formed by a variety of 3-D printers, including Figure 5 The Powder Bed Fusion (PBF) 3-D Printer 500 and many PBF variants. To avoid obscuring the concepts of the present disclosure, these steps are in no particular order and are directed to additive manufacturing of various parts. Therefore, Figure 6 Individual processes for 3-D printers are not included, at least because such printers may differ significantly in operation, but may be suitable for use in additive manufacturing of the integrated fuel cell injection unit 200.

[0122] Referring to logic block 602, the 3-D printer may form a body having a cylindrical shape (or another suitable shape) to define an acoustic attenuation volume. The volume may be formed by body 314 ( Figure 3 ) to form walls and other components for sound suppression. Referring to logic block 604, the 3-D printer may also print incrementally (e.g., on a slice-by-slice basis, as described above with respect to Figure 5 The venturi tube may be printed so that it has a directional component that is longitudinal along the body so that the venturi tube may form the stack anode inlet at its end.

[0123] Referring to logic block 606, the 3-D printer may print an injector nozzle having an output aligned with the venturi for selectively injecting hydrogen into the venturi. It is noteworthy that in a powder bed fusion process, due to the layer-by-layer nature of printing and profile laser scanning, some or each of these components may be formed at least partially simultaneously. For at least this reason, the printing steps are not in a particular time order.

[0124] Referring to logic block 608, the 3-D printer may enclose the injector nozzle within a gap that extends to the hole in the surface of the body to recover unused hydrogen. In the context of the PDF 3-D printer 500, one way to accomplish this step is to leave the relevant geometric portion of the CAD file corresponding to the gap blank so that when slicing, the area corresponding to the gap is not scanned by the laser beam. In this way, the final build will include a gap filled with loose powder, which can be removed using a variety of techniques.

[0125] Referring to logic block 610, the 3-D printer may integrate the heat exchanger into the acoustic attenuation volume. Here again, the process may require the generation of a CAD representation of the heat exchanger within the body. The 3-D printer may simultaneously print the lattice structure and the body in certain areas, thereby using precision laser or electron beam scanning to combine the lattice structure of the cells.

[0126] With reference to logic block 612, a 3-D printer may form a hole and a receptacle for installing a custom syringe to control hydrogen flow. In some embodiments, the receptacle and / or syringe may be customized in whole or in part. Thus, for example, a receptacle or syringe may be a customized item or a commercial off-the-shelf (COTS) item, rather than additively manufactured. In one example, if the receptacle is additively manufactured, but the syringe is customized, a 3-D printer may form an integrated fuel cell injection unit 200 having one or more gaps at the bottom to accommodate the corresponding syringe. After removing stray powder from the completed build and performing post-processing (polishing, applying fluid, etc.), the manufacturer may insert a custom syringe through the hole at the bottom of the build 516 and ensure that the syringe is securely placed in the receptacle. In some cases, glue or adhesive may be used to ensure that the custom syringe is properly coupled to the receptacle and hole. In other cases, the syringe is additively manufactured, or partially additively manufactured. It may be beneficial to pause printing just after hole formation so that non-printing measures to seal or secure the syringe can be easily performed before printing resumes to complete the integrated fuel cell injection unit 200.

[0127] Another benefit of the principles disclosed herein is that, unlike conventional manufacturing techniques, where sharp edges and awkward angles are often difficult, if not impossible, to avoid, the resolution of modern 3-D printers is very high, and the geometric resolution of the print jobs is so precise that a wide variety of shapes can be formed. Many existing additive manufacturing techniques, including the techniques disclosed herein, can be used to eliminate the sharp edges and draft angles present in existing fuel injection units.

[0128] The detailed description and drawings or figures are support and description of the present teaching, but the scope of the present teaching is limited only by the claims. Although some best modes and other embodiments for carrying out the present teaching have been described in detail, there are various alternative designs and embodiments for practicing the present teaching defined in the appended claims. Moreover, the present disclosure explicitly includes combinations and sub-combinations of the elements and features presented above and below.

Claims

1. An additively manufactured hydrogen fuel cell injection unit, comprising: a body including a noise attenuation volume integrated therein, a first end of the body including a hole for mounting a syringe; an injector assembly including an injector tube and a stack anode inlet at the second end of the body, the stack anode inlet configured to inject hydrogen into the fuel cell; a heat exchanger integrated within the noise attenuation volume and comprising a three-periodic minimal surface (TPMS) lattice structure of cells arranged therein, the TPMS lattice structure configured to heat hydrogen flowing through the TPMS lattice structure, each end surface of the heat exchanger being separated from the first end and the second end of the body by a respective volume; as well as an injector nozzle coupled to the interior of the body and aligned with the injector near the first end of the body, the injector nozzle being surrounded by a gap that opens to a recirculation path inlet of the body for recapture of residual hydrogen proximate the recirculation path inlet, wherein the injection tube protrudes through the heat exchanger and is aligned with the injector nozzle such that the injection tube passes hydrogen through the stack anode inlet.

2. The fuel cell injection unit according to claim 1, wherein: The hydrogen delivered to the fuel cell from the stack anode inlet includes: (1) pressurized hydrogen originating from the injector; (2) residual hydrogen near the recirculation path inlet; and (3) hydrogen exiting the heat exchanger.

3. The fuel cell injection unit according to claim 1, wherein: The second end of the body includes an inlet coupled to a hydrogen source; A volume between a first end surface of the heat exchanger and the first end of the body is a first volume; The volume between the second end surface of the heat exchanger and the second end of the body is a second volume; as well as The second end surface of the heat exchanger is shaped with a geometric gradient configured to enable hydrogen received from the inlet at the second end of the body to be evenly distributed in the second volume as it enters and passes through the heat exchanger to enable uniform heat addition of the hydrogen.

4. The fuel cell injection unit according to claim 1, wherein: a first end surface of the heat exchanger and the first end of the body defining a first volume into which heated hydrogen exiting the heat exchanger flows; as well as The first end surface of the heat exchanger is shaped to form a gradient so that the heated hydrogen is more evenly distributed as it exits the heat exchanger into the first volume.

5. The fuel cell injection unit according to claim 4, wherein: The gradient is at least partially conical in shape.

6. The fuel cell injection unit according to claim 1, wherein: The TPMS grid structure includes a plurality of cells forming two channels, wherein a first channel passes hydrogen through the heat exchanger and a second channel passes a fluid to heat the hydrogen.

7. The fuel cell injection unit according to claim 6, wherein: One side of the body includes two holes for passing the fluid through the second channel of the heat exchanger.

8. The fuel cell injection unit according to claim 1, wherein: The injector is configured to be selectively activated to controllably cause hydrogen to flow from a volume proximate the first end of the body through the injector nozzle and the injection tube for discharge into the fuel cell.

9. The fuel cell injection unit according to claim 1, wherein: The injection tube includes a venturi tube, the venturi tube and the injector are configured to generate a low pressure in the gap to introduce the residual hydrogen into the gap through a recirculation path inlet and into the fuel cell through the injection tube via the stack anode inlet.

10. An additively manufactured fuel cell injection unit, comprising: a body having a noise attenuation volume therein; a first end of the body including a hole for mounting a hydrogen injector; an injector assembly including an injector tube coupled to a stack anode inlet at the second end of the body for injecting hydrogen into the fuel cell; a heat exchanger comprising a lattice structure of cells integrated within the noise attenuation volume, the lattice structure configured to heat hydrogen flowing therethrough, each end surface of the heat exchanger separating a respective volume from the first end and the second end of the body, a surface of the heat exchanger adjacent each respective volume comprising a gradient; an ejector nozzle coupled to the output of the injector at the first end of the body, the ejector nozzle being surrounded by a gap leading to a recirculation path inlet of the body for recapture of excess hydrogen; as well as An injection tube protrudes through the heat exchanger and is aligned with the injector nozzle such that the injection tube is configured to deliver hydrogen to the fuel cell via the stack anode inlet.

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