Impact force mitigation system and method for an electrochemical fuel cell stack
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-24
- Publication Date
- 2026-08-11
Smart Images
Figure CN116072943B_ABST
Abstract
Description
Technical Field
[0001] This disclosure generally relates to electrochemical fuel cell systems for converting hydrogen-rich fuels into electricity. More specifically, aspects of this disclosure relate to active and passive systems for mitigating impact forces in fuel cell stacks. Background Technology
[0002] Currently manufactured motor vehicles, such as modern automobiles, were initially equipped with a powertrain that operated to propel the vehicle and power its onboard electronics. For example, in automotive applications, a vehicle powertrain is typically represented by a prime mover that transmits drive torque to the vehicle's final drive system (e.g., differential, axles, corner modules, wheels, etc.) via automatic or manual power transmission. Historically, automobiles have been powered by reciprocating piston internal combustion engine (ICE) components due to their immediate availability and relatively low cost, light weight, and overall efficiency. Such engines include compression ignition (CI) diesel engines, spark ignition (SI) gasoline engines, two-stroke, four-stroke, and six-stroke architectures, and rotary engines, among others, as some non-limiting examples. Hybrid electric vehicles and fully electric vehicles (collectively referred to as "electrically driven vehicles"), on the other hand, utilize alternative power sources to propel the vehicle and thus minimize or eliminate reliance on fossil fuel-based engines for traction power.
[0003] All-electric vehicles (FEVs), commonly known as "electric vehicles," are electrically driven vehicle configurations that completely eliminate the internal combustion engine and associated peripheral components from the powertrain system, instead relying on a rechargeable energy storage system (RESS) and traction motors for vehicle propulsion. In battery-based FEVs, the engine components, fuel supply system, and exhaust system of ICE-based vehicles are replaced by one or more traction motors, traction battery packs, and battery cooling and charging hardware. In contrast, hybrid electric vehicles (HEVs) use multiple traction power sources to propel the vehicle, most commonly combining internal combustion engine components with traction motors powered by batteries or fuel cells. Because hybrid electric vehicles can obtain power from sources other than the engine, the HEV engine can be completely or partially shut off, with the vehicle propelled by electric motors.
[0004] A fuel cell is an electrochemical device that converts a hydrogen-rich fuel, such as liquid hydrogen or methanol, and an oxidant, such as air or polyoxygen, into electricity through a redox reaction. To generate the electricity needed to power motor vehicles, many fuel cells are connected in series or parallel to form a fuel cell stack to achieve higher output voltage and allow for greater current consumption. For example, a typical automotive fuel cell stack can have more than two hundred cells. These fuel cell stacks receive reactant gases as the cathode input, typically as a metered flow of ambient air forced through the stack by a compressor. During normal operation, the stack does not consume a quantifiable mass of oxygen; some residual oxygen is output as cathode exhaust gas, which may include water as a byproduct of the stack. The fuel cell stack also receives hydrogen or hydrogen-rich reactant gases as the anode input, which flows into the anode side of the stack. For proper fuel cell stack operation, the hydrogen distribution within the anode flow channels typically remains substantially constant.
[0005] Fuel cell designs commonly used in automotive applications utilize a solid polymer electrolyte membrane (PEM), also known as a "proton exchange membrane," to provide ion transport between the anode and cathode. A proton exchange membrane fuel cell (PEMFC) employs a solid polymer electrolyte (SPE) proton-conducting membrane, such as a perfluorosulfonic acid membrane, to separate product gases and provide electrical insulation for the electrodes in addition to proton conduction. The anode and cathode may comprise finely dispersed catalytic particles, such as platinum, supported on carbon particles and mixed with an ionomer. This catalytic mixture is deposited on the sides of the membrane to form the anode and cathode layers. The combination of the anode layer, cathode layer, and electrolyte membrane defines a membrane electrode assembly (MEA), in which the anode and cathode catalysts are supported on opposite surfaces of the ion-conducting solid polymer membrane. The MEA is sandwiched between a diffusion medium (DM) on the anode and cathode sides, which is formed of a conductive and permeable material, such as carbon fabric or paper. The DM layer and MEA are pressed between conductive unipolar or bipolar flow field plates, which act as secondary current collectors to collect current from the DMs, which function as primary current collectors. To mitigate unwanted fluid leakage between plates, polymer or raised-bead seals can be installed along the plate interfaces. Summary of the Invention
[0006] This paper presents an impact mitigation system for electrochemical fuel cell stacks, methods for manufacturing and operating such systems, and an electric vehicle with an impact-damping capability for the fuel cell stack. As an example, the active impact mitigation system and method employ a real-time clock (RTC) in cooperation with a system control module to monitor the stack lifetime of the fuel cell stack. Using the stack lifetime data, the system controller estimates the degree of aging of the fuel cell stack using a lookup table stored in memory containing a predetermined relationship between stack lifetime and seal creep. System sensors, such as load cells, triaxial accelerometers, or linear force sensors, detect the onset of a mechanical impact on the fuel cell stack, which may be caused by a vehicle collision, a collision with a pothole, or a curb. The system control module predicts the severity of the mechanical system impact, i.e., the magnitude of the resulting internal stack forces, and assesses whether the fuel cells in the stack will reach the maximum seal force limit or the minimum seal force threshold. If so, the system control module activates a pair of capsules or actuators packaged at opposite ends of the stack to: (a) reduce the stack compression force by a predetermined amount for a predetermined duration if the fuel cell stack is determined to be in the early stage of aging; or (b) increase the stack compression force by a predetermined amount for a predetermined duration if the fuel cell stack is determined to be in the late stage of aging.
[0007] In addition to active impact mitigation, passive impact force mitigation systems for electrochemical fuel cell stacks have been proposed. In one example, pushers and endplates are located at each longitudinal end of the fuel cell stack, with the pusher positioned inside the endplate and sandwiching the stacked fuel cells between them. A biasing member, such as a helical compression spring or a pneumatic cylinder, is positioned between each adjacent pusher-endplate pair. In the event of a mechanical system impact, the pusher moves toward its corresponding endplate; the biasing member absorbs and modifies the resulting impact. During a mechanical system impact, the front upper pusher travels toward its endplate; the biasing member allows for slight decompression of the stack and thus avoids damage from the resulting impact. To limit the pusher travel length, one or more travel blocks may be located between each pusher and endplate. Furthermore, shoulder screws may pass through the pusher and thread-mate with the endplate to limit the pusher travel in one direction. To further mitigate internal stacking forces, the fuel cell system may inject a surge of fluid pressure (e.g., 80-100 kPa within less than 15 milliseconds) into the stacked fuel cells at the onset of the impact event.
[0008] Various aspects of this disclosure relate to impact mitigation systems for electrochemical fuel cell stacks, such as those used in fuel cell electric vehicles (FCEVs). In one example, the fuel cell system includes multiple electrochemical fuel cells, such as PEM-type fuel cells, stacked face-to-face along the stack axis to define a fuel cell stack with opposing longitudinal ends (e.g., the top and bottom axial ends of a vertical stack). The fuel cell stack may be housed within a protective housing and fluidly coupled to a refillable hydrogen fuel tank and an ambient air compressor. A pair of pushers abut the longitudinal ends of the fuel cell stack, thereby clamping the fuel cells between them. Each pusher is movably mounted within the protective housing to translate linearly along the stack axis. Fixed end plates are positioned face-to-face and spaced apart from each pusher, such that the end plates and pushers are arranged as discrete pairs. Placed between the pushers and end plates in each pair are corresponding force modification devices. These force modification devices modify the stacking forces applied to the fuel cell stack, for example, as a result of an impact event.
[0009] Additional aspects of this disclosure relate to FCEVs equipped with high-voltage (HV) fuel cell systems with impact damping capabilities. As used herein, the terms “vehicle” and “motor vehicle” are used interchangeably and synonymously to include any relevant transportation platform, such as passenger cars (e.g., hybrid electric, all-electric, fully and partially automated driving, etc.), commercial vehicles, industrial vehicles, tracked vehicles, motorcycles, off-road and all-terrain vehicles (ATVs), watercraft, aircraft, etc. For non-automotive applications, the disclosed concepts can be implemented for all logically related uses, including stand-alone power plants, portable power packs, backup generator systems, pumping equipment, residential uses, electric vehicle charging stations (EVCS), etc. In one example, an electrically driven vehicle includes a body with a passenger compartment, multiple wheels mounted to the body (e.g., via corner modules coupled to an integral or body-frame chassis), and other standard original equipment. One or more electric traction motors operate individually (e.g., for an FEV powertrain) or in combination with engine components (e.g., for an HEV powertrain) to selectively drive one or more wheels to propel the vehicle. A rechargeable traction battery pack can be optionally mounted on the vehicle body and is operable to store electrical power for the traction motor.
[0010] Continuing with the preceding example, the electric vehicle also includes a fuel cell system mounted on the vehicle body and selectively operable to generate electricity to power traction motors, vehicle accessories, etc. This fuel cell system comprises at least one fuel cell stack having multiple electrochemical fuel cells stacked face-to-face along a central stack axis. A pair of push plates press against the longitudinal ends of the fuel cell stack; these push plates are movable along the stack axis. A pair of end plates are positioned face-to-face and spaced apart from the push plates, such that each pair of adjacent push plates and end plates defines a discrete plate pair. Passive or active force modification devices are positioned between the push plates and end plates in each plate pair. These devices selectively increase / decrease the stacking force applied to the fuel cell stack, for example, depending on stack aging and stacking force intensity.
[0011] Various aspects of this disclosure also relate to system control logic, processor-executable control programs, and computer-readable media (CRM) for manufacturing and / or operating impact mitigation systems for electrochemical fuel cell stacks. In one example, a method for assembling a fuel cell system is proposed. This representative method, in any order and in any combination with any of the choices and features disclosed above and below, includes: stacking a plurality of electrochemical fuel cells face-to-face along a stack axis to define a fuel cell stack having opposing first and second longitudinal ends; abutting first and second pusher plates abutting respectively against the first and second longitudinal ends of the fuel cell stack such that the first and second pusher plates are movable along the stack axis; positioning first and second end plates respectively in a face-spaced relationship with the first and second pusher plates such that the first pusher plate and the first end plate define a first plate pair, and the second pusher plate and the second end plate define a second plate pair; and placing a first force modification device between the first plate pairs and a second force modification device between the second plate pairs, the first and second force modification devices being configured to increase and / or decrease the stacking force applied to the fuel cell stack.
[0012] For any disclosed system, vehicle, and method, each force modification device may include a bladder system or a linear actuator. In this case, the fuel cell system employs a resident or remote system controller communicatively connected to and programmed to control the bladder system / linear actuator. The fuel cell system may employ an impact sensor to detect the onset of an impact event that applies impact force to the fuel cell stack. The impact sensor outputs one or more sensor signals indicating the onset of the impact event to the system controller. Alternatively, an electronic real-time clock monitors the stack lifetime of the fuel cell stack and outputs one or more clock signals indicating it to the system controller. One or more resident or remote memory devices may store a lookup table with stack aging data that associates each of a plurality of fuel cell stack lifetimes with a corresponding one of a plurality of seal creep levels.
[0013] For any disclosed system, vehicle, and method, the system controller may be programmed to: receive a sensor signal indicating the onset of an impact event from the impact sensor; estimate the degree of fuel cell stack aging using monitored stack lifetime and stack aging data in response to detecting the impact event; determine whether the severity of the stacking force caused by the impact event reaches a predetermined threshold; and if so, responsively transmit one or more command signals to the bladder system / linear actuator to modify the applied stacking force based on the estimated degree of fuel cell stack aging. These command signals may cause the bladder system / linear actuator to: reduce the stacking force by a first predetermined amount for a first predetermined duration if the degree of fuel cell stack aging is less than a predetermined early stage threshold; and increase the stacking force by a second predetermined amount for a second predetermined duration if the degree of fuel cell stack aging is greater than a predetermined late stage threshold. These predetermined amounts and durations may vary depending on the monitored stack lifetime and the severity of the stacking force caused by the impact event.
[0014] For any disclosed system, vehicle, and method, each force modification device may include a biasing member compressed between a corresponding pair of endplates and pushplates. In this case, the fuel cell system may include a fluid source, such as a hydrogen-based fuel container and / or an oxidizer compressor, which is fluidly connected to the fuel cell stack. A fluid injection device controls the injection of fluid from the fluid source into the fuel cell stack. A system controller is operable to command the injection of gas into the fuel cell stack at a predetermined pressure within a predetermined deployment time in response to the detection of an impact event that results in a stacking force being applied to the fuel cell stack.
[0015] For any disclosed system, vehicle, and method, the fuel cell system may encapsulate one or more travel limiting blocks between each pair of pusher plates and endplates. These travel limiting blocks limit the travel length of the pusher plates along the stack axis under the stacking forces applied to the stack. Alternatively, one or more travel limiting shoulders, such as shouldered screws or wall protrusions, may be provided between each pusher plate and the fuel cell stack. These travel limiting shoulders limit the travel direction of the pusher plates along the stack axis.
[0016] The present invention also includes the following technical solutions.
[0017] Option 1. A fuel cell system, comprising:
[0018] Multiple electrochemical fuel cells are stacked face-to-face along the stack axis to define a fuel cell stack having opposing first and second longitudinal ends;
[0019] The first and second pusher plates are respectively adjacent to the first and second longitudinal ends of the fuel cell stack and are movable along the stack axis;
[0020] First and second end plates, respectively positioned facing and spaced apart from the first and second push plates, to define the first and second plate pairs; and
[0021] First and second force modification devices are respectively placed within the first and second plate pairs and configured to modify the stacking forces applied to the fuel cell stack.
[0022] Option 2. The fuel cell system according to Option 1, wherein the first and second force modification devices include first and second capsule systems or linear actuators, and the fuel cell system further includes an electronic system controller communicatively connected to and operable to control the first and second capsule systems or linear actuators.
[0023] Option 3. The fuel cell system according to Option 2 further includes an impact sensor, which is operable to detect the onset of an impact event that causes the stacking force to be applied to the fuel cell stack, and outputs a sensor signal indicating the event to the electronic system controller.
[0024] Option 4. The fuel cell system according to Option 3 further includes an electronic real-time clock, which is operable to track the stack lifetime of the monitored fuel cell stack and outputs a clock signal indicating it to the electronic system controller.
[0025] Option 5. The fuel cell system according to Option 4 further includes a memory device that stores stack aging data that associates each of the plurality of fuel cell stack lifetimes with a corresponding one of the plurality of seal creep levels.
[0026] Option 6. The fuel cell system according to Option 5, wherein the system controller is programmed to:
[0027] Receive a sensor signal indicating the start of the impact event from the impact sensor;
[0028] In response to the detection of the impact event, the monitored stack lifetime and the stack aging data are used to determine the estimated degree of fuel cell stack aging;
[0029] Determine whether the severity of the stacking force caused by the impact event reaches a predetermined threshold; and
[0030] In response to the severity of the stacking force reaching the predetermined threshold, a command signal is transmitted to the first and second capsule systems or linear actuators to modify the stacking force based on the estimated degree of fuel cell stack aging.
[0031] Option 7. The fuel cell system according to Option 6, wherein the command signal causes the first and second capsule systems or linear actuators to:
[0032] If the aging degree of the fuel cell stack is less than a predetermined early stage threshold, the stacking force is reduced by a first predetermined amount for a first predetermined duration; and
[0033] If the aging degree of the fuel cell stack exceeds a predetermined late stage threshold, the stacking force is increased by a second predetermined amount over a second predetermined duration.
[0034] Option 8. The fuel cell system according to Option 7, wherein the first predetermined amount and the second predetermined amount, as well as the first predetermined duration and the second predetermined duration, vary according to the monitored stack lifetime and the severity of the stacking force caused by the impact event.
[0035] Option 9. The fuel cell system according to Option 1, wherein the first and second force modification devices include first and second biasing members, each of the first and second biasing members being compressed between corresponding pairs of plates in the first and second plate pairs.
[0036] Option 10. The fuel cell system according to Option 9 further includes:
[0037] A fluid source, whose fluid is connected to the fuel cell stack;
[0038] A fluid injection device that controls the injection of fluid from the fluid source into the fuel cell stack; and
[0039] A system controller, communicatively connected to the fluid injection device, is operable to command the injection of fluid into the fuel cell stack at a predetermined pressure within a predetermined deployment time in response to the detection of an impact event causing the stacking force.
[0040] Option 11. The fuel cell system according to Option 9 further includes first and second travel limiting blocks, each located between corresponding pairs of the first and second plate pairs, and configured to limit the travel length of the first and second push plates along the stack axis.
[0041] Option 12. The fuel cell system according to Option 11 further includes first and second travel limiting shoulders, which are correspondingly disposed between the fuel cell stack and the first and second pushers, and configured to limit the travel direction of the first and second pushers along the stack axis.
[0042] Option 13. An electric vehicle, comprising:
[0043] Body;
[0044] Multiple wheels attached to the vehicle body;
[0045] A traction motor, attached to the vehicle body and operable to drive one or more of the wheels, thereby propelling the electric vehicle; and
[0046] A fuel cell system, attached to the vehicle body and operable to power the traction motor, the fuel cell system comprising:
[0047] Multiple electrochemical fuel cells are stacked face-to-face along the stack axis to define a fuel cell stack having opposing first and second longitudinal ends;
[0048] The first and second pusher plates are respectively adjacent to the first and second longitudinal ends of the fuel cell stack and are movable along the stack axis;
[0049] First and second end plates, respectively positioned facing and spaced apart from the first and second push plates, to define the first and second plate pairs; and
[0050] First and second force modification devices are respectively placed within the first and second plate pairs and configured to selectively increase and decrease the stacking force applied to the fuel cell stack.
[0051] Option 14. A method for assembling a fuel cell system, the method comprising:
[0052] Multiple electrochemical fuel cells are stacked face-to-face along the stack axis to define a fuel cell stack having opposing first and second longitudinal ends;
[0053] The first and second pusher plates are respectively abutted against the first and second longitudinal ends of the fuel cell stack, such that the first and second pusher plates can move along the stack axis;
[0054] The first and second end plates are positioned accordingly to be face-spaced from the first and second push plates, such that the first push plate and the first end plate define a first plate pair, and the second push plate and the second end plate define a second plate pair; and
[0055] A first force modification device is placed between the first plate pairs, and a second force modification device is placed between the second plate pairs, the first and second force modification devices being configured to modify the stacking force applied to the fuel cell stack.
[0056] Option 15. The method according to Option 14, wherein the first and second force modification devices include first and second capsule systems or linear actuators, and the method further includes communicatively connecting an electronic system controller to the first and second capsule systems or linear actuators.
[0057] Option 16. The method of Option 15 further includes communicatively connecting an impact sensor to the electronic system controller, the impact sensor being operable to detect the onset of an impact event that causes the stacking force and output a sensor signal indicating it.
[0058] Option 17. The method according to Option 16 further includes communicatively connecting an electronic real-time clock (RTC) to the electronic system controller, the electronic RTC being operable to track the stack lifetime of the fuel cell stack and output a clock signal indicating it.
[0059] Option 18. The method of Option 17 further includes communicatively connecting a memory device to the electronic system controller, the memory device storing stack aging data that associates each of the plurality of fuel cell stack lifetimes with a corresponding one of the plurality of seal creep levels.
[0060] Option 19. The method according to Option 14, wherein the first and second force modification devices include first and second biasing members that are correspondingly compressed between the first and second plate pairs.
[0061] Option 20. The method according to Option 19 further includes:
[0062] Connect the fluid source to the fuel cell stack;
[0063] A fluid injection device is fluidly connected to the fluid source, the fluid injection device being operable to control the injection of fluid from the fluid source into the fuel cell stack; and
[0064] A system controller is connected to the fluid injection device, which is operable to command the fluid to be injected into the fuel cell stack at a predetermined pressure within a predetermined deployment time in response to the detection of an impact event that causes the stacking force.
[0065] The above summary does not represent every embodiment or aspect of this disclosure. Rather, the foregoing features and advantages, as well as other features and accompanying advantages, will become apparent when taken in conjunction with the accompanying drawings and the appended claims, through the following detailed description of illustrative examples and models for implementing this disclosure. Furthermore, this disclosure expressly includes any and all combinations and sub-combinations of the elements and features described above and below. Attached Figure Description
[0066] Figure 1 It is an elevated perspective view of a representative motor vehicle, which is a schematic illustration of an example of a fuel cell system with impact mitigation capabilities according to various aspects of this disclosure.
[0067] Figure 2 yes Figure 1 An enlarged cross-sectional side view of a portion of a fuel cell system, showing a fuel cell stack with raised bead seals and micro-seals according to various aspects of the disclosed concept.
[0068] Figure 3 This is a partial schematic side view of a representative fuel cell system with an electrochemical fuel cell stack and a representative active impact mitigation system, based on various aspects of the disclosed concepts.
[0069] Figure 4 This is a partial schematic side view of a representative fuel cell system with an electrochemical fuel cell stack and a representative active / passive impact mitigation system, based on various aspects of the disclosed concepts.
[0070] Figure 5 It is a partial schematic side view of a representative fuel cell system with an electrochemical fuel cell stack and a representative passive impact mitigation system, based on various aspects of the disclosed concepts.
[0071] Representative embodiments of this disclosure are shown by way of non-limiting example in the accompanying drawings and are described in more detail below. However, it should be understood that the novelty of this disclosure is not limited to the specific forms shown in the drawings listed above. Rather, this disclosure is intended to cover all modifications, equivalents, combinations, sub-combinations, substitutions, groupings, and alterations that fall within the scope of this disclosure as covered, for example, by the appended claims. Detailed Implementation
[0072] This disclosure allows for embodiments in many forms. Representative examples of this disclosure are shown in the accompanying drawings and are described in detail herein with the understanding that these embodiments are provided as illustrations of the disclosed principles and not as limitations on the broad aspects of this disclosure. Therefore, elements and limitations described, for example in the “Abstract,” “Technical Field,” “Background Art,” “Summary of the Invention,” “Description of Drawings,” and “Detailed Description” sections but not expressly set forth in the claims should not be incorporated into the claims, individually or collectively, by implication, inference, or otherwise. Furthermore, the drawings discussed herein may not be drawn to scale and are provided purely for illustrative purposes. Therefore, the specific and relative dimensions shown in the drawings should not be construed as limiting.
[0073] For the purposes of this specific implementation, unless otherwise stated: the singular form includes the plural and vice versa; the terms “and” and “or” should be both conjunctions and adversative conjunctions; the terms “any” and “all” should both mean “any and all”; and the terms “including,” “contains,” “comprising,” “containing,” “having,” and their arrangement should each mean “including but not limited to.” Furthermore, approximate terms, such as “approximately,” “almost,” “substantially,” “roughly,” “approximately,” etc., may each be used herein in the sense of, for example, “within, close to, or almost within,” or “within 0-5% of,” or “within acceptable manufacturing tolerances,” or any logical combination thereof. Finally, directional adjectives and adverbs, such as head, stern, inside, outside, starboard, port, vertical, horizontal, up, down, forward, aft, left, right, etc., when the vehicle is operatively oriented on a horizontal travel surface, may be relative to the motor vehicle, for example, relative to the forward direction of the motor vehicle.
[0074] Referring now to the accompanying drawings, in which the same reference numerals refer to the same features throughout several views. Figure 1A representative vehicle, generally designated 10 and described herein as a passenger car-type fuel cell electric vehicle (FCEV) for illustrative purposes, is shown. The vehicle 10 shown, also referred to herein as a “motor vehicle” or simply a “vehicle,” is merely an exemplary application through which the novel aspects of this disclosure can be practiced. Similarly, the implementation of this concept in a PEM-type fuel cell system should also be understood as a representative implementation of the novel concepts disclosed herein. Thus, it will be understood that aspects of this disclosure can be applied to other fuel cell architectures, incorporated into any logically related type of vehicle, and equally applicable to both automotive and non-automotive applications. Finally, only selected components are shown and will be described in further detail herein. Nevertheless, the vehicles, fuel cell systems, and battery stack stress mitigation devices discussed below may include numerous additional and alternative features, as well as other available peripheral components and hardware, for performing the various methods and functions of this disclosure.
[0075] Packaged within the body 12 of the vehicle 10 is a representative fuel cell system 14, which powers one or more traction motors, such as an electric motor generator unit (MGU) 16, which is operable to drive a combination of the vehicle's wheels 18. Figure 1 The proton exchange membrane fuel cell system 14 is equipped with one or more fuel cell stacks 20, each consisting of a plurality of PEM-type fuel cells 22 electrically connected in series or parallel to each other. In the illustrated architecture, each fuel cell 22 is a multilayer structure having an anode side 24 and a cathode side 26, which are separated by a proton-conducting perfluorosulfonic acid membrane 28. An anode diffusion medium layer 30 is disposed on the anode side 24 of the PEMFC 22, wherein an anode catalyst layer 32 is disposed between the membrane 28 and the corresponding diffusion medium layer 30 and operatively connects the membrane 28 and the corresponding diffusion medium layer 30. Similarly, a cathode diffusion medium layer 34 is disposed on the cathode side 26 of the PEMFC 22, wherein a cathode catalyst layer 36 is disposed between the membrane 28 and the corresponding diffusion medium layer 34 and operatively connects the membrane 28 and the corresponding diffusion medium layer 34. The two catalyst layers 32 and 36 cooperate with the membrane 28 to wholly or partially define a membrane electrode assembly (MEA) 38.
[0076] Diffusion media layers 30 and 34 are porous, providing fluid inlet transport to and from the MEA 38. An anode flow field plate (or “first plate”) 40 is disposed adjacent to the anode diffusion media layer 30 on the anode side 24. Similarly, a cathode flow field plate (or “second plate”) 42 is disposed adjacent to the cathode diffusion media layer 34 on the cathode side 26. A coolant flow channel 44 traverses each of plates 40 and 42 to allow cooling fluid to flow through the fuel cell 22. Fluid inlet ports and manifolds guide hydrogen-rich fuel and oxidant to pathways in the anode and cathode flow field plates 40, 42. The central active region of plate 40 facing the anode of the proton conduction membrane 28 may be configured with an anode flow field consisting of serpentine flow channels for distributing hydrogen on opposite surfaces of the membrane 28. The MEA 38 and plates 40, 42 may be stacked together between stainless steel clamps and single-end plates. These clamps may be electrically insulated from the end plates by gaskets or dielectric coatings. The fuel cell system 14 may also employ anode recirculation, wherein anode recirculation gas is supplied from the exhaust manifold through the anode recirculation line to recirculate hydrogen back to the inlet of the anode side 24 in order to preserve the hydrogen gas in the stack 20.
[0077] A hydrogen (H2) inlet flow, whether gaseous, concentrated, entrained, or otherwise, is delivered from a hydrogen source, such as fuel storage tank 46, to the anode side 24 of the fuel cell stack 20 via a fluid injector 47 coupled to a (first) fluid inlet conduit or hose 48. Anode exhaust exits the stack 20 via a (first) fluid outlet conduit or hose 50. A compressor or pump 52 provides a cathode inlet flow, such as ambient air and / or concentrated gaseous oxygen (O2), to the cathode side 26 of the stack 20 via a (second) fluid inlet line or manifold 54. Cathode exhaust exits the stack 20 via a (second) fluid outlet conduit or manifold 56. Flow control valves, flow restrictors, filters, and other available devices for regulating fluid flow may be provided by… Figure 1 The PEMFC system 14 is implemented. The electricity generated by the fuel cell stack 20 and output by the fuel cell system 14 can be transmitted for storage in the on-board traction battery pack 82 within the rechargeable energy storage system (RESS) 80.
[0078] Figure 1The fuel cell system 14 may also include a thermal subsystem operable to control the temperature of the fuel cell stack 20 during pre-conditioning, break-in, and post-conditioning. As illustrated in the example, a cooling fluid pump 58 pumps cooling fluid through a coolant loop 60 to the fuel cell stack 20 and into coolant channels 44 in each cell 22. A radiator 62 and a heater 64 fluidly coupled in the coolant loop 60 are used to maintain the stack 20 at a desired operating temperature. The fuel cell conditioning system may be equipped with various sensing devices for monitoring system operation and the progress of fuel cell break-in. For example, a (first) temperature sensor 66 monitors the temperature of the coolant at the coolant inlet of the fuel cell stack 20, and a (second) temperature sensor 68 measures the temperature of the coolant at the coolant outlet of the stack 20. An electrical connector or cable 74 connects the fuel cell stack 20 to an electrical power load 76, which can be used to draw current from each cell 22 in the stack 20 during the stack break-in period. The voltage / current sensor 70 is operable to measure, monitor, or otherwise detect the fuel cell voltage and / or current of the fuel cell 22 in the stack 20 during break-in operation.
[0079] A programmable electronic control unit (ECU) 72 helps control the operation of the fuel cell system 14. As an example, the ECU 72 receives one or more temperature signals T1 from one or more of the temperature sensors 66, 68, which indicate the temperature of the fuel cell stack 20; the ECU 72 can be programmed to responsively issue one or more command signals C1 to adjust the operation of the stack 20. Figure 1 The ECU 72 also receives one or more voltage signals V1 from the voltage sensor 70; the ECU 72 can be programmed to issue one or more command signals C2 in response to adjust the operation of the hydrogen source 46 and / or the compressor / pump 52, thereby regulating the electrical output of the stack 20. Figure 1 The ECU 72 is also shown receiving one or more coolant temperature signals T2 from sensors 66 and / or 68; the ECU 72 can be programmed to responsively issue one or more command signals C3 to adjust the operation of the fuel cell's thermal system. Additional sensor signals S N It can be received by ECU 72, and the attached control command C N This can be issued from ECU 72, for example, to control any other subsystems or components illustrated and / or described herein. ECU 72 can issue command signals to deliver the released hydrogen and liquid H2O from cathode side 26 through fluid discharge conduit 56 to water separator 78. Figure 1There, hydrogen and water from the cathode combine with consumed hydrogen discharged from the anode through fluid discharge conduit 50. The ECU 72 can then command the water separator 78 to separate the hydrogen from the water and, if desired, recycle the separated hydrogen back to the anode fluid inlet.
[0080] Continue to refer to Figure 1 The traction battery pack 82 includes an array or rechargeable lithium-ion (secondary) battery module 84. Aspects of the disclosed concepts are similarly applicable to other electrical storage cell architectures, including those employing nickel-metal hydride (NiMH) batteries, lead-acid batteries, lithium-metal batteries, or other suitable types of rechargeable electric vehicle batteries (EVBs). Each battery module 84 may include a series of electrochemical battery cells, such as pouch-type lithium-ion (Li-ion) or lithium-ion polymer battery cells 86. For example, a single lithium-ion battery module 84 may be represented by a group of 10-45 battery cells stacked side-by-side and connected in parallel or series for storing and supplying electrical energy. Although described as silicon-based lithium-ion "pouch cell" batteries, these cells 86 may be adapted to other configurations, including cylindrical and prismatic configurations.
[0081] Next, turn to Figure 2 This image shows an enlarged cross-sectional view of a selected portion of a fuel cell system 114 used to convert hydrogen-rich fuel and oxidant into electricity via a redox reaction. Despite the different appearance, the above references are envisioned... Figure 1 Any features and options described in fuel cell system 14 can be combined individually or in any combination with Figure 2-5 In fuel cell systems 114, 214, 314, and 414, and vice versa. As a similarity, fuel cell systems 114, 214, 314, and 414 contain multiple individual fuel cells 122, which are stacked face-to-face on top of each other. Each fuel cell 122 may be substantially identical to each other and may contain... Figure 1 The elements shown and explained above regarding fuel cell 22. For example, each individual fuel cell 122 may employ a pusher plate 138, a pair of flow field plates 140 and 142, and a sub-shield 125 placed between and separating the plates 140 and 142 of adjacent cells 122.
[0082] Each flow field plate 140 may be formed with one or more raised bead seals 129, each of which may extend around the outer periphery of the flow field plate 140 and / or around an internal orifice extending through the respective flow field plate 140. Figure 2As shown, each beaded seal 129 of the fuel cell system 114 has a polymer micro-seal 131 on its top, which is disposed on the opposing outer surface of each respective beaded seal 129. During the manufacture of the fuel cell system 114, flow field plates 140, 142 may be compressed together to deform the beaded seal 129 and apply a target load to the seal 129 and the micro-seal 131 to ensure proper sealing performance.
[0083] During a mechanical shock event on fuel cell system 114, such as during a collision or drop of the system, the front cell of the fuel cell stack closest to the applied force may experience a positive g-force. This g-force results in increased sealing forces within the flow field plate seals to resist inertial forces applied to the sealed areas of the reciprocating fuel cells within the stack. Due to excessive compression caused by the increased gravity, the seals in the front fuel cells may undergo inelastic deformation and failure. Conversely, the rear cells may effectively experience negative g-forces, leading to reduced sealing forces in the sealed areas; due to insufficient sealing forces, internal system fluids may leak from the rear cells. In practice, when the stack is subjected to applied loads from a mechanical shock event, each cell within the stack will experience different dynamic loads depending on its location within the stack.
[0084] Fuel cell system modeling and testing have shown that the sealing force of the flow field plate seals typically decreases during the system's operational life, for example, due to creep and material degradation of the sealing material after stack construction. Consequently, seal failure caused by excessive compression at the front cell in the fuel cell stack can be a major problem during the early stages of the fuel cell's operational life. On the other hand, in the later stages of the fuel cell's life, insufficient sealing force at the rear cell during collisions or other shock events can become a major problem for system maintenance and continued function. With this understanding, different system requirements exist for mitigating the effects of applied forces transmitted by shocks at the front and rear cells, as well as at different stages of the fuel cell's operational life.
[0085] This paper presents systems and methods for selectively controlling sealing forces in a fuel cell stack, for example, during a "stack orientation" impact event, to prevent sealing forces from exceeding a predetermined maximum sealing force limit or falling below a predetermined minimum sealing force threshold. For active impact mitigation systems, the fuel cell system controller or control module can assess the degree of fuel cell stack aging based on a predetermined relationship between measured stack lifetime and seal creep. Using appropriate sensing devices, the active system can detect the occurrence of mechanical system impacts (e.g., collisions, bumps, etc.) and simultaneously determine the severity of the event, i.e., whether one of the aforementioned sealing force thresholds is likely to be reached. If the estimated fuel cell stack aging is in an early stage (e.g., less than approximately two years of use), the active impact mitigation system reduces the impact force applied to the stack by a predetermined amount over a predetermined duration. If the estimated fuel cell stack aging is in a later stage of life (e.g., more than approximately five years of use), the system increases the stack force by a predetermined amount over a predetermined duration. These features can also be used to mitigate the effects of impact forces to prevent damage in the active regions of the fuel cell stack.
[0086] Figure 3 The illustration shows a representative fuel cell system 214 with an active impact mitigation system 250, which is used to alter the stacking forces applied to the stack 120 of the electrochemical fuel cell 122, such as those caused by external impact forces transmitted by collisions. Figure 3 The fuel cell system 214 is shown having a plurality of electrochemical fuel cells 122 (e.g., 300-400 or more cells) stacked horizontally or vertically, one abutting another, along a central stack axis AA to define a fuel cell stack 120, wherein the top or left (first) longitudinal end is opposite to the bottom or right (second) longitudinal end. The fuel cell stack 120 is housed within a protective housing 252, which is fluidly coupled to a hydrogen source and an oxidant source, for example... Figure 1 The fuel cell system 214 includes a fuel storage tank 46 and an air compressor / pump 52. The fuel cell housing 252 may be an electrically insulated, hermetically sealed container fabricated with one or more transverse sidewalls 254, wherein a pair of rigid end plates 256 close the top and bottom open ends of the housing 252. It should be understood that the fuel cell system 214 may include any number and type of fuel cell designs, which may be encapsulated within a container construction similar to or different from that shown in the accompanying drawings.
[0087] The impact mitigation system 250 typically consists of a pair of movable push plates 258 located inside the protective housing 252. Each push plate 258 is adjacent to a corresponding longitudinal end of the fuel cell stack 120 and can be freely translated linearly along the stack axis AA (e.g., in...). Figure 3(The pusher plate 258 is moved up and down in a reciprocating manner). Furthermore, each pusher plate 258 is positioned facing away from a corresponding end plate 256, such that the parallel end plates 256 and pusher plates 258 are arranged as two discrete plate pairs located at the longitudinal ends of the housing 252. The end plates 256 are rigidly mounted to the sidewall 254, allowing the fuel cell stack 120 and the adjacent pusher plate 258 to move uniformly between the end plates 256.
[0088] Displaced within each plate pair, i.e., sandwiched between an end plate 256 and a push plate 258, is a force modification device 260, which can be selectively operated to reduce and / or increase the stacking force applied to the fuel cell stack 120 due to an impact event. According to the illustrated example, each force modification device 260 is depicted as a fluid bladder system, a linear actuator, or other suitable electro-hydraulic or pneumatic modification device. In at least one contemplated embodiment, the force modification device 260 uses an electromagnet paired with a magnetorheological (MR) fluid within the hydraulic cylinder of the shock absorber to continuously change the force modification rate. Changes in the magnetic charge within the trigger electromagnet alter the viscosity and thus the force modification coefficient of the MR fluid. The force modification device 260 can be configured to apply a predetermined force of at least, for example, approximately 3.0-3.5 kN or greater, within a predetermined reaction deploy time of, for example, approximately 10-20 ms or less.
[0089] Continue to refer to Figure 3 The active impact mitigation system 250 can selectively activate and adjust the output of the force modification device 260 during a detected impact event using closed-loop feedback control. By way of example, and not limitation, the electronic impact sensor 274 monitors the system 250 to detect the onset of an impact event (e.g., an elastic or inelastic collision, a bump, etc.) that results in an impact force being applied to the fuel cell stack 120. Upon detecting such an event, the electronic impact sensor 274 will output one or more sensor signals indicating its presence to a resident or remote system controller 272. It is contemplated that the impact sensor 274 may employ a variety of different configurations, including pneumatic, hydraulic, or capacitive load cells, bilateral or trilateral capacitive, piezoelectric, or compression accelerometers, cylindrical, shear, or ring force sensors, or other devices suitable for sensing mechanical impacts on the fuel cell system 214. The subsequent impact mitigation process can be directly responsive to the system detection of an impact event that results in an external impact force applied to the stack 120, along with accompanying internal stacking forces.
[0090] An electronic real-time clock (RTC) 276 monitors the real-time or near-real-time operational life (“stack life”) of the fuel cell stack 120 and outputs one or more RTC signals indicating this life to the system controller 272. Upon detecting a mechanical shock to the system 214, the system controller 272 retrieves stack life data from the RTC 276 and simultaneously accesses stack aging data stored in a resident or remote memory device 278 or other suitable non-transitory computer-readable medium. This stack aging data correlates a sequence of fuel cell stack lifespans (e.g., in increments of years, months, days, etc., or a cumulative spectrum of previous shock events, fuel cell operation, etc.) with corresponding seal degradation levels (e.g., estimated seal creep percentage, seal tensile strength, seal peel strength, etc.). As the fuel cell system 114 ages, system seals and other “softgoods” may lose their integrity; by tracking system life and predicting system aging, the shock mitigation system 250 can adjust its response at a given event to accommodate the specific aging-related needs of the system 214.
[0091] It can be implemented as a discrete controller or a set of microcontrollers or an embedded central system controller (e.g., Figure 1 The control module inside the ECU72) Figure 3 The electronic system controller 272 is communicatively connected to and programmed to control the two force modification devices 260. Processor-executable instructions stored in memory enable the programmable controller 272 to invoke an initialization program for the impact force mitigation scheme. This routine can be executed in real-time, near real-time, continuously, systematically, intermittently, and / or at regular intervals, such as every 10 or 100 milliseconds, during normal and continuous operation of the vehicle 10. Upon completion of the control operations associated with the impact force mitigation scheme, the scheme can advance to the END end-block operation and temporarily terminate, or alternatively, it can cycle back to the START end-block operation and run in a continuous loop.
[0092] During system operation, system controller 272 may receive a sensor signal from impact sensor 274 indicating the onset of an impact event with a generated applied force. Upon detecting an impact event, system controller 272 may responsively estimate the degree of fuel cell stack aging based at least in part on stack lifetime data received from RTC 276 and stack aging data stored in memory device 278. For example, RTC 276 may indicate a real-time stack lifetime of 28 months and 14 days. Using one of the stack aging lookup tables stored in memory, system controller 272 may interpolate between seal degradation levels at 28 and 29 months to predict the current "age" of the stack (e.g., estimated seal creep of 18%). Simultaneously, controller 272 may determine whether the level of stack aging has not exceeded a predetermined early stage threshold (e.g., less than approximately 20-30% of estimated seal creep) or has exceeded a predetermined late stage threshold (e.g., greater than approximately 70-80% of estimated seal creep). As an alternative to tracking stack lifetime, System 250 can monitor cell and / or total stack voltage as a way to diagnose symptoms of load loss in the active region. Alternatively, a displacement sensor can measure the compression length at the push plate. Figure 4 This is used to compare the calibration length with the as-built clearance for detecting load loss.
[0093] In addition to tailoring the system response to specific age-related requirements of the stack, the shock force mitigation system 250 is also capable of adjusting its shock force response to a specific intensity for a given event. For example, the system controller 272 assesses the severity of a detected shock event and, consequently, whether the severity of the applied force caused by the shock event reaches a predetermined threshold. Predetermined subroutines within the shock force mitigation scheme implement algorithms for system calibration to evaluate, for example, accelerometer data from a time window associated with the initial portion of the detected event to determine whether it is an actual collision or some minor event. For an actual collision event, in-stack load sensors can then track the intensity of the resulting shock force applied to the stack.
[0094] In response to the estimated / measured severity of the stacking force reaching a predetermined threshold, the system controller 272 transmits one or more command signals to one or both force modification devices 260 to increase or decrease the stacking force based on the estimated degree of fuel cell stack aging and an optional intensity of the stacking force. As a non-limiting example, when it is determined that the degree of fuel cell stack aging is less than a predetermined early stage threshold, the operable force modification device 260 reduces the stacking force by a predetermined amount for a predetermined duration. Conversely, when it is determined that the degree of fuel cell stack aging is greater than a predetermined late stage threshold, the operable force modification device 260 replenishes and thus strengthens the stacking force by another predetermined amount for another predetermined duration. The predetermined amount and duration of the impact force mitigation system 250 attenuating / replenishing the stacking force can be selectively varied based on the monitored stack lifetime and the severity of the stacking force caused by the impact event.
[0095] exist Figure 3 Some or all of the operations illustrated in the diagram and further described in detail above may represent algorithms corresponding to processor-executable instructions, which are stored, for example, in main memory, secondary memory, or remote memory (e.g., Figure 2 The functions described above and below may be performed in the memory device 278, and for example, via an electronic controller, processing unit, logic circuit, or other module or device or network of modules / devices (e.g., ECU 72 and / or controller 272), to perform any or all of the functions associated with the disclosed concepts. It should be appreciated that the order of execution of the operations may be changed, additional operations may be added, and certain described operations may be modified, combined, or eliminated.
[0096] Figure 4 and Figure 5 Correspondingly, the architectures of representative fuel cell systems 314, 414 with other representative active / passive shock mitigation systems 350 and 450 are presented. In both examples, shock mitigation systems 350, 450 employ multiple bias members 360, each of which is compressed between the end plate 256 and the push plate 258 of a corresponding plate pair. These bias members 360 serve as force-reducing devices to passively modify the stacking forces applied to the fuel cells 122 in the stack 120. Although shown as a compression type helical spring, the bias members 360 may employ other constructions, including leaf springs, diaphragms, cylinders, etc. Furthermore, each system 350, 450 may employ a single bias member or three or more bias members.
[0097] As a point of comparison between the systems shown Figure 4The impact mitigation system 350 can be a purely passive system operating without manual input or controller intervention. In this example, a pair of travel limiting blocks 372 are located between the end plate 256 and push plate 258 of each plate pair. A pair of travel limiting shoulder features, such as the screw heads of shouldered screws 374, are disposed between the fuel cell stack 120 and each push plate 258. Each shouldered screw 374 passes through an unthreaded through-hole in one of the push plates 258 and mates with an internally threaded blind hole in one of the end plates 256. The mating depth of the shouldered screws 374 can be adjusted, for example, to set the desired travel length and to accommodate system-to-system manufacturing tolerances. It should be understood that more or fewer than four travel limiting blocks 372 and / or four shouldered screws 374 can be incorporated into any impact mitigation system architecture described herein. Similarly, the travel blocks 372 and shouldered screws 374 can be replaced with alternative features, such as integrally formed or fixedly mounted protrusions projecting from the inner surfaces of the end plate 256 and the shell sidewall 254, respectively.
[0098] When the fuel cell system 314 experiences an impact event, the fuel cell stack 120 and pusher plate 258 will travel, for example as a single component, toward and away from the end plate 256, limited by the compression and expansion of the bias member 360. The compression / expansion of the bias member 360 will gradually dissipate and modify the stacking forces experienced by the fuel cell stack 120. During this stack movement, the pusher plate 258 may collide with and press against the travel limit block 372; in doing so, the block 372 limits the outer travel length of the pusher plate 258 along the stack axis AA. Similarly, the pusher plate 258 may collide with and press against the screw head of the shoulder screw 374; in doing so, the shoulder screw 374 limits the inner travel length and direction of travel of the pusher plate 258.
[0099] Next reference Figure 5 The impact mitigation system 450 can be a hybrid active / passive system, providing both passive damping and automatic force modification by the controller. Figure 4 Similar to system 350, the impact mitigation system 450 employs a pair of axially aligned bias members 360 to passively modify the stacking forces applied to the cells 122 in the stack 120. However, in this case, a fluid source 472 is operatively connected via a fluid conduit 474 to a bladder 260 within the fuel cell system housing 252. A fluid injection device 476 controls the timing and pulse width of the fluid injection from the fluid source 472 into the fuel cell stack 120. Figure 5 In this context, fluid source 472 and fluid jet device 476 are depicted as distinct, dedicated devices employed by system 450 solely for modifying impact force. However, for example, for system simplicity and cost, it may be desirable for fluid source 472 and fluid jet device 476 to accordingly include... Figure 1The fuel storage tank 46 and injector 47 are configured to minimize any redundancy in components. Upon detection of a mechanical impact on the fuel cell system 414, the system controller 272 may responsively command the fluid injection device 476 to inject fluid into the fuel cell stack 120 at a predetermined pressure within a predetermined deployment time.
[0100] During dynamic loading of a fuel cell stack, the applied load (“sealing force”) on the system seals may exceed the seal bonding and material strength, potentially leading to buckling strength or elongation at break of the seals in the front cells of a high-load stack (HLS) during a beginning-of-life (BOL) impact event. Furthermore, negative sealing forces in a low-load stack (LLS) during an end-of-life (EOL) impact event can cause temporary leaks and / or permanent damage to the bonding strength between micro-seals and metal beads or between elastic beads and bipolar substrates in the rear cells. As described above, actively and passively controlling the sealing force helps prevent seal failure and / or loss of sealing capability during mechanical impact events of fuel cell stacks with impact loads along the stack direction (e.g., along axis AA).
[0101] Stacking force control during a BOL (Break-Off) impact event can actively / passively reduce the sealing force of the entire stack to ensure that the front cells do not reach or exceed the maximum sealing force limit. In this case, the fuel cell system has not yet reached a level of aging where the rear cells will experience sealing forces sufficient to meet / exceed the maximum sealing force limit, and the force reduction will not be large enough to subject the rear cells to negative sealing forces reaching or falling below the minimum sealing force threshold. On the other hand, stacking force control during an EOL (End-Off) impact event can actively / passively increase the sealing force of the entire stack to ensure that the rear cells do not reach or fall below the minimum sealing force threshold. In this case, the fuel cell system has reached a level of aging where the rear cells may experience negative sealing forces sufficient to cause the rear cells to reach the minimum sealing force threshold. As a result, the system actively / passively increases the sealing force across the entire stack in such a way that the negative sealing force is adequately mitigated without simultaneously increasing the positive sealing force on the front cells in a manner that would cause them to reach or exceed the maximum sealing force limit. In addition to managing stack load during collisions or other system impact events, the disclosed impact force mitigation system can also be used to manage load during normal system operation.
[0102] In some embodiments, aspects of this disclosure may be implemented by a computer-executable instruction program, such as a program module, generally referred to as a software application or application program, which is executed by any controller or controller variant described herein. In non-limiting examples, the software may include routines, programs, objects, components, and data structures that perform specific tasks or implement specific data types. The software may form an interface to allow a computer to react to an input source. The software may also cooperate with other code segments to initiate various tasks in response to data received from a source incorporating received data. The software may be stored on any of a variety of memory media, such as CD-ROMs, disks, and semiconductor memories (e.g., various types of RAM or ROM).
[0103] Furthermore, aspects of this disclosure can be practiced using a variety of computer system and computer network configurations, including multiprocessor systems, microprocessor-based or consumer-programmable electronic devices, minicomputers, mainframes, etc. Additionally, aspects of this disclosure can be practiced in distributed computing environments, where tasks are executed using resident and remote processing devices linked via communication networks. In distributed computing environments, program modules can reside on both local and remote computer storage media, including memory storage devices. Therefore, aspects of this disclosure can be implemented in computer systems or other processing systems using a variety of hardware, software, or combinations thereof.
[0104] Any method described herein may include machine-readable instructions for execution by: (a) a processor; (b) a controller; and / or (c) any other suitable processing means. Any algorithm, software, control logic, protocol, or method disclosed herein may be implemented as software stored on a tangible medium such as flash memory, solid-state drive (SSD) memory, hard disk drive (HDD) memory, CD-ROM, digital versatile disc (DVD), or other storage devices. The entire algorithm, control logic, scheme, or method and / or portions thereof may alternatively be executed by means other than a controller and / or implemented in firmware or dedicated hardware in a manner available (e.g., by application-specific integrated circuits (ASICs), programmable logic devices (PLDs), field-programmable logic devices (FPLDs), discrete logic, etc.). Furthermore, while a particular algorithm may be described with reference to the flowcharts and / or workflow diagrams depicted herein, many other methods for implementing the exemplary machine-readable instructions may also be used alternatively.
[0105] Various aspects of this disclosure have been described in detail with reference to the illustrated embodiments; however, those skilled in the art will recognize that many modifications can be made thereto without departing from the scope of this disclosure. This disclosure is not limited to the precise construction and composition disclosed herein; any and all modifications, alterations, and variations that are apparent from the foregoing description are within the scope of this disclosure as defined by the appended claims. Moreover, this concept explicitly includes any and all combinations and sub-combinations of the foregoing elements and features.
Claims
1. A fuel cell system, comprising: Multiple electrochemical fuel cells are stacked face-to-face along the stack axis to define a fuel cell stack having opposing first and second longitudinal ends; The first and second pusher plates are respectively adjacent to the first and second longitudinal ends of the fuel cell stack and are movable along the stack axis; First and second end plates, respectively positioned facing away from the first and second push plates, to define the first and second plate pairs; First and second force modification devices, respectively placed within the first and second plate pairs, and configured to modify the stacking force applied to the fuel cell stack; A memory device that stores stack aging data that associates each of a plurality of fuel cell stack lifetimes with a corresponding one of a plurality of seal creep levels; as well as An electronic system controller, connected to the memory device and operable to control the first and second force modification devices based on the stack aging data. The fuel cell system further includes: A fluid source, whose fluid is connected to the fuel cell stack; and A fluid injection device that controls the injection of fluid from the fluid source into the fuel cell stack. The electronic system controller is communicatively connected to the fluid injection device and is operable to command the fluid to be injected into the fuel cell stack at a predetermined pressure within a predetermined deployment time in response to the detection of an impact event that causes the stacking force.
2. The fuel cell system according to claim 1, wherein, The first and second force modification devices include first and second capsule systems or linear actuators, wherein the electronic system controller is communicatively connected to and operable to control the first and second capsule systems or linear actuators.
3. The fuel cell system of claim 2 further includes an impact sensor operable to detect the onset of an impact event that causes the stacking force to be applied to the fuel cell stack, and outputs a sensor signal indicating the event to the electronic system controller.
4. The fuel cell system of claim 3 further includes an electronic real-time clock, the electronic real-time clock being operable to track the stack lifetime of the monitored fuel cell stack and outputting a clock signal indicating it to the electronic system controller.
5. The fuel cell system according to claim 4, wherein, The electronic system controller is programmed to: Receive a sensor signal indicating the start of the impact event from the impact sensor; In response to the detection of the impact event, the monitored stack lifetime and the stack aging data are used to determine the estimated degree of fuel cell stack aging; Determine whether the severity of the stacking force caused by the impact event reaches a predetermined threshold; as well as In response to the severity of the stacking force reaching the predetermined threshold, a command signal is transmitted to the first and second capsule systems or linear actuators to modify the stacking force based on the estimated degree of fuel cell stack aging.
6. The fuel cell system according to claim 5, wherein, The command signal causes the first and second capsule systems or linear actuators to: If the aging degree of the fuel cell stack is less than a predetermined early stage threshold, the stacking force is reduced by a first predetermined amount for a first predetermined duration. as well as If the aging degree of the fuel cell stack exceeds a predetermined late stage threshold, the stacking force is increased by a second predetermined amount over a second predetermined duration.
7. The fuel cell system according to claim 6, wherein, The first predetermined amount and the second predetermined amount, as well as the first predetermined duration and the second predetermined duration, vary according to the monitored stack lifetime and the severity of the stacking force caused by the impact event.
8. The fuel cell system according to claim 1, wherein, The first and second force modification devices include first and second biasing members, each of which is compressed between corresponding pairs of plates in the first and second plate pairs.
9. The fuel cell system of claim 8, further comprising first and second travel limiting blocks, each located between corresponding pairs of the first and second plate pairs, and configured to limit the travel length of the first and second push plates along the stack axis.
10. The fuel cell system of claim 9, further comprising first and second travel limiting shoulders, the first and second travel limiting shoulders being disposed respectively between the fuel cell stack and the first and second pushers, and configured to limit the travel direction of the first and second pushers along the stack axis.
11. An electric vehicle, comprising: Body; Multiple wheels attached to the vehicle body; A traction motor, which is attached to the vehicle body and is operable to drive one or more of the wheels to propel the electric vehicle. as well as A fuel cell system, attached to the vehicle body and operable to power the traction motor, the fuel cell system comprising: Multiple electrochemical fuel cells are stacked face-to-face along the stack axis to define a fuel cell stack having opposing first and second longitudinal ends; The first and second pusher plates are respectively adjacent to the first and second longitudinal ends of the fuel cell stack and are movable along the stack axis; First and second end plates, respectively positioned facing away from the first and second push plates, to define the first and second plate pairs; First and second force modification devices, respectively placed within the first and second plate pairs, are configured to selectively increase and decrease the stacking force applied to the fuel cell stack. A memory device storing stack aging data that associates each of a plurality of fuel cell stack lifetimes with a corresponding one of a plurality of seal creep levels; and An electronic system controller, connected to the memory device and operable to control the first and second force modification devices based on the stack aging data. The fuel cell system mentioned above also includes: A fluid source, whose fluid is connected to the fuel cell stack; and A fluid injection device that controls the injection of fluid from the fluid source into the fuel cell stack. The electronic system controller is communicatively connected to the fluid injection device and is operable to command the fluid to be injected into the fuel cell stack at a predetermined pressure within a predetermined deployment time in response to the detection of an impact event that causes the stacking force.
12. A method for assembling a fuel cell system, the method comprising: Multiple electrochemical fuel cells are stacked face-to-face along the stack axis to define a fuel cell stack having opposing first and second longitudinal ends; The first and second pusher plates are respectively abutted against the first and second longitudinal ends of the fuel cell stack, such that the first and second pusher plates can move along the stack axis; The first and second end plates are positioned accordingly to be face-to-face separated from the first and second push plates, such that the first push plate and the first end plate define a first plate pair, and the second push plate and the second end plate define a second plate pair; as well as A first force modification device is placed between the first plate pairs, and a second force modification device is placed between the second plate pairs, the first and second force modification devices being configured to modify the stacking force applied to the fuel cell stack; The electronic system controller is communicatively connected to a memory device that stores stack aging data that associates each of the multiple fuel cell stack lifetimes with a corresponding one of the multiple seal creep levels. as well as The electronic system controller is connected to the first and second force modification devices to control the first and second force modification devices based on the stack aging data. The method further includes: Connect the fluid source to the fuel cell stack; A fluid injection device is fluidly connected to the fluid source, the fluid injection device being operable to control the injection of fluid from the fluid source into the fuel cell stack; and An electronic system controller is connected to the fluid injection device, which is operable to command the fluid to be injected into the fuel cell stack at a predetermined pressure within a predetermined deployment time in response to the detection of an impact event that causes the stacking force.
13. The method according to claim 12, wherein, The first and second force modification devices include first and second capsule systems or linear actuators, and the method further includes communicatively connecting the electronic system controller to the first and second capsule systems or linear actuators.
14. The method of claim 13, further comprising communicatively connecting an impact sensor to the electronic system controller, the impact sensor being operable to detect the onset of an impact event resulting in the stacking force and outputting a sensor signal indicating it.
15. The method of claim 14, further comprising communicatively connecting an electronic real-time clock to the electronic system controller, the electronic real-time clock being operable to track the stack lifetime of the fuel cell stack and output a clock signal indicating thereafter.
16. The method according to claim 12, wherein, The first and second force modification devices include first and second biasing members that are correspondingly compressed between the first and second plate pairs.
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