Ejector and fuel cell system having ejector

Abstract

Provided is an ejector having: an urging member configured to urge an inner nozzle toward the front end thereof, and an outer nozzle comprising an inflow port configured to cause a first working fluid to flow inside the outer nozzle. The inner nozzle comprises a pressure receiving part disposed further on the rear end side compared to the inflow port and configured to receive the pressure of the first working fluid in the rear end direction opposing the urging force of the urging member. The urging load of the urging member is larger than the load received by the pressure receiving part in a pressure normal state in which the pressure of the first working fluid is in a use range, and is smaller than the load received by the pressure receiving part in a pressure abnormal state in which the pressure of the first working fluid is larger than a maximum value of the use range.

Description

Ejector and fuel cell system having ejector

[0001] The present disclosure relates to an ejector that generates negative pressure by flowing a working fluid and causes a target fluid to flow by the action of the negative pressure, and a fuel cell system having the ejector.

[0002] Patent Document 1 discloses an ejector that draws in a target fluid (hydrogen off-gas) by using negative pressure generated by a working fluid (hydrogen gas) injected from an outer nozzle and an inner nozzle, and discharges a mixed fluid (mixed gas) of the injected working fluid and the drawn-in target fluid from a discharge port via a diffuser.

[0003] Japanese Patent Application Laid-Open No. 2020-56365

[0004] In an ejector such as that disclosed in Patent Document 1, if a failure (abnormality) occurs in a component located upstream of the outer nozzle in the flow of working fluid, causing an abnormality in the pressure of the working fluid, high-pressure working fluid may flow into the fuel cell, causing malfunction of the fuel cell. Therefore, it is desirable to be able to quickly detect the abnormality in the pressure of the working fluid.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and has an object to provide an ejector that can quickly detect abnormal pressure in the working fluid, and a fuel cell system having this ejector.

[0006] One aspect of the present disclosure made to solve the above-described problems is an ejector having a main casing, an outer nozzle disposed within the main casing and configured to eject a first working fluid, and an inner nozzle disposed inside the outer nozzle and configured to eject a second working fluid, the ejector having a biasing member biasing the inner nozzle toward its tip, the outer nozzle having an inlet for allowing the first working fluid to flow into the inside of the outer nozzle, the inner nozzle having a pressure-receiving portion, located rearward of the inlet, that receives the pressure of the first working fluid toward the rear against the biasing force of the biasing member, the biasing load of the biasing member being greater than the load received by the pressure-receiving portion under normal pressure conditions where the pressure of the first working fluid is within an operating range, and being smaller than the load received by the pressure-receiving portion under abnormal pressure conditions where the pressure of the first working fluid is greater than the maximum value of the operating range.

[0007] According to this aspect, the biasing load of the biasing member is smaller than the load received by the pressure-receiving portion when the pressure of the first working fluid is abnormal. Therefore, when the pressure of the first working fluid is abnormal, the load received by the pressure-receiving portion causes the inner nozzle to move toward the rear end against the biasing force of the biasing member. As a result, the tip end of the inner nozzle moves toward the rear end, increasing the flow path cross-sectional area of ​​the tip end of the outer nozzle. This increases the amount of fluid ejected from the outer nozzle, and the outlet pressure of the outer nozzle (i.e., the pressure at a position downstream of the outer nozzle in the fluid flow) increases more quickly. Therefore, by detecting the outlet pressure of the ejector (or the outlet pressure of the outer nozzle), an abnormality in the pressure of the first working fluid can be quickly detected.

[0008] In the above aspect, it is preferable that the outer nozzle has a flow rate restriction section at its tip end that restricts the cross-sectional area of ​​the flow path, and that the tip end of the inner nozzle is positioned within the flow rate restriction section when the pressure is normal, but moves to the rear end side of the flow rate restriction section when the pressure is abnormal.

[0009] According to this aspect, when a pressure abnormality occurs in the first working fluid, the tip end of the inner nozzle moves to a position rearward of the flow rate restricting portion of the outer nozzle, thereby increasing the flow path cross-sectional area of ​​the flow rate restricting portion of the outer nozzle. This more reliably increases the amount of fluid ejected from the outer nozzle, thereby more quickly increasing the outlet pressure of the ejector. Therefore, by detecting the outlet pressure of the ejector, a pressure abnormality in the first working fluid can be detected more effectively and quickly.

[0010] In the above aspect, it is preferable that the main casing has a first working fluid supply port for supplying the first working fluid to the inlet, the outer nozzle is attached to the main casing via a sealing member at a tip portion of the inner circumferential surface of the casing that is further tip-side than the first working fluid supply port on the inner circumferential surface of the main casing, and the inner nozzle is attached to the main casing via a sealing member at a rear portion of the inner circumferential surface of the casing that is further rear-side than the first working fluid supply port on the inner circumferential surface of the main casing, and the inner diameter of the rear portion of the inner circumferential surface of the casing is larger than the inner diameter of the tip portion of the inner circumferential surface of the casing.

[0011] According to this aspect, the pressure-receiving area of ​​the pressure-receiving portion can be increased. Therefore, in the event of a pressure abnormality in the first working fluid, the inner nozzle moves toward the rear end more quickly due to the load received by the pressure-receiving portion, against the biasing force of the biasing member. Therefore, the pressure abnormality in the first working fluid can be detected more quickly.

[0012] Another aspect of the present disclosure made to solve the above problems is a fuel cell system having an ejector, the ejector having a main casing, an outer nozzle arranged in the main casing and spraying a first working fluid, an inner nozzle arranged inside the outer nozzle and spraying a second working fluid, and a biasing member biasing the inner nozzle toward its tip, the outer nozzle having an inlet through which the first working fluid flows into the inside of the outer nozzle, and the inner nozzle has a pressure-receiving member at a rear end side of the inlet that receives the pressure of the first working fluid toward the rear end against the biasing force of the biasing member. a pressure measuring unit that measures the pressure of the fluid downstream of the outer nozzle, and a determination unit that determines whether or not the pressure is abnormal based on the measurement value of the pressure measuring unit, and the determination unit determines that the pressure is abnormal when the amount of change in the measurement value of the pressure measuring unit per unit time exceeds a predetermined amount.

[0013] According to this aspect, an abnormality in the pressure of the first working fluid can be quickly detected based on the amount of change per unit time in the pressure of the fluid downstream of the outer nozzle.

[0014] In another aspect of the present disclosure made to solve the above problems, the ejector includes a main body casing, an outer nozzle disposed in the main body casing and ejecting a first working fluid, an inner nozzle disposed inside the outer nozzle and ejecting a second working fluid, and an urging member urging the inner nozzle toward its tip end, the outer nozzle having an inlet through which the first working fluid flows into the inside of the outer nozzle, the inner nozzle having a pressure receiving portion located on the rear end side of the inlet and receiving a pressure of the first working fluid toward the rear end against the urging force of the urging member, The biasing load of the biasing member is greater than the load received by the pressure receiving part when the pressure of the first working fluid is within a normal pressure range and is within the operating range, but is smaller than the load received by the pressure receiving part when the pressure of the first working fluid is abnormal and is greater than the maximum value of the operating range.The fuel cell system has a pressure measuring part that measures the pressure of the fluid downstream of the outer nozzle, and a judgment part that judges whether the pressure is abnormal based on the measurement value of the pressure measuring part, and the judgment part judges that the pressure is abnormal when the measurement value of the pressure measuring part is greater than a predetermined value.

[0015] According to this aspect, an abnormality in the pressure of the first working fluid can be quickly detected based on the value of the pressure of the fluid downstream of the outer nozzle.

[0016] According to the ejector and the fuel cell system having the ejector of the present disclosure, pressure abnormalities in the working fluid can be quickly detected.

[0017] Fig. 1 is a schematic configuration diagram of a fuel cell system of the present embodiment; Fig. 2 is a front cross-sectional view of an ejector of the present embodiment; Fig. 3 is an enlarged view of an outer nozzle, an inner nozzle and their surrounding areas in the ejector of the present embodiment, showing a state when the pressure of a first working fluid is normal; Fig. 4 is an enlarged view of an outer nozzle, an inner nozzle and their surrounding areas in the ejector of the present embodiment, showing a state when the pressure of a first working fluid is abnormal; and Fig. 5 is a view showing an example of behavior of the outlet pressure of the ejector when the pressure of a first working fluid is abnormal.

[0018] An embodiment of an ejector and a fuel cell system having the ejector of the present disclosure will be described. In the following description, "upstream" means upstream in the flow of a fluid, and "downstream" means downstream in the flow of a fluid.

[0019] <Overview of Fuel Cell System> Figure 1 shows a schematic diagram of a fuel cell system 1 in this embodiment. This fuel cell system 1 is mounted on an electric vehicle and is used to supply power to its drive motor (not shown). The fuel cell system 1 includes a fuel cell (FC) 11. The fuel cell 11 is supplied with fuel gas (hydrogen gas) and oxidant gas (air) to generate power. The power generated by the fuel cell 11 is supplied to the drive motor (not shown) via an inverter (not shown).

[0020] On the anode side of the fuel cell 11, there are provided a hydrogen supply passage 12 as a fuel supply passage for supplying hydrogen gas to the fuel cell 11, a hydrogen circulation passage 13 as a fuel circulation passage for circulating fuel off-gas (hydrogen off-gas) discharged from the fuel cell 11 to the hydrogen supply passage 12, and an ejector 14 provided at the connection between the hydrogen supply passage 12 and the hydrogen circulation passage 13. Hydrogen gas flows through the hydrogen supply passage 12 from a hydrogen tank 15.

[0021] In the hydrogen supply passage 12 upstream of the ejector 14, a hydrogen pressure sensor 16, a pressure reducing valve 17, and a hydrogen pressure sensor 18 are provided, in that order from the upstream side (i.e., the hydrogen tank 15 side). The high-pressure hydrogen gas flowing from the hydrogen tank 15 is reduced in pressure by the pressure reducing valve 17, and then the pressure of the hydrogen gas is adjusted by the ejector 14. The hydrogen pressure sensor 16 detects the pressure of the hydrogen gas on the inlet side of the pressure reducing valve 17, while the hydrogen pressure sensor 18 detects the pressure of the hydrogen gas on the outlet side of the pressure reducing valve 17.

[0022] Furthermore, a first injector 19A and a second injector 19B, each consisting of an electromagnetic valve, are provided in the hydrogen supply passage 12 upstream of the ejector 14 and downstream of the hydrogen pressure sensor 18. The inlet sides of the injectors 19A, 19B are connected in parallel to the hydrogen tank 15 via the hydrogen supply passage 12. The outlet sides of the injectors 19A, 19B are connected via the hydrogen supply passage 12 to two different nozzles 55, 56 (see FIG. 2, etc.) provided in the ejector 14. Note that linear solenoid valves may be provided instead of the first injector 19A and the second injector 19B.

[0023] A gas-liquid separator 20 for separating gas and liquid is provided in the hydrogen circulation passage 13. The gas-liquid separator 20 separates moisture from the hydrogen off-gas, directs only the hydrogen off-gas toward the ejector 14, and discharges the moisture to the outside via a discharge passage 21. The discharge passage 21 is provided with an exhaust / drain valve 22 made of an electromagnetic valve.

[0024] On the other hand, an air supply passage 31 serving as an oxidant gas supply passage for supplying air to the fuel cell 11, and an air discharge passage 32 for discharging air off-gas discharged from the fuel cell 11 are provided on the cathode side of the fuel cell 11. An air pump 33 is provided in the air supply passage 31 for adjusting the amount of air supplied to the fuel cell 11. An air pressure sensor 34 is provided in the air supply passage 31 downstream of the air pump 33. The air pressure sensor 34 detects the pressure of the air supplied to the fuel cell 11. Downstream of the air pressure sensor 34, a motor-driven on-off valve 36 controls the supply and cut-off of air. An intercooler 37 for cooling the air discharged from the air pump 33 is also provided in the air supply passage 31. A motor-driven flow rate adjustment valve 35 is also provided in the air discharge passage 32.

[0025] An air bypass passage 38 is provided on the cathode side of the fuel cell 11. A motor-driven bypass valve 39 is provided in this air bypass passage 38. When it is desired to cause the fuel cell 11 to generate electricity, the on-off valve 36 is opened and the bypass valve 39 is closed. When it is desired to cause the fuel cell 11 not to generate electricity but to drive the air pump 33, the on-off valve 36 is closed and the bypass valve 39 is opened.

[0026] In the above-described configuration, hydrogen gas from the hydrogen tank 15 flows through the hydrogen supply passage 12 and is supplied to the fuel cell 11 via the pressure reducing valve 17, the injectors 19A and 19B, and the ejector 14. The hydrogen gas supplied to the fuel cell 11 is used to generate electricity in the fuel cell 11 and then discharged from the fuel cell 11 as hydrogen off-gas to the hydrogen circulation passage 13. The discharged hydrogen off-gas is separated from water in the gas-liquid separator 20 and then circulated to the hydrogen supply passage 12 via the ejector 14. At this time, negative pressure is generated in the ejector 14 by the hydrogen gas flowing through the ejector 14, and the hydrogen off-gas is drawn into the ejector 14 by the negative pressure, where it is mixed with the hydrogen gas and circulated to the hydrogen supply passage 12.

[0027] 1, the fuel cell system 1 further includes a controller 40. The controller 40 controls the injectors 19A, 19B to adjust the flow rate (amount of hydrogen) of hydrogen gas flowing to the ejector 14. The controller 40 controls the exhaust drain valve 22 to adjust the exhaust drain from the exhaust passage 21. The controller 40 also controls the air pump 33 and the on-off valve 36 to adjust the flow rate of air supplied to the fuel cell 11. The controller 40 also controls the flow adjustment valve 35 to adjust the flow rate of air off-gas discharged from the air discharge passage 32.

[0028] The controller 40 receives detection signals from the hydrogen pressure sensor 16, the hydrogen pressure sensor 18, and the air pressure sensor 34. The controller 40 also receives voltage and current values ​​related to power generation by the fuel cell 11. The controller 40 also receives detection signals from a pressure sensor 91, which will be described later. The controller 40 includes a central processing unit (CPU) and memory, and controls the injectors 19A, 19B, the air pump 33, etc., based on a predetermined control program stored in the memory in order to control the amount of hydrogen and air supplied to the fuel cell 11.

[0029] In this embodiment, the fuel cell system 1 has a pressure sensor 91 that measures the pressure of hydrogen gas (more specifically, a mixed gas of hydrogen gas and hydrogen off-gas) at a position downstream of the ejector 14 (more specifically, an outer nozzle 55, which will be described later). The measurement value of the pressure sensor 91 is taken into a determination unit 92 of the controller 40. The pressure sensor 91 is an example of a "pressure measurement unit" in the present disclosure.

[0030] As will be described in detail later, the fuel cell system 1 also includes a determination unit 92 that determines whether or not the pressure of the first working fluid WF1 is abnormal, based on the measurement value of the pressure sensor 91. In the example shown in FIG. 1 , the determination unit 92 is provided as part of the controller 40, but is not limited to this and may be provided separately from the controller 40.

[0031] <Outline of Ejector> Next, an outline of the ejector 14 will be described.

[0032] 2, the ejector 14 has a main body casing 41. The main body casing 41 is formed in a tubular shape to allow the flow of the working fluid (i.e., hydrogen gas) and the target fluid (i.e., hydrogen off-gas).

[0033] The main casing 41 is provided with a first working fluid supply port 51, a second working fluid supply port 52, a target fluid supply port 53, a negative pressure generating chamber 54, an outer nozzle 55, an inner nozzle 56, a diffuser 57, a discharge port 58, and a plug 59.

[0034] The first working fluid supply port 51 is a supply port through which the first working fluid WF1 sent from the first injector 19A is supplied, and supplies the first working fluid WF1 to an inlet 55a (described later) provided in the outer nozzle 55, and is connected to outer injection holes 61 (see FIG. 3) which are flow paths in the gap between the outer nozzle 55 and the inner nozzle 56. The second working fluid supply port 52 is a supply port through which the second working fluid WF2 sent from the second injector 19B is supplied, and is connected to inner injection holes 62 (see FIG. 3) which are flow paths inside the inner nozzle 56.

[0035] The target fluid supply port 53 is a supply port through which the target fluid is supplied, and communicates with the negative pressure generating chamber 54. The negative pressure generating chamber 54 is a space portion for generating negative pressure by the working fluid.

[0036] The outer nozzle 55 and the inner nozzle 56 are each formed in a substantially cylindrical shape and are made of stainless steel, resin, etc. The inner nozzle 56 is provided inside the outer nozzle 55.

[0037] The outer nozzle 55 is disposed in the main casing 41 and sprays the first working fluid WF1 supplied from the first working fluid supply port 51. The outer nozzle 55 has an inlet 55a that allows the first working fluid WF1 to flow into the inside of the outer nozzle 55.

[0038] 3, the outer nozzle 55 is provided with a flow rate restricting section 71 at its tip end that restricts the cross-sectional area of ​​the flow path (so that the cross-sectional area of ​​the flow path is smaller than that of portions other than the tip end). In this embodiment, the outer nozzle 55 is provided with an outer O-ring groove 55b in which an O-ring 83 is disposed, on the outer peripheral surface of the outer nozzle 55, closer to the tip end than the inlet 55a. The outer nozzle 55 is attached to the main casing 41 via the O-ring 83. The O-ring 83 is an example of a "sealing member" in the present disclosure.

[0039] The inner nozzle 56 is disposed within the outer nozzle 55 and sprays the second working fluid WF2 supplied from the second working fluid supply port 52. In this embodiment, the inner nozzle 56 is provided with an inner O-ring groove 56b in which an O-ring 84 is disposed, on the outer circumferential surface of the inner nozzle 56, closer to the rear end than a pressure-receiving portion 82 (described later). The inner nozzle 56 is attached to the main casing 41 via the O-ring 84. The O-ring 84 is an example of a "sealing member" in the present disclosure.

[0040] The flow rate restricting portion 71, which is the tip of the outer nozzle 55, and the tip 72 of the inner nozzle 56 are disposed in the negative pressure generating chamber 54. The flow rate restricting portion 71 and the tip 72 are the ends of the outer nozzle 55 and the inner nozzle 56 on the downstream side in the flow direction of the working fluid (hereinafter simply referred to as the "downstream side"; left side in FIG. 2), respectively, and are the portions where the inner diameter is narrowed to a minimum.

[0041] The diffuser 57 is a flow path that communicates with the negative pressure generating chamber 54, sucks in the target fluid by using the negative pressure generated by the working fluid, merges the target fluid with the working fluid, and sends it to the discharge port 58. The discharge port 58 is a portion that discharges the working fluid and the target fluid that have flowed through the diffuser 57 to the outside. A plug 59 is attached to the inside of the main casing 41 to close an opening on the rear end side of the main casing 41 (i.e., the side opposite the discharge port 58).

[0042] Here, as an example, as shown in Figures 2 and 3, the outer nozzle 55, inner nozzle 56, and diffuser 57 are arranged in a coaxial positional relationship (i.e., a positional relationship in which their respective axes coincide).

[0043] The ejector 14 configured in this manner generates negative pressure in the negative pressure generating chamber 54 by the first working fluid WF1 and the second working fluid WF2, which are supplied from the first working fluid supply port 51 and the second working fluid supply port 52 and sprayed from the inner nozzle 56 and the outer nozzle 55, and this negative pressure causes the target fluid to be drawn into the negative pressure generating chamber 54 from the target fluid supply port 53. The ejector 14 then flows the target fluid together with the working fluid to the diffuser 57 and discharges it from the discharge port 58 toward a supply destination (e.g., the fuel cell 11).

[0044] More specifically, the first working fluid WF1 supplied to the first working fluid supply port 51 flows to the outer nozzle 55, is injected from its outer injection holes 61 into the negative pressure generating chamber 54, flows through the diffuser 57, and is discharged from the discharge port 58. Meanwhile, the second working fluid WF2 supplied to the second working fluid supply port 52 flows to the inner nozzle 56, is injected from its inner injection holes 62 into the negative pressure generating chamber 54, flows through the diffuser 57, and is discharged from the discharge port 58.

[0045] This flow of working fluid generates negative pressure in the negative pressure generating chamber 54, and the target fluid supplied to the target fluid supply port 53 is sucked into the negative pressure generating chamber 54 by this negative pressure, flows through the diffuser 57 together with the working fluid, is mixed with the working fluid, and is released from the discharge port 58.

[0046] <Regarding detection of pressure abnormality of the first working fluid> In the event of a failure (i.e., a malfunction) of a component (e.g., the pressure reducing valve 17) located upstream of the outer nozzle 55, abnormally high-pressure hydrogen gas flows from the pressure reducing valve 17 to the first injector 19A, causing a pressure abnormality in the first working fluid WF1 supplied from the first injector 19A to the inlet 55a of the outer nozzle 55 via the first working fluid supply port 51. In this case, high-pressure first working fluid WF1 may flow from the ejector 14 into the fuel cell 11, causing a malfunction in the fuel cell 11. Therefore, it is desirable to quickly detect the pressure abnormality of the first working fluid WF1 and take measures to deal with the failure of the component located upstream of the outer nozzle 55.

[0047] Therefore, in this embodiment, the structures of the outer nozzle 55 and the inner nozzle 56 are devised so that an abnormality in the pressure of the first working fluid WF1 can be detected quickly.

[0048] 2 to 4, the ejector 14 has a spring 81 that biases the inner nozzle 56 toward its tip (i.e., toward the left in FIGS. 2 to 4). The spring 81 is provided between the rear end 73 of the inner nozzle 56 and the plug 59. The spring 81 is an example of the "biasing member" of the present disclosure.

[0049] The inner nozzle 56 also has a pressure-receiving portion 82 at a position rearward (i.e., to the right in FIGS. 2 to 4) of the inlet 55a of the outer nozzle 55. The pressure-receiving portion 82 is formed by a surface (i.e., a surface formed in the up-down direction in FIGS. 2 to 4) that is perpendicular or substantially perpendicular to the axial direction of the inner nozzle 56 (i.e., the left-right direction in FIGS. 2 to 4).

[0050] The pressure-receiving portion 82 receives the pressure of the first working fluid WF1 supplied from the inlet 55a toward the rear end against the biasing force of the spring 81. That is, the first working fluid WF1 supplied from the first working fluid supply port 51 is supplied from the inlet 55a to the inside of the outer nozzle 55, and then flows from the gap δ between the outer nozzle 55 and the inner nozzle 56 (see FIGS. 3 and 4) toward the pressure-receiving portion 82, and the pressure of the first working fluid WF1 acts on the pressure-receiving portion 82.

[0051] At this time, the biasing load (i.e., spring load) of the spring 81 is set to be greater than the load received by the pressure-receiving portion 82 when the pressure of the first working fluid WF1 is normal (i.e., the load received when the maximum operating pressure is applied), but smaller than the load received by the pressure-receiving portion 82 when the pressure of the first working fluid WF1 is abnormal. Here, "when the pressure of the first working fluid WF1 is normal" refers to when the pressure of the first working fluid WF1 is within a normal operating range. Furthermore, "when the pressure of the first working fluid WF1 is abnormal" refers to when the pressure of the first working fluid WF1 is greater than the maximum value of the normal operating range (i.e., the maximum operating pressure) (i.e., abnormal pressure).

[0052] More specifically, the biasing load of the spring 81 is set so that (maximum operating pressure of the first working fluid WF1 × pressure-receiving area of ​​the pressure-receiving portion 82) < (biasing load of the spring 81) < (abnormal pressure of the first working fluid WF1 × pressure-receiving area of ​​the pressure-receiving portion 82).

[0053] In this way, the biasing load of the spring 81 is smaller than the load received by the pressure-receiving portion 82 when the pressure of the first working fluid WF1 is abnormal. Therefore, when the pressure of the first working fluid WF1 is abnormal, the load received by the pressure-receiving portion 82 causes the inner nozzle 56 to move toward the rear end against the biasing force of the spring 81, as shown in FIG. 4 . As a result, the tip end 72 of the inner nozzle 56 moves toward the rear end, and the flow path cross-sectional area of ​​the flow rate restricting portion 71 of the outer nozzle 55 becomes larger than when the pressure of the first working fluid WF1 is normal (i.e., as shown in FIG. 3 ). Therefore, the flow rate of hydrogen gas (more specifically, the mixed gas of the first working fluid WF1 and the second working fluid WF2) injected from the outer nozzle 55 increases, and the outlet pressure of the outer nozzle 55 (i.e., the pressure of hydrogen gas at a position downstream of the outer nozzle 55) quickly rises.

[0054] This also causes a rapid increase in the outlet pressure of the ejector 14 (i.e., the pressure of the hydrogen gas released from the discharge port 58 (see FIG. 2) of the ejector 14). Therefore, by detecting the increase in the outlet pressure of the ejector 14 with the pressure sensor 91 (see FIG. 1), the determination unit 92 can quickly detect a pressure abnormality in the first working fluid WF1 based on the measurement value of the pressure sensor 91. Therefore, it is possible to quickly take measures to deal with failures of components located upstream of the outer nozzle 55.

[0055] Furthermore, when the pressure of the first working fluid WF1 is normal, the tip 72 of the inner nozzle 56 is disposed within the flow rate restriction section 71 of the outer nozzle 55 as shown in FIG. 3, whereas when the pressure of the first working fluid WF1 is abnormal, the tip 72 moves rearward of the flow rate restriction section 71 as shown in FIG. 4.

[0056] In this way, when the pressure of the first working fluid WF1 becomes abnormal, the tip 72 of the inner nozzle 56 moves out of contact with the flow rate restricting portion 71 of the outer nozzle 55, more effectively increasing the flow path cross-sectional area of ​​the flow rate restricting portion 71 of the outer nozzle 55. This more effectively increases the flow rate of hydrogen gas injected from the outer nozzle 55, and the outlet pressure of the outer nozzle 55 and the outlet pressure of the ejector 14 rise quickly. Therefore, by detecting an increase in the outlet pressure of the ejector 14 with the pressure sensor 91, a pressure abnormality in the first working fluid WF1 can be more effectively and quickly detected.

[0057] The outer nozzle 55 is attached to the main casing 41 via an O-ring 83 at a front end portion 41aa of the inner circumferential surface of the casing, which is located further forward than the first working fluid supply port 51 on the inner circumferential surface 41a of the main casing 41. The inner nozzle 56 is attached to the main casing 41 via an O-ring 84 at a rear end portion 41ab of the inner circumferential surface of the casing, which is located further rearward than the first working fluid supply port 51 on the inner circumferential surface 41a of the main casing 41. An inner diameter D2 of the rear end portion 41ab of the casing inner circumferential surface is larger than an inner diameter D1 of the front end portion 41aa of the casing inner circumferential surface.

[0058] This increases the pressure-receiving area of ​​the pressure-receiving portion 82, whose outer diameter is approximately equal to the inner diameter D2 of the casing inner circumferential surface rear end portion 41ab. Therefore, when a pressure abnormality occurs in the first working fluid WF1, the inner nozzle 56 moves toward the rear end more quickly due to the load received by the pressure-receiving portion 82, against the biasing force of the spring 81. Therefore, a pressure abnormality in the first working fluid WF1 can be detected more quickly.

[0059] In this embodiment, as shown in FIG. 5, in the event of a failure, i.e., when the pressure of the first working fluid WF1 is abnormal, the slope of the increase in the outlet pressure of the ejector 14 (i.e., the amount of change (amount of increase) per unit time) is larger than in a conventional ejector (i.e., an ejector in which the inner nozzle 56 does not have a pressure-receiving portion 82), and the time required to detect the pressure abnormality of the first working fluid WF1 can also be shortened.

[0060] In this way, since the outlet pressure of the ejector 14 increases in the event of a failure, it is possible to determine whether or not a pressure abnormality has occurred in the first working fluid WF1 based on the slope of the increase in the outlet pressure of the ejector 14. Therefore, the determination unit 92 determines that a pressure abnormality has occurred in the first working fluid WF1 when the amount of change per unit time in the measurement value of the pressure sensor 91 exceeds a predetermined amount. Note that the "predetermined amount" is, for example, 1.1 times the amount of change per unit time in the measurement value of the pressure sensor 91 when the pressure of the first working fluid WF1 is normal.

[0061] Alternatively, the determination unit 92 may determine that a pressure abnormality has occurred in the first working fluid WF1 when the measurement value of the pressure sensor 91 is greater than a predetermined value (for example, the system abnormality detection pressure Pfail in FIG. 5 ). The system abnormality detection pressure Pfail is, for example, 1.1 times the system operation upper limit pressure Pmax. The system operation upper limit pressure Pmax is the maximum value of the outlet pressure of the ejector 14 when the pressure of the first working fluid WF1 is normal.

[0062] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible within the scope of the gist of the present disclosure.

[0063] For example, the pressure sensor 91 may be provided inside the ejector 14 , in which case it may be provided at a position downstream of the outer nozzle 55 inside the ejector 14 .

[0064] REFERENCE SIGNS LIST 1 fuel cell system 11 fuel cell (FC) 12 hydrogen supply passage 13 hydrogen circulation passage 14 ejector 16 hydrogen pressure sensor 17 pressure reducing valve 18 hydrogen pressure sensor 19A first injector 19B second injector 40 controller 41 main body casing 41a inner circumferential surface 41aa casing inner circumferential surface front end portion 41ab casing inner circumferential surface rear end portion 51 first working fluid supply port 52 second working fluid supply port 53 target fluid supply port 54 negative pressure generating chamber 55 outer nozzle 55a inlet 55b outer O-ring groove 56 inner nozzle 56b inner O-ring groove 57 diffuser 58 discharge port 59 plug 61 outer injection hole 62 inner injection hole 71 flow rate restricting portion 72 front end portion 73 rear end portion 81 Spring 82 Pressure receiving portion 83 O-ring 84 O-ring 91 Pressure sensor 92 Determination portion WF1 First working fluid WF2 Second working fluid D1 Inner diameter (of the leading end portion of the inner circumferential surface of the casing) D2 Inner diameter (of the trailing end portion of the inner circumferential surface of the casing) Pfail System abnormality detection pressure Pmax System operation upper limit pressure

Claims

1. An ejector having a main casing, an outer nozzle arranged within the main casing for spraying a first working fluid, and an inner nozzle arranged inside the outer nozzle for spraying a second working fluid, the ejector having a biasing member for biasing the inner nozzle toward its tip, the outer nozzle having an inlet for allowing the first working fluid to flow into the inside of the outer nozzle, the inner nozzle having a pressure-receiving part, located rearward of the inlet, that receives the pressure of the first working fluid toward the rear end against the biasing force of the biasing member, the biasing load of the biasing member being greater than the load received by the pressure-receiving part when the pressure of the first working fluid is within a usable range and is under normal pressure, but being smaller than the load received by the pressure-receiving part when the pressure of the first working fluid is above the maximum value of the usable range and is under abnormal pressure.

2. An ejector according to claim 1, wherein the outer nozzle is provided with a flow rate restricting section at its tip that restricts the cross-sectional area of ​​the flow path, and the tip of the inner nozzle is positioned within the flow rate restricting section when the pressure is normal, but moves to the rear end side of the flow rate restricting section when the pressure is abnormal.

3. An ejector according to claim 1 or 2, wherein the main casing is provided with a first working fluid supply port for supplying the first working fluid to the inlet, the outer nozzle is attached to the main casing via a sealing member at a tip end portion of the inner circumferential surface of the casing that is further tip-side than the first working fluid supply port on the inner circumferential surface of the main casing, and the inner nozzle is attached to the main casing via a sealing member at a rear end portion of the inner circumferential surface of the casing that is further rear-end than the first working fluid supply port on the inner circumferential surface of the main casing, and the inner diameter of the rear end portion of the inner circumferential surface of the casing is larger than the inner diameter of the tip end portion of the inner circumferential surface of the casing.

4. A fuel cell system having an ejector, the ejector comprising: a main casing; an outer nozzle arranged within the main casing and spraying a first working fluid; an inner nozzle arranged inside the outer nozzle and spraying a second working fluid; and a biasing member for biasing the inner nozzle towards its tip, wherein the outer nozzle has an inlet for allowing the first working fluid to flow into the inside of the outer nozzle, and the inner nozzle has a pressure receiving part rearward of the inlet that receives the pressure of the first working fluid towards the rear against the biasing force of the biasing member, the biasing load of the biasing member being greater than the load received by the pressure receiving part when the pressure of the first working fluid is within a usable range and is normal, but is smaller than the load received by the pressure receiving part when the pressure of the first working fluid is abnormal and is greater than the maximum value of the usable range, and the fuel cell system comprises: a pressure measuring part for measuring the pressure of the fluid downstream of the outer nozzle; and a determining part for determining whether or not the pressure is abnormal based on the measurement value of the pressure measuring part, The fuel cell system having an ejector, wherein the determining unit determines that the pressure is abnormal when a change in the value measured by the pressure measuring unit per unit time exceeds a predetermined amount.

5. A fuel cell system having an ejector, the ejector comprising: a main casing; an outer nozzle arranged within the main casing and spraying a first working fluid; an inner nozzle arranged inside the outer nozzle and spraying a second working fluid; and a biasing member for biasing the inner nozzle towards its tip, wherein the outer nozzle has an inlet for allowing the first working fluid to flow into the inside of the outer nozzle, and the inner nozzle has a pressure receiving part rearward of the inlet that receives the pressure of the first working fluid towards the rear against the biasing force of the biasing member, the biasing load of the biasing member being greater than the load received by the pressure receiving part when the pressure of the first working fluid is within a usable range and is normal, but is smaller than the load received by the pressure receiving part when the pressure of the first working fluid is abnormal and is greater than the maximum value of the usable range, and the fuel cell system comprises: a pressure measuring part for measuring the pressure of the fluid downstream of the outer nozzle; and a determining part for determining whether or not the pressure is abnormal based on the measurement value of the pressure measuring part, The fuel cell system having an ejector, wherein the determining unit determines that the pressure is abnormal when the value measured by the pressure measuring unit is greater than a predetermined value.

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