Ejector and fuel cell system having ejector

Abstract

Provided is an ejector having an urging member configured to urge an outside nozzle and an inside nozzle in toward the front end thereof. When the pressure of a first working fluid is larger than the maximum value of a use range, the outside nozzle moves in the rear end direction opposite the urging force of the urging member, and the outside nozzle closes the first working fluid supply port, or the inside nozzle moves in the rear end direction opposite the urging force of the urging member thus closing the inflow port of the inside nozzle.

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 a malfunction of the fuel cell. Therefore, it is desirable to respond appropriately to the abnormality in the pressure of the working fluid as soon as possible.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide an ejector that can respond promptly and appropriately to pressure abnormalities in the working fluid, and a fuel cell system having this ejector.

[0006] One aspect of the present disclosure made to solve the above problems is an ejector comprising: a main casing; an outer nozzle disposed within the main casing and configured to inject a first working fluid; an inner nozzle disposed inside the outer nozzle and configured to inject a second working fluid; and a first working fluid supply port for supplying the first working fluid into the main casing, wherein the outer nozzle is an ejector having an inlet for allowing the first working fluid to flow into the outer nozzle; the outer nozzle has a biasing member for biasing the outer nozzle and the inner nozzle toward their tip ends; and when a pressure abnormality occurs in which the pressure of the first working fluid is greater than a maximum value within an operating range, the outer nozzle moves toward the rear end against the biasing force of the biasing member, so that the outer nozzle blocks the first working fluid supply port, or the inner nozzle moves toward the rear end against the biasing force of the biasing member, so that the inner nozzle blocks the inlet.

[0007] According to this aspect, when the pressure of the first working fluid becomes abnormal, the first working fluid supply port is blocked by the outer nozzle, or the inlet is blocked by the inner nozzle, so that the first working fluid with an abnormal pressure can be prevented from flowing downstream of the ejector, thereby making it possible to respond promptly and appropriately to the pressure abnormality of the first working fluid.

[0008] In the above aspect, it is preferable that the outer nozzle has a pressure-receiving portion, located rearward of the inlet, that receives the pressure of the first working fluid toward the rearward end against the biasing force of the biasing member, and that in the event of a pressure abnormality, the first working fluid supply port is blocked by a portion of the outer peripheral surface of the outer nozzle that is forward of the inlet.

[0009] According to this aspect, when the pressure of the first working fluid becomes abnormal, the outer surface of the outer nozzle blocks the first working fluid supply port, thereby more reliably preventing the first working fluid with abnormal pressure from flowing downstream of the ejector.

[0010] In the above aspect, there is provided a seal member disposed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and a tip-side seal member groove formed on the outer peripheral surface of the outer nozzle for disposing the seal member further forward than the inlet, and when the amount of movement of the outer nozzle and the inner nozzle toward the rear end in the event of the pressure abnormality is A, the distance between the rear end of the first working fluid supply port and the tip end of the tip-side seal member groove is B, the distance between the tip end of the tip-side seal member groove and the tip end of the outer peripheral surface of the outer nozzle is C, and the diameter of the first working fluid supply port is D, it is preferable that the relationships B<A and (A-B+D)<C are satisfied.

[0011] According to this aspect, when the pressure of the first working fluid becomes abnormal, the outer nozzle and the inner nozzle move toward the rear end, and the first working fluid supply port can be blocked between the tip end of the outer nozzle on the outer peripheral surface and the tip end of the tip seal member groove. Therefore, when the pressure of the first working fluid becomes abnormal, it is possible to more reliably prevent the first working fluid with an abnormal pressure from flowing downstream of the ejector.

[0012] In the above aspect, it is preferable that 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 that the outer 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 that 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.

[0013] According to this aspect, the pressure-receiving area of ​​the pressure-receiving portion can be increased. Therefore, when the pressure of the first working fluid becomes abnormal, the outer nozzle and the inner nozzle move toward the rear end more quickly against the biasing force of the biasing member due to the load received by the pressure-receiving portion. Therefore, the first working fluid supply port can be blocked more quickly, and the first working fluid with abnormal pressure can be prevented from flowing downstream of the ejector.

[0014] In the above aspect, it is preferable that the inner nozzle has a protrusion on its outer peripheral surface, and that the protrusion is located forward of the inlet when the pressure of the first working fluid is normal and within a usable pressure range, and that the inner nozzle moves rearward and blocks the inlet with the protrusion when the pressure is abnormal.

[0015] According to this aspect, when the pressure of the first working fluid becomes abnormal, the inlet is blocked by the protrusion of the inner nozzle, so that the first working fluid with abnormal pressure can be more reliably prevented from flowing downstream of the ejector.

[0016] Another aspect of the present disclosure made to solve the above problems is an ejector having a main body casing, an outer nozzle arranged in the main body casing and spraying a first working fluid, an inner nozzle arranged inside the outer nozzle and spraying a second working fluid, and a first working fluid supply port for supplying the first working fluid into the main body casing, wherein the outer nozzle has an inlet for causing the first working fluid to flow into the inside of the outer nozzle, a first flow path through which the first working fluid flows is formed between an inner circumferential surface of the outer nozzle and an outer circumferential surface of the inner nozzle, and a second flow path through which the second working fluid flows is formed inside the inner nozzle, the outer nozzle has a pressure receiving portion, 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; and when the pressure of the first working fluid is within a normal pressure range, the first working fluid supply port is connected to the first flow path, and the first working fluid flows through the first flow path; and when the pressure of the first working fluid is abnormal, and the pressure is higher than the maximum value of the usage range, the outer nozzle and the inner nozzle move rearward against the biasing force of the biasing member, and the first working fluid supply port is connected to a third flow path formed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and the first working fluid flows through the third flow path.

[0017] According to this aspect, the flow path through which the first working fluid flows is different between the first flow path and the third flow path when the pressure of the first working fluid is normal and when the pressure is abnormal, so the way in which the pressure of the fluid is transmitted downstream of the ejector is different. Therefore, by measuring the outlet pressure of the ejector, it is possible to detect the pressure abnormality of the first working fluid early. In this way, it is possible to respond promptly and appropriately to the pressure abnormality of the first working fluid.

[0018] In the above aspect, it is preferable that the cross-sectional area of ​​the third flow path is larger than the cross-sectional area of ​​the first flow path.

[0019] According to this aspect, the flow rate of the first working fluid is greater in the third flow path than in the first flow path. Therefore, the outlet pressure of the ejector increases more quickly when the pressure of the first working fluid flowing through the third flow path is abnormal than when the pressure of the first working fluid flowing through the first flow path is normal. Therefore, by measuring the outlet pressure of the ejector, it is possible to detect the pressure abnormality of the first working fluid at an early stage.

[0020] In the above aspect, it is preferable that the valve has a sealing member arranged between the outer peripheral surface of the outer nozzle and the inner peripheral surface of the main casing, and a tip-side sealing member arrangement portion formed to arrange the sealing member on the outer peripheral surface of the outer nozzle further forward than the inlet, and that when the amount of movement of the outer nozzle and the inner nozzle toward the rear end in the event of the pressure abnormality is A and the distance between the rear end side end of the first working fluid supply port and the tip end side end of the tip-side sealing member arrangement portion is E, the relationship E < A is satisfied.

[0021] According to this aspect, when the pressure of the first working fluid is abnormal, the outer nozzle and the inner nozzle move toward the rear end, more reliably connecting the first working fluid supply port to the third flow path and allowing the first working fluid supplied from the first working fluid supply port to flow through the third flow path. This more reliably makes it possible to make the manner in which the pressure of the fluid downstream of the ejector is transmitted differently when the pressure of the first working fluid is normal and when the pressure is abnormal. Therefore, by more reliably measuring the outlet pressure of the ejector, it is possible to detect the pressure abnormality of the first working fluid at an early stage.

[0022] In the above aspect, it is preferable that 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 that the outer 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 that 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.

[0023] 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 outer nozzle and the inner nozzle move 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.

[0024] 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 first working fluid supply port for supplying the first working fluid into the main casing, the outer nozzle having an inlet for allowing the first working fluid to flow into the outer nozzle, a first flow path for the first working fluid to flow between an inner circumferential surface of the outer nozzle and an outer circumferential surface of the inner nozzle, and a second flow path for the second working fluid to flow inside the inner nozzle, the outer nozzle having an urging member for urging the outer nozzle and the inner nozzle toward their forward ends, the outer nozzle having a pressure of the first working fluid to be directed rearward against the urging force of the urging member, on a rear end side of the inlet and a pressure receiving section that receives pressure toward the first working fluid, and when the pressure of the first working fluid is within a normal pressure range, the first working fluid supply port is connected to the first flow path, and the first working fluid flows through the first flow path, and when the pressure of the first working fluid is abnormal, and the pressure is higher than the maximum value of the usage range, the outer nozzle and the inner nozzle move toward the rear end against the biasing force of the biasing member, and the first working fluid supply port is connected to a third flow path formed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and the first working fluid flows through the third flow path. The fuel cell system has a pressure measuring section that measures the pressure of the fluid downstream of the outer nozzle, and a determining section that determines whether the pressure abnormality has occurred based on the measurement value of the pressure measuring section, and the determining section determines that the pressure abnormality has occurred when the amount of change per unit time of the measurement value of the pressure measuring section exceeds a predetermined amount.

[0025] 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.

[0026] 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 first working fluid supply port for supplying the first working fluid into the main casing, the outer nozzle having an inlet for causing the first working fluid to flow into the outer nozzle, a first flow path for the first working fluid to flow between an inner circumferential surface of the outer nozzle and an outer circumferential surface of the inner nozzle, and a second flow path for the second working fluid to flow inside the inner nozzle, the outer nozzle having an urging member for urging the outer nozzle and the inner nozzle toward their tip ends, the outer nozzle having a rear end side relative to the inlet, which is configured to apply pressure of the first working fluid to the rear end side of the outer nozzle against the urging force of the urging member. and a pressure receiving section that receives pressure in an end direction, and when the pressure of the first working fluid is within a normal pressure range, the first working fluid supply port is connected to the first flow path, and the first working fluid flows through the first flow path, and when the pressure of the first working fluid is abnormal, and the pressure is higher than the maximum value of the usage range, the outer nozzle and the inner nozzle move toward the rear end against the biasing force of the biasing member, and the first working fluid supply port is connected to a third flow path formed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and the first working fluid flows through the third flow path.The fuel cell system is characterized by having: a pressure measuring section that measures the pressure of the fluid downstream of the outer nozzle; and a determination section that determines whether the pressure abnormality has occurred based on the measurement value of the pressure measuring section, and the determination section that determines that the pressure abnormality has occurred when the measurement value of the pressure measuring section is higher than a predetermined value.

[0027] 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.

[0028] The ejector and fuel cell system having the ejector of the present disclosure can quickly and appropriately respond to pressure abnormalities in the working fluid.

[0029] FIG. 1 is a schematic configuration diagram of a fuel cell system of a first embodiment. FIG. 2 is a front sectional view of an ejector of the first embodiment. FIG. 3 is an enlarged view of an outer nozzle, an inner nozzle, and their surrounding areas in an ejector of the first embodiment, showing a state when the pressure of the first working fluid is normal. FIG. 4 is an enlarged view of an outer nozzle, an inner nozzle, and their surrounding areas in an ejector of the first embodiment, showing a state when the pressure of the first working fluid is abnormal. FIG. 5 is a schematic configuration diagram of a fuel cell system of a second embodiment. FIG. 6 is a front sectional view of an ejector of the second embodiment. FIG. 7 is an enlarged view of an outer nozzle, an inner nozzle, and their surrounding areas in an ejector of the second embodiment, showing a state when the pressure of the first working fluid is normal. FIG. 8 is an enlarged view of an outer nozzle, an inner nozzle, and their surrounding areas in an ejector of the second embodiment, showing a state when the pressure of the first working fluid is abnormal. FIG. 9 is a diagram showing an example of the behavior of the outlet pressure of the ejector when the pressure of the first working fluid is abnormal. FIG. 10 is an enlarged view of an outer nozzle, an inner nozzle, and their surrounding areas in an ejector of a third embodiment, showing a state when the pressure of the first working fluid is normal. FIG. Fig. 12 is a view of the inner nozzle of the third embodiment as seen from the left side of Fig. 11. Fig. 13 is a top view of the inner nozzle of the third embodiment. Fig. 14 is an enlarged view of the outer nozzle, the inner nozzle and their surrounding areas in the ejector of the third embodiment, showing a state where the pressure of the first working fluid is abnormal. Fig. 15 is a top view of the inner nozzle of a modified example of the third embodiment.

[0030] 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.

[0031] First Embodiment First, the first embodiment will be described.

[0032] <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).

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 pressure sensor 91 is an example of the "pressure measurement unit" of the present disclosure.

[0043] <Outline of Ejector> Next, an outline of the ejector 14 will be described.

[0044] 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).

[0045] 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.

[0046] 3, the first working fluid supply port 51 is a supply port through which the first working fluid WF1 sent from the first injector 19A (see FIG. 1) is supplied into the main casing 41, and supplies the first working fluid WF1 to an inlet 55c (described later) provided in the outer nozzle 55, and is connected to a first flow path 61 through which the first working fluid WF1 flows in the gap between the inner circumferential surface 55b of the outer nozzle 55 and the outer circumferential surface 56a of 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 (see FIG. 1) is supplied into the main casing 41, and is connected to a second flow path 62 through which the second working fluid WF2 flows inside the inner nozzle 56.

[0047] 2, the target fluid supply port 53 is a supply port through which the target fluid is supplied, and is connected to the negative pressure generating chamber 54. The negative pressure generating chamber 54 is a space portion for generating negative pressure by the working fluid.

[0048] 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. In this embodiment, the inner nozzle 56 is press-fitted and fixed into the outer nozzle 55.

[0049] 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 55c that allows the first working fluid WF1 to flow into the inside of the outer nozzle 55.

[0050] As shown in Fig. 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 a tip-side O-ring groove 55d in which an O-ring 83 is disposed, located on its outer peripheral surface 55a closer to the tip than the inlet 55c. The outer nozzle 55 is also provided with a rear-side O-ring groove 55e in which an O-ring 84 is disposed, located on its outer peripheral surface 55a closer to the rear than a pressure-receiving section 82 (described later). The outer nozzle 55 is attached to the main casing 41 via the O-rings 83 and 84.

[0051] The O-ring 83 and the O-ring 84 are each an example of a "sealing member" in the present disclosure. The tip-side O-ring groove 55d is an example of a "tip-side sealing member groove" in the present disclosure.

[0052] The inner nozzle 56 is disposed within the outer nozzle 55 and injects the second working fluid WF2 supplied from the second working fluid supply port 52 .

[0053] 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 downstream ends (left side in FIG. 2 ) of the outer nozzle 55 and the inner nozzle 56, respectively, and are portions where the inner diameter is narrowed to a minimum.

[0054] 2, 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., on the opposite side from the discharge port 58).

[0055] 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).

[0056] 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).

[0057] 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 the first flow path 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 the second flow path 62 into the negative pressure generating chamber 54, flows through the diffuser 57, and is discharged from the discharge port 58.

[0058] 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.

[0059] <Response to Pressure Abnormality of 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, hydrogen gas with an abnormal pressure 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 55c 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 take appropriate action promptly against the pressure abnormality of the first working fluid WF1.

[0060] Therefore, in this embodiment, the structures of the outer nozzle 55 and the inner nozzle 56 are devised so that an appropriate response can be made promptly to the abnormality in the pressure of the first working fluid WF1.

[0061] 2 to 4, the ejector 14 has a spring 81 that biases the outer nozzle 55 and the inner nozzle 56 toward their distal ends (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 biases the inner nozzle 56 toward its distal end, and also biases the outer nozzle 55 toward its distal end via the inner nozzle 56. The spring 81 is an example of a "biasing member" in the present disclosure.

[0062] The outer nozzle 55 also has a pressure-receiving portion 82 at a position on the outer peripheral surface 55a rearward of the inlet 55c (i.e., to the right in FIGS. 2 to 4). 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 outer nozzle 55 (i.e., the left-right direction in FIGS. 2 to 4).

[0063] The pressure receiving portion 82 receives the pressure of the first working fluid WF1 supplied from the first working fluid supply port 51 in the rear direction against the biasing force of the spring 81 .

[0064] 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).

[0065] 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).

[0066] In this embodiment, when the pressure of the first working fluid WF1 becomes abnormal, as shown in FIG. 4, the outer nozzle 55 and the inner nozzle 56 move toward the rear end against the biasing force of the spring 81, and block the first working fluid supply port 51 at the blocking area PA, which is a portion of the outer surface 55 a of the outer nozzle 55 that is closer to the tip than the inlet 55 c (more specifically, closer to the tip than the tip-side O-ring groove 55 d).

[0067] 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, so when the pressure of the first working fluid WF1 is abnormal, the load received by the pressure-receiving portion 82 causes the outer nozzle 55 and the inner nozzle 56 to move toward the rear end against the biasing force of the spring 81. Furthermore, since the first working fluid supply port 51 is blocked by the blocking portion PA on the outer peripheral surface 55a of the outer nozzle 55, the area of ​​the passage through which the first working fluid WF1 flows can be reduced, and the first working fluid WF1 with an abnormal pressure can be prevented from flowing downstream of the ejector 14. In this way, it is possible to respond promptly and appropriately to a pressure abnormality in the first working fluid WF1.

[0068] Furthermore, in order to prevent the first working fluid WF1 with an abnormal pressure (i.e., high pressure) from flowing into the fuel cell 11 due to, for example, a failure of the pressure reducing valve 17, it is conceivable to provide a relief valve (not shown) between the ejector 14 and the fuel cell 11 located downstream of the ejector 14. In this case, when the pressure of the first working fluid WF1 is abnormal, the area of ​​the passage through which the first working fluid WF1 flows can be reduced as described above to prevent the first working fluid WF1 with an abnormal pressure from flowing downstream of the ejector 14, thereby making it possible to reduce the size of the relief valve and thereby miniaturize the fuel cell system 1.

[0069] More specifically, the dimensions are set as follows. First, let A be the amount of movement of the outer nozzle 55 and the inner nozzle 56 toward the rear end when the pressure of the first working fluid WF1 is abnormal. Furthermore, let B be the distance, in the axial direction (left-right direction in FIG. 3 ) of the outer nozzle 55 and the inner nozzle 56, between the rear end 51a of the first working fluid supply port 51 and the front end 55da of the front O-ring groove 55d when the pressure of the first working fluid WF1 is normal. Furthermore, let C be the distance, in the axial direction of the outer nozzle 55 and the inner nozzle 56, between the front end 55da of the front O-ring groove 55d and the front end 55aa of the outer peripheral surface 55a of the outer nozzle 55 (i.e., the length of the blocked area PA). Furthermore, let D be the diameter of the first working fluid supply port 51. The relationships B<A and (A−B+D)<C are satisfied.

[0070] As a result, in the event of a pressure abnormality in the first working fluid WF1, the outer nozzle 55 and the inner nozzle 56 move rearward to block the first working fluid supply port 51 between the tip end 55aa of the outer peripheral surface 55a of the outer nozzle 55 and the tip end 55da of the tip O-ring groove 55d (i.e., the blocked portion PA). Therefore, in the event of a pressure abnormality in the first working fluid WF1, it is possible to more reliably prevent the first working fluid WF1 with an abnormal pressure from flowing downstream of the ejector 14. Note that the tip end 55aa is a boundary portion on the outer peripheral surface 55a of the outer nozzle 55 between a portion where the outer diameter of the outer nozzle 55 is constant (i.e., the blocked portion PA) and a portion where the outer diameter of the outer nozzle 55 gradually decreases toward the tip end (i.e., the flow rate restricting portion 71).

[0071] The outer nozzle 55 is attached to the main casing 41 via an O-ring 83 at a casing inner peripheral surface front end portion 41aa, which is located further forward than the first working fluid supply port 51 on the inner peripheral surface 41a of the main casing 41. The outer nozzle 55 is attached to the main casing 41 via an O-ring 84 at a casing inner peripheral surface rear end portion 41ab, which is located further rearward than the first working fluid supply port 51 on the inner peripheral surface 41a of the main casing 41. An inner diameter D2 of the casing inner peripheral surface rear end portion 41ab is larger than an inner diameter D1 of the casing inner peripheral surface front end portion 41aa.

[0072] 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 rear end portion 41ab of the casing inner peripheral surface. Therefore, when an abnormality occurs in the pressure of the first working fluid WF1, the outer nozzle 55 and the inner nozzle 56 move 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, the outer peripheral surface 55a of the outer nozzle 55 can more quickly block the first working fluid supply port 51, thereby preventing the first working fluid WF1 with an abnormal pressure from flowing downstream of the ejector 14.

[0073] Second Embodiment Next, a second embodiment will be described. Explanation of the points common to the first embodiment will be omitted, and only the points different from the first embodiment will be described.

[0074] 5, the fuel cell system 1 has 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 a pressure sensor 91, as will be described in detail later. 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.

[0075] <Overview of the Ejector> In this embodiment, as shown in FIGS. 6 to 8 , a third flow path 63 is formed between the inner circumferential surface 41a of the main body casing 41 and the outer circumferential surface 55a of the outer nozzle 55. A tip-side O-ring arrangement portion 55f in which an O-ring 83 is arranged is formed on the outer circumferential surface 55a of the outer nozzle 55, closer to the tip of the inlet 55c. This tip-side O-ring arrangement portion 55f is formed to protrude from the outer circumferential surface 55a toward the inner circumferential surface 41a of the main body casing 41. This leaves a gap between the outer circumferential surface 55a, which is closer to the tip of the tip-side O-ring arrangement portion 55f, and the inner circumferential surface 41a of the main body casing 41, and this gap forms the third flow path 63. The tip-side O-ring arrangement portion 55f is an example of a “tip-side seal member arrangement portion” in the present disclosure.

[0076] <Regarding Detection of Pressure Abnormality of First Working Fluid> In this embodiment, as shown in FIG. 7 , when the pressure of the first working fluid WF1 is normal, the first working fluid supply port 51 is connected to the first flow path 61, and the first working fluid WF1 flows through the first flow path 61. On the other hand, as shown in FIG. 8 , when the pressure of the first working fluid WF1 is abnormal, the outer nozzle 55 and the inner nozzle 56 move toward the rear end against the biasing force of the spring 81, and the first working fluid supply port 51 is connected to the third flow path 63, and the first working fluid WF1 flows through the third flow path 63. The flow path cross-sectional area CA3 of the third flow path 63 is larger than the flow path cross-sectional area CA1 of the first flow path 61. Note that the flow path cross-sectional area CA3 of the third flow path 63 is, for example, seven times larger than the flow path cross-sectional area CA1 of the first flow path 61.

[0077] In this way, the flow path through which the first working fluid WF1 flows is different between the first flow path 61 and the third flow path 63 depending on whether the pressure of the first working fluid WF1 is normal or abnormal. This means that the manner in which the fluid pressure is transmitted to the downstream side of the ejector 14 differs. Specifically, the flow rate of the first working fluid WF1 is greater through the third flow path 63 than through the first flow path 61. Therefore, the outlet pressure of the ejector 14 increases more quickly when the first working fluid WF1 flows through the third flow path 63 and the pressure is abnormal than when the pressure of the first working fluid WF1 flows through the first flow path 61 and the pressure is normal. Therefore, by measuring the change (i.e., increase) in the outlet pressure of the ejector 14 using the pressure sensor 91, the pressure abnormality of the first working fluid WF1 can be detected early. In this way, the pressure abnormality of the first working fluid WF1 can be dealt with promptly and appropriately.

[0078] More specifically, the dimensions are set as follows. First, let A be the amount of movement of the outer nozzle 55 and the inner nozzle 56 toward the rear end when the pressure of the first working fluid WF1 is abnormal. Furthermore, let E be the distance in the axial direction (left-right direction in FIG. 7 ) of the outer nozzle 55 and the inner nozzle 56 between the rear end 51 a of the first working fluid supply port 51 and the front end 55 fa of the front O-ring arrangement portion 55 f when the pressure of the first working fluid WF1 is normal. The relationship E<A is satisfied here.

[0079] As a result, when the pressure of the first working fluid WF1 is abnormal, the outer nozzle 55 and the inner nozzle 56 move toward the rear end, allowing the first working fluid WF1 supplied from the first working fluid supply port 51 to flow into the third flow path 63. Therefore, when the pressure of the first working fluid WF1 is abnormal, the fluid pressure is more reliably transmitted to the downstream side of the ejector 14 earlier than when the pressure is normal. Therefore, by measuring the increase in the outlet pressure of the ejector 14, the pressure abnormality of the first working fluid WF1 can be more reliably detected at an early stage.

[0080] The inner diameter D2 of the rear end portion 41ab of the inner circumferential surface of the casing is larger than the inner diameter D1 of the front end portion 41aa of the inner circumferential surface of the casing.

[0081] 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 rear end portion 41ab of the casing inner circumferential surface. Therefore, when an abnormality in the pressure of the first working fluid WF1 occurs, the outer nozzle 55 and the inner nozzle 56 move 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, an abnormality in the pressure of the first working fluid WF1 can be detected more quickly.

[0082] In this embodiment, as shown in FIG. 9, 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 outer nozzle 55 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.

[0083] 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.

[0084] 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. 9 ). 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.

[0085] Third Embodiment Next, a third embodiment will be described. Explanation of points common to the first and second embodiments will be omitted, and only points different from the first and second embodiments will be described.

[0086] In this embodiment, when the pressure of the first working fluid WF1 becomes abnormal, the inner nozzle 56 moves toward the rear end against the biasing force of the spring 81, and the inner nozzle 56 closes the inlet 55c of the outer nozzle 55. Note that in this embodiment, the inner nozzle 56 is not press-fitted and fixed to the outer nozzle 55, and is therefore movable relative to the outer nozzle 55.

[0087] 10 to 14, the inner nozzle 56 is provided with protrusions 56b on its outer circumferential surface 56a that protrude radially outward of the inner nozzle 56 (the vertical direction in FIG. 10). As shown in FIGS. 11 and 12, two protrusions 56b are provided in the circumferential direction of the inner nozzle 56. As shown in FIG. 10, when the pressure of the first working fluid WF1 is normal, the protrusions 56b are located closer to the front end than the inlet 55c of the outer nozzle 55 (to the left in FIG. 10).

[0088] At this time, the first working fluid WF1 is able to flow through areas where no protrusions 56b are provided (i.e., areas between two protrusions 56b in the circumferential direction of the inner nozzle 56).

[0089] 10 and 14, a clearance δ (i.e., a gap) is provided between the inner circumferential surface 55b of the outer nozzle 55 and the outer circumferential surface 56a of the inner nozzle 56. The size of this clearance δ is set to a value that does not affect the flow rate when the central axes of the outer nozzle 55 and the inner nozzle 56 are misaligned, and is set to a value that allows the inner nozzle 56 to move relative to the outer nozzle 55 when an abnormality occurs in the pressure of the first working fluid WF1.

[0090] When the pressure of the first working fluid WF1 becomes abnormal, the pressure of the first working fluid WF1 acts on the pressure-receiving portion 101 at the rear end 73 of the inner nozzle 56 via the clearance δ between the inner circumferential surface 55b of the outer nozzle 55 and the outer circumferential surface 56a of the inner nozzle 56. As a result, as shown in Figure 14, the outer nozzle 55 does not move, but the inner nozzle 56 moves toward the rear end, and the inlet 55c of the outer nozzle 55 is blocked by the protrusion 56b of the inner nozzle 56.

[0091] In this way, when the pressure of the first working fluid WF1 becomes abnormal, the protrusion 56b of the inner nozzle 56 blocks the inlet 55c of the outer nozzle 55, thereby more reliably preventing the first working fluid WF1 with abnormal pressure from flowing downstream of the ejector 14.

[0092] The outer shape of the protrusion 56b of the inner nozzle 56 is, for example, quadrangular (e.g., rectangular) when viewed from above as shown in Fig. 13, but as a modified example, it may be elliptical when viewed from above as shown in Fig. 15. Furthermore, one protrusion 56b may be provided, or three or more protrusions 56b may be provided.

[0093] 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.

[0094] 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 .

[0095] Furthermore, in the event of a pressure abnormality, the blocked portion PA on the outer peripheral surface 55 a of the outer nozzle 55 is not limited to blocking the entire first working fluid supply port 51, but may reduce the area of ​​the passage through which the first working fluid WF1 flows by blocking a portion of the first working fluid supply port 51. Similarly, in the event of a pressure abnormality, the protrusion 56 b of the inner nozzle 56 is not limited to blocking the entire inlet 55 c of the outer nozzle 55, but may reduce the area of ​​the passage through which the first working fluid WF1 flows by blocking a portion of the inlet 55 c of the outer nozzle 55.

[0096] 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 40 Controller 41 Main body casing 41a Inner circumferential surface 41aa Front end portion of casing inner circumferential surface 41ab Rear end portion of casing inner circumferential surface 51 First working fluid supply port 51a Rear end end 52 Second working fluid supply port 53 Target fluid supply port 54 Negative pressure generating chamber 55 Outer nozzle 55a Outer circumferential surface 55aa Front end end 55b Inner circumferential surface 55c Inlet 55d Front O-ring groove 55da Front end end 55e Rear O-ring groove 55f Front O-ring arrangement portion 55fa Front end end 56 Inner nozzle 56a Outer circumferential surface 56b Projection 57 Diffuser 58 Discharge port 59 Plug 61 First flow path 62 Second flow path 63 Third flow path 73 Rear end portion 81 Spring 82 Pressure receiving portion 83 O-ring 84 O-ring 91 Pressure sensor 92 Determination portion 101 Pressure receiving portion WF1 First working fluid WF2 Second working fluid PA Blockage portion A Distance B Distance C Distance D Diameter E Distance D1 Inner diameter (of the tip end portion of the inner circumferential surface of the casing) D2 Inner diameter (of the rear end portion of the inner circumferential surface of the casing) CA1 Flow path cross-sectional area (of the first flow path) CA3 Flow path cross-sectional area (of the third flow path) Pfail System abnormality detection pressure δ Clearance

Claims

1. An ejector comprising: a main casing; an outer nozzle disposed within the main casing for injecting a first working fluid; an inner nozzle disposed inside the outer nozzle for injecting a second working fluid; and a first working fluid supply port for supplying the first working fluid into the main casing, the outer nozzle having an inlet for allowing the first working fluid to flow into the inside of the outer nozzle; the ejector further comprising a biasing member for biasing the outer nozzle and the inner nozzle toward their tip ends, wherein, in the event of a pressure abnormality in which the pressure of the first working fluid is greater than the maximum value of an operating range, the outer nozzle moves toward the rear end against the biasing force of the biasing member, and the outer nozzle closes the first working fluid supply port; or the inner nozzle moves toward the rear end against the biasing force of the biasing member, and the inner nozzle closes the inlet.

2. An ejector according to claim 1, wherein the outer nozzle is provided with a pressure receiving section, located rearward of the inlet, that receives the pressure of the first working fluid in a rearward direction against the biasing force of the biasing member, and in the event of a pressure abnormality, the first working fluid supply port is blocked by a section of the outer peripheral surface of the outer nozzle that is forward of the inlet.

3. An ejector according to claim 1 or 2, comprising: a seal member arranged between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle; and a tip side seal member groove formed on the outer peripheral surface of the outer nozzle to arrange the seal member further forward than the inlet, wherein the relationship B<A and (A-B+D)<C are satisfied, where A denotes the amount of movement of the outer nozzle and the inner nozzle toward the rear end in the event of the pressure abnormality, B denotes the distance between the rear end side edge of the first working fluid supply port and the tip side edge of the tip side seal member groove, C denotes the distance between the tip side edge of the tip side seal member groove and the tip side edge of the outer peripheral surface of the outer nozzle, and D denotes the diameter of the first working fluid supply port.

4. An ejector according to claim 3, wherein 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 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.

5. An ejector according to claim 1, wherein the inner nozzle has a protrusion on its outer circumferential surface, and the protrusion is located forward of the inlet when the pressure of the first working fluid is normal and within the operating range, and when the pressure is abnormal, the inner nozzle moves rearward and the protrusion closes the inlet.

6. An ejector having: a main body casing; an outer nozzle arranged within the main body casing and spraying a first working fluid; an inner nozzle arranged inside the outer nozzle and spraying a second working fluid; and a first working fluid supply port for supplying the first working fluid into the main body casing, wherein the outer nozzle has an inlet for allowing the first working fluid to flow into the inside of the outer nozzle; a first flow path for the first working fluid is formed between the inner peripheral surface of the outer nozzle and the outer peripheral surface of the inner nozzle; and a second flow path for the second working fluid is formed inside the inner nozzle, wherein the ejector has a biasing member for biasing the outer nozzle and the inner nozzle toward their forward ends, and the outer nozzle has 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, and when the pressure of the first working fluid is within a normal pressure range and is within a usable range, the first working fluid supply port is connected to the first flow path, and the first working fluid flows through the first flow path, when a pressure abnormality occurs in which the pressure of the first working fluid is greater than a maximum value in a usage range, the outer nozzle and the inner nozzle move toward the rear end against the biasing force of the biasing member, the first working fluid supply port communicates with a third flow path formed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and the first working fluid flows through the third flow path.

7. The ejector according to claim 6, wherein the cross-sectional area of ​​the third flow path is larger than the cross-sectional area of ​​the first flow path.

8. An ejector according to claim 6 or 7, comprising: a seal member arranged between the outer peripheral surface of the outer nozzle and the inner peripheral surface of the main casing; and a tip-side seal member arrangement section formed on the outer peripheral surface of the outer nozzle to arrange the seal member further forward than the inlet, wherein the ejector satisfies the relationship E<A, where A denotes the amount of movement of the outer nozzle and the inner nozzle toward the rear end in the event of a pressure abnormality, and E denotes the distance between the rear end of the first working fluid supply port and the tip end of the tip-side seal member arrangement section.

9. An ejector according to claim 8, wherein 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 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.

10. A fuel cell system having an ejector, the ejector having: a main casing; an outer nozzle arranged within the main casing for injecting a first working fluid; an inner nozzle arranged inside the outer nozzle for injecting a second working fluid; and a first working fluid supply port for supplying the first working fluid into the main casing, the outer nozzle having an inlet for allowing the first working fluid to flow into the inside of the outer nozzle; a first flow path for the first working fluid to flow between the inner peripheral surface of the outer nozzle and the outer peripheral surface of the inner nozzle; a second flow path for the second working fluid to flow inside the inner nozzle; a biasing member for biasing the outer nozzle and the inner nozzle toward their forward ends; and the outer nozzle having a pressure receiving portion, located rearward of the inlet, for receiving the pressure of the first working fluid toward the rear end against the biasing force of the biasing member, and when the pressure of the first working fluid is abnormal and the pressure is greater than the maximum value of the usage range, the outer nozzle and the inner nozzle move toward the rear end against the biasing force of the biasing member, the first working fluid supply port communicates with a third flow path formed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and the first working fluid flows through the third flow path; the fuel cell system comprises: a pressure measuring unit that measures the pressure of the fluid downstream of the outer nozzle; and a determination unit that determines whether the pressure abnormality has occurred based on the measurement value of the pressure measuring unit, and the determination unit determines that the pressure abnormality has occurred when the amount of change per unit time of the measurement value of the pressure measuring unit exceeds a predetermined amount.

11. A fuel cell system having an ejector, the ejector comprising: a main casing; an outer nozzle disposed within the main casing for injecting a first working fluid; an inner nozzle disposed inside the outer nozzle for injecting a second working fluid; and a first working fluid supply port for supplying the first working fluid into the main casing, the outer nozzle having an inlet for allowing the first working fluid to flow into the inside of the outer nozzle; a first flow path for the first working fluid to flow between the inner peripheral surface of the outer nozzle and the outer peripheral surface of the inner nozzle; a second flow path for the second working fluid to flow inside the inner nozzle; a biasing member for biasing the outer nozzle and the inner nozzle toward their forward ends; and the outer nozzle having a pressure receiving portion, located rearward of the inlet, for receiving the pressure of the first working fluid toward the rear end against the biasing force of the biasing member, and when the pressure of the first working fluid is abnormal and the pressure is greater than the maximum value of the usage range, the outer nozzle and the inner nozzle move toward the rear end against the biasing force of the biasing member, the first working fluid supply port communicates with a third flow path formed between the inner peripheral surface of the main casing and the outer peripheral surface of the outer nozzle, and the first working fluid flows through the third flow path; the fuel cell system comprises: a pressure measuring unit that measures the pressure of the fluid downstream of the outer nozzle; and a determination unit that determines whether 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 measurement value of the pressure measuring unit is greater than a predetermined value.

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