JP2009145046A - Hydrogen embrittlement sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of hydrogen embrittlement in a high-pressure hydrogen system, without depending on the selection of a material corresponding to a material test or the result thereof. <P>SOLUTION: A diaphragm member 2, which comprises a material most easily subjected to hydrogen embrittlement in the use material of the high-pressure hydrogen system, is provided to a sensor body 10 and the breakdown of the diaphragm member 2 is detected and decides that there is hydrogen embrittlement in the high-pressure hydrogen system. A hydrogen embrittlement phenomenon is monitored through a breakdown phenomenon in the diaphragm member 2 for detecting the hydrogen embrittlement or the effect thereof, before the constituent parts of the system are broken down. It is preferable that a stress concentrated part 3 for promoting the breakdown of the diaphragm member 2 is preferably formed to the diaphragm member 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrogen embrittlement sensor. More specifically, the present invention relates to an improvement in technology for coping with the hydrogen embrittlement phenomenon in high pressure hydrogen systems.

  The fuel cell system includes a piping system for supplying and discharging reaction gas (oxidizing gas and hydrogen gas as fuel gas) to the fuel cell, a power system for charging and discharging electric power, and a control system for overall control of the entire system. System is configured. In addition, a fuel cell system including, for example, a polymer electrolyte fuel cell is a kind of high-pressure hydrogen system including a tank (high-pressure hydrogen tank) that stores hydrogen gas at a high pressure.

One of the major problems in such a high-pressure hydrogen system is hydrogen embrittlement. This is a phenomenon (referred to as a hydrogen embrittlement phenomenon) in which hydrogen enters a metal material from a high-pressure hydrogen atmosphere to cause the material to degenerate and possibly lead to destruction. For example, in the current high-pressure hydrogen system, materials that satisfy the standards regarding the hydrogen embrittlement phenomenon are mainly used. As for prediction and determination of the hydrogen embrittlement phenomenon, techniques such as predicting hydrogen embrittlement cracks using dummy bolts have been proposed (see, for example, Patent Documents 1 and 2).
JP 2002-365202 A JP 2005-147712 A

  However, at present, only two types of materials are approved for use in high-pressure hydrogen systems, which is a major limitation in component design, and various tests and research have been conducted to solve the problem of large limitations. (For example, material data on hydrogen embrittlement is acquired in the NEDO hydrogen project). However, because there are only a few facilities in Japan that can perform strength tests in high-pressure hydrogen, the tests are dangerous, and there are legal restrictions, the problem is solved by users and designers of the system. It is not progressing at the speed expected by those concerned.

  Then, an object of this invention is to provide the hydrogen embrittlement sensor which can solve the subject of the hydrogen embrittlement in a high pressure hydrogen system.

  In order to solve this problem, the present inventor has made various studies. The above-described hydrogen embrittlement phenomenon is in the research stage, and the current situation is that the data is extremely insufficient. On the other hand, there is also a demand to select a higher-strength and cheaper material as soon as possible in response to a request for cost reduction and weight reduction of a fuel cell vehicle equipped with a fuel cell system. Under such a background, the present inventor, who has repeatedly studied from the viewpoint of predicting the hydrogen embrittlement phenomenon, has obtained new knowledge that leads to the solution of such problems.

  The hydrogen embrittlement sensor of the present invention is based on such knowledge, and the sensor body includes a diaphragm member made of a material most likely to be hydrogen embrittled among the materials used in the high-pressure hydrogen system, and detects the breakage of the diaphragm member. It is configured to determine hydrogen embrittlement in the high pressure hydrogen system.

  Currently, materials are tested under conditions of high-pressure hydrogen, and measures are taken to cope with hydrogen embrittlement by selecting materials according to the test results and using them in the system. It will be difficult in the future to completely suppress embrittlement. In this regard, in the present invention, a diaphragm member made of a material that is most likely to be embrittled among the materials used in the high-pressure hydrogen system is used, and the hydrogen embrittlement phenomenon is monitored through a fracture phenomenon in the diaphragm member. Thus, it is possible to detect hydrogen embrittlement and its influence before the system components are damaged. Such a hydrogen embrittlement sensor is only required to be arranged in any one of the high-pressure hydrogen systems, and the problem of hydrogen embrittlement can be solved without performing a material test or selection as in the past.

  In this hydrogen embrittlement sensor, it is preferable that the diaphragm member is formed with a stress concentration portion that promotes breakage of the diaphragm member. In such a case, the hydrogen embrittlement phenomenon in the system can be detected with higher sensitivity. Furthermore, it is also preferable that the stress concentration portion is formed on the side opposite to the side receiving the pressure of the diaphragm member.

  Moreover, the hydrogen embrittlement sensor concerning this invention is equipped with the pressure detection element inside the sealed space formed with a sensor body and a diaphragm member. In this case, the pressure detecting element is configured so as not to react with high-pressure hydrogen that enters when the diaphragm member breaks or to impair the function due to pressure.

  Moreover, it is preferable that the inside of the sealed space is filled with an inert gas or a low activity gas. With such a structure, when the diaphragm member is broken, the reaction between oxygen and the like in the sealed space and hydrogen can be suppressed.

  In the hydrogen embrittlement sensor according to the present invention, the diaphragm member includes two diaphragms, a pressure receiving diaphragm and a fracture detection diaphragm. The pressure receiving diaphragm is deformed by receiving the pressure of the high-pressure hydrogen, and the breakage can be detected by the action of the breakage detecting diaphragm corresponding to the deformation. Furthermore, in this case, it is also preferable that the pressure receiving diaphragm and the fracture detection diaphragm are arranged in parallel.

  In the present invention, the failure detection diaphragm and the sensor body are integrated, and the failure detection sensor is provided on the atmospheric release side of the failure detection diaphragm. For example, a strain gauge can be used as the breakage detection sensor.

  Alternatively, in the hydrogen embrittlement sensor, it is also preferable that the fracture detection diaphragm and the sensor body are separate, and a fracture detection sensor such as a strain gauge is provided on the atmospheric release side of the fracture detection diaphragm. The failure detection diaphragm is attached to the sensor body, for example, by welding, brazing or the like. In the hydrogen embrittlement sensor having such a structure, hydrogen that has passed through the pressure-receiving diaphragm and has entered the sealed space composed of two diaphragms (the pressure-receiving diaphragm and the failure detection diaphragm) passes through the failure detection diaphragm. Can be released to the atmosphere. Further, even if hydrogen enters in this way, it can be released to the atmosphere, so that the selection range of the material for the diaphragm material for fracture detection can be expanded. In this case, it is preferable that the fracture detection diaphragm is made of a material that allows hydrogen to permeate more easily than the pressure receiving diaphragm. Furthermore, it is preferable that the material is a sintered material having a porous interior and pressure strength, and the outside of the sintered material is covered with a ferritic stainless steel or a steel plate.

  In the hydrogen embrittlement sensor according to the present invention, the thickness and shape of the diaphragm member is such that the static fracture load of the diaphragm member obtained by a fracture test in high-pressure hydrogen is at least twice the actual operating load. The safety factor is set to be lower than the safety factor used for designing the actual part.

  Furthermore, the high-pressure hydrogen system according to the present invention includes any of the hydrogen embrittlement sensors described above.

  According to the present invention, the problem of hydrogen embrittlement in a high-pressure hydrogen system can be solved.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 6 show an embodiment of the present invention. The hydrogen embrittlement sensor 1 according to the present invention includes a diaphragm member 2 made of a material that is most prone to hydrogen embrittlement among the materials used in the high-pressure hydrogen system 100 in the sensor body 10, and detects the breakage of the diaphragm member 2 to detect the high pressure It is configured to determine hydrogen embrittlement in the hydrogen system 100 (see FIG. 4 and the like). In the following, an overall configuration example of a fuel cell system (hereinafter denoted by reference numeral 100), which is an example of the high-pressure hydrogen system 100, will be described first, and then the hydrogen embrittlement sensor 1 will be described.

  FIG. 1 shows a schematic configuration of a fuel cell system 100 in the present embodiment. As shown in the figure, a fuel cell system 100 includes a fuel cell 101, an oxidizing gas supply / discharge system (hereinafter also referred to as an oxidizing gas piping system) 300 that supplies air (oxygen) as an oxidizing gas to the fuel cell 101, a fuel A fuel gas supply / discharge system (hereinafter also referred to as a fuel gas piping system) 400 that supplies hydrogen as a gas to the fuel cell 101, a refrigerant piping system 500 that supplies the refrigerant to the fuel cell 101 and cools the fuel cell 101, A power system 600 that charges and discharges the power of the system and a control unit 700 that performs overall control of the entire system are provided.

  The fuel cell 101 is formed of, for example, a solid polymer electrolyte type and has a stack structure in which a large number of cells (single cells) 2 are stacked. Each cell 2 has an air electrode on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode on the other surface, and a pair of separators 20 so as to sandwich the air electrode and the fuel electrode from both sides. is doing. Fuel gas is supplied to the fuel gas flow path of one separator 20, and oxidizing gas is supplied to the oxidizing gas flow path of the other separator 20, and the fuel cell 101 generates electric power by this gas supply.

  The oxidizing gas piping system 300 includes a supply path 111 through which the oxidizing gas supplied to the fuel cell 101 flows, and a discharge path 112 through which the oxidizing off gas discharged from the fuel cell 101 flows. The supply path 111 is provided with a compressor 114 that takes in the oxidizing gas via the filter 113, and a humidifier 115 that humidifies the oxidizing gas fed by the compressor 114. The oxidizing off-gas flowing through the discharge path 112 is subjected to moisture exchange by the humidifier 115 through the back pressure regulating valve 116, and is finally exhausted into the atmosphere outside the system as exhaust gas. The compressor 114 takes in the oxidizing gas in the atmosphere by driving the motor 114a.

  The fuel gas piping system 400 includes a hydrogen supply source 121, a supply path 122 through which hydrogen gas supplied from the hydrogen supply source 121 to the fuel cell 101 flows, and a supply path for supplying hydrogen offgas (fuel offgas) discharged from the fuel cell 101. A circulation path 123 for returning to the confluence point A of 122, a pump 124 that pumps the hydrogen off gas in the circulation path 123 to the supply path 122, and a discharge path 125 that is branched and connected to the circulation path 123. .

  The hydrogen supply source 121 is composed of, for example, a high-pressure tank or a hydrogen storage alloy, and is configured to be able to store, for example, 35 MPa or 70 MPa of hydrogen gas. When the main valve 126 of the hydrogen supply source 121 is opened, hydrogen gas flows out to the supply path 122. The hydrogen gas is finally depressurized to, for example, about 200 kPa by the pressure regulating valve 127 and other pressure reducing valves, and supplied to the fuel cell 101.

  A shutoff valve 128 is provided on the upstream side of the confluence point A of the supply path 122. The circulation system of the hydrogen gas is configured by sequentially communicating a flow path on the downstream side of the joining point A of the supply path 122, a fuel gas flow path formed in the separator of the fuel cell 101, and the circulation path 123. Yes. The hydrogen pump 124 circulates and supplies the hydrogen gas in the circulation system to the fuel cell 101 by driving the motor 124a.

  The discharge passage 125 is provided with a purge valve 133 that is a shut-off valve. By appropriately opening the purge valve 133 when the fuel cell system 100 is in operation, impurities in the hydrogen off gas are discharged together with the hydrogen off gas to a hydrogen diluter (not shown). By opening the purge valve 133, the concentration of impurities in the hydrogen off-gas in the circulation path 123 decreases, and the concentration of hydrogen in the hydrogen off-gas circulated increases.

  The refrigerant piping system 500 includes a refrigerant circulation channel 141 communicating with a cooling channel in the fuel cell 101, a cooling pump 142 provided in the refrigerant circulation channel 141, and a radiator that cools the refrigerant discharged from the fuel cell 101. 143, a bypass flow path 144 that bypasses the radiator 143, and a three-way valve (switching valve) 145 that sets the flow of cooling water to the radiator 143 and the bypass flow path 144. The cooling pump 142 circulates and supplies the refrigerant in the refrigerant circulation channel 141 to the fuel cell 101 by driving the motor 142a.

  The power system 600 includes a high-voltage DC / DC converter 161, a battery 162, a traction inverter 163, a traction motor 164, and various auxiliary inverters 165, 166, and 167. The high-voltage DC / DC converter 161 is a direct-current voltage converter that adjusts the direct-current voltage input from the battery 162 and outputs it to the traction inverter 163 side, and the direct-current input from the fuel cell 101 or the traction motor 164. And a function of adjusting the voltage and outputting it to the battery 162. The charge / discharge of the battery 162 is realized by these functions of the high-voltage DC / DC converter 161. Further, the output voltage of the fuel cell 101 is controlled by the high voltage DC / DC converter 161.

  The battery 162 is configured such that battery cells are stacked and a constant high voltage is used as a terminal voltage, and surplus power can be charged or power can be supplementarily supplied under the control of a battery computer (not shown). The traction inverter 163 converts a direct current into a three-phase alternating current and supplies it to the traction motor 164. The traction motor 164 is, for example, a three-phase AC motor, and constitutes a main power source of, for example, a vehicle on which the fuel cell system 100 is mounted.

  Auxiliary machine inverters 165, 166, and 167 are motor control devices that control driving of corresponding motors 114a, 124a, and 142a, respectively. Auxiliary machine inverters 165, 166, and 167 convert a direct current into a three-phase alternating current and supply it to motors 114a, 124a, and 142a, respectively. Auxiliary machine inverters 165, 166, and 167 are, for example, pulse width modulation type PWM inverters, which convert a DC voltage output from fuel cell 101 or battery 162 into a three-phase AC voltage in accordance with a control command from control unit 700. The rotational torque generated by each motor 114a, 124a, 142a is controlled.

  The control unit 700 is configured as a microcomputer including a CPU, a ROM, and a RAM inside. The CPU executes a desired calculation according to the control program, and performs various processes and controls such as a thawing control of the pump 124 described later. The ROM stores control programs and control data processed by the CPU. The RAM is mainly used as various work areas for control processing. The control unit 700 inputs detection signals such as various pressure sensors, temperature sensors, and outside air temperature sensors used in the gas system (300, 400) and the refrigerant piping system 500, and outputs control signals to each component.

  Subsequently, an embodiment of the hydrogen embrittlement sensor 1 according to the present invention will be described (see FIG. 2 and the like).

<First Embodiment>
The hydrogen embrittlement sensor 1 includes a diaphragm member 2 made of a material that is most likely to be hydrogen embrittled among the materials used in the fuel cell system (high-pressure hydrogen system) 100 in the sensor body 10, and detects the breakage of the diaphragm member 2 The fuel cell system 100 is configured to determine hydrogen embrittlement.

  The sensor body 10 constitutes the main body of the hydrogen embrittlement sensor 1, and a dent that forms the cavity 4 is provided on the tip side thereof. A mounting screw portion 9 is formed on the outer periphery of the sensor body 10, and the hydrogen embrittlement sensor 1 of this embodiment is attached to a predetermined location of the fuel cell system 100 by the mounting screw portion 9 to monitor hydrogen embrittlement. Used for An O-ring 6 is provided as a sealing means in the vicinity of the escape of the mounting screw portion 9 (see FIG. 2).

  The diaphragm member 2 is a thin plate-like member formed so as to be informed of the influence of the hydrogen embrittlement phenomenon by breaking. As the material of the diaphragm member 2, it is conceivable to adopt a steel material such as SCM435 in addition to stainless steel SUS304, SUS410, SUS430, etc., which are considered to be susceptible to hydrogen embrittlement. In this embodiment, such a material is processed into a disk shape and attached to the tip of the sensor body 10 by welding or brazing, for example. Thus, the diaphragm member 2 attached to the tip of the sensor body 10 receives the pressure P of high-pressure hydrogen on the outer surface thereof (see FIG. 2).

  The surface of the diaphragm member 2 may be flat, but it is preferable that the diaphragm member 2 has a shape that promotes breakage. For example, the diaphragm member 2 in this embodiment has a stress concentration portion 3 formed of a notch on the surface of the high-pressure hydrogen side (the side receiving the pressure P of high-pressure hydrogen) (see FIG. 2). In this case, the stress in the stress concentration portion 3 is locally increased and the diaphragm member 2 is easily broken, so that the hydrogen embrittlement phenomenon in the fuel cell system 100 can be detected with higher sensitivity. In the present embodiment, a step is provided on the surface of the diaphragm member 2 so that the central portion of the diaphragm member 2 is thinner than other portions.

  In this case, it is also preferable to appropriately change the radius r of the fillet portion on both sides of the step bottom (see FIGS. 2 and 3). By appropriately changing the radius r of the fillet portion, the stress concentration rate in the stress concentration portion 3 of the diaphragm member 2 can be variously changed.

  Moreover, the pressure detection element 5 is provided in the inside of the sealed space (hollow part 4) formed with the sensor body 10 and the diaphragm member 2 (refer FIG. 2). The pressure detection element 5 detects a pressure change in the sealed space (cavity 4) when the diaphragm member 2 is deformed or broken due to hydrogen embrittlement, and outputs a detection signal through the pressure detection element electrode 8. To do. The pressure detection element 5 of the present embodiment is configured such that when the diaphragm member 2 is broken, it does not react with high-pressure hydrogen that enters the cavity 4 and does not impair the function due to pressure. Furthermore, the pressure detection element electrode 8 is provided so as to protrude from the base end side of the hydrogen embrittlement sensor 1 through the sensor body 10 (see FIG. 2).

  In the present embodiment, the inside of the sealed space (cavity 4) is filled with an inert gas or a low activity gas in advance. When the diaphragm member 2 breaks down, the high-pressure hydrogen gas and oxygen in the cavity 4 may react instantaneously. In this embodiment, however, hydrogen and oxygen This avoids falling into an unfavorable state. As such a gas, not only a rare gas such as argon can be used, but also a gas having low reactivity with hydrogen gas such as nitrogen gas can be used.

<Second Embodiment>
The sensor body 10 constitutes the main body of the hydrogen embrittlement sensor 1, and a dent that forms the cavity 4 is provided on the tip side thereof. A mounting screw portion 9 is formed on the outer periphery of the sensor body 10, and the hydrogen embrittlement sensor 1 of this embodiment is attached to a predetermined location of the fuel cell system 100 by the mounting screw portion 9 to monitor hydrogen embrittlement. Used for An O-ring 6 is provided as a sealing means in the vicinity of the escape of the mounting screw portion 9 (see FIG. 4).

  The diaphragm member 2 is a thin plate-like member formed so as to be informed of the influence of the hydrogen embrittlement phenomenon by breaking. In the present embodiment, a material that is susceptible to hydrogen embrittlement is processed into a disk shape and attached to the tip of the sensor body 10 by, for example, welding or brazing (see FIG. 6. The part welded by laser is shown). Thus, the diaphragm member 2 attached to the tip of the sensor body 10 receives the pressure P of high-pressure hydrogen on its outer surface (see FIG. 4).

  The surface of the diaphragm member 2 may be flat, but it is preferable that the diaphragm member 2 has a shape that promotes breakage. For example, in the diaphragm member 2 in the present embodiment, the stress concentration portion 3 formed of a notch is formed on the surface on the atmosphere opening side (the side communicating with the atmosphere and the above-described cavity 4 side in the present embodiment) ( (See FIGS. 4 and 5). In this case, the stress in the stress concentration portion 3 is locally increased and the diaphragm member 2 is easily broken, so that the hydrogen embrittlement phenomenon in the fuel cell system 100 can be detected with higher sensitivity. In the present embodiment, the stress concentration portion 3 composed of a linear notch is illustrated, but of course this is only an example and other shapes and structures may be used. Moreover, although the stress concentration part 3 in this embodiment is formed in the opposite side (cavity part 4 side) to the side which receives the hydrogen pressure P of the diaphragm member 2, the side which receives hydrogen pressure P contrary to this Or may be formed on both sides.

<Third Embodiment>
The hydrogen embrittlement sensor 1 of the present embodiment has a structure in which the diaphragm member 2 includes two diaphragms, a pressure receiving diaphragm 2a and a fracture detection diaphragm 2b (see FIG. 7).

  For example, in the hydrogen embrittlement sensor 1 in the above-described embodiment (second embodiment), when the hydrogen gas that has permeated through the diaphragm member 2 enters the cavity 4, the internal pressure of the cavity 4 gradually increases. If the internal pressure is increased in this way, there is a possibility that it is erroneously determined as if the diaphragm member 2 is broken even if the diaphragm member 2 is not broken. In this respect, in this embodiment, the diaphragm member 2 has a structure composed of two members, and a detection signal is output by an action when one of the diaphragms (destruction detection diaphragm 2b) is deformed by receiving the pressure P of high-pressure hydrogen. Therefore, the possibility of making an erroneous determination as described above is extremely low.

  The failure detection diaphragm 2b in the present embodiment has a structure integrated with the sensor body 10 (see FIG. 7). Further, on the rear surface side (atmosphere release side) of the failure detection diaphragm 2b, for example, a strain detection element 11 made of a strain gauge is provided as an example of a sensor capable of detecting the deformation action of the failure detection diaphragm 2b. Yes. The strain detection element 11 detects the strain of the failure detection diaphragm 2b when the pressure receiving diaphragm member 2a is broken due to hydrogen embrittlement, and outputs a detection signal through the strain detection element electrode 12 (see FIG. 7).

  In such a hydrogen embrittlement sensor 1, it is preferable that the pressure-receiving diaphragm 2a and the fracture detection diaphragm 2b are arranged in parallel as in the present embodiment (see FIG. 7). In such a case, a sealed space without an inclined surface can be formed between the two diaphragms 2a and 2b, and the strain of the failure detection diaphragm 2b when the pressure receiving diaphragm 2a breaks is more easily generated.

  In addition, the hydrogen embrittlement sensor 1 of the present embodiment in which the fracture sensor (strain detection element 11) is provided on the atmosphere opening side of the fracture detection diaphragm 2b has a part of the fracture sensor (strain detection element 11) converted to hydrogen. It is also a structure that is difficult to touch. Therefore, it is possible to omit the explosion-proof structure that has been conventionally provided.

<Fourth Embodiment>
In the hydrogen embrittlement sensor 1 of the present embodiment, the diaphragm member 2 includes two diaphragms, a pressure receiving diaphragm 2 a and a fracture detection diaphragm 2 b, and the fracture detection diaphragm 2 b has a separate structure from the sensor body 10. (See FIG. 8). A breakdown detection sensor (strain detection element 11) such as a strain gauge is provided on the atmospheric release side of the breakdown detection diaphragm 2b. The failure detection diaphragm 2b is attached to the sensor body 10 by welding, brazing or the like, for example.

  In the hydrogen embrittlement sensor 1 having such a structure, since the selection range of the material constituting the fracture detection diaphragm 2b can be expanded, the pressure reception diaphragm 2a is transmitted, and two diaphragms (the pressure reception diaphragm 2a and the fracture detection diaphragm 2b) are transmitted. Hydrogen that has entered the sealed space (cavity portion 4) constituted by the diaphragm 2b) can be further transmitted through the fracture detection diaphragm 2b and released to the atmosphere.

  Here, the fracture detection diaphragm 2b is preferably made of a material that allows hydrogen to pass through more easily than the pressure receiving diaphragm 2a. For example, the material is preferably a sintered material having a porous interior and pressure strength, and the outside of the sintered material is covered with a ferritic stainless steel or a steel plate. It will be as follows if a specific example of a material is given and demonstrated.

As a first example, the pressure receiving diaphragm 2a is austenitic stainless steel (diffusion coefficient is about 10 ^-14 cm ² / sec, the diffusion is slow, such as hydrogen gas), the as the material of the collapse detection diaphragms 2b ferrite or Martensitic stainless steel or steel material is preferred. Gas diffusion in these materials is about 10 ⁹ times faster than that of austenitic stainless steel (diffusion coefficient is about 10 ⁻⁵ cm ² / sec).

  As a second example, when the pressure-receiving diaphragm 2a is ferritic stainless steel or steel (diffusion is fast. The diffusion speed of both materials is the same level), a stainless sintered material is sandwiched between ferrite stainless steel plates or steel plates, etc. (See FIG. 9).

In the case of the failure detection diaphragm 2b illustrated in FIG. 9, the thickness of the outer ferrite stainless steel plate indicated by reference numeral 2b _out is as thin as possible than that of the pressure receiving diaphragm 2a as long as pressure resistance can be secured. In this case, the basic pressure resistance at the same time to provide a sintered material of the center (inside) indicated by the reference numeral 2b _in, if the pressure receiving diaphragm 2a is damaged through the sintered material 2b _in the porous Since a large amount of hydrogen may leak out, the outside is covered with a stainless steel plate 2b _out for the purpose of preventing this. Sintered material 2b _in the central hydrogen permeation is faster than the pressure receiving diaphragm 2a as a whole since it does not become a failure of the hydrogen permeation. Considering corrosion resistance, ferritic stainless steel is suitable, but a steel plate may be adopted. Such a failure detection diaphragm 2b can be integrated with the sensor body 10 by welding or brazing. In the case of the above-described structure, it is possible to satisfy the contradictory characteristics of speeding up hydrogen gas permeation while ensuring pressure resistance.

  As is clear from the description in the above embodiments, the hydrogen embrittlement sensor 1 according to the present invention has the most embrittlement among materials used in a high-pressure hydrogen system (for example, the fuel cell system 100). Using the diaphragm member 2 made of the material to be worried about, the hydrogen embrittlement phenomenon can be monitored through the fracture phenomenon in the diaphragm member 2 using the pressure change or the strain change as a parameter. For this reason, the hydrogen embrittlement sensor 1 formed separately is not subjected to the current method of selecting a material according to the result of the material test under high-pressure hydrogen conditions and using it in the system. It is possible to monitor the hydrogen embrittlement phenomenon simply by attaching it to this location, and it is possible to solve the problem of hydrogen embrittlement without conducting a material test or making a selection as in the past. In addition, the hydrogen embrittlement sensor 1 when placed in a high-pressure hydrogen system is also preferable in that it can make a more accurate determination on hydrogen embrittlement because it is affected by pressure and temperature fluctuations in the actual system.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the fuel cell system 100 suitable for a vehicle is illustrated as an example of a high-pressure hydrogen system to which the hydrogen embrittlement sensor 1 can be applied (see FIG. 1), but the present invention can also be applied to other high-pressure facilities. Needless to say.

  In addition, the diaphragm member 2 (or the pressure receiving diaphragm 2a and the fracture detection diaphragm 2b constituting the diaphragm member 2) described in each of the above-described embodiments can be further set to a predetermined form (thickness and shape). For example, the thickness and shape of the diaphragm member 2 (or the pressure-receiving diaphragm 2a and the failure detection diaphragm 2b constituting the diaphragm member 2) are determined by a static fracture load of the diaphragm member 2 obtained in advance by a fracture test in high-pressure hydrogen. May be designed to be at least twice the actual operating load. That is, when designing the thickness and notch shape of the diaphragm portion 2, the static fracture load is measured in advance in a hydrogen test, and this value is at least twice the safety factor with respect to the actual operating load. You may design as follows. “Twice” here is based on the fact that the fatigue strength in hydrogen is based on approximately half of the static strength, and can be appropriately changed according to various forms.

  Further, when designing the diaphragm portion 2 (or the pressure receiving diaphragm 2a constituting the diaphragm portion 2), the safety factor may be set to be lower than the safety factor used for designing the actual part (part actually used). That is, since the diaphragm portion 2 (or the pressure-receiving diaphragm 2a constituting the diaphragm portion) in the present invention should be destroyed earlier under the influence of hydrogen embrittlement, the safety factor of the actually used component (the component is different from other components). If the safety factor is set to be lower than the normal safety factor when actually used as a component, it is suitable as a component used for monitoring.

It is a figure which shows the structural example of the fuel cell system which is an example of a high pressure hydrogen system. It is a fragmentary sectional view showing a 1st embodiment of a hydrogen embrittlement sensor concerning the present invention. It is the elements on larger scale of the stress concentration part formed in the diaphragm member. It is a fragmentary sectional view which shows 2nd Embodiment of the hydrogen embrittlement sensor concerning this invention. It is a figure which shows the example of a shape by the side of air release of a diaphragm member. It is a figure which expands and shows the part which welded the diaphragm member to the sensor body with the laser. It is a fragmentary sectional view showing a 3rd embodiment of a hydrogen embrittlement sensor. It is a fragmentary sectional view showing a 4th embodiment of a hydrogen embrittlement sensor. It is a figure which shows the structural example of the diaphragm for a destruction detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydrogen embrittlement sensor, 2 ... Diaphragm member, 2a ... Pressure receiving diaphragm. 2b: Diaphragm for failure detection, 3 ... Stress concentration portion, 4 ... Cavity (sealed space formed by sensor body and diaphragm member), 5 ... Pressure detection element, 10 ... Sensor body, 11 ... Strain detection element (destruction) Detection sensor), 100 ... Fuel cell system (high pressure hydrogen system)

Claims (13)

  The sensor body is provided with a diaphragm member made of the material most likely to be hydrogen embrittled among the materials used in the high pressure hydrogen system, and is configured to detect the hydrogen embrittlement in the high pressure hydrogen system by detecting the breakage of the diaphragm member. Hydrogen embrittlement sensor.   The hydrogen embrittlement sensor according to claim 1, wherein a stress concentration portion that promotes the destruction of the diaphragm member is formed in the diaphragm member.   The hydrogen embrittlement sensor according to claim 2, wherein the stress concentration portion is formed on a side opposite to a side receiving the pressure of the diaphragm member.   The hydrogen embrittlement sensor according to any one of claims 1 to 3, further comprising a pressure detection element in a sealed space formed by the sensor body and the diaphragm member.   The hydrogen embrittlement sensor according to claim 4, wherein the sealed space is filled with an inert gas or a low activity gas.   The hydrogen embrittlement sensor according to any one of claims 1 to 5, wherein the diaphragm member includes two diaphragms, a pressure receiving diaphragm and a fracture detection diaphragm.   The hydrogen embrittlement sensor according to claim 6, wherein the pressure receiving diaphragm and the fracture detection diaphragm are arranged in parallel.   The hydrogen embrittlement sensor according to claim 6 or 7, wherein the fracture detection diaphragm and the sensor body are integrated, and a fracture detection sensor is provided on the atmospheric release side of the fracture detection diaphragm.   The hydrogen embrittlement sensor according to claim 6 or 7, wherein the failure detection diaphragm and the sensor body are separate bodies, and a failure detection sensor is provided on the atmosphere release side of the failure detection diaphragm.   The hydrogen embrittlement sensor according to claim 9, wherein the fracture detection diaphragm is made of a material that allows hydrogen to permeate more easily than the pressure-receiving diaphragm.   11. The hydrogen embrittlement sensor according to claim 10, wherein the material is a sintered material having a porous inside and having a pressure strength, and the outside of the sintered material is covered with a ferritic stainless steel or a steel plate.   The thickness and shape of the diaphragm member is designed so that the static fracture load of the diaphragm member obtained by the fracture test in high-pressure hydrogen is at least twice the actual operating load, and for designing the actual parts The hydrogen embrittlement sensor according to any one of claims 1 to 11, wherein the hydrogen embrittlement sensor is set to a safety factor lower than a used safety factor.   A high-pressure hydrogen system comprising the hydrogen embrittlement sensor according to any one of claims 1 to 12.

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