WO2009116593A1

WO2009116593A1 - Hydrogen generator

Info

Publication number: WO2009116593A1
Application number: PCT/JP2009/055338
Authority: WO
Inventors: 敏夫堀口; ロバート・ジェイチャートン; ジュリア・エスウィーヴィング; ダーレン・ピースキャッターグッド
Original assignee: オリンパス株式会社
Priority date: 2008-03-21
Filing date: 2009-03-18
Publication date: 2009-09-24
Also published as: JP2009227512A

Abstract

Disclosed is a hydrogen generator comprising a plurality of fuel pellets (10) formed of a material containing a compound capable of evolving hydrogen upon being heated, a pressure-resistant container for storing the plurality of fuel pellets, and a control substrate loaded with a controller for regulating the evolution of hydrogen from the fuel pellets. A plurality of igniters corresponding to the plurality of fuel pellets are installed on a substrate (30) within the pressure-resistant container. The plurality of fuel pellets are placed on the respective igniters and are separated from each other by a lattice-shaped frame formed of a hydrogen-impermeable heat insulating member (32).

Description

Hydrogen generator

The present invention relates to a hydrogen generator for supplying hydrogen gas to a hydrogen fuel cell for generating electric energy.

2. Description of the Related Art Mobile information devices such as mobile phones, PDAs, and digital cameras have mainly used rechargeable secondary batteries such as lithium ion batteries as a power source. In recent years, along with the demands for high functionality, multi-function, high speed, and long-time driving of these devices, small fuel cells are expected as a new power source, and some prototypes or trials have started.

Unlike conventional secondary batteries, the fuel cell does not require charging, and can be put into a state where the device can be operated for a long time simply by replenishing the fuel or replacing the fuel cartridge. Among these fuel cells, hydrogen fuel cells that use hydrogen as fuel can increase the power density due to their characteristics, so that they can handle a certain amount of peak load in accordance with conventional secondary batteries. As a battery, application to portable information devices and the like is being studied. In particular, in the case of portable information devices, the key is how to store hydrogen in a compact and lightweight manner.

In US Patent Application Publication No. 2005/0227136, it is proposed that a tank made of a hydrogen storage alloy is filled with hydrogen and used. However, hydrogen storage alloys are heavy and large in size, and are not suitable for portable information devices. When the hydrogen absorbed in the hydrogen storage alloy is used, it is necessary to refill the tank with hydrogen by some method. Therefore, there is a problem that infrastructure for that purpose must be prepared.

In order to solve these problems related to hydrogen storage alloys, WO 02/18267 discloses a hydrogen generator that generates hydrogen by thermally decomposing a substance containing a large amount of hydrogen such as ammonia and borane. Proposed. According to this method, since hydrogen is generated from the solid fuel, it is not necessary to newly prepare a heavy and large hydrogen storage alloy tank or an infrastructure for filling the hydrogen storage alloy with gaseous hydrogen.

However, the physical structure of the hydrogen generator described in the above international application can be applied to general uses such as a portable generator that can be used outdoors, but cannot be applied to a hydrogen generator of a very small size. . In portable information devices such as digital cameras and PDAs, the size and shape of the hydrogen generator is the same size and shape as the current primary or secondary battery (for example, 18650 size (diameter approximately 18 mm × height approximately 65 mm)) is desired. Such a size and shape is impossible in the structure of the hydrogen generator.

In addition, the international application describes a small concrete means for heating the temperature of ammonia borane to 100 ° C. or higher in order to generate hydrogen from ammonia borain in the hydrogen generator for portable information devices. It has not been.

Furthermore, it does not describe the specific structure of the hydrogen generator, the configuration of each part, the control means, etc. for making the hydrogen generator small.

The present invention has been made in view of the above points, and can generate hydrogen stably and efficiently from a material containing a compound that generates hydrogen even in a small size. It aims at providing the hydrogen generator which can improve generation amount.

According to one aspect of the hydrogen generator of the present invention,
A plurality of fuel pellets composed of a material containing a compound that generates hydrogen when heated;
A pressure vessel for storing the plurality of fuel pellets;
A controller for controlling hydrogen generation from the fuel pellets;
A substrate disposed in the pressure vessel;
A plurality of igniters provided corresponding to the plurality of fuel pellets on the substrate and heating the corresponding fuel pellets, such that each one fuel pellet is disposed thereon;
A grid-like frame composed of a heat-insulating member that is impermeable to hydrogen for isolating each of the fuel pellets from other fuel pellets;
A hydrogen generator is provided.

FIG. 1 is a diagram showing a configuration of fuel pellets used in a hydrogen generator. FIG. 2 is a diagram showing the configuration of the hydrogen generator according to the first embodiment of the present invention. FIG. 3 is a diagram showing an internal structure of the hydrogen generator shown in FIG. FIG. 4 is a diagram showing a configuration of the hydrogen generator when the control substrate is taken out of the pressure vessel of the hydrogen generator as a modification of the first embodiment. FIG. 5 is a top view of the hydrogen generation unit. FIG. 6 is a cross-sectional view of the hydrogen generation unit. FIG. 7A is a diagram showing a horizontal positional relationship of the generator with respect to the lattice-shaped heat insulating member. FIG. 7B is a diagram showing a horizontal positional relationship of heat mix, ammonia borane, and aluminum foil with respect to the lattice-shaped heat insulating member. FIG. 7C is a diagram illustrating a horizontal positional relationship of the carbon filter with respect to the lattice-shaped heat insulating member. FIG. 7D is a diagram illustrating a horizontal positional relationship of the lid with respect to the lattice-shaped heat insulating member. FIG. 8 is a diagram illustrating a configuration of a drive circuit of the igniter. FIG. 9 is a schematic diagram for explaining a method of connecting a drive control signal to the generator. FIG. 10 is a schematic diagram for explaining another connection method of the drive control signal to the generator. FIG. 11 is a diagram showing a part of the correspondence between the input signal and the output signal of the decoder. FIG. 12 is a block configuration diagram of a controller mounted on the control board. FIG. 13 is a flowchart of the operation sequence of the microcontroller (CPU). FIG. 14 is a diagram showing the internal structure of the hydrogen generator according to the second embodiment of the present invention. FIG. 15 is a diagram showing an internal structure of a modification of the hydrogen generator according to the second embodiment. FIG. 16 is a top view of a hydrogen generator according to a third embodiment of the present invention. FIG. 17 is a top view of a modification of the hydrogen generator according to the third embodiment.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[First embodiment]
Before describing the hydrogen generator according to the first embodiment of the present invention, the principle of hydrogen generation will be described.

As shown in FIG. 1, a fuel pellet 10 used in a hydrogen generator includes an ammonia borane (NH ₃ BH ₃ ) 12 that is a hydrogen generating compound, and a heat mix 14 for heating the ammonia borane 12. Is composed of. The ammonia borain 122 and the heat mix 14 are each solidified into a predetermined shape, here, a cylindrical shape by applying an appropriate pressure. Then, the fuel pellet 10 is configured by further applying pressure to the ammonia borane 122 and the heat mix 14 so as to be integrated. The pressure applied to the ammonia / borane 12 is required to be preferably a value of 50 MPa to 250 MPa experimentally.

Here, the ammonia borain 12 and the heat mix 14 will be described.
Ammonia / borane 12 contains about 20% hydrogen by mass, is a solid hydrogen source that is solid and non-explosive at room temperature, and generates hydrogen by thermal decomposition. If the volume is the same, it contains twice as much hydrogen as liquid hydrogen. Ammonia borane 12 is usually a powder, but is a substance that can be pressed into a hard pellet, rod, cone, or the like by applying pressure as necessary.

The ammonia borane 12 is thermally decomposed in three stages by raising the temperature to generate hydrogen. That is, when ammonia borane 12 is heated, it melts at about 100 ° C. to become a liquid, and then generates one molecule of hydrogen. The reaction formula in that case is as the following formula (1), and this is the first stage hydrogen generation reaction.

NH ₃ BH ₃ → NH ₂ BH ₂ + H ₂ (1)
This reaction is an exothermic reaction, and the temperature of the ammonia borane 12 itself rises due to the heat of reaction, and proceeds to the second stage hydrogen generation reaction. That is, the NH ₂ BH ₂ produced in the first stage hydrogen generation reaction further increases in temperature and generates one molecule of hydrogen at about 150 ° C. The reaction formula in that case is as the following formula (2), and this is the second stage hydrogen generation reaction.

NH ₂ BH ₂ → NHBH + H ₂ (2)
This reaction is also an exothermic reaction and theoretically generates heat sufficient to raise the temperature of NHBH to a temperature at which NHBH can perform the third stage of thermal decomposition. When the temperature exceeds about 480 ° C., the remaining NHBH generates the last molecule of hydrogen. The reaction formula in that case is as the following formula (3), and this is the third stage hydrogen generation reaction.

NHBH → BN + H ₂ (3)
Theoretically, this third stage hydrogen generation reaction also generates sufficient heat for complete pyrolysis.

Thus, the ammonia borane 12 generates three molecules of hydrogen from one molecule when heated.

On the other hand, the heat mix 14 is a mixture of lithium aluminum hydride (LiAlH ₄ ) and ammonium chloride (NH ₄ Cl). This becomes a heat source that generates heat by itself when given a small amount of heat by a heater or the like from the outside, and heats the ammonia borane 12. Further, not only as a heat source, but some hydrogen is generated as in the following formula (4).

LiAlH ₄ + NH ₄ Cl → LiCl + AlN + 4H ₂ (4)
The heat mix 14 is not limited to such a mixture of LiAlH ₄ and NH ₄ Cl, but is necessary for the ammonia borane 12 to start thermal decomposition when a small amount of heat is applied from the outside. Any material may be used as long as it has a characteristic of generating heat by itself.

The fuel pellet 10 composed of such ammonia borane 12 and heat mix 14 has a diameter of 3 mm to 10 mm and an overall height of about 3 mm to 10 mm in consideration of use for portable information equipment. It is preferable. According to the experiments by the present inventors, hydrogen could be generated with high efficiency in pellets having a diameter of about 5.2 mm and a height of about 3.4 mm. In this fuel pellet 10, the ratio of ammonia borain 12 to heat mix 14 is set to a mass ratio of about 4: 1 to 5: 1 so that hydrogen generation with the highest yield is experimentally performed. It has been confirmed.

Next, a hydrogen generator using the fuel pellet 10 as described above will be described.
As shown in FIG. 2, the case of the hydrogen generator according to the first embodiment of the present invention is a pressure vessel 16 because hydrogen is generated therein, and is made of a sufficiently strong member such as stainless steel. The A hydrogen generation port 18 is provided on one side surface of the pressure vessel 16 of the hydrogen generator. A carbon filter (not shown) that absorbs impurities other than hydrogen is incorporated inside the hydrogen generation port 18. The hydrogen generation port 18 is externally provided with a stop valve (not shown) that can be opened and closed from the outside. Further, a connector 20 for inputting and outputting electrical signals is also provided on the side surface where the hydrogen generation port 18 is provided. The connector 20 is provided with an output terminal for a signal indicating the state of the hydrogen generator and an input terminal for a signal for controlling the operation. The connector 20 is connected to a device (not shown) located outside the hydrogen generator by a cable (not shown).

Also, a rupturable plate 22 is provided on one surface, for example, the upper surface, of the pressure vessel 16 of the hydrogen generator. The rupturable plate 22 is a commercially available component configured to be broken when the pressure applied to the rupturable plate 22 exceeds a predetermined pressure. This is a safety device that prevents the hydrogen generator from entering a dangerous state such as an explosion by rupturing the rupturable plate 22 before the internal pressure of the pressure vessel 16 exceeds the maximum pressure resistance due to some abnormal operation. The rupturable plate 22 may be a mechanical valve such as a safety valve PRV (Pressure Relief Valve).

In addition, in order to maintain an airtight state, a member for preventing leakage of an O-ring or the like is used in combination on the hydrogen generator 18, the connector 20, and the rupture plate 22 attached to the pressure vessel 16 of the hydrogen generator.

Next, the internal structure of such a hydrogen generator will be described with reference to FIG.
A control board 24 on which a control circuit for controlling the operation of the hydrogen generator is mounted is disposed inside the pressure vessel 16 of the hydrogen generator. The control board 24 is configured by heat resistance and insulation such as glass epoxy and phenol resin. The control board 24 is connected to the connector 20 on one end side. A connector 26 is provided on the other end side of the control board 24.

A connector 28A provided on the board 30A can be connected to the connector 26. A lattice-like heat insulating member 32A is arranged on the substrate 30A. Further, a connector 34A is further provided on the surface of the board 30A opposite to the connector 28A. A connector 28B provided on the board 30B can be connected to the connector 34A. On the substrate 30B, a lattice-like heat insulating member 32B is arranged. Further, a connector 34B is further provided on the side opposite to the connector 28B. Here, the unit composed of the substrate 30A, the connector 28A, the heat insulating member 32A, and the connector 34A, and the unit composed of the substrate 30B, the connector 28B, the heat insulating member 32B, and the connector 34B are hydrogen generation units and are the same. It is. These two hydrogen generation units are connected by a connector 28B and a connector 34A, and further they are connected to the control board 24 by a connector 28A and a connector 26. In this embodiment, the connector 34B is a dummy that is not connected anywhere.

As shown in FIG. 4, the control substrate 24 may be disposed outside the pressure vessel 16 of the hydrogen generator. That is, the connector 28A comes out from the lower side of the pressure vessel 16 and the connector 26 of the control board 24 is connected to the connector 28A. Such a configuration is economical because the control board 24 is hardly affected by a rise in temperature, a change in pressure, etc., and can withstand multiple uses.

3 and 4 show an example in which the hydrogen generation units are arranged in two stages, but the number of stages is of course not limited thereto. It is also possible to arrange a plurality of hydrogen generation units in the depth direction of the figure.

Next, the hydrogen generation unit will be described in detail. Since the two hydrogen generation units have the same structure, in the following description, unless specifically required, the

substrates

30A and 30B are the substrate 30, the

connectors

28A and 28B are the connectors 28, and the

heat insulating members

32A and 32B are thermally insulated. The member 32 and the

connectors

34A and 34B will be described as the connector 34.

That is, in the hydrogen generation unit, a lattice-like heat insulating member 32 is bonded onto the substrate 30 as shown in FIG. In each lattice, one fuel pellet 10 as shown in FIG. 1 is stored. Although this lattice-shaped heat insulating member 32 has a thickness of about 1 mm, depending on the material, it has a heat insulating function and strength. Further, the inner diameter of the lattice has a slightly larger dimension than the diameter of the cylindrical fuel pellet 10 stored therein. For example, in the case of the fuel pellet 10 having a diameter of 5.2 mm, the inner diameter of the lattice is set to 5.4 mm square with an allowance of 0.1 mm. By providing an appropriate margin in this way, it is possible to prevent problems such as tilting and holding when the fuel pellets 10 are stored in the lattice. On the contrary, the inside of the lattice is too large. It can be prevented that the fuel pellets 10 move and play in the lattice, and normal hydrogen generation is not performed away from the igniter. The lattice-like heat insulating member 32 is bonded to the substrate 30 with, for example, an adhesive having a caulking function so that there is no gap. In the example of FIG. 5, the fuel pellets 10 that can store a total of 35 fuel pellets 10 in 7 rows and 5 columns are shown, but the number is not limited to this.

The lattice-shaped heat insulating member 32 is formed of a heat insulating member that does not allow gas such as hydrogen to pass through, and prevents heat generated when hydrogen is generated from one fuel pellet 10 from the periphery of the fuel pellet 10. Has function. With this function, heat necessary for hydrogen generation is not dissipated from the periphery of the fuel pellet 10 and is not transmitted to the surrounding fuel pellet 10, that is, has a heat retaining and heat insulating function. This heat retention / heat insulation function becomes more important as the fuel pellet 10 becomes smaller, and it becomes necessary to use a member having a lower thermal conductivity and a higher heat-resistant temperature. In addition, since it is necessary to endure the high temperature of about 150 degreeC as a material of the grid | lattice-like heat insulation member 32, an epoxy resin, a polycarbonate resin, etc. can be used. Further, depending on conditions such as when the heat generation time is short, a member such as wood can be used.

The method of manufacturing the lattice-shaped heat insulating member 32 is limited to the case of a resin material, but there are a method of manufacturing by integral molding using a mold and a method of combining a plurality of members obtained by cutting a plate-shaped member. The method is also acceptable. However, an airtight state must be maintained between adjacent lattices.

A thin aluminum foil having a thickness of 0.01 to 0.02 mm may be pasted on the surface of the lattice-like heat insulating member 32. By sticking the aluminum foil, the heat generated from the fuel pellets 10 in the lattice is reflected by the aluminum foil and returned to the fuel pellets 10, thereby further increasing the temperature of the fuel pellets 10. When the size of the fuel pellet 10 is small, it is necessary to prevent the heat generated from the fuel pellet 10 from escaping as much as possible. Therefore, it is more effective to apply the aluminum foil.

The lattice-like heat insulating member 32 is in contact with the periphery of the cylindrical fuel pellet 10, and a gap between the lattice-like heat insulating member 32 and the fuel pellet 10 is formed at a corner portion. This gap also has a function as a space for hydrogen generated from the fuel pellet 10. That is, the case of the hydrogen generator is a sealed pressure vessel 16, and if hydrogen is generated inside, the internal pressure rises. For this reason, if there is no space inside the pressure vessel 16, it is necessary to design a pressure resistant to withstand a high pressure because the pressure rises rapidly. On the other hand, if there is a space somewhere inside the pressure vessel 16, the pressure rise can be reduced. Of course, there is also a method of designing a grid that does not provide the gap and providing a pressure relief space somewhere inside the hydrogen generator. However, it is not preferable because the shape of such a lattice is complicated and the balance of the space inside the hydrogen generator is poor. In the embodiment of FIG. 5, by providing the gaps uniformly within the pressure vessel 16 of the hydrogen generator, the overall balance can be improved and the pressure resistance design can be suppressed to a low pressure. Therefore, it is advantageous that the degree of freedom of design can be widened, cost reduction and safety improvement can be achieved.

Next, the state around the fuel pellets 10 stored in the lattice on the hydrogen generation unit will be described.

Further, in the hydrogen generation unit, as shown in FIG. 6, a mica insulating sheet 36 is disposed on the substrate 30, and an igniter 38 is provided on the substrate 30 corresponding to each fuel pellet 10. . The igniter 38 generates heat by flowing a current in accordance with a control signal from a control circuit (not shown) mounted on the control board 24. As a result, the heat mix 14 is reacted to generate heat, and the ammonia borane 12 is heated by the heat to generate hydrogen. As described above, the heat mix 14 and the ammonia borane 12 constitute the cylindrical fuel pellet 10.

On each fuel pellet 10, an aluminum foil 40 having a circular thickness of 0.01 to 0.02 mm and the same diameter as the diameter of the fuel pellet 10 is placed. The aluminum foil 40 reflects heat generated from the heat mix 14 ignited by the igniter 38 and heat generated from the hydrogen generation reaction generated from the ammonia borane 12 due to the heat. Reflection by the aluminum foil 40 has a function of helping heat stay around the fuel pellet 10 instructed to generate hydrogen.

On the aluminum foil 40, a square carbon filter 42 having a size substantially matching the inner dimension of the lattice is placed. The carbon filter 42 has a function of absorbing impurities other than hydrogen. And the cover 44 of a circular heat insulation member is arranged on it. The lid 44 is slightly larger than the diameter of the fuel pellet 10 and is large enough to enter the lattice opening without any gap. The lid 44 prevents the fuel pellets 10, the carbon filter 42, and the like inside the lattice from moving due to a reaction when hydrogen is generated. The lid 44 of the heat insulating member can be made of the same material as the lattice-shaped heat insulating member 32, that is, epoxy resin, polycarbonate resin, wood, or the like.

As can be seen from FIG. 6, a cylindrical fuel pellet 10 is stored in a square lattice, and a circular aluminum foil 40, a square carbon filter 42, and a circular insulating member lid 44 are laminated in that order. Has been. Here, the reason why only the carbon filter 42 is square is as follows.

There is a gap between the square lattice and the cylindrical fuel pellet 10. If the carbon filter 42 is circular, the gap is exposed above the grid. When hydrogen is generated in this state, if an impurity is generated, the impurity goes out of the lattice as it is. If the impurities cannot be absorbed by the impurity absorption filter attached to the hydrogen generation port 18, the impurities will flow out to the hydrogen fuel cell. In a hydrogen fuel cell, high purity is required for hydrogen. If the hydrogen purity is low, the hydrogen fuel cell is destroyed. In order to prevent this, it is necessary to prevent impurities from flowing out at the stage of each fuel pellet 10. Therefore, the carbon filter 42 needs to have a square shape that matches the inner radius of the lattice.

Another reason is that when an experiment was conducted with the aluminum foil 40 and the lid 44 similarly squared, a problem occurred. That is, the heat during the reaction is accumulated inside the lattice, and the heat is transmitted to the other fuel pellets 10 around it, and the reaction is started up to the fuel pellets 10 that did not instruct the generation of hydrogen. In order to prevent such a false reaction, it is necessary to have a structure in which heat during the reaction escapes to some extent. For these reasons, the shapes of the aluminum foil 40, the carbon filter 42, and the lid 44 are determined.

FIGS. 7A to 7D are views showing the horizontal positional relationship of the igniter 38, the heat mix 14, the ammonia borane 12, the aluminum foil 40, the carbon filter 42, and the lid 44 with respect to the lattice-like heat insulating member 32. FIG. is there.

FIG. 7A shows a case where the generator 38 is a surface mount type resistor as described later, and the outer shape is a square. The figure shows that the center point of the generator 38 substantially coincides with the center point of the grid-like plane formed by the grid-like heat insulating member 32. Similarly, when the outer shape of the resistor is rectangular, the center point is arranged at a position that substantially coincides with the center point of the lattice-shaped plane formed by the lattice-shaped heat insulating member 32.

FIG. 7B shows that the center points of the cylindrical heat mix 14, the ammonia borane 12, and the aluminum foil 40 substantially coincide with the center points of the lattice openings formed by the lattice-shaped heat insulating members 32. ing. The figure also shows that the length of one side of the lattice opening is slightly larger than the members of the heat mix 14, the ammonia borane 12, and the aluminum foil 40, and there is a gap.

FIG. 7C shows that the carbon filter 42 is the same size as the lattice aperture, and that its center points necessarily coincide.

7D, the diameter of the lid 44 is almost the same as one side of the lattice opening, and unlike the heat mix 14, the ammonia borane 12, and the aluminum foil 40, there is no gap between one side of the lattice opening. It is shown that.

As described above, the horizontal positional relationship between the fuel pellet 10 and the igniter 38 is regulated by the lattice-shaped heat insulating member 32 so that the respective center points are substantially coincident with each other. In this way, the heat generated from the igniter 38 is accurately transmitted to the heat mix 14 below the fuel pellet 10. As a result, the heat mix 14 sufficiently heats the ammonia borane 12, Hydrogen can be generated from the borane 12 to the maximum extent.

Next, the ignition device 38 will be described.
The igniter 38 is disposed at a position corresponding to each grid on the substrate 30, and is positioned so that the heat mix 14 of each fuel pellet 10 is in contact therewith. As described above, positioning is performed so that the center of the igniter 38 and the center of the fuel pellet 10 substantially coincide. The igniter 38 is a surface mount type resistor.

As shown in FIG. 8, the surface-mounted resistor 46 constituting the igniter 38 has one end connected to DC + 12V, which is the power supply voltage of the drive circuit, via the current path of the drive FET 48, and the other end connected to GND. It is connected. A drive control signal 50 which is a digital signal indicating a voltage value of High level and Low level is applied to a control terminal of the drive FET 48 from a control circuit (not shown) mounted on the control board 24. The drive FET 48 is turned on when the drive control signal 50 is at a high level, and is turned off when the drive control signal 50 is at a low level.

Therefore, in a state where no ignition is performed, the drive control signal 50 is at a low level, the drive FET 48 is in an OFF state, and no current flows through the resistor 46. Next, when the drive control signal 50 becomes high level and the drive FET 48 is turned on, a current flows through the resistor 46. If the resistor 46 is 4Ω, for example, since the power supply voltage is + 12V, a current of about 2.8A flows even if the voltage drop of the FET is about 0.6V. Therefore, the power consumed by the resistor 46 of the igniter 38 is 4 * 2.8 * 2.8 = about 31 W. Since this 31 W of electric power is consumed by the surface mount resistor 46, the temperature rapidly rises and the heat mix 14 can be heated.

In addition, although this generator 38 used the resistor for surface mounting as the resistor 46, the same effect can be acquired even if it prints directly on a board | substrate using a printing technique. In that case, the thickness of the resistor 46 can be reduced, and the trouble of mounting the surface mounting resistor on the substrate by means such as soldering can be saved, resulting in an increase in circuit reliability. it can. Therefore, it is more preferable to make the hydrogen generator smaller.

In the present embodiment, a total of 35 ignition units 38 as described above are required in a single hydrogen generation unit as shown in FIG. As the layout, a surface mounting resistor 46 is mounted on the upper surface of the substrate 30 (the same surface as the mounting surface of the fuel pellet 10), and a driving FET 48 for driving is mounted on the lower surface of the substrate 30. And a wiring pattern for connecting the connector 34 is arranged using both the upper surface and the lower surface of the substrate 30.

In this case, as shown in the schematic diagram of FIG. 9, 35 drive control signals 50 are applied via the connector 34 to the 35 igniters 38 arranged on the substrate 30. This connection method requires an independent drive control signal line for each substrate. That is, when there is one substrate 30, 35 drive control signal lines are sufficient, but when there are five substrates 30, 35 × 5 = 175 drive control signal lines are required. This is a factor that increases the number of pins of the connector 34 because these many drive control signal lines pass through the connector 34.

Therefore, a connection method as shown in FIG. 10 may be used. Here, the board | substrate 30, the connector 34, and the ignition device 38 are the same as that of the structure of FIG. In this connection method, the drive control signal 50 to each of the igniters 38 is applied from the output terminal of the decoder 52 with 6 inputs and 64 outputs. A 6-bit digital signal 54 is input to the input terminal of the decoder 52 from the control board 24 via the connector 34, and an enable signal 56 that enables the board 30 to operate. Here, the 6-bit digital signal 54 is a signal for determining which of the igniters 38 is turned on. Since the input signal is 6 bits, firing can be instructed to a maximum of 2 to the sixth power, that is, 64 of the 38 igniters. A 6-bit digital signal 54 and an enable signal 56 are input to the decoder 52 via the connector 34. The decoder 52 is activated only when the enable signal 56 is at a high level, that is, “1”.

For example, as shown in FIG. 11, the correspondence between the input signal and the output signal of the decoder 52 can be made. This figure shows that any one of the 64 output signals is “1”, that is, a high level, uniquely corresponding to the 64 types of patterns of the input signal. This high level signal may be input to the igniter 38 as the drive control signal 50. Since only six driving signals are required for the substrate 30 and can be used in common by the respective substrates 30, the number of driving signals does not increase even when the number of substrates increases. However, one enable signal 56 for enabling each substrate 30 is required for each substrate 30. However, in the case of this method, the number of necessary signal lines can be greatly reduced to 6 + 1 = 7 when the number of the substrates 30 is one and 6 + 5 * 1 = 11 even when the number of the substrates 30 is five. .

Next, the operation of the hydrogen generator will be described. Here, although not shown, it is assumed that a hydrogen fuel cell is connected to the tip of the hydrogen generating port 18 and an external stop valve is opened.

A controller (not shown) mounted on the control board 24 selects one igniter 38 and allows a predetermined current to flow for a certain period of time. As a result, the resistor 46 in the igniter 38 generates heat to heat the heat mix 14, and the heat heats the ammonia borane 12 to generate hydrogen. At this time, a small amount of hydrogen is also generated from the heat mix 14. The generated hydrogen is discharged from the hydrogen generation port 18 through a carbon filter (not shown) built in the inlet of the hydrogen generation port 18.

The operation sequence of hydrogen generation in this example is as follows.
As shown in FIG. 12, the controller 58 mounted on the control board 24 includes a microcontroller 60, a nonvolatile memory 62, a igniter selector 64, a secondary battery 66, and a charging circuit 68. The controller 58 is connected to a pressure sensor 70 that is also mounted on the control board 24 or attached to an arbitrary location in the hydrogen generator.

The microcontroller 60 is a control unit that controls the operation of the entire hydrogen generator, and is configured by a one-chip microcomputer that integrally has functions such as a CPU, a memory, and an input / output port. The non-volatile memory 62 records the usage state of the fuel pellet 10, and is an electrically rewritable memory such as an EEPROM or a flash memory. The igniter selector 64 generates a signal for selecting the igniter 38 to be ignited. The secondary battery 66 supplies power to the controller 58, and a lithium ion battery or a nickel metal hydride battery is used. The charging circuit 68 charges the secondary battery 66 with electric power supplied from a hydrogen fuel cell to which the present hydrogen generator is connected. The pressure sensor 70 measures the pressure inside the pressure vessel 16 of the hydrogen generator. The drive selector signal 64 (also the enable signal 56 in the case of FIG. 10) is generated by the fire selector 64.

In FIG. 12, the portion surrounded by the alternate long and short dash line is an electronic circuit supplied with power by the secondary battery 66, and the portion surrounded by the broken line is the controller 58.

The nonvolatile memory 62 is configured to be freely readable and writable, and is assigned to record the usage state of each fuel pellet 10 at a memory address corresponding to one to one. Therefore, by designating one address of the nonvolatile memory 62, it is possible to set the use state of the fuel pellet 10 corresponding to the address and to check the use state. As an example showing the usage state of the nonvolatile memory 62, the fuel pellet 10 is unused when the memory value is "FFH" in hexadecimal, the fuel pellet 10 is used when "80H", and "00H" Indicates that the fuel pellet 10 is not installed. When searching for unused fuel pellets 10, the contents of the nonvolatile memory 62 may be scanned to find “FFH”. By using a non-volatile memory as a memory for recording the state of the fuel pellet 10, even when the hydrogen generator is removed and connected to another hydrogen fuel cell without using up all the fuel pellets 10, Since it can know whether it is unused, it is efficient.

As shown in FIG. 13, the microcontroller 60 first inputs the value of the pressure sensor 70 (step S11). At this time, it is also possible to reduce the influence of noise by inputting the value of the pressure sensor 70 a plurality of times and taking the average value.

Next, it is determined whether or not the value of the input pressure sensor 70 is larger than a predetermined value (step S12). This predetermined value is a limit value of the amount of hydrogen that can be continuously generated by the hydrogen fuel cell to which the present hydrogen generator is connected. In other words, if the hydrogen pressure inside the pressure vessel 16 of the hydrogen generator becomes smaller than the predetermined value, the hydrogen fuel cell cannot continuously generate power unless hydrogen is newly generated. On the other hand, when hydrogen is generated from the ammonia / borane 12, the yield of hydrogen generation is affected by the initial ambient pressure when the ammonia / borane 12 is heated. According to the results of experiments conducted by the inventor, when hydrogen is generated by heating each fuel pellet 10, the hydrogen generation yield is higher when the ambient pressure is 5 atm (500,000 Pascals) or more. It was also found that the hydrogen generation yield does not increase so much at 10 atmospheres or more. Therefore, it is desirable that the predetermined value is 5 atm (500,000 Pascal) or more and does not exceed the maximum withstand pressure (10 atm (1 million Pascal)) of the pressure vessel 16 of the hydrogen generator.

If it is determined in step S12 that the value of the pressure sensor 70 is larger than the predetermined value, the process returns to the input of the pressure sensor value in step S11.

On the other hand, if it is determined in step S12 that the value of the pressure sensor 70 is equal to or less than the predetermined value, it is checked whether there is a hydrogen generation request (step S13). This hydrogen generation request is generated from a host device to which the microcontroller 60 is connected. If it is not necessary to operate the hydrogen fuel cell and generate power, for example, when the device to which the hydrogen fuel cell is connected is in a sleep state, it is not necessary to generate power. Wait until it occurs (step S14).

If a hydrogen generation request is generated (step S14), the contents of the nonvolatile memory 62 are scanned to search for unused fuel pellets 10 (step S15). This scan may be performed only at the beginning, and the result may be recorded at a predetermined address in the nonvolatile memory 62, and the scan of the nonvolatile memory 62 may be omitted after the first time. If all the fuel pellets 10 are used and there are no unused fuel pellets 10 (step S16), a fuel shortage error is reported to the host device using this hydrogen generator (step S17). . In this example, a fuel shortage error is reported when there are no unused fuel pellets 10. However, when the number of unused fuel pellets 10 decreases, a low fuel remaining warning is reported. May be.

On the other hand, when there is an unused fuel pellet 10 (step S16), the unused fuel pellet 10 is selected, and a predetermined amount is set in the igniter 38 corresponding to the selected unused fuel pellet 10. To start the operation of generating hydrogen from the corresponding fuel pellet 10 (step S18).

Thereafter, the value of the nonvolatile memory 62 at the location corresponding to the used fuel pellet 10 is rewritten from unused to used (step S19). In step S18, hydrogen generation from the fuel pellets 10 was started. However, since it takes some time to actually generate hydrogen, after waiting for a certain time (step S20), the process returns to step S11.

These hydrogen generation reactions are performed at a high speed, and hydrogen is generated at a higher speed than required for power generation in a hydrogen fuel cell. For this purpose, a small amount of ammonia borane 12 is intermittently generated in a pressure vessel 16 of a hydrogen generator, which is a pressure resistant reactor. When hydrogen is generated in the pressure resistant reactor, the internal pressure increases, and when the fuel cell uses hydrogen, the internal pressure decreases. The loop of step S11 and step S12 is continued until the internal pressure falls below a predetermined pressure value. Then, by detecting that the internal pressure has fallen below a predetermined pressure value, it is possible to continuously generate power by starting the hydrogen generation of another ammonia borane 12.

As described above, according to the first embodiment, the entire structure of the hydrogen generator for generating hydrogen by subdividing the ammonia and borane 12 into pellets is presented, and as an indispensable element, the generator 38 Specifically, the fuel pellet 10 holding means, the heat retaining / insulating method of the heat generated during the generation of hydrogen, and the operation control flow of the hydrogen generator are specifically presented, so that hydrogen can be efficiently generated from the ammonia / borane 12. It is possible to realize a small hydrogen generator that can be used.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the second embodiment, components having the same functions as those in the first embodiment are denoted by the same reference numerals.

In FIG. 14, a substrate 30C is the same substrate as the

substrates

30A and 30B. The heat insulating member 32C is a lattice-like heat insulating member similar to the

heat insulating members

32A and 32B. Further, the connector 34C is a connector similar to the

connectors

34A and 34B.

Here, the substrate 30A, the heat insulating member 32A, and the connector 34A are combined to form one hydrogen generating unit, and the substrate 30B, the heat insulating member 32B, and the connector 34B are combined to form one hydrogen generating unit, and the substrate 30C One hydrogen generation unit is configured by combining the heat insulating member 32C and the connector 34C. These hydrogen generation units are connected to the control board 24 via

connectors

72A, 72B and 72C, respectively. A control circuit for controlling the operation of the hydrogen generator is mounted on the control board 24 as in the first embodiment. Further, it is connected to a host device of this hydrogen generator via a connector 20.

In this embodiment, each hydrogen generation unit is independently connected to the control board 24 via

connectors

34A, 34B, and 34C. Therefore, the hydrogen generation unit using all the fuel pellets 10 can be detached and attached independently without detaching other hydrogen generation units. Further, since the control substrate 24 is arranged upright, the space inside the hydrogen generator can be used more effectively than the structure of the first embodiment.

Further, the hydrogen generator according to the second embodiment may have an internal structure as shown in FIG. 15, components having the same functions as those in FIG. 14 are denoted by the same reference numerals.

That is, in this modification, the control substrate 24 that was inside the pressure vessel 16 of the hydrogen generator shown in FIG. 14 is taken out of the pressure vessel 16. The three hydrogen generation units are connected to the relay board 74 via the connector 34A and the connector 72A, the connector 34B and the connector 72B, and the connector 34C and the connector 72C. Then, the signal from the relay board 74 goes out of the pressure vessel 16 by the connector 76 and reaches the control board 24 by connecting the connector 76 to the connector 78 on the control board 24. With this configuration, the control board 24 is hardly affected by a rise in temperature, a change in pressure, and the like, and is economical because it can withstand multiple uses.

Since the operation of the hydrogen generator in this embodiment is the same as that in the first embodiment, a description thereof will be omitted.

14 and 15 show examples in which the hydrogen generation units are arranged in three stages, but it is needless to say that the present invention is not limited to this. It is also possible to arrange a plurality of hydrogen generation units in the depth direction of the figure.

[Third embodiment]
Next, a third embodiment of the present invention will be described. In the third embodiment, components having the same functions as those in the first embodiment are denoted by the same reference numerals.

In this embodiment, as shown in FIG. 16, a lattice-like heat insulating member 32 is arranged on a substrate 30 so that the opening forms an equilateral triangle, and the fuel pellets 10 are arranged therein. It is. In this case, the connector 34 is mounted on the substrate 30, and the outer shape of the substrate 30 is a hexagon.

Moreover, as shown in FIG. 17, the lattice-like heat insulating member 32 may be arranged on the substrate 30 so that the opening thereof has a regular hexagonal shape, and the fuel pellets 10 may be arranged therein. . In this case, the connector 34 is mounted on the substrate 30 and the outer shape of the substrate 30 is a regular hexagon.

Even in the case of such a regular triangular or regular hexagonal lattice opening, the size of the lattice is such that each side of the opening is in contact with the diameter of the cylindrical fuel pellet 10 with a gap of about 0.1 mm. adjust. This facilitates the loading of the fuel pellets 10 and prevents the fuel pellets 10 from greatly deviating from the igniter when hydrogen is generated.

Also in this embodiment, although not shown, a circular aluminum foil 40, a regular triangular or regular hexagonal carbon filter 42, and a circular heat insulating member lid 44 are laminated on the fuel pellet 10 in this order. Yes. Only the shape of the carbon filter is different from that of the first embodiment.

When the openings of the lattice-like heat insulating member 32 as shown in FIG. 17 are regular hexagons, the volume of the gap with the cylindrical fuel pellet 10 is such that the openings as shown in FIG. 16 or FIG. Compared to the square case, it becomes smaller. Therefore, more fuel pellets 10 can be mounted on the same volume of hydrogen generator, and the amount of generated hydrogen per unit volume increases, so that the energy density per unit volume can be increased.

The outer shape of a hydrogen generator using such a hydrogen generation unit is a hexagonal column in the case of FIG. 16, and a regular hexagonal column or a cylinder in the case of FIG. In the case of a cylindrical shape, a useless space generated near the outer periphery of the cylinder can be reduced by reducing the diameter of the internal fuel pellet 10. Therefore, it becomes close to the shape of an existing cylindrical secondary battery or the like, and can be easily replaced with the secondary battery.

Also in this embodiment, as in the second embodiment, the position of the control substrate 24 can be set either inside or outside the pressure vessel 16 of the hydrogen generator.

The present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the gist of the present invention. .

Claims

A plurality of fuel pellets (10) composed of a material containing a compound that generates hydrogen when heated;
A pressure vessel (16) for storing the plurality of fuel pellets;
A controller (58) for controlling hydrogen generation from the fuel pellets;
In a hydrogen generator having
A substrate (30; 30A, 30B; 30A, 30B, 30C) disposed in the pressure vessel;
A plurality of igniters (38) provided corresponding to the plurality of fuel pellets on the substrate and heating the corresponding fuel pellets, such that each one fuel pellet is disposed thereon;
A grid-like frame composed of heat insulating members (32; 32A, 32B; 32A, 32B, 32C) that do not allow hydrogen to separate each of the fuel pellets from other fuel pellets;
The hydrogen generator further comprising:
The hydrogen generator according to claim 1, wherein the igniter uses heat generated by passing a current through a surface-mounted resistor (46) or a printed resistor printed on a substrate.
The hydrogen generator according to claim 1, wherein the lattice frame is made of an epoxy resin or a polycarbonate resin.
In the opening of the lattice-like frame, the lowermost part of the fuel pellet is arranged so as to contact the generator,
The hydrogen generator further includes a circular aluminum foil (40), a filter (42) for absorbing impurities other than hydrogen, and a circular heat insulating member (44), which are sequentially stacked on the fuel pellet.
The shape and size of the aluminum foil and the heat insulating member coincides with the shape and size of the contact surface of the fuel pellet to the igniter,
2. The hydrogen generator according to claim 1, wherein a shape and a size of the filter coincide with a shape and a size of an opening of the lattice-like frame.