HYDROGEN SUPPLYING APPARATUS AND METHOD FOR CONTROLLING

HYDROGEN SUPPLYING APPARATUS

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates to a hydrogen supplying apparatus and to a

method for controlling a hydrogen supplying apparatus.

2. Description of the Related Art

[0002] In a conventional hydrogen supplying apparatus, such as proposed in

Japanese Patent Application Publication No. 2004-111167 (JP-A-2004-111167), hydrogen

that contains high-concentration odorizing agent is added to pure hydrogen released from

a tank in response to the odorizing agent concentration in the hydrogen flowing in an

odorized hydrogen circulation path, which includes the target of the hydrogen supply (for

example, a fuel cell), to control the odorizing agent concentration in the hydrogen

supplied to the target of the hydrogen supply and is supplied to the odorized hydrogen

circulation path.

[0003] In the art described in the Japanese Patent Application Publication No.

2004-111167 (JP-A-2004-111167), an odorizing agent treated hydrogen tank that stores

hydrogen into which is mixed a high-concentration odorizing agent is required.

Because the odorizing agent treated hydrogen tank stores hydrogen and the odorizing

agent, its size increases, leading to an increase in the size of the system. Considering

this point, because if the odorizing agent treated hydrogen tank is made small, the amount

of stored odorizing agent becomes less than if only the odorizing agent is stored, there is

a possibility that the cycle of replenishing the tank with odorizing agent treated hydrogen

(replacing the odorizing agent treated hydrogen tank) becomes short. Also, in the art of

the Japanese Patent Application Publication No. 2004-111167 (JP-A-2004-111167),

because the amount of odorizing agent treated hydrogen mixed with the pure hydrogen is

not considered, there is a possibility of variations occurring in the odorizing agent

concentration in the hydrogen supplied to the odorizing agent treated hydrogen

circulation path.

SUMMARY OF THE INVENTION

[0004] The present invention provides a hydrogen supply apparatus and control

method that can suppress an increase in the size of the apparatus and can lengthen the

cycle of replenishing the odorizing agent tank with odorizing agent.

[0005] The present invention also provides a hydrogen supply apparatus and

control method that is able to supply hydrogen, in which non-uniformity of an odorizing

agent concentration is suppressed, to the hydrogen supply target.

[0006] Aspects of the present invention adopt the following configurations.

[0007] A hydrogen supply apparatus according to first aspect of the present

invention includes a hydrogen tank; a hydrogen supply path through which hydrogen

from the hydrogen tank is supplied to a hydrogen supply target; a branching path that

branches from the hydrogen supply path, in which a portion of the hydrogen supplied

from the hydrogen tank flows; addition means for adding an odorizing agent to the

hydrogen flowing in the branching path; a buffer tank that stores the odorizing agent

treated hydrogen; and supplying means for supplying the odorizing agent treated

hydrogen stored in the buffer tank to the hydrogen supply path.

[0008] According to the first aspect of the present invention, the odorizing agent

is added to hydrogen at the branching path, after storing it at the buffer tank to approach a

uniform concentration of odorizing agent, and the odorizing agent treated hydrogen in the

buffer tank is fed to the hydrogen supply path and mixed with hydrogen flowing in the

hydrogen supply path. By doing this, the odorizing agent treated hydrogen tank as in

conventional art is not required, thereby enabling a reduction in the size of the apparatus

and lengthening of the cycle of replenishing the tank with odorizing agent.

[0009] A hydrogen supply target according to the first aspect of the present

invention is a fuel cell, wherein the supplying means may supply the odorizing agent

treated hydrogen, in accordance with a hydrogen consumption amount in the fuel cell, to

the hydrogen supply path. Alternatively, the supplying means according to the first

aspect of the present invention may supply an amount of the odorizing agent treated

hydrogen, based on a generated electrical current in the fuel cell that is a hydrogen supply

target, to the hydrogen supply path. By doing this, it is possible to add the odorizing

agent to hydrogen in proportion to the hydrogen consumption amount and generated

electrical current, thereby suppressing non-uniformity of an odorizing agent

concentration in the hydrogen.

[0010] A hollow fiber module having an aperture with respect to the hydrogen

supply path may be disposed in the hydrogen supply pass according to the first aspect of

the present invention, and the supplying means may supply the odorizing agent treated

hydrogen into the hollow fiber module. By doing this, it is possible to mix the odorizing

agent treated hydrogen diffused in the hollow fiber module into the hydrogen that flows

in the hydrogen supply path, thereby uniformly mixing the odorizing agent into the

hydrogen.

[0011] The hydrogen supply apparatus according to the first aspect of the present

invention may further include means for adjusting a contact surface area between the

hydrogen flowing in the hydrogen supply path and the odorizing agent treated hydrogen

that is supplied into the hydrogen supply path by the supplying means. By doing this, it

is possible to adjust a supply amount of the odorizing agent with respect with the

hydrogen.

[0012] The first aspect of the present invention may be a configuration in which a

plurality of hollow fiber modules having apertures with respect to the hydrogen supply

path are disposed therein, each hollow fiber modules may have a different aperture

surface area. In addition, the supplying means may include a plurality of supply inlets

that supply the odorizing agent treated hydrogen into the hollow fiber modules.

[0013] The first aspect of the present invention may further include hydrogen

flow amount measuring means disposed upstream from a branching point of the hydrogen

supply path and the branching path, and may be configured so that the addition means

adds an odorizing agent in accordance with a hydrogen flow amount measured by the

hydrogen flow amount measuring means. By doing this, it is possible to add the

odorizing agent in accordance with the hydrogen amount supplied to the fuel cell.

[0014] The configuration of the addition means according to the first aspect of the

present invention may include an odorizing agent storage tank, and a valve that, when

closed, blocks a flow between the branching path and the odorizing agent tank, and that,

when open, forms a flowing passage in which a portion of the hydrogen flowing in the

branching path is introduced into the odorizing agent storage tank and, after coming into

contact with the odorizing agent in the odorizing agent storage tank, returns to the

branching path.

[0015] The configuration of the addition means according to the first aspect of the

present invention may include an odorizing agent storage tank, a hollow fiber module

disposed in the branching path and having an aperture opening with respect to the

branching path, and odorizing agent supplying means for supplying the odorizing agent

in the odorizing agent storage tank into the hollow fiber module.

[0016] The addition means according to the first aspect of the present invention

may include an odorizing agent storage tank, a plurality of hollow fiber modules disposed

in the branching path and having apertures opening with respect to the branching path,

and a plurality of odorizing agent supplying means for supplying the odorizing agent in

the odorizing agent storage tank into the hollow fiber modules. The plurality of hollow

fiber modules may have mutually different aperture surface areas.

[0017] By adopting the above-described configuration of the addition means, it is

possible to supply odorizing agent treated hydrogen with suppressed non-uniformity of

the odorizing agent concentration into the buffer tank. This can miniaturize the capacity

of buffer tank.

[0018] The second aspect of the present invention is a method for controlling

hydrogen supply in the hydrogen supply apparatus of the first aspect, which includes

supplying the odorizing agent treated hydrogen to the hydrogen supply path, in

accordance with a hydrogen consumption amount in the hydrogen supply target.

BRIEF DESCRIPTION OFTHE DRAWINGS

The foregoing and further features and advantages of the invention will become

apparent from the following description of example embodiments with reference to the

accompanying drawings, wherein like numerals are used to represent like elements, and

wherein:

FIG. 1 shows the configuration of a fuel cell system to which a hydrogen supplying

apparatus according to a first embodiment of the present invention may be applied;

FIG. 2 shows a configuration example 1 of supplying odorizing agent treated

hydrogen stored in the buffer tank to a main pipe;

FIG. 3 is a graph showing the relationship between the fuel cell current value

(hydrogen consumption amount) and the injection amount;

FIG. 4 shows a configuration example 2 of supplying odorizing agent treated

hydrogen stored in the buffer tank to the main pipe;

FIG. 5 shows a configuration example 3 of supplying odorizing agent treated

hydrogen stored in the buffer tank to the main pipe;

FIG. 6 shows a configuration example 1 of the addition unit shown in FIG 1;

FIG. 7 shows a configuration example 2 of the addition unit shown in FIG. 1; and

FIG. 8 shows a configuration example 3 of the addition unit shown in FIG 1.

DETAILED DESCRIPTION OF EMBODIMENTS

[0019] Embodiments of the present invention are described below, with reference

made to the accompanying drawings. These embodiments are examples, and do not

restrict the configuration of an embodiment of the present invention.

[0020] An embodiment of the present invention will now be generally described,

using a fuel cell system that uses hydrogen as a fuel gas, in which an odorizing agent is

added to the hydrogen gas to facilitate the detection of hydrogen leakage. In this

embodiment, a hydrogen supplying apparatus and a method for controlling the hydrogen

supplying apparatus that adds a minute amount of odorizing agent to hydrogen in

response to the hydrogen consumption amount (fuel cell current) of the fuel cell will be

described.

[0021] The hydrogen supplying apparatus of this embodiment has the following

features. The hydrogen (H ₂ ) and the odorizing agent are mixed (agitated) in a buffer

tank, and the odorizing agent treated hydrogen in the buffer tank is fed (for example,

injected) to a hydrogen supply path to the fuel cell in response to the hydrogen

consumption amount (fuel cell current). The contact surface between the hydrogen and

the odorizing agent is adjusted by using a butterfly valve and a hollow fiber with a

different aperture surface area (hole diameter and hole density), to adjust the odorizing

agent concentration in the hydrogen.

[0022] The configuration of the fuel cell system will now be described. FIG. 1

shows an example of the configuration of a fuel cell system to which a hydrogen

supplying apparatus according to the present invention is applied. The fuel cell system

shown in FIG. 1 is mounted on board a vehicle, although the hydrogen supplying

apparatus may also be applied to a stationary type of fuel cell system. The fuel cell 1

shown in FIG. 1 is a solid polymer electrolyte fuel cell (PEFC), although the present

invention is not limited in application to a PEFC. The present invention may be applied

to a hydrogen supply target other than a fuel cell.

[0023] In FIG. 1, the fuel cell 1 has a cell stack formed by stacking a plurality of

cells. Each cell has a solid polymer electrolyte membrane, a fuel electrode (anode) and

an air electrode (oxidant electrode: cathode) that sandwich the solid polymer electrolyte

membrane from each side, and a fuel electrode side separator and air electrode side

separator that sandwich the fuel electrode and the air electrode.

[0024] The fuel electrode has a diffusion layer and a catalyst layer. Fuel

containing hydrogen, such as hydrogen gas or a hydrogen-rich gas, is supplied to the fuel

electrode by a fuel supply system. The fuel supplied to the fuel electrode diffuses in the

diffusion layer and reaches the catalyst layer. At the catalyst layer, the hydrogen is

separated into protons (hydrogen ions) and electrons. The hydrogen ions pass through

the solid polymer electrolyte membrane and migrate to the air electrode, and the electrons

pass through an external circuit and migrate to the air electrode.

[0025] The air electrode has a diffusion layer and a catalyst layer, and an

oxidizing gas such as air is supplied to the air electrode by an oxidizing gas supply

system. The oxidizing gas supplied to the air electrode is diffused by the diffusion layer

and reaches the catalyst layer. At the catalyst layer, a reaction between the oxidizing gas,

the hydrogen ions that pass through the solid polymer electrolyte membrane and reach

the air electrode, and electrons that pass through the external circuit and reach the air

electrode produces water. The electrons passing through the external circuit when the

reaction occurs at the fuel electrode and the air electrode are used as electrical energy for

a load 2 that is connected between the terminals of the cell stack of the fuel cell 1.

[0026] A fuel supply/discharge system is connected to the fuel cell 1 to supply

and discharge fuel. The fuel cell 1 is also connected to an oxidant supply/discharge

system that supplies and discharges an oxidant. In FIG. 1 the fuel supply/discharge

system is shown, the configuration of which is described below.

[0027] The fuel supply system has a hydrogen supply path, which supplies

hydrogen gas, stored under high pressure in the hydrogen tank 3, from the hydrogen tank

3 to a fuel inlet provided in the fuel cell 1. The hydrogen supply path has an adjusting

valve 4 that is connected to the hydrogen tank 3 and that adjusts the flow amount of

hydrogen gas supplied from the hydrogen tank 3, a hydrogen flow meter (HFM) 5 that

measures the flow amount of hydrogen passing through the adjusting valve 4, and a pipe

6 that connects the hydrogen flow meter 5 and the fuel cell 1.

[0028] The hydrogen supply system also has a branching path that branches from

the hydrogen supply path. The branching path has a branch pipe 7 that branches from

the pipe 6; a pump 8 connected to the branch pipe 7; a pipe 9; an addition unit 10 for

addition an odorizing agent connected to the pump 8 via the pipe 9; a buffer tank 11 that

stores hydrogen to which odorizing agent has been added (odorizing agent treated

hydrogen) by the addition unit 10; and an injector 13 that serves as a supplying means to

inject (supply) the odorizing agent treated hydrogen from the buffer tank 11 into the a

pipe 6.

[0029] The fuel discharge system has the following configuration. A discharge

valve (for example, an electromagnetic valve) 15 is connected to the fuel outlet of the

fuel cell 1 via the pipe 14. The discharge valve 15 is connected to a diluter 16 via a pipe

16A. A circulating pump 18 is connected to the pipe 14 via the branching pipe 17, and

the circulating pump 18 is connected to the pipe 6 via the pipe 19. By adopting this

configuration, when the discharge valve 15 is in the closed condition, by the driving of

the circulating pump 18, the hydrogen gas discharged from the fuel cell 1 passes through

the pipe 17, the circulating pump 18, the pipe 19, and the pipe 6, and is again supplied to

the fuel cell 1, so that the hydrogen gas circulates via a circulation path through the fuel

cell 1. In contrast, when the discharge valve 15 is open, the hydrogen gas discharged to

the pipe 14 passes through the discharge valve 15 and reaches the diluter 16 and, after it

is diluted, is discharged to the atmosphere.

[0030] The operation of the fuel supplying/discharging system is controlled by a

control system. The control system has an ECU (electronic control unit) 20 serving as a

control means. The ECU 20 includes a processor such as a CPU, a storage device

(memory, such as a volatile memory) that stores a program and data used when executing

a program, and an I/O (input/output) interface.

[0031] The ECU 20, by the processor executing a program stored in the storage

device, controls the operation of the fuel supply/discharge system, Data stored

beforehand in the storage device, the hydrogen gas flow amount input from the hydrogen

flow meter 5, and the current generated by the fuel cell 1 (fuel cell current) measured by

the ammeter 12 connected in series with the fuel cell 1 are used at the time of program

execution. The ECU 20 is configured to receive a signal from the hydrogen flow meter

5 indicating the hydrogen gas flow amount and a signal from the ammeter 12 indicating

the fuel cell current value (these signals being shown by broken line arrows in FIG. 1).

[0032] The ECU 20, in accordance with the program, executes controls such as

opening/closing control and opening adjustment (adjustment of the hydrogen gas flow

amount) of the adjusting valve 4, on/off and rotational amount (ejection amount) control

of the pump 8 and the circulating pump 18, opening/closing control of the discharge

pump 15, operating control of the injector 13, and adjustment of the amount of odorizing

agent added by the addition unit 10. To do this, the ECU 20 provides control signals

(refer to the broken line arrow in FIG. 1) to the adjusting valve 4, the pump 8, the addition

unit 10, the injector 13, the discharge valve 15, and the circulating pump 18.

[0033] The configuration of the hydrogen supplying apparatus will now be

described. In the fuel cell system shown in FIG. 1, the constituent elements that form

the hydrogen supply path and the branching path form the hydrogen supplying apparatus

according to an embodiment of the present invention, the configuration of which is

described below in detail.

[0034] In FIG. 1, when the fuel cell 1 is operating, hydrogen gas from the

hydrogen tank 3 is supplied to the fuel cell 1 via the hydrogen supply path. When the

ECU 20 opens the adjusting valve 4, the hydrogen gas supplied from the hydrogen tank 3

flows to downstream from the adjusting valve 4, where the pressure is low (the hydrogen

gas is shown in FIG. 1 by the straight line arrows). The hydrogen gas passes through the

pipe 6 (main pipe) and is supplied to the fuel cell 1 for use in electrical generation.

When this occurs, the ECU 20 closes the discharge valve 15 and drives the circulating

pump 18 as necessary to circulate the hydrogen gas in the circulation path.

[0035] Then the ECU 20 drives the pump 8 to draw a portion of the hydrogen gas

flowing in the pipe 6 into the branching path (the pipe (sub-pipe) side) and the addition

unit 10 acts as an addition means to add (inject) odorizing agent into the hydrogen gas, it

is sent to the buffer tank 11. In the buffer tank 11 the hydrogen gas and the odorizing

agent are mixed together to achieve a uniform odorizing agent concentration. The ECU

20 provides a control signal to the injector 13 serving as a supplying means to cause the

injector 13 to inject the odorizing agent treated hydrogen gas held in the buffer tank 11

into the pipe 6 (refer to the configuration example 1 shown in FIG. 2). By doing this,

the inside of the pipe 6 downstream from the injector 13 receives a flow of odorizing

agent treated hydrogen gas which is supplied to the fuel cell 1 (in FIG. 1 and FIG. 2, the

odorizing agent treated hydrogen gas is indicated by a chain line arrows).

[0036] The operation of the injector 13 is controlled based on the current

generated by the fuel cell 1, which is measured by the ammeter 12 (fuel cell current,

which can be treated as being equivalent to the hydrogen gas consumption amount in the

fuel cell 1), and the flow amount of hydrogen gas in accordance with the generated

current.

[0037] In this case, the fuel cell current value (for example, the accumulated

current value per unit of time) and the hydrogen flow amount from the hydrogen tank 3

(the hydrogen flow amount to the fuel cell 1) are proportionally related. That is, the

supply of hydrogen is controlled so that the greater the fuel cell current generated, the

more hydrogen gas is supplied to the fuel cell I . In accordance with the fuel cell current

value received from the ammeter 12, the ECU 20 adjusts the opening of the adjusting

valve 4 to cause an amount of hydrogen gas to flow downstream (to the main pipe 6) in

proportion to the fuel cell current value. The flow amount of hydrogen gas passing

through the adjusting valve 4 is measured by the hydrogen flow meter 5 and notification

is given thereof to the ECU 20.

[0038] The ECU 20 controls the operation of the addition unit 10 to add an

amount of odorizing agent that is proportional to the flow amount of the hydrogen gas.

The ECU 20 controls the injection operation of the injector 13 to achieve a uniform

odorizing agent concentration in the hydrogen gas that passes through the pipe 6 and is

supplied to the fuel cell 1.

[0039] The injector 13 is configured to inject, with each injection, a minute

amount of odorizing agent treated hydrogen gas into the pipe 6. For example, the ECU

20 varies the amount of odorizing agent treated hydrogen gas injected or the number of

injections of the injector 13 in accordance with the hydrogen gas flow amount measured

by the hydrogen flow meter 5. FIG 3 is a graph showing the relationship between the

fuel cell current value (hydrogen consumption amount) and the injection amount. For

example, as shown in FIG. 3, the ECU 20 controls the injection amount of the injector 13

in proportion to the fuel cell current value (hydrogen consumption amount). In this

manner the mixture ratio of odorizing agent and hydrogen is adjusted to supply the fuel

cell 1 with an odorizing agent treated hydrogen gas having a uniform odorizing agent

concentration.

[0040] In this embodiment, the example shown is one in which even if the liquid

odorizing agent accumulates in the buffer tank 11, the injector 13 is applied so that the

odorizing agent can be atomized and supplied into the pipe 6. As long as it is possible

to adjust the amount of odorizing agent treated hydrogen gas supplied into the pipe 6, it is

possible to apply a valve such as an electromagnetic valve in place of the injector 13.

[0041] The addition unit 10 has an odorizing agent tank that stores odorizing

agent. The odorizing agent inside the odorizing agent tank comes into contact with the

hydrogen gas flowing in the branching path (pipe 9) to add the odorizing agent to the

hydrogen gas. It is possible to store in the odorizing agent tank odorizing agent in gas,

liquid, or solid (gel) form. The capacity of the odorizing agent tank can be made

smaller than the capacity of a tank of storing odorizing agent treated hydrogen. In

particular, when storing odorizing agent that is a liquid or a solid (gel), it is possible to

make the odorizing agent tank small, and to lengthen the replacement time cycle

(odorizing agent replenishment period) for the odorizing agent tank.

[0042] The addition unit 10 adds odorizing agent by, for example, causing the

odorizing agent in the odorizing agent tank to come into contact with the hydrogen gas

flowing through the pipe 9. Alternatively, the addition unit 10 may have a configuration

such that it adds an odorizing agent by injecting a gas or mist odorizing agent into the

flow of hydrogen gas within the pipe 9.

[0043] The buffer tank 11, for example, may cause a swirl within the buffer tank

11 by the collision between hydrogen gas introduced from the addition unit 10 and

odorizing agent at the inner wall thereof, the odorizing agent being thereby stirred and

distributed uniformly throughout the hydrogen gas. Alternatively, a configuration may

be adopted in which a stirring vane (stirring member) is disposed in the buffer tank 11 to

mix the hydrogen gas and odorizing agent in the buffer tank 11.

[0044] FIG. 2 shows a configuration example 1 in which the injector 13 merely

directly injects odorizing agent treated hydrogen gas into the pipe 6. In place of this

configuration example 1, the configuration of FIG. 4 (configuration example 2) maybe

applied. FIG. 4 shows the configuration example 2, in which odorizing agent treated

hydrogen gas is supplied to the pipe 6 (main pipe). As shown in FIG. 4, in the

configuration example 2, a hollow fiber module 21 is disposed inside the pipe 6,

odorizing agent treated hydrogen gas injected from the nozzle of the injector 13 being

injected into the hollow fiber module 21.

[0045] The hollow fiber module 21 has a cylindrical shape, and has a plurality of

through holes 22 on the wall surface in the circumferential direction thereof that

communicate with the inside of the hollow fiber module 21. The inside of the hollow

fiber module 21 and the inside of the pipe 6 communicate via the holes 22. The

odorizing agent treated hydrogen gas that is injected into the hollow fiber module 21

diffuses and then passes through the holes 22 and flows out into the pipe 6, where it

mixes with the hydrogen gas flowing in the pipe 6. By applying this type of

configuration, it is possible to uniformly mix odorizing agent treated hydrogen gas from

the buffer tank 11 with the hydrogen gas flowing in the pipe 6.

[0046] By combining the foregoing configuration with injection amount control

based on the fuel cell current, in comparison with a configuration (refer to FIG. 2) in

which the odorizing agent treated hydrogen gas is directly injected into the pipe 6, finer

control is possible of the mixing ratio of hydrogen gas and odorizing agent, and it is

possible to achieve a uniform odorizing agent concentration in the odorizing agent treated

hydrogen gas supplied to the fuel cell 1. In particular, with the above-described

configuration, it is possible to achieve a uniform odorizing agent concentration even if

the flow speed of the hydrogen gas flowing in the pipe 6 is not uniform.

[0047] In place of the configuration example 2 shown in FIG 4, the configuration

shown in FIG 5 may be used. FIG. 5 shows the configuration example 3 related to the

supply of odorizing agent treated hydrogen gas to the pipe 6 (main pipe). In the

configuration example 3 shown in FIG. 5, a plurality of injectors (shown by example as

injectors 13 A, 13B, and 13C in FIG. 5) are provided between the buffer tank 11 and the

pipe 6 that communicate between these two elements. A plurality of hollow fiber

modules 21A, 21B, and 21C are additionally provided paired with the injectors 13A, 13B,

and 13C in the pipe 6.

[0048] The hollow fiber modules 21 A, 21 B, and 21 C have a plurality of holes 22,

which communicate between the inside of the hollow fiber modules and the inside of the

pipe 6. The hollow fiber modules 2IA, 21B, and 21C are configured to have mutually

different aperture surface areas with respect to the pipe 6. For example, the

configuration is one in which the ratio of holes in the surface of the modules (the hole

density, which is the number of holes per unit surface area) differs between hollow fiber

modules. Alternatively, the configuration is one in which the hole diameter differs

between hollow fiber modules. Alternatively, the configuration is one in which the hole

density and hole diameter differ between hollow fiber modules. The aperture surface

area is expressed as the total value of the surface areas of the holes 22. In the example

shown in FIG. 5, a configuration is applied in which the aperture surface areas of the

hollow fiber modules increase in the sequence of hollow fiber modules 21 C, 21 B, and

21 A. The aperture surface area forms the contact surface area within the module

between the odorizing agent treated hydrogen gas and the hydrogen gas in the pipe 6, the

configuration being such that, depending upon the hollow fiber module that is used, the

contact surface area between the odorizing agent treated hydrogen gas and the hydrogen

gas differs.

[0049] By adopting the foregoing configurations, for a given same amount of

odorizing agent treated hydrogen gas injected from the injectors 13 A, 13B, and 13C, the

amount of odorizing agent treated hydrogen gas passing through the holes 22 and flowing

out from the inside of the pipe 6 differs.

[0050] In the configuration example shown in FIG. 5, the ECU 20 executes, for

example, the following adjustment of the odorizing agent concentration in the odorizing

agent treated hydrogen gas supplied to the fuel cell 1 from the pipe 6. The ECU 20 may

execute a control so that the injectors 13A, 13B, and 13C inject odorizing agent treated

hydrogen gas in parallel. Alternatively, the ECU 20 may execute a control to select one

of the injectors 13 A, 13B, and 13C to inject odorizing agent treated hydrogen gas from

only the selected injector.

[0051] If injection is done in parallel from the injectors 13A, 13B, and 13C, when

the amount of added odorizing agent (odorizing agent treated hydrogen gas supply

amount) is to be increased (the added amount being determined by the hydrogen gas flow

amount), the ECU 20 increases the injection amount (or the number of injections per unit

of time) of the injectors 13A, 13B, and 13C. On the other hand, if the amount of added

odorizing agent is to be decreased, the ECU 20 decreases the injection amount (or

number of injections per unit of time) of the injectors 13 A, 13B, and 13C.

[0052] In contrast, if one of the injectors 13 A, 13B, and 13C is selectively used,

when the amount of odorizing agent (the supply amount of odorizing agent treated

hydrogen gas) to be added is to be increased, the ECU 20, in response to the amount of

the increase, causes only the selected injector paired with a hollow fiber module having a

large aperture surface area (for example, the injector 13 A, which is paired with the

hollow fiber module 21A) to inject odorizing agent treated hydrogen gas. On the other

hand, if the amount of odorizing agent to be added is to be decreased, the ECU 20, in

response to the amount of the decrease, causes only the selected injector paired with a

hollow fiber module having a small aperture surface area (for example, the injector 13C,

which is paired with the hollow fiber module 21C) to inject odorizing agent treated

hydrogen gas. Even when selectively using the injectors 13A, 13B, and 13C, it is

possible to vary the added amount by increasing and decreasing the amount injected

(number of injections) by the selected injector.

[0053] By the above-described control, the amount of odorizing agent treated

hydrogen gas supplied is adjusted in response to the fuel cell current (hydrogen

consumption amount), enabling supply to the fuel cell 1 of odorizing agent treated

hydrogen gas having a uniform odorizing agent concentration.

[0054] Examples of the configuration of the addition unit 10 will now be

described. FIG. 6 shows configuration example 1 of the addition unit 10. The addition

unit 10 shown in FIG. 6 has an odorizing agent tank 25 that is connected to the pipe 9

(sub-pipe) connected to the buffer tank 11, and a butterfly valve 26 (corresponding to a

valve in the present invention) that is provided at the boundary part between the

odorizing agent tank 25 and the pipe 9. When the butterfly valve 26 is closed, the

odorizing agent tank 25 is closed, so that the inside of the pipe 9 and the inside of the

odorizing agent tank 25 are blocked. In contrast, when the butterfly valve 26 is open,

the inside of the pipe 9 and the inside of the odorizing agent tank 25 communicate with

one another.

[0055] The operations (amount of opening and time of opening) of the butterfly

valve 26 are controlled by, for example, the ECU 20. The ECU 20, in response to the

hydrogen gas flow amount measured by the hydrogen flow meter 5, controls the butterfly

valve 26 to open more, the larger is the amount of flow of hydrogen gas. Alternatively,

the ECU 20 may control the opening time of the butterfly valve 26 per unit of time (for

example, the number repetitions of opening and closing the butterfly valve 26).

[0056] Odorizing agent is stored in the odorizing agent tank 25, in any of the

forms of gas, liquid, or solid (for example, a gel). In this case, the odorizing agent is

store in either liquid or gel form. When the butterfly valve 26 is open, a portion of the

hydrogen gas flowing in the pipe 9 flows into the odorizing agent tank 25, comes into

contact with the surface of the odorizing agent and causes the odorizing agent to

evaporate. Additionally, a portion of the hydrogen gas flows again into the pipe 9, to

bring away the evaporated gaseous odorizing agent, and reaches the buffer tank 11. In

this manner, the butterfly valve 26 forms a flow passage in which a part of the hydrogen

flowing in the branching path (pipe 9) is introduced into the odorizing agent tank 25 and,

after coming into contact with the odorizing agent in the odorizing agent tank 25, returns

the branching path (pipe 9). In this manner, the ECU 20 adjusts the amount of odorizing

agent that is added to the hydrogen gas by controlling the amount of opening and/or the

opening time per unit of time of the butterfly valve 26.

[0057] FIG. 7 shows the configuration example 2 of the addition unit 10. The

addition unit 10 shown in FIG. 7 has an odorizing agent 27 that stores odorizing agent, an

injector 28 that is disposed between the odorizing agent tank 27 and the pipe 9 (sub-pipe)

and that serves as an odorizing agent supplying means, and a hollow fiber module 29

disposed inside the pipe 9. The hollow fiber module 29, similar to the hollow fiber

module 21, has a cylindrical shape and has a plurality of (through) holes 30 in the wall

surface thereof, the inside of the hollow fiber module 29 and the inside of the pipe 9

communicating via the holes 30.

[0058] A nozzle of the injector 28 opens toward the inside of the hollow fiber

module 29, and the injector 28 injects odorizing agent into the hollow fiber module 29.

The odorizing agent tank 27 stores, for example, odorizing agent in liquid form, and

atomized odorizing agent is injected into the hollow fiber module 29 by the injector 28.

The odorizing agent injected in the hollow fiber module 29 first remains within the

hollow fiber module 29 comes into contact and mixes with the hydrogen gas that passes

through the holes 30, flows in the pipe 9, and then reaches the buffer tank 11.

[0059] The ECU 20, in accordance with the hydrogen flow amount (measured by

the hydrogen flow meter 5) responsive to the fuel cell current value (hydrogen

consumption amount), provides a control signal to the injector 28 to control the amount

injected thereby. By doing this, it is possible to increase and decrease the amount of

odorizing agent that is added, based on the fuel cell current value. By applying the

hollow fiber module 29, it is possible to achieve a uniform odorizing agent concentration

in the hydrogen gas that reaches the buffer tank 11, thereby contributing to the uniformity

of the odorizing agent concentration distribution within the buffer tank 11. By doing

this, it is possible to reduce the capacity of the buffer tank 11. Also, as long as the

odorizing agent is sufficiently stirred in the buffer tank 11, the hollow fiber module 29

may be omitted.

[0060] FIG. 8 shows the configuration example 3 of the addition unit 10. The

addition unit 10, shown in FIG. 8, has an odorizing agent tank 27 that stores odorizing

agent, a plurality of injectors serving as odorizing agent supplying means (in the case of

FIG. 8, injectors 28A, 28B, and 28C) disposed between the odorizing agent tank 27 and

the pipe 9 (sub-pipe), and a plurality of hollow fiber modules 29 A, 29B, and 29C, paired

with the injectors 28A, 28B, and 28C and disposed inside the pipe 9.

[0061] The hollow fiber modules 29A, 29B, and 29C have the same type of

configuration as the hollow fiber modules 21A, 21B, and 21C, and have holes with

aperture surface areas increasing in the sequence of hollow fiber modules 29C, 29B, and

29A. The configuration of the odorizing agent tank 27 is the same as in the

configuration example 2.

[0062] The ECU 20 is configured to control the injectors 28A, 28B, 28C in

parallel or select one injector. If the injectors 28A, 28B, 28C are used in parallel, when

the amount of added odorizing agent (the added amount being determined by the

hydrogen gas flow amount) is to be increased, the ECU 20 increases the injection amount

(or the number of injections per unit of time) of the injectors 28A, 28B, and 28C. On

the other hand, if the amount of added odorizing agent is to be decreased, the ECU 20

decreases the injection amount (or number of injections per unit of time) of the injectors

28A, 28B, and 28C.

[0063] In contrast, if one of the injectors 28A, 28B, and 28C is selectively used,

when the amount of added odorizing agent (the added amount being determined by the

hydrogen gas flow amount) is to be increased, the ECU 20, in response to the amount of

the increase, causes only the selected injector paired with a hollow fiber module having a

large aperture surface area (for example, the injector 28A, which paired with the hollow

fiber module 29A) to inject odorizing agent. On the other hand, if the amount of

odorizing agent to be added is to be decreased, the ECU 20, in response to the amount of

the decrease, causes only the selected injector paired with a hollow fiber module having a

small aperture surface area (for example, the injector 28C, which paired with the hollow

fiber module 29C) to inject odorizing agent treated hydrogen gas.

[0064] By the above-described control, the amount of odorizing agent added is

adjusted in accordance with the fuel cell current (hydrogen consumption amount), and it

is possible to send into the buffer tank 11 hydrogen gas having a uniform odorizing agent

concentration.

[0065] In the above-described configuration example 2 and configuration

example 3 of the addition unit 10, it is possible to apply an electromagnetic valve in place

of the injectors. Also, although the above-described embodiment is for the example of a

hydrogen tank 3 that stores high-pressure hydrogen gas, the hydrogen supplying

apparatus of this embodiment may also be applied to a hydrogen tank holding a

hydrogen-occluding alloy (MH) or a hydrogen tank storing liquid hydrogen.

Additionally, the pump 8 may be a valve.

[0066] The foregoing embodiment of the present invention suppresses an increase

in the size of the apparatus and provides a hydrogen supplying apparatus capable of

lengthening the odorizing agent replenishment cycle. The foregoing embodiment also

provides a hydrogen supplying apparatus that supplies hydrogen, in which

non-uniformity in the odorizing agent concentration is suppressed, to the hydrogen

supply target in which non-uniformity in the odorizing agent concentration is suppressed.