JP2011132892A - Diaphragm pump for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm pump for fuel cells, having high operation efficiency and easily reducing the size. <P>SOLUTION: The diaphragm pump for the fuel cells includes a first pump chamber 41A performing intake and discharge with a first diaphragm 44A, a second pump chamber 41B performing intake and discharge with a second diaphragm 44B arranged opposite to the first diaphragm 44A, a crank shoe 62 having a hole 61 and connecting the first diaphragm 44A with the second diaphragm 44B, a drive motor, and a crankshaft 74 driven by the drive motor, fitted slidably in the hole 61 and linearly reciprocating the crank shoe 62. The first pump chamber 41A, the first diaphragm 44A, the crank shoe 62, the second diaphragm 44B and the second pump chamber 41 are arranged in sequence along the linear reciprocation direction. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a fuel cell system that contributes to a reduction in environmental load, and more particularly to a fuel cell diaphragm pump that is optimal for use in a household fuel cell system.

Conventionally, in a domestic fuel cell system, city gas or LP gas (liquefied propane gas), which is a fuel gas, is pressurized (pressurized) by a booster pump and conveyed to a reformer, mainly containing hydrogen and carbon monoxide. The reformed gas is reformed.
As a booster pump, a diaphragm pump driven by a motor or a solenoid is mainly used.
As this diaphragm pump, a pump having a plurality of pump chambers is known as being effective in efficiently transferring liquid or gas (fluid) while suppressing pulsation (see, for example, Patent Document 1). .

JP-A-8-338370

In general, in a domestic fuel cell system, a diaphragm pump that conveys fuel gas is desired to be more excellent in operation efficiency, safety, durability, and maintainability because of its nature.
In addition, since the home fuel cell system is assumed to be installed in a general household, it is desired to reduce the size and weight of the system as a whole, and the diaphragm pump used as a booster pump is naturally reduced in size and weight. It is desired.
Accordingly, an object of the present invention is to provide a diaphragm pump for a fuel cell that has been made in view of the above-described circumstances and has high operating efficiency and can be easily downsized.

  In order to achieve the above object, a first aspect of the present invention is a diaphragm pump for a fuel cell having a suction port through which fuel gas is sucked and a discharge port through which the fuel gas is discharged, wherein the first suction valve And a first discharge valve, and includes a first pump chamber that performs suction and discharge by a first diaphragm, a second suction valve, and a second discharge valve, and is disposed opposite to the first diaphragm. A second pump chamber that performs suction and discharge by the second diaphragm, a crank shoe having a hole and connecting the first diaphragm and the second diaphragm, a drive motor, and a drive motor And an eccentric member that is slidably fitted in the hole and linearly reciprocates the crank shoe, and includes the first pump chamber, the first pump along the linear reciprocating direction. Diaphragm, Serial crank shoe, said second diaphragm and said second pump chamber is characterized by being arranged in this order.

  According to the above configuration, the first diaphragm and the second diaphragm are linearly reciprocated by the drive motor via the crank shoe, so that the pump chamber can be compared with a structure in which the diaphragm drive is driven to swing. Therefore, it is not necessary to secure a useless space only for driving the diaphragm, so that high efficiency can be achieved, and the first diaphragm and the second diaphragm fuel are alternately sucked and discharged, resulting in torque fluctuations. Since the load applied to the drive motor and the amount of load fluctuation can be reduced, noise caused by vibration can be reduced, and a small drive motor can be used, and the device size can be reduced. .

The second aspect of the present invention is characterized in that, in the first aspect, the drive motor and the eccentric member are integrally removable.
According to the said structure, since a drive motor and the said eccentric member can be attached or detached integrally, a maintainability improves.

  According to a third aspect of the present invention, in any one of the first and second aspects, the first diaphragm and the second diaphragm are attached to the crank shoe via a diaphragm holder, and the diaphragm holder is A first disc-shaped hold member disposed in the pump chamber, and a second disc-shaped hold member that cooperates with the first hold member to clamp the diaphragm. The diameter is set to be larger than that of the first holding member.

According to the above configuration, the degree of freedom of deformation of the diaphragm can be increased at the time of inhalation, and the effective suction volume can be increased. At the time of discharge, the degree of freedom of deformation of the diaphragm can be reduced, and the effective increase of the discharge volume can be increased. Thus, the efficiency of the fuel cell diaphragm pump can be increased.
The volume of residual gas in the pump chamber to increase the degree of freedom of the diaphragm during suction to increase the suction volume (volume in the pump chamber at the bottom dead center), and to suppress the deformation of the diaphragm during discharge and increase the discharge volume (Pump chamber volume at top dead center) can be reduced.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the inner wall surface of the first pump chamber and the second pump chamber facing the diaphragm has a shape of a diaphragm at the time of top dead center. It is characterized by being shaped along.
According to the above configuration, the gap formed between the diaphragm when the diaphragm reaches the top dead center and the inner wall surface facing the diaphragm can be reduced, and the liquid or gas in the pump chamber can be reliably pumped. Since it can be pushed out of the room, the pump efficiency can be improved.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a plurality of bearings are provided between the motor main body and the eccentric member in the rotation output shaft of the drive motor. .
According to the above configuration, the rotation output shaft of the motor accompanying the eccentric operation of the eccentric member can be more reliably suppressed, the long-term reliability of the fuel cell diaphragm pump can be secured, and the rotation output shaft can be prevented from shaking. Generation of noise can be suppressed by suppressing the accompanying vibration.
In this case, the bearing may be a ball bearing, and a ball bearing bearing having a larger number of grounding points and the rotation output shaft of the motor may be used as the ball bearing bearing on the eccentric member side. According to the above configuration, in the ball bearing on the side of the eccentric member having a larger fluctuation width, the vibration can be reliably suppressed and long-term reliability can be ensured.

A sixth aspect of the present invention is the eccentric member main body according to any one of the first to fifth aspects, wherein the eccentric member is attached to an output rotation shaft of a motor and rotates integrally with the motor rotation shaft. A sliding bearing that is rotatably fitted to the eccentric member body, and the eccentric member body is slidably fitted to the hole via the sliding bearing. It is characterized by that.
Therefore, the rotation of the eccentric member is not directly transmitted to the crank shoe, and the eccentric member can be smoothly slid in the hole.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the suction path from the suction port and the suction port to the first and second suction valves, and the first and second from the discharge port. The member constituting the discharge passage leading to the second discharge valve is formed of metal.
According to the above configuration, the durability and safety can be further improved.

According to an eighth aspect of the present invention, in the seventh aspect, the metal is an aluminum alloy.
According to the said structure, weight reduction can be achieved, maintaining durability and safety | security.

  According to the present invention, there is an effect that it is possible to configure a fuel cell diaphragm pump that has high operating efficiency and can be easily downsized.

It is the schematic which shows an example of a fuel cell system. It is an external appearance perspective view of a fuel pump. It is (a) top view and (b) front view of a fuel pump. It is AA arrow sectional drawing of Fig.3 (a). It is a BB arrow sectional view of Drawing 3 (b).

Next, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating an example of a fuel cell system.
The fuel cell system 10 includes a fuel tank 11, and the fuel F in the fuel tank 11 flows into the desulfurizer 13 by a fuel cell diaphragm pump (hereinafter referred to as a fuel pump) 12 of the present invention. At this time, the fuel gas FG containing hydrogen from the carbon monoxide selective oxidation reactor 24 is added to the fuel F as necessary.

The fuel desulfurized by the desulfurizer 13 is mixed with the water supplied from the water tank 15 by the water pump 16, introduced into the vaporizer 17, vaporized, and sent to the reformer 18.
Thereby, the reformer 18 is heated by the heating burner 20 mainly using the anode off gas AG of the fuel cell 19 as fuel.

The reformed gas in the reformed gas is processed by the reactor 21 equipped with a catalyst, and the resulting mixed gas containing hydrogen and carbon monoxide is converted into a high temperature shift reactor 22 equipped with a catalyst and a low temperature shift, respectively. By sequentially passing through the reactor 23 and the carbon monoxide selective oxidation reactor 24, the concentration of carbon monoxide is reduced to a level that does not affect the characteristics of the fuel cell.
The fuel cell 19 includes an anode (fuel electrode) 25, a cathode (air electrode) 26, and a solid polymer membrane (electrolyte) 27.

Fuel gas FG containing high-purity hydrogen obtained by the above method is introduced on the anode 25 side, and air AR sent from the air blower 28 is introduced on the cathode 26 side. In addition, it is also possible to comprise so that it may humidify with the humidifier which is not shown in figure as needed.
At this time, in the anode 25, a reaction in which hydrogen gas becomes protons and emits electrons proceeds, and in the cathode 26, a reaction in which oxygen gas obtains electrons and protons to become water proceeds. In order to promote these reactions, a catalyst is used for the anode 25 and the cathode 26.
The load circuit 29 is electrically connected to the anode 25 and the cathode 26.
As described above, the anode off gas AG is combusted in the burner, used for heating the reformer 18, and discharged. Further, the cathode off gas CG is discharged from an exhaust port (not shown).

Next, the configuration of the fuel pump will be described.
FIG. 2 is an external perspective view of the fuel pump.
3A is a plan view of the fuel pump, and FIG. 3B is a front view thereof.
The fuel pump 12 can be broadly divided into a manifold portion 31 in which a fuel gas intake passage and a discharge passage are formed, and a pair of pump head portions 32A and 32B in which a pump chamber having a fluororubber diaphragm is formed. A motor with a built-in driving force transmission mechanism 33 for transmitting a driving force to the diaphragms of both pump head portions 32A and 32B, and a motor with a driving force applied to the diaphragm via the driving force transmission mechanism Part 34.

FIG. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is a cross-sectional view taken along the line BB in FIG.
The manifold portion 31 is attached to the pump head portions 32A and 32B by screws 31A, and includes a suction port 35 through which fuel is sucked and a discharge port 36 through which fuel is discharged, and the pump head portions 32A and 32B are provided therein. A suction path 35A and a discharge path 36A communicating with each other are formed.

  An aluminum alloy is used as the material of the manifold portion 31. Aluminum has a specific gravity of about one-third that of iron and belongs to the lighter of the metals, so it can be lighter while maintaining durability and safety compared to using other metals. Has contributed.

  The pump head portion 32A communicates with a suction passage 35A of the manifold portion 31, communicates with a suction passage 42 communicated with a first pump chamber 41A, which will be described later, and a discharge passage 36A of the manifold portion 31, and communicates with the first pump chamber 41A. The discharge path 43 is provided.

The suction passage 42 is provided with a first suction valve 45A that functions as a check valve that opens and closes by reciprocating movement of the first diaphragm 44A, and the check valve that opens and closes by reciprocation of the first diaphragm 44A is provided in the discharge passage 43. A first discharge valve 46A is provided.
The pump head portion 32A includes a first pump head case 47A and a second pump head case 47B.
The suction path 42 and the discharge path 43 described above are formed in the first pump head case 47A.

The first intake valve 45A is stored in the first valve storage portion 48A of the second pump head case 47B, and the first discharge valve 46A is stored in the second valve storage portion 48B. . Further, the second pump head case 47B cooperates with the first diaphragm 44A to constitute the first pump chamber 41A.
Similarly, the pump head portion 32B communicates with a suction passage 35A of the manifold portion 31, communicates with a suction passage 52 communicated with a second pump chamber 41B, which will be described later, and a discharge passage 36A of the manifold portion 31, and communicates with the second pump chamber. A discharge path 53 communicating with 41B is provided.

The suction passage 52 is provided with a second suction valve 45B that functions as a check valve that opens and closes by reciprocating movement of the second diaphragm 44B, and the check valve that opens and closes by reciprocation of the second diaphragm 44B is provided in the discharge passage 53. Is provided as a second discharge valve 46B.
The pump head portion 32B includes a first pump head case 57A and a second pump head case 57B.
The suction path 52 and the discharge path 53 described above are formed in the first pump head case 57A.
Further, the above-described second intake valve 45B is accommodated in the first valve accommodating portion 58A of the second pump head case 57B, and the above-described second discharge valve 46B is accommodated in the second valve accommodating portion 58B. . Further, the second pump head case 47B cooperates with the second diaphragm 44B to constitute a second pump chamber 41B.

The drive mechanism 33 includes a substantially hexagonal plate-like crank shoe 62 having a sliding long hole 61 in the center.
The crank shoe 62 is made of a resin such as polyacetal or polyethylene, and at one end thereof, a holder fixing screw hole 67A to which a screw 66 for fixing the diaphragm holder 65 for holding the first diaphragm 44A is screwed is fixed. Is provided. The other end of the crank shoe 62 is provided with a holder fixing screw hole 67B into which a screw 66 for fixing the diaphragm holder 65 that holds the second diaphragm 44B is screwed.

The diaphragm holder 65 is configured by a pair of disk-shaped members 65A and 65B having a disk shape, and the diameter of the disk-shaped member 65A located in the pump chamber is the diameter of the disk-shaped member 65B located in the drive mechanism section 33. Is smaller than
In this case, the diameter of the disk-shaped member 65A is set to a diameter that can substantially block the suction passages 42, 52 and the discharge paths 43, 53, and the diameter of the disk-shaped member 65B is set to the first pump chamber 41A and the second pump chamber 41B. The pump chamber 41B has a value close to the maximum inner diameter.

This is to increase the degree of freedom of the diaphragms 44A and 44B at the time of suction to increase the suction volume (pump chamber volume at the bottom dead center) and to suppress the deformation of the diaphragm at the time of discharge to increase the discharge volume. This is to reduce the volume of the residual gas in the room (the volume of the pump room at the top dead center).
As a result, the suction efficiency and the discharge efficiency are increased, and the pump efficiency is increased.
In this case, the disk-shaped members 65A and 65B constituting the diaphragm holder 65 are made of polyoxymethylene or butylene terephthalate.

  The motor unit 34 includes a DC brushless motor (drive motor) 71 to which a cable is connected, and a crankshaft (eccentric member) 74 fixed to a rotor shaft (rotation output shaft) 72 of the DC brushless motor 71 with a fixing screw 73. A ball bearing 75 fitted to the crankshaft 74 is provided. The ball bearing 75 is slidably fitted in the sliding long hole 61 of the crank shoe 62 and slides in the sliding long hole 61. It is configured as follows.

In this case, the DC brushless motor 71 is fixed to the motor holder 78 with screws, and the motor holder 78 is further fixed to the drive mechanism unit 33 with four screws 79.
Therefore, the DC brushless motor 71, the crankshaft 74, and the ball bearing sliding mechanism 75 can be attached to and detached from the drive mechanism unit 33 by simply removing the four screws 79, and maintenance such as component replacement is possible. Is easy.

Furthermore, a plurality (two in this embodiment) of ball bearings 76 and 77 are provided between the motor main body 71 </ b> A and the crankshaft 74 in the rotor shaft 72 of the DC brushless motor 71.
According to the configuration in which a plurality (two in the present embodiment) of ball bearings 76 and 77 are provided, the shake of the rotor shaft 72 of the DC brushless motor 71 accompanying the eccentric operation of the crankshaft 74 can be more reliably suppressed. The long-term reliability of the fuel pump 12 can be ensured, and the vibration caused by the shake of the rotor shaft 72 can be suppressed to suppress the generation of noise.

  As a result, the rotation of the rotor shaft 72 of the DC brushless motor 71 causes the center shaft 74A of the crankshaft 74 to move while drawing a circle 74C centering on the rotation shaft 72A of the rotor shaft 72, and the ball bearing sliding mechanism 75 is moved. By moving up and down in FIG. 4 while sliding in the sliding long hole 61, the crank shoe is linearly moved in the left-right direction in FIG. 4 or FIG. 5, and the first diaphragm 44A and the second diaphragm are moved. 44B is linearly reciprocated in the left-right direction.

4 and 5, the first diaphragm 44A is the discharge side, and the second diaphragm 44B is the suction side.
In this case, the peripheral edge portion 81 of the surface facing the first diaphragm 44A or the second diaphragm 44B of the first pump chamber 41A and the second pump chamber 41B is a thick portion, and the first diaphragm 44A or the second diaphragm 44A is the second diaphragm 44A. When the diaphragm 44B is located at the top dead center (in FIGS. 4 and 5, the first diaphragm 44A side), a gap with the first diaphragm 44A or the second diaphragm 44B is hardly formed.
The reason for this configuration is that the first diaphragm 44A and the second diaphragm 44B are linearly reciprocated, so that the diaphragm drive is performed only in the pump chamber as compared with the case of swinging the diaphragm drive. This is because it is not necessary to secure a useless space.

  As described above and as described above, the diameter of the disk-shaped member 65B constituting the diaphragm holder 65 is made larger than that of the disk-shaped member 65A, and the first pump chamber 41A or the second pump chamber 41B is made. Therefore, it is possible to contribute to improving the pumping efficiency by improving the discharge efficiency.

Next, the operation of the fuel pump of the embodiment will be described.
When the DC brushless motor 71 is driven to rotate the crankshaft 74 and the center shaft 74A of the crankshaft moves to the left in FIG. 4 or FIG. 5, the first diaphragm 44A and the second diaphragm 44B are moved to FIG. As shown in FIG.
Thereby, the first suction valve 45A is closed, the first discharge valve 46A is opened, the second suction valve 45B is opened, and the second discharge valve 46B is closed.

As a result, the fuel in the first pump chamber 41 </ b> A is pushed into the first discharge valve 46 </ b> A by the first diaphragm 44 </ b> A supported by the disc-like member 65 </ b> B and sent into the desulfurizer 13 through the discharge passage 43. It becomes.
On the other hand, in the second pump chamber 41B, the second diaphragm 44B supported by the disk-shaped member 65A causes the second pump chamber 41B to have a negative pressure, and the second pump chamber 41B includes a second suction valve 45B. Fuel is supplied from the fuel tank 11.

Thereafter, when the crankshaft further rotates and the crankshaft central axis 74A moves to the leftmost side in FIG. 4 or FIG. 5, the diaphragm holder 65 on the first pump chamber 41A side reaches the top dead center and the fuel gas flows. The discharge is completed, and the diaphragm holder 65 on the second pump chamber 41B side reaches the bottom dead center and completes the suction of the fuel gas.
Then, when the DC brushless motor 71 is driven to rotate the crankshaft 74 and the crankshaft center axis 74A is moved to the right in FIG. 4 or FIG. 5, this causes the first diaphragm 44A and the second diaphragm 44B to move. Move to the right.

As a result, the first suction valve 45A is open, the first discharge valve 46A is closed, the second suction valve 45B is closed, and the second discharge valve 46B is open.
As a result, in the first pump chamber 41A, the first diaphragm 44A supported by the disk-shaped member 65A causes the first pump chamber 41A to have a negative pressure, and the first pump chamber 41A has a first suction valve 45A. The fuel is supplied from the fuel tank 11 via.

On the other hand, the fuel in the second pump chamber 41B is pushed into the second discharge valve 46B by the second diaphragm 44 supported by the disk-like member 65B, and sent to the desulfurizer 13 through the second discharge passage 53. It will be.
After that, when the crankshaft further rotates and the crankshaft central axis 74A moves to the rightmost side in FIG. 4 or FIG. 5, the diaphragm holder 65 on the first pump chamber 41A side reaches bottom dead center, and the fuel gas The suction is completed, and the diaphragm holder 65 on the second pump chamber 41B side reaches the top dead center and completes the discharge of the fuel gas.

Thereafter, by repeating the above operation, the suction operation and the discharge operation are continued in parallel, and the first diaphragm 44A and the second diaphragm 44B in the first pump chamber 41A and the second pump chamber 41B. Regardless of the operation state, the load on the DC brushless motor 71 is the same, and it can be transported with a lower load compared to the case of transporting the same volume of fuel using one pump chamber.
Therefore, it is possible to use a small motor with a relatively low output as the DC brushless motor 71 while maintaining high pump efficiency (intake efficiency and discharge efficiency), and the fuel pump 12 can be reduced in size and noise. .

DESCRIPTION OF SYMBOLS 10 Fuel cell system 12 Fuel pump 19 Fuel cell 25 Anode 26 Cathode 27 Solid polymer film 31 Manifold part 32A Pump head part 32B Pump head part 33 Drive mechanism part 34 Motor part 35 Suction port 35A Suction path 36 Ejection port 36A Ejection path 41A First pump chamber 41B Second pump chamber 42 Suction passage 43 Discharge passage 44A First diaphragm 44B Second diaphragm 45A First suction valve 45B Second suction valve 46A First discharge valve 46B Second discharge valve 47A First pump head case 47B Second pump head case 52 Suction passage 53 Discharge passage 57A First pump head case 57B Second pump head case 61 Sliding long hole 62 Crank shoe 65 Diaphragm holder 65A Disc member 65B Disc member 71 DC brushless motor 71A Motor body 72 Rotor shaft 74 Crankshaft 75 Ball bearing sliding mechanism 76, 77 Ball bearing bearing 78 Motor holder

Claims (8)

A fuel cell diaphragm pump having a suction port for sucking fuel gas and a discharge port for discharging the fuel gas,
A first pump chamber that includes a first suction valve and a first discharge valve, and performs suction and discharge by a first diaphragm;
A second pump chamber comprising a second suction valve and a second discharge valve, wherein suction and discharge are performed by a second diaphragm disposed opposite to the first diaphragm;
A crank shoe having a hole and connecting the first diaphragm and the second diaphragm;
A drive motor;
An eccentric member that is driven by the drive motor and is slidably fitted in the hole to linearly reciprocate the crank shoe;
The fuel is characterized in that the first pump chamber, the first diaphragm, the crank shoe, the second diaphragm, and the second pump chamber are sequentially arranged along the linear reciprocating direction. A diaphragm pump for batteries. The fuel cell diaphragm pump according to claim 1,
A diaphragm pump for a fuel cell, wherein the drive motor and the eccentric member are integrally removable. The diaphragm pump for a fuel cell according to claim 1 or 2,
The first diaphragm and the second diaphragm are attached to the crank shoe via a diaphragm holder,
The diaphragm holder includes a disk-shaped first hold member disposed in a pump chamber, and a disk-shaped second hold member that cooperates with the first hold member to sandwich the diaphragm.
The diameter of the second hold member is set larger than the diameter of the first hold member.
A diaphragm pump for a fuel cell. The diaphragm pump for a fuel cell according to any one of claims 1 to 3,
A diaphragm pump for a fuel cell, wherein inner walls facing the diaphragms of the first pump chamber and the second pump chamber have a shape along the shape of the diaphragm at the top dead center. The diaphragm pump for a fuel cell according to any one of claims 1 to 4,
A diaphragm pump for a fuel cell, wherein two sets of bearings are provided between a motor body of an output shaft of the drive motor and the eccentric member. The diaphragm pump for a fuel cell according to any one of claims 1 to 5,
The eccentric member is attached to a motor rotation shaft and rotates integrally with the motor rotation shaft;
A sliding bearing that is rotatably fitted to the eccentric member body, and
A diaphragm pump for a fuel cell, wherein the eccentric member main body is slidably fitted into the hole via the sliding bearing. The diaphragm pump for a fuel cell according to any one of claims 1 to 6,
The members constituting the suction port and the suction path from the suction port to the first and second suction valves and the discharge path from the discharge port to the first and second discharge valves are formed of metal. A diaphragm pump for a fuel cell. The diaphragm pump according to claim 7,
A diaphragm pump for a fuel cell, wherein the metal is an aluminum alloy.

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