KR100987113B1 - Apparatus for supplying air of fuel cell - Google Patents

Abstract

The present invention relates to a fuel supply device for a fuel cell, wherein the fuel supply device includes a piezoelectric driver, and an inlet and an outlet are provided at one side thereof, and receive the driving force of the piezoelectric driver to suck the fuel through the inlet and the outlet. And a chamber for discharging, a body for fixing the piezoelectric driver and the chamber, a check valve module configured to respectively correspond to the inlet and the outlet of the chamber, and a control unit for controlling driving of the piezoelectric driver. Characterized in that the configuration. The present invention configured as described above can easily optimize the driving, noise and vibration is not generated, there is an advantage that can improve the fuel cell output performance according to the pulsation supply.

Fuel cell, liquid, piezo actuator, chamber, check valve module

Description

Fuel supply device of fuel cell {APPARATUS FOR SUPPLYING AIR OF FUEL CELL}

The present invention relates to a fuel supply device for a fuel cell, and more particularly, to a fuel supply device for a fuel cell which can improve the fuel cell output efficiency without generating easy optimization and noise and vibration.

In general, a fuel cell is a power generation system that converts chemical energy directly into electrical energy by an electrochemical reaction between hydrogen and oxygen.

The hydrogen may supply pure hydrogen directly to the fuel cell system, or may supply hydrogen by reforming materials such as methanol, ethanol, natural gas, and the like. The oxygen may directly supply pure oxygen to the fuel cell system, or may supply oxygen included in normal air using an air pump or the like.

Fuel cells include polymer electrolyte fuel cells and direct methanol fuel cells operating at room temperature or below 100 ° C, phosphoric acid fuel cells operating near 150 to 200 ° C, and molten carbonate fuel cells operating at high temperatures of 600 to 700 ° C. And solid oxide fuel cells operating at high temperatures of 1000 ° C or higher. Each of these fuel cells has basically the same operation principle of generating electricity, but different fuel types, catalysts, and electrolytes are used.

Among them, the direct methanol fuel cell (DMFC) is a direct methanol fuel cell, which mixes liquid high concentration methanol with water and supplies it as a fuel directly to an electric generator using a fluid pump. Therefore, a reformer for generating hydrogen is not required, and thus, miniaturization is possible, and fuel is easily stored and handled.

Such a fuel cell is connected to a fuel tank 1 filled with gasoline or other hydrocarbon (LNG, LPG, CH 3 OH ...) fuel as shown in FIG. 1, and connected to the fuel tank 1. A reformer 2 for producing hydrogen from the supplied fuel, and an oxidation reaction of hydrogen generated from the reformer 2 connected to the reformer 2 and a reduction reaction of oxygen supplied separately occur simultaneously. And a stack (3) generated together with heat, and a power converter (4) connected to the stack (3) and converting direct current (DC) obtained from the stack (3) into alternating current (AC) electricity, which is commercially available. .

In the figure, 2a is a reactor, 2b is a burner, 3a is an electrolyte membrane, 3b is a fuel electrode, 3c is a cathode, 6 is a feed water pump, and 7 is a humidifier.

A schematic process of generating electricity using the fuel cell of the conventional structure as described above is as follows.

After the gasoline or hydrocarbon-based fuel flows from the fuel tank 1 into the reactor 2a of the reformer 2 by a controller (not shown), steam and oxygen are added to the fuel filled in the reactor 2a. And the burner 2b of the reformer 2 is operated so that the reforming reaction proceeds, and hydrogen generated through the reforming reaction is supplied to the fuel electrode 3b of the stack 3 and the other side Oxygen (O ₂ ) is supplied to the cathode 3c, and an oxidation reaction occurs at the anode 3b, and a reduction reaction occurs at the cathode 3c, and electrons generated in this process are transferred to the cathode 3b. Electricity and heat are generated while moving to 3c), which is converted into alternating current electricity through the power converter 4 and used to drive various electrical appliances.

In the fuel cell, when the electrolyte membrane 3a of the stack 3 is dried, the conductivity of hydrogen ions (H +) decreases or the electrolyte membrane shrinks, thereby increasing the contact resistance between the membrane and the electrode. Always supply water with hydrogen to).

However, in this prior art, the fluid pump for supplying fuel may adversely affect the use environment because noise and vibration are caused.

In addition, since a large amount of power is required to operate the fluid pump, the efficiency of fuel cell operation is reduced by supplying a separate power or consuming power produced by the fuel cell.

The present invention for solving the above problems is to provide a fuel supply device of a fuel cell that can eliminate the noise and vibration generation, and can easily optimize the drive over the entire operating range.

It also aims to improve fuel cell output by pulsating fuel.

In order to achieve the above object, the present invention provides a fuel supply device for a fuel cell, and includes a piezoelectric driver and an inlet and an outlet at one side thereof, and receives and discharges fuel through the inlet and the outlet by receiving the driving force of the piezoelectric driver. And a check valve module configured to respectively correspond to the inlet and outlet of the chamber, the check valve module for determining the intake and discharge of fuel, and a control unit for controlling the driving of the piezoelectric driver. It is characterized by.

The chamber may include a space portion communicating with the suction port and the discharge port, and an elastic membrane for closing one side of the space portion may be provided to provide the driving force to the elastic membrane.

The piezoelectric driver may be a linear piezoelectric driver.

In addition, the chamber and the body, characterized in that formed integrally.

The piezoelectric driver may be driven by adjusting the number of pulses.

The piezoelectric driver may be driven by adjusting the operation rate.

The piezoelectric driver may be driven at a frequency of 10 Hz or less.

In addition, the piezoelectric driver is characterized in that it is further provided with a fixing member coupled to the body.

In addition, the check valve module, characterized in that consisting of a silicon plate provided between the glass plate provided in the upper / lower surface and the glass plate.

The present invention constructed and operated as described above optimizes the driving efficiency of the piezoelectric actuator by adjusting the number of driving pulses, and utilizes an independent control factor in such a manner that the supply flow rate of the fuel supply device is adjusted to the operation rate, thereby driving the entire driving range. There is an advantage that can be easily optimized.

In addition, by separating the driving frequency of the piezoelectric driver and the reciprocating frequency of the piston, it is possible to increase the efficiency of the check valve module by operating at a piezoelectric driving frequency outside the audible region.

In addition, since the fuel is pulsated at a low frequency, the fuel cell output performance is improved by activating secondary flow of the fuel at the fuel cell anode to improve supply characteristics.

Hereinafter, a preferred embodiment of a fuel supply device of a fuel cell according to the present invention with reference to the accompanying drawings in detail as follows.

2 is a perspective view showing a fuel supply device of a fuel cell according to the present invention, Figure 3a is an exploded perspective view showing a fuel supply device of a fuel cell according to the present invention, Figure 3b is a detailed view showing a check valve module according to the present invention, Figure 4 is a cross-sectional view showing a chamber operation process of a fuel supply device of a fuel cell according to the present invention, Figure 5 is a view showing a fuel transfer process through the chamber and the check valve module according to the present invention.

6 is a schematic overall configuration diagram of a fuel cell using a fuel supply device according to the present invention, Figure 7 is a graph showing the result of the supply flow rate for the stroke at the same power consumption according to the present invention, Figure 8 is in accordance with the present invention It is a graph showing the result of the supply flow rate to the operation rate at the same number of drive pulses.

The fuel supply device 10 of the fuel cell according to the present invention includes a piezoelectric driver 100 in which a rod is linearly driven, and an inlet port and an outlet port are provided on one side thereof, and receives the driving force of the piezoelectric driver. A chamber 200 for sucking and discharging fuel through the 220, a body 300 for fixing the piezoelectric driver and the chamber, and a check valve module 400 for selectively blocking the inlet and the outlet of the chamber. And it characterized in that it comprises a control unit 500 for controlling the piezoelectric driver.

The piezoelectric driver 100 is a driving force generated in the load according to the application of voltage using the piezoelectric element (PZT), in the present invention provides an operating force for fuel supply using a linear piezoelectric driver.

In more detail, the piezoelectric driver 100 may include a piezoelectric element 110, a vibration rod 120 connected to the piezoelectric element 110, and a sleeve 130 and a piston for transmitting a driving force according to the vibration of the vibration rod 120. 140.

Therefore, when a voltage is applied to the piezoelectric element, this causes repetitive deformation and the vibration rod 120 vibrates. At this time, the piston is moved along the vibration rod by the frictional force of the vibration rod and the inertia of the sleeve connected to the piston 140.

Therefore, when the piston is moved forward or backward, the elastic membrane to be contacted later will be deformed forward / backward.

In addition, in the present invention, the stroke of the piston is adjusted by adjusting the number of forward and backward pulses of the piezoelectric driver to realize the maximum supply flow rate by consuming the same power with the piezoelectric driver 100.

In addition, by adjusting the operation rate of the piezoelectric driver 100 to minimize power consumption, it is a method of supplying the minimum amount of fuel required according to the output of the fuel cell. In this case, the operation rate refers to the ratio of the time of driving the pulses to the piezoelectric actuator in the entire driving cycle, and the total driving cycle refers to the sum of the waiting time and the actual driving time without driving.

Alternatively, operating at low reciprocating frequencies of less than 10 Hz and large reciprocating strokes maximizes drive efficiency.

On the other hand, the piezoelectric driver 100 is additionally provided with a fixing member 150, the vibration rod and the piston of the piezoelectric driver is coupled to the fixing member to move forward / backward.

The chamber 200 is a suction and discharge process for receiving and delivering a liquid fuel from the reservoir to supply fuel to a direct cell fuel cell (DMFC) in a reservoir where liquid fuel is stored. As a result, the suction port 210 and the discharge port 220 are formed, and the space portion 230 is formed inwardly so as to communicate with the suction port 210 and the discharge port 220.

In addition, the inlet and outlet are formed on the opposite side of the space portion is formed in an open state, the open surface is provided with an elastic membrane 240 made of an elastic material to close the space 230.

At this time, the elastic membrane is fixed to the piston 140 of the piezoelectric driver 100 so as to elastically move back and forth according to the operation of the piezoelectric driver to change the volume of the space part. That is, the amount of fuel sucked into the space part is controlled.

Therefore, when the rod of the piezoelectric driver reverses, the elastic membrane is stretched backwards to increase the volume of the space portion, and fuel is sucked into the space portion through the suction port. Fuel is discharged through.

As will be described later, a check valve module is provided for intake and discharge of fuel through the inlet and outlet, and suction and discharge are selectively performed.

In a preferred embodiment, the elastic membrane may be a latex (LATEX) material, and the material or structure (wrinkle type) easily stretched even with a small force, it is irrelevant to use a variety of durable elastic material.

Body 300 is for supporting the piezoelectric actuator and the chamber, it is manufactured in a suitable size and shape using a metal or synthetic resin.

Here, the body 300 may be formed integrally with the chamber 200 or may be separately formed and fixed with the body. In addition, the piezoelectric driver is fixed to the body 300 through a fixing means such as a screw, the body 300 is coupled through the fixing member 150.

The check valve module 400 is coupled to a pair of two check valves in communication with the inlet and outlet of the chamber 200, and determines the opening and closing according to the intake / discharge of the fuel. The check valve module 400 is coupled to the suction / discharge port is formed to correspond to the inlet and outlet of the chamber.

The check valve module according to the present invention is manufactured by a MEMS process, and is manufactured to manually control the flow path by installing a silicon membrane having a thickness of about 10 μm in the upper and lower glass plates.

In addition, the inside of the check valve module is divided into an internal space in which suction and discharge are formed, and each has a suction / exhaust port for connecting to the outside, and the silicon membrane in the center interrupts the flow.

The valve valve module connected to the chamber 200 determines the flow direction of the fuel. When the elastic membrane increases as the rod retracts the piezoelectric actuator, and the volume of the space increases, one valve opens and the fuel is sucked through the inlet of the chamber. . At this time, the other valve is closed.

When the rod of the piezoelectric driver 100 is advanced for fuel injection, the elastic membrane is pressed and one open valve is closed, and the fuel sucked into the space is discharged through the discharge port. At this time, the other valve that was closed is opened to supply fuel.

The control unit 500 controls the piezoelectric driver 100, and controls the piezoelectric driver to achieve the optimum efficiency by controlling the number of pulses and the operation rate as mentioned above in the description of the piezoelectric actuator.

The driving efficiency of the piezoelectric actuator 100 is optimized to drive frequency of high frequency, the hydraulic efficiency of the fuel supply device optimizes the stroke by the number of driving pulses, and the fuel supply flow rate is controlled by the operation rate.

That is, the control unit corresponds to a power supply unit and must supply an appropriate voltage and current according to the specification of the piezoelectric driver. The piezoelectric actuator is controlled by applying an ultrasonic frequency of several tens of kHz or more, and a plurality of driving pulses are applied in one direction so that the reciprocating motion of the piezoelectric actuator is performed at a low frequency of several Hz.

One of the great advantages of the fuel supply device according to the invention is that the PZT drive frequency and the piston drive frequency can be separated from each other. The PZT drive frequency is controlled to a value optimized for PZT displacement efficiency, and the piston drive frequency is controlled to a value optimized for valve efficiency and piston speed.

Referring to Fig. 7, in general, the longer the stroke length of the piston (the larger the deformation of the elastic membrane), the lower the speed of the piston, which reduces the flow rate. On the contrary, shortening the stroke length of the piston reduces the rectification efficiency of the check valve module. This also reduces the flow rate.

Due to these two contradictory characteristics, maximum flow rates occur at specific stroke lengths. Therefore, the fuel pump according to the present invention can adjust the stroke length only by the number of pulses, so that it can be easily operated at the stroke length which is the optimum flow rate without affecting other factors.

On the other hand, the maximum performance is also important in the fuel supply device (micro pump) of the fuel cell, but more important than that is the performance maintenance characteristic in a wide operating range. If the pump is operated at maximum performance even when the fuel cell output is small, it will eventually generate unnecessary energy consumption, thereby reducing system efficiency.

Therefore, in the present invention, a method of adjusting the driving ratio is selected as the easiest method of controlling the flow rate. The driving ratio is the ratio of the time that the pump drives during the whole time. When the driving ratio is 100%, the pump is driven continuously. When the driving ratio is 50%, it corresponds to one cycle after the piston has finished one cycle of movement. This is the case when there is no operation for a while. If the flow rate can be controlled by the driving ratio alone, it means that the driving efficiency can be maintained without affecting the already optimized driving frequency, driving displacement, piston speed, etc., thus maintaining the highest efficiency within the operating conditions.

8 shows the flow rate characteristics according to the change in driving ratio. It can be seen that the driving ratio increases almost linearly. Since the driving ratio is proportional to the energy consumption rate, it shows a very useful characteristic that the flow rate changes linearly with respect to the energy consumption.

The present invention constructed and operated as described above can easily optimize the operating range, has no noise, and has the advantage of improving fuel cell output performance.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described.

Rather, it will be apparent to those skilled in the art that many changes and modifications to the present invention are possible without departing from the spirit and scope of the appended claims. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

1 is a schematic configuration diagram showing a conventional fuel cell system,

2 is a perspective view showing a fuel supply device for a fuel cell according to the present invention;

3a is an exploded perspective view showing a fuel supply device for a fuel cell according to the present invention;

Figure 3b is a detailed view showing a check valve module according to the present invention,

4 is a cross-sectional view showing a chamber operation process of a fuel supply device of a fuel cell according to the present invention;

5 is a view showing a fuel transfer process through a chamber and a check valve module according to the present invention;

6 is a schematic overall configuration diagram of a fuel cell using a fuel supply device according to the present invention;

7 is a graph showing the result of the supply flow rate for the stroke at the same power consumption according to the present invention,

8 is a graph showing the results of the supply flow rate for the operation rate at the same number of drive pulses in accordance with the present invention.

<Description of the symbols for the main parts of the drawings>

100: piezoelectric driver 200: chamber

210: inlet 220: outlet

230: space portion 240: elastic membrane

300: body 400: check valve module

500 control unit 10 fuel supply device

Claims (9)

In the fuel supply device of a fuel cell, Piezoelectric drivers; A chamber having a suction port and a discharge port at one side thereof, and receiving a driving force of the piezoelectric driver to suck and discharge fuel through the suction port and the discharge port; A body fixing the piezoelectric driver and the chamber; Check valve module is provided corresponding to the inlet and outlet of the chamber to determine the intake and discharge of the fuel; And And a control unit for controlling the driving of the piezoelectric driver. The method of claim 1, wherein the chamber, And a space portion communicating with the suction port and the discharge port is provided, and an elastic membrane for closing one side of the space portion is provided so that the piezoelectric driver provides a driving force to the elastic membrane. The method of claim 1, wherein the piezoelectric driver, A fuel supply device for a fuel cell, characterized in that the linear piezoelectric driver. The method of claim 1, wherein the chamber and the body, A fuel supply device for a fuel cell, characterized in that formed integrally. The piezoelectric driver according to claim 1 or 3, wherein A fuel cell fuel supply apparatus, characterized in that for driving by adjusting the number of pulses. The piezoelectric driver according to claim 1 or 3, wherein A fuel supply device for a fuel cell, characterized in that for driving by adjusting the operation rate. The piezoelectric driver according to claim 1 or 3, wherein A fuel supply device for a fuel cell, which is driven at a frequency of 10 Hz or less. The method of claim 1, wherein the piezoelectric driver, A fuel supply device for a fuel cell, further comprising a fixing member coupled to the body. The method of claim 1, wherein the check valve module, A fuel supply device for a fuel cell, comprising a glass plate provided on top and bottom surfaces and a silicon membrane provided between the glass plates.

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