JP6926988B2 - Fuel gas supply device - Google Patents

Description

The present invention relates to a fuel gas supply device.

The fuel cell system may be provided with an ejector to mix the fuel off gas discharged from the fuel cell with the fuel gas supplied to the fuel cell. The ejector, in principle, recirculates the fuel off gas to the fuel cell by exchanging momentum between the fuel gas and the fuel off gas.

Therefore, when liquid water is mixed with the fuel off gas, the momentum after replacement is reduced due to the mass of the liquid water, and the circulating flow rate of the fuel off gas is reduced. As a means for removing water from the fuel off gas recirculated in the fuel cell, for example, a technique of providing two brackish water separators in the recirculation path (reflux path) through which the fuel off gas flows is known (for example, Patent Document). 1).

Japanese Unexamined Patent Publication No. 2007-42394

However, in the steam separator, the flow of the fuel off gas is disturbed due to the expansion of the flow path area of the fuel off gas, so that a pressure loss occurs in the recirculation path. Therefore, as the number of steam separators increases, the pressure loss also increases accordingly, and as a result, there is a problem that the circulation flow rate of the fuel off gas decreases.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel gas supply device capable of suppressing a decrease in the circulation flow rate of fuel off gas to a fuel cell.

The fuel gas supply device described in the present specification is a fuel gas supply device for supplying fuel gas to a fuel cell, wherein the fuel cell is charged with a pressure accumulator for accumulating the fuel gas and the fuel gas flowing in from the accumulator. The ejector has an ejector that mixes the fuel off gas that is recirculated into the fuel cell and introduces the fuel off gas into the fuel cell. Due to the negative pressure generated by the fuel, the fuel off gas extends along the nozzle between the suction chamber where the fuel off gas is sucked from the suction port on the vertically lower side of the nozzle and the nozzle and the suction port, and the end portion on the tip end side of the nozzle. Is provided with a plate member separated from the inner wall of the suction chamber, and the fuel off gas passes between the plate member and the inner wall of the suction chamber when viewed from the suction direction of the fuel off gas sucked from the suction port. The area of the gap is larger than the area of the suction port .

According to the present invention, it is possible to suppress a decrease in the circulation flow rate of the fuel off gas to the fuel cell.

It is a block diagram which shows an example of a fuel cell system. It is sectional drawing which shows the ejector of the comparative example. It is sectional drawing which shows the ejector of an Example. It is sectional drawing which shows the example of the ejector provided with two nozzles. It is sectional drawing which shows the example of the ejector provided with three nozzles.

FIG. 1 is a configuration diagram showing an example of a fuel cell system. The fuel cell system is installed in, for example, a fuel cell vehicle, but is not limited to this.

The fuel cell system includes a fuel cell 1, an ECU (Electronic Control Unit) 6, a fuel gas supply device 9, a compressor 80, a humidifier 81, cathode supply paths R10 and R11, and cathode discharge paths R12 and R13. Has.

The fuel gas supply device 9 supplies fuel gas to the fuel cell 1. The fuel gas supply device 9 includes a fuel tank 2, a pressure regulating valve 3, an injector 4, an ejector 5, a main stop valve 70, a gas-liquid separator 71, a purge valve 72, and anode supply paths R20 to R23. , Has an anode discharge path R24 to R26 and a recirculation path R27.

The fuel cell 1 is a solid polymer fuel cell, which is configured by stacking a plurality of single cells each having a membrane electrode assembly, and air containing oxygen as an example of an oxidizing agent gas is supplied to the cathode. Then, hydrogen gas is supplied to the anode as an example of the fuel gas. The fuel cell 1 generates electricity by chemically reacting the oxidant gas and the fuel gas in each single cell.

The oxidant gas is supplied to the fuel cell 1 via the cathode supply paths R10 and R11. The oxidant off gas is discharged from the fuel cell 1 to the outside via the cathode discharge paths R12 and R13.

The compressor 80 introduces an oxidant gas from the outside air and compresses it. The compressor 80 sends the oxidant gas to the humidifier 81 via the cathode supply path R10.

The humidifier 81 humidifies the oxidant gas and sends it to the cathode of the fuel cell 1 via the cathode supply path R11. Fuel off gas is introduced into the humidifier 81 from the fuel cell 1 via the cathode discharge path R12. The humidifier 81 humidifies the fuel gas with the water contained in the fuel off gas. The humidifier 81 discharges the fuel off gas to the outside from the cathode discharge path R13.

The fuel tank 2 is an example of a pressure accumulator, and stores fuel gas by accumulating it. A main check valve 70 is connected to the outlet of the fuel tank 2. The main check valve 70 is maintained in an open state during power generation of the fuel cell 1 according to the control of the ECU 6. The fuel gas flows from the main check valve 70 through the anode supply path R20 and enters the pressure regulating valve 3.

The pressure regulating valve 3 adjusts the pressure of the fuel gas flowing from the fuel tank 2 into the injector 4 according to a control signal from the ECU 6. The fuel gas that has passed through the pressure regulating valve 3 flows into the injector 4 via the anode supply path R21. The injector 4 injects the fuel gas flowing from the fuel tank 2 according to the control signal from the ECU 6. The fuel gas injected from the injector 4 flows into the ejector 5 via the anode supply path R22.

The ejector 5 mixes the fuel gas injected from the injector 4 with the fuel off gas recirculated in the fuel cell 1 and introduces the fuel gas into the fuel cell 1. Fuel off gas is sucked into the ejector 5 from the recirculation path R27. The fuel gas mixed with the fuel off gas is supplied to the fuel cell 1 from the anode supply path R23.

The fuel off gas flows from the fuel cell 1 through the anode discharge path R24 and enters the gas-liquid separator 71. The gas-liquid separator 71 separates and stores the liquid water from the fuel off gas, and sends the fuel off gas to the recirculation path R27.

The purge valve 72 is connected to the gas-liquid separator 71 via the anode discharge path R25. The purge valve 72 is opened and closed under the control of the ECU 6. When the purge valve 72 is opened, the fuel off gas and the liquid water in the gas-liquid separator 71 are discharged to the outside from the anode discharge passages R25 and R26.

The ECU 6 controls the operation of the fuel cell system. The ECU 6 is composed of, for example, a CPU (Central Processing Unit) and a memory, and operates according to a program that drives the CPU.

FIG. 2 is a cross-sectional view showing an example of the ejector 5 of the comparative example. The ejector 5 has a nozzle 50, a suction chamber 51, and a diffuser 52. The inlet of the nozzle 50 is connected to the anode supply path R22, and the fuel gas is ejected from the nozzle 50 as indicated by reference numeral P0. The nozzle 50 has a substantially cylindrical shape as an example.

Further, the suction chamber 51 accommodates the nozzle 50, and as indicated by reference numeral P1, the fuel off gas is sucked by the negative pressure generated by the fuel gas ejected from the nozzle 50. The suction chamber 51 has a substantially rectangular parallelepiped shape, and a suction port 51a for sucking fuel off gas is provided on the vertically downward side (see reference numeral g) of the nozzle 50. The suction port 51a is connected to the recirculation path R27, and the fuel off gas is sucked into the suction chamber 51 from the recirculation path R27 through the suction port 51a and mixed with the fuel gas ejected from the nozzle 50.

As indicated by reference numeral P2, fuel gas and fuel off gas flowing from the suction chamber 51 toward the fuel cell 1 flow through the diffuser 52. The diffuser 52 includes a tapered portion 52a, a parallel portion 52b, and a divergent portion 52c. The tapered portion 52a is a flow path whose cross-sectional area narrows from the suction chamber 51 toward the parallel portion 52b. The parallel portion 52b is a flow path having a constant cross-sectional area connecting the tapered portion 52a and the divergent portion 52c. The parallel portion 52b has a substantially cylindrical shape. The divergent portion 52c is a flow path whose cross-sectional area expands from the parallel portion 52b toward the anode supply path R22.

With the above structure, the fuel gas is introduced into the suction chamber 51 from the nozzle 50, and the fuel off gas is sucked into the suction chamber 51 from the suction port 51a by the negative pressure due to the injection of the fuel gas. The fuel gas and the fuel off gas are mixed and supplied from the diffuser 52 to the anode of the fuel cell 1 via the anode supply path R23. That is, the ejector 5 recirculates the fuel off gas to the fuel cell 1 using the fuel gas ejected from the nozzle 50 as a drive source.

In principle, the ejector 5 recirculates the fuel off gas to the fuel cell by exchanging momentum between the fuel gas and the fuel off gas. Therefore, when liquid water is mixed with the fuel off gas, the momentum after replacement is reduced due to the mass of the liquid water, and the circulating flow rate of the fuel off gas is reduced.

Therefore, the ejector 5 of the embodiment is provided with a simple gas-liquid separation means.

FIG. 3 is a cross-sectional view showing the ejector 5 of the embodiment. Reference numeral G1 indicates a cross section similar to that in FIG. 2, and reference numeral G2 indicates a cross section along the line AA of the cross-sectional view of reference numeral G1. Further, reference numeral G3 indicates a cross section along line BB of the cross-sectional view of reference numeral G2, and indicates a cross section along line CC of the cross-sectional view of reference numeral G4. In FIG. 3, the same reference numerals are given to the configurations common to those in FIG. 2, and the description thereof will be omitted.

As compared with the comparative example, a baffle plate 53 is added to the configuration of the ejector 5. The baffle plate 53 is a rectangular plate member extending along the nozzle 50 between the nozzle 50 and the suction port 51a. In the baffle plate 53, the end portion 53a on the tip 50a side of the nozzle 50 and the end portions 53c and 53d on both side surfaces along the extending direction of the nozzle 50 are separated from the inner wall 51b of the suction chamber 51. Further, in the baffle plate 53, the end portion 53b on the root side of the nozzle 50 is fixed to the inner wall 51b of the suction chamber 51. The baffle plate 53 may be integrally molded with the suction chamber 51, or may be molded separately from the suction chamber 51 and adhered to the inner wall 51b of the suction chamber 51 with an adhesive or the like.

As described above, the fuel off gas enters the suction chamber 51 from the recirculation path R27 through the suction port 51a. At this time, the total area of the gaps between the end portions 53a, 53c, 53d and the inner wall 51b is larger than the area of the suction port 51a when viewed from the vertically downward g (see reference numerals G3 and G4). Therefore, the area through which the fuel off gas can pass is larger in the suction chamber 51 than in the recirculation path R27. Further, the area of the plate surface of the baffle plate 53 is larger than the area of the suction port 51a.

Since the suction port 51a is located vertically below g of the baffle plate 53, the fuel off gas in the suction chamber 51 hits the baffle plate 53 and passes between the end portions 53a, 53c, 53d of the baffle plate 53 and the inner wall 51b to pass through the diffuser 52. Introduced in. At this time, when the ejector 5 is viewed from the side (see reference numeral G1), the fuel off gas is directed from the suction port 51a to the tip end 50a of the nozzle 50 so as to be directed from the suction port 51a to the end portion 53a and the inner wall of the baffle plate 53. It flows between 51b.

In this way, when the fuel off gas is sucked from the suction port 51a, it flows in the same direction as the flow of the fuel gas ejected from the tip 50a of the nozzle 50 and is introduced into the diffuser 52. The pressure loss of the fuel off gas caused by 53 is suppressed.

Further, the liquid water (water generated by the power generation reaction) contained in the fuel off gas adheres to the baffle plate 53 as water droplets. That is, the baffle plate 53 functions as a simple gas-liquid separation means. Therefore, water is removed from the fuel off gas before the fuel off gas is mixed with the fuel gas ejected from the nozzle 50. As a result, the mass of the fuel off gas mixed with the fuel gas in the suction chamber 51 is reduced, so that the decrease in the circulation flow rate of the fuel off gas is suppressed. Here, since the baffle plate 53 extends between the nozzle 50 and the suction port 51a so that the liquid water does not adhere to the nozzle 50 and does not cover the entire nozzle 50, the pressure loss of the fuel off gas caused by the baffle plate 53 is generated. It is suppressed.

Here, if the liquid water adheres to the injection portion of the nozzle 50, if the temperature of the fuel cell 1 drops below the freezing point, the ejection portion may freeze and block. However, according to this embodiment, since the baffle plate 53 suppresses the liquid water from adhering to the nozzle 50, it is possible to suppress the blockage of the ejection portion of the nozzle 50.

The liquid water adhering to the baffle plate 53 falls vertically downward g due to, for example, gravity or vibration. The dropped liquid water enters the gas-liquid separator 71 through the recirculation path R27, and is discharged to the outside from the gas-liquid separator 71, for example, by the anode discharge paths R25 and R26. Therefore, as indicated by reference numeral D, the liquid water is discharged from the recirculation passage R27 through the suction port 51a to reach the obstruction plate 53 and then again through the suction port 51a into the recirculation passage R27.

In this way, the ejector 5 is configured to reduce the pressure loss of the fuel off gas, and the liquid water can be removed from the fuel off gas. Therefore, the pressure loss of the fuel off gas is reduced as compared with the case where another gas-liquid separator 71 is added to the recirculation path R27. This is because if another gas-liquid separator 71 is added, the pressure loss may increase due to the change in the cross-sectional area of the flow path at the inlet and outlet of the gas-liquid separator 71. This is because there is no pressure loss at the inlet and outlet of the gas-liquid separator 71. Therefore, according to the fuel gas supply device 9 of the present embodiment, it is possible to suppress a decrease in the circulation flow rate of the fuel off gas to the fuel cell 1.

The ejector 5 of this example includes only one nozzle 50, but may include two or more nozzles as described below.

FIG. 4 is a cross-sectional view showing an example of an ejector 5 including two nozzles 54 and 55. Reference numeral G11 indicates a cross section similar to that in FIG. 2, and reference numeral G12 indicates a cross section taken along the line LL of the cross-sectional view of reference numeral G11. In FIG. 4, the same reference numerals are given to the configurations common to those in FIG. 3, and the description thereof will be omitted.

The ejector 5 of this example is provided with two nozzles 54 and 55. Fuel gas branched from the anode supply path R22 via a three-way valve or the like is introduced into the nozzles 54 and 55, for example. For example, the ECU 6 controls a three-way valve so that one or both of the nozzles 54 and 55 eject fuel gas according to the state of the fuel cell 1.

A baffle plate 53 is provided between the nozzles 54 and 55. The nozzle 54 is located above the baffle plate 53, and the nozzle 55 is located below the baffle plate 53. That is, the baffle plate 53 extends between the nozzle 54 on the upper side and the suction port 51a. Therefore, it is possible to prevent the liquid water in the fuel off gas from being mixed with the fuel gas ejected from the nozzle 54.

The nozzle 54 is preferably used when the ratio of the circulating flow rate of the fuel off gas to the flow rate of the fuel gas which is the driving source of the ejector 5 is larger than that of the other nozzle 55 and the flow rate of the ejected fuel gas is large. Therefore, the diameter of the nozzle 54 should be larger than the diameter of the nozzle 55.

The nozzle 54 is used when the load on the fuel cell 1 is large. In such a case, for example, when a large amount of fuel gas is supplied to the fuel cell 1 when the fuel cell 1 is started, or when the fuel cell 1 is started in an environment below the freezing point, a high concentration fuel gas is supplied to the fuel cell 1. There is a case of supplying to. In the latter case, not only liquid water but also ice may be present in the recirculation path R27, so that the action of the baffle plate 53 improves the starting performance of the fuel cell 1.

Further, reference numeral G13 indicates a cross section of the ejector 5 of another embodiment corresponding to the cross section of reference numeral G12. In the ejector 5 of this example, the baffle plate 53 is divided into two baffle plates 53r and 53s as compared with the ejector 5 of the reference numeral G12. The baffle plates 53r and 53s extend between the nozzle 54 on the upper side and the suction port 51a. Each of the baffle plates 53r and 53s is fixed to the inner wall 51b of the suction chamber 51 on one side surface thereof, but the end portion of the nozzles 54 and 55 on the distal end side is separated from the inner wall 51b. Therefore, each of the baffle plates 53r and 53s has the same effect as that of the baffle plate 53.

FIG. 5 is a cross-sectional view showing an example of an ejector 5 including three nozzles 54 to 56. Reference numerals G21 and G22 correspond to the cross sections of reference numerals G12 in FIG. 4, respectively. In FIG. 5, the same reference numerals are given to the configurations common to those in FIG. 4, and the description thereof will be omitted.

In the ejector 5 of this example, a new nozzle 56 is added below the nozzles 54 and 55 of the ejector 5 shown by the reference numeral G12 in FIG. The ECU 6 controls a three-way valve or the like so that fuel gas is ejected from at least one of the nozzles 54 to 56.

The baffle plate 53 extends along the nozzles 54 to 56. The baffle plate 53 may be provided between the nozzles 54 and 55 as indicated by the reference numeral G21, or may be provided between the nozzles 55 and 56 as indicated by the reference numeral G22.

In the example of reference numeral G21, since the baffle plate 53 extends between the nozzle 54 and the suction port 51a, it is possible to prevent the liquid water in the fuel off gas from being mixed with the fuel gas ejected from the nozzle 54. Further, in the example of reference numeral G22, since the baffle plate 53 extends between the nozzles 54 and 55 and the suction port 51a, it is possible to prevent the liquid water in the fuel off gas from being mixed with the fuel gas ejected from the nozzles 54 and 55. NS.

As described above, even when the ejector 5 is provided with the three nozzles 54 to 56, the above-mentioned effects can be obtained.

The embodiments described above are examples of preferred embodiments of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

1 Fuel cell 2 Fuel tank (accumulation unit)
5 Ejector 9 Fuel gas supply device 50, 54-56 Nozzle 51 Suction chamber 51a Suction port 51b Inner wall 53 Baffle plate (plate member)
53a-53d end

Claims (1)

In a fuel gas supply device that supplies fuel gas to a fuel cell
The accumulator that accumulates the fuel gas and the accumulator
It has an ejector that mixes the fuel gas that has flowed in from the accumulator with the fuel off gas that is recirculated in the fuel cell and introduces the fuel gas into the fuel cell.
The ejector is
The nozzle from which the fuel gas is ejected and
A suction chamber accommodating the nozzle and sucking the fuel off gas from a suction port on the vertically lower side of the nozzle due to a negative pressure generated by the fuel gas ejected from the nozzle.
A plate member extending along the nozzle between the nozzle and the suction port and having a tip end portion of the nozzle separated from the inner wall of the suction chamber is provided .
The area of the gap through which the fuel off gas passes between the plate member and the inner wall of the suction chamber is larger than the area of the suction port when viewed from the suction direction of the fuel off gas sucked from the suction port.
Fuel gas supply device.

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