JP2003100335A - Fuel cell system and ejector circulation equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ejector circulation equipment and a fuel cell system in which no variable mechanism is provided in the ejector, while a starting fuel gas and an exhaust circulation gas can be mixed in a fixed ratio in the wide actuation range of gas flow rate. SOLUTION: An ejector 7 has a first supply mouth 9 connected to a first nozzle, a second supply mouth 10 connected to the down stream of the first nozzle and the upper stream of a second nozzle having a cross sectional area larger than that of the first nozzle, and a third supply mouth 11 connected to the down stream of the second nozzle. In a low loading of the fuel cell, shutout valve 18 is closed, then a three-way valve 16 is settled in a first state opening directing to the second supply mouth 10 to supply the starting fuel gas into the first supply mouth 9, and to supply the exhausted circulation gas from a fuel electrode 2 to the second supply mouth 10. In a high loading, the shutout valve is opened, then the three-way valve 16 is settled in a second state opening directing to the third supply mouth 11 to supply the starting fuel gas into the second supply mouth 10, and to supply the exhaust circulation gas into the third supply mouth 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system and an ejector circulator suitable for a fuel cell, and more particularly to a fuel cell system and an ejector circulator having enhanced circulation performance of exhausted fuel gas over a wide operating range. .

[0002]

2. Description of the Related Art A fuel cell is one in which hydrogen is supplied as a fuel gas to a fuel electrode and air containing oxygen is supplied to an air electrode to electrochemically react hydrogen with oxygen to directly generate electricity. Yes, high power generation efficiency can be obtained even on a small scale, and it is also environmentally friendly.

Further, in recent years, by using a solid polymer ion exchange membrane as an electrolyte, a small size and high output can be achieved, and a solid polymer type fuel cell which does not require an aqueous acid solution is a fuel cell using hydrogen gas. It is attracting attention as a method.

In a fuel cell, a fuel gas containing hydrogen and an air containing oxygen are supplied to a fuel electrode and an air electrode which face each other with a solid polymer membrane interposed therebetween. With the aim of reducing the consumption of raw fuel gas in this fuel cell and lowering the utilization rate of hydrogen gas to improve the output characteristics, the exhaust gas from the fuel electrode of the fuel cell is recirculated and externally supplied. Many recirculation systems have been devised, which are mixed with newly supplied rich fuel gas of hydrogen and supplied to the fuel electrode of the fuel cell.

It has been known that the power generation efficiency of a fuel cell is improved by keeping the amount of exhausted fuel gas to be recirculated and the amount of fuel gas newly supplied from the outside at a certain ratio or more. The ejector is well known as a circulation device that mixes two flows, but since negative pressure and dragging due to the flow rate of the supplied fuel gas are used as the driving force for circulation, a wide range of operation of the supplied fuel gas amount and circulating gas flow rate is achieved. It is difficult to keep above a certain level in the area.

As an example of a variable displacement ejector for expanding the ejector operating region, Japanese Patent Laid-Open Publication No. 7-185284 in which a flow passage area of the entire ejector is variable by using a slide mechanism or a needle-shaped adjusting rod is inserted into a nozzle. JP-A-8-338398 discloses that the nozzle area can be changed by changing the position of the adjusting rod. However, both of them have a structure in which the variable mechanism is controlled from outside the ejector, so that a seal structure is added to the sliding portion. There is a need.

[0007]

However, since hydrogen, which is a working gas of a fuel cell, has a very small molecular size, it is attempted to seal the hydrogen gas at the sliding part of the ejector equipped with the above conventional variable mechanism. Then, not only high processing accuracy is required for the seal portion, but also the friction of the seal portion is increased, and controllability is impaired.

In view of the above problems, it is an object of the present invention to mix the raw fuel gas and the exhaust circulation gas at a constant mixing ratio in an operating region where the gas flow rate is wide without providing a variable mechanism in the ejector. An ejector circulation device and a fuel cell system with improved fuel gas circulation performance using the ejector circulation device.

[0009]

In order to achieve the above object, the invention according to claim 1 provides a fuel cell main body having a fuel electrode and an air electrode, an exhaust circulation gas discharged from the fuel electrode, and a hydrogen concentration. In a fuel cell system having an ejector circulation device that mixes a raw fuel gas with a high fuel gas into a fuel gas, and a flow path that supplies the fuel gas mixed in the ejector circulation device to the fuel electrode, Is at least 2 of the first supply port, the second supply port, and the third supply port.
Fluid to be supplied from one of the two is mixed and discharged from the discharge port, the first nozzle connected to the first supply port opens toward the first mixing chamber, and the second supply port is provided in the first mixing chamber. A second nozzle having a larger cross-sectional area than the first nozzle from the first mixing chamber toward the second mixing chamber is provided forward of the ejection direction of the first nozzle, and a third supply port is opened in the second mixing chamber. At the same time, the second mixing chamber communicates with the discharge port through the throat part and the diffuser part in sequence, supplies the raw fuel gas to the first supply port, and supplies the raw fuel gas and the exhaust circulation gas to the second supply port. It is a gist to control either of them to be switchably supplied and to supply the exhaust circulation gas to the third supply port when the raw fuel gas is supplied to the second supply port.

In order to achieve the above object, the invention according to claim 2 is the fuel cell system according to claim 1, wherein when the output of the fuel cell system is lower than a predetermined value, a low load is applied.
The fuel cell system is operated in the first state in which the raw fuel gas is supplied from the first supply port, the exhaust circulation gas is supplied from the second supply port, and the exhaust circulation gas is supplied to the third supply port is cut off. When the load is higher than the predetermined value, the raw fuel gas is supplied from at least one of the first supply port and the second supply port, and the exhaust circulation gas is supplied from the third supply port in the second state. That is the summary.

In order to achieve the above object, the invention according to claim 3 provides the fuel cell system according to claim 2,
The gist is to operate in the second state during a transition in which the output of the fuel cell system increases.

In order to achieve the above object, the invention according to claim 4 is the fuel cell system according to any one of claims 1 to 3, in which a pipe for supplying raw fuel gas to the first supply port is provided. Is equipped with a first pressure control valve,
A second pressure adjusting valve is provided in the pipe for supplying the raw fuel gas to the second supply port, and the pressure of the raw fuel gas supplied to the first supply port and the pressure of the raw fuel gas supplied to the second supply port are adjusted. The point is that it can be controlled independently.

To achieve the above object, the invention according to claim 5 mixes fluids supplied from at least two of the first supply port, the second supply port, and the third supply port, and discharges the mixture from the discharge port. In the ejector circulation device, the first nozzle connected to the first supply port opens toward the first mixing chamber,
The second supply port opens to the mixing chamber, the second nozzle having a larger cross-sectional area than the first nozzle opens from the first mixing chamber to the second mixing chamber, and the third supply port opens to the second mixing chamber. In addition, the gist is that the second mixing chamber is connected to the discharge port through the throat part and the diffuser part in this order.

[0014]

According to the first aspect of the present invention, a fuel cell body having a fuel electrode and an air electrode, an exhaust circulation gas discharged from the fuel electrode and a raw fuel gas having a high hydrogen concentration are mixed. In the fuel cell system having an ejector circulation device that uses the fuel gas as a fuel gas and a flow path that supplies the fuel gas mixed by the ejector circulation device to the fuel electrode, the ejector circulation device includes a first supply port and a second supply port. The fluid supplied from at least two of the supply port and the third supply port is mixed and discharged from the discharge port, and the first fluid is connected to the first supply port.
The nozzle is opened toward the first mixing chamber, the second supply port is opened in the first mixing chamber, and the first nozzle is substantially coaxial with the first nozzle from the first mixing chamber to the second mixing chamber. A second nozzle having a large cross-sectional area is provided and a third nozzle is provided in the second mixing chamber.
While the supply port opens, the second mixing chamber has a throat section,
The raw fuel gas is supplied to the first supply port, and either the raw fuel gas or the exhaust circulation gas is switchably supplied to the second supply port. When the raw fuel gas is supplied to the supply port, the exhaust circulation gas is controlled to be supplied to the third supply port.
One of the first nozzle and the second nozzle of the ejector circulation device can be selectively used as the drive flow source depending on the operating state of the fuel cell, and the operating region of the ejector circulation device can be expanded while suppressing leakage of hydrogen gas. There is an effect that can be.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, when the output of the fuel cell system is lower than a predetermined value and the load is low, the raw fuel gas is supplied from the first supply port. , The exhaust circulation gas is supplied from the second supply port,
When the engine is operated in the first state in which the pipe for supplying the exhausted circulating gas to the supply port is shut off, and the output of the fuel cell system is at a predetermined value or higher under high load, the fuel is discharged from at least one of the first supply port and the second supply port. Since the operation is performed in the second state in which the fuel gas is supplied and the exhaust circulation gas is supplied from the third supply port, the nozzle diameter and the throat diameter can be appropriately selected according to the load of the fuel cell system. There is an effect that a high exhaust gas circulation amount can be maintained over the entire operating region.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the invention, the fuel cell system is operated in the second state during a transition in which the output of the fuel cell system increases. The effect is that the amount of hydrogen generated can be increased rapidly, and the pressure of the stack fuel electrode can be increased rapidly until it corresponds to the increased power generation amount.

According to the invention of claim 4, in addition to the effects of the invention of claims 1 to 3, a first pressure adjusting valve is provided in the pipe for supplying the raw fuel gas to the first supply port. At the same time, a second pressure adjusting valve is provided in the pipe for supplying the raw fuel gas to the second supply port, and the pressure of the raw fuel gas supplied to the first supply port and the pressure of the raw fuel gas supplied to the second supply port. By making them independently controllable, there is an effect that the circulation amount of the exhaust circulation gas can be maintained in a wide operating region while maintaining good controllability of the supply amount of the raw fuel gas.

According to the fifth aspect of the present invention, there is provided an ejector circulation device for mixing fluids supplied from at least two of the first supply port, the second supply port and the third supply port and discharging the mixed fluids from the discharge port. Then, the first nozzle connected to the first supply port is opened toward the first mixing chamber, the second supply port is opened in the first mixing chamber, and the first nozzle is provided in front of the ejection direction of the first nozzle.
A second nozzle having a larger cross-sectional area than the first nozzle is provided from the mixing chamber toward the second mixing chamber, a third supply port is opened in the second mixing chamber, and the second mixing chamber has a throat portion and a diffuser portion. Since the fluid is communicated with the discharge port sequentially, when the first fluid is supplied from the first supply port and the second fluid is supplied from the second supply port, the first nozzle operates, As an ejector circulation device having two different characteristics that the second nozzle having a larger cross-sectional area than the first nozzle operates when the first fluid is supplied from the supply port and the second fluid is supplied from the third supply port Since it works, there is an effect that the operating flow rate region of the ejector circulation device can be expanded.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system configuration diagram showing a main configuration of a fuel cell system according to the present invention.
It is suitable as a power source for an electric vehicle that has a large load change from idling to high-speed traveling.

In FIG. 1, a fuel cell body (hereinafter referred to as a stack) 1 has a fuel electrode 2 and an air electrode 3. In practice, the stack 1 is equipped with cooling system piping, power output lines, various sensors, etc., but only the gas system is shown in this figure.

The fuel electrode 2 and the air electrode 3 are joined inside the stack 1 with an electrolyte membrane made of a solid polymer therebetween, and hydrogen is ionized at the fuel electrode 2 to separate into hydrogen ions and electrons. The hydrogen ions move from the fuel electrode 2 side to the air electrode 3 side in the electrolyte membrane using water as a medium, and the electrons return from the fuel electrode 2 to the air electrode 3 through the external load circuit, and hydrogen ions, electrons, and oxygen DC power generation is performed by an electrochemical reaction in which water is combined with the air electrode 3.

In this embodiment, a method of directly holding hydrogen as fuel is shown. Hydrogen gas is compressed and held in the hydrogen storage tank 4 in a high pressure state. The higher the filling pressure of the hydrogen storage tank 4, the more the traveling distance per filling can be extended and the tank volume can be reduced. Since it is difficult to control the supply pressure from the high pressure of the hydrogen storage tank 4 to the stack 1 at a time, the downstream pressure can be substantially controlled downstream of the hydrogen storage tank 4 via the pressure reducing valve 5. After the pressure is reduced to a constant value, hydrogen gas, which is the raw fuel gas, is supplied to the pressure regulating valve 6 arranged further downstream. A pressure sensor 19 that measures the hydrogen gas pressure after pressure adjustment is provided downstream of the pressure adjustment valve 6.
A branch portion 8 that branches in two directions is provided downstream of 9. A first supply port 9 provided in an ejector circulation device (hereinafter abbreviated as an ejector) 7 is connected to one downstream side of the branch portion 8, and hydrogen gas whose pressure is adjusted by a pressure adjusting valve 6 is supplied. .

The ejector 7 is provided with a second nozzle in addition to a first nozzle connected to the first supply port 9 as will be described later, and the second nozzle is provided downstream of the first nozzle and upstream of the second nozzle. It is connected to the second supply port 10, the downstream side of the second nozzle is connected to the third supply port 11, and these supply ports 9, 10, 1 are connected.
The gases supplied from 1 are mixed and discharged from the discharge port 12.

A hydrogen gas supply pipe connected to the second supply port 10 of the ejector 7 from the other downstream side of the branch portion 8 via a shutoff valve 18 and a circulating gas exhausted from the fuel electrode 2 of the stack 1 The exhaust circulation gas pipe supplied through the one-way valve 16 is connected. With this configuration, the shutoff valve 18 and the three-way valve 1
By switching No. 6, it is possible to switch between the hydrogen gas whose pressure is reduced from the hydrogen storage tank or the exhaust circulation gas for the gas supplied to the second supply port 10.

Further, the ejector 7 has a third supply port 11 to which the other side of the three-way valve 16 is connected, so that the exhaust circulation gas can be supplied.

The outlet 12 of the ejector 7 is connected to a humidifier 13 so that the fuel gas mixed in the ejector 7 is humidified to a substantially water vapor saturated state. The humidified fuel gas is supplied to the fuel electrode 2 of the stack 1 and part of hydrogen is consumed by power generation. From the outlet of the fuel electrode 2, exhausted circulation gas containing hydrogen which has not been used for power generation is discharged, but the outlet of the fuel electrode is connected to a branch portion 14 that branches in two directions. A three-way valve 16 is connected to one side of the branch portion 14, and the other side of the branch portion 14 is opened to the outside via a purge valve 15. If the power output demand of the stack suddenly becomes small, the hydrogen in the circulation pipe cannot be completely consumed by the stack. At that time, the purge valve 15 is opened to release the surplus hydrogen gas to the outside.

With the above structure, in the ejector 7, the hydrogen gas coming from the hydrogen storage tank 4 and the fuel electrode 2 of the stack 1
The exhaust circulation gas having a low pressure after passing through is mixed and flowed to the downstream side.
When passing through 3, the steam necessary for the reaction in the electrolytic membrane in the stack is humidified, and after being heated to a temperature suitable for the reaction, it flows into the fuel electrode 2 of the stack 1.

Then, the fuel electrode 2 of the stack 1 consumes hydrogen, and the remaining residual hydrogen gas is discharged from the stack 1 and sent to the ejector 7 again.

On the other hand, although not shown in the figure, a compressor for taking in the atmosphere, compressing it and sending it to the air line is installed upstream of the stack to the air electrode. Similarly to hydrogen, the air compressed by the compressor also passes through the humidifier, is humidified to a substantially saturated state, and then flows into the stack 1. Then, the air gas left after consuming the oxygen content in the air at the air electrode 3 of the stack 1 passes through the pressure control valve of the air line and is released to the atmosphere together with the moisture produced by the reaction in the stack. The air pressure is controlled by the pressure control valve so that the air pressure becomes a predetermined pressure as required.

Although not shown in FIG. 1, the water produced at the air electrode is recovered by a water recovery device provided in the middle of the air line, and the recovered water is pressurized by a pressure pump to the humidifier 1.
3 and is reused as cooling water for the stack 1.

Further, the pressure regulating valve 6 has a role of controlling the flow rate of hydrogen supplied to the stack, and the pressure sensor 20 arranged upstream of the stack 1 so that the hydrogen pressure of the fuel electrode becomes a value suitable for the amount of power generation. While adjusting the output value of, the amount of hydrogen existing in the hydrogen gas circulation system is adjusted to a predetermined value according to the required load, and the amount of hydrogen consumed by power generation is replenished. 6 branch 8
While measuring the output value of the pressure sensor 19 provided in the pressure adjusting valve 6
The opening degree of is controlled.

FIG. 2 shows a sectional structure of the ejector 7 in this embodiment. The ejector 7 is an ejector circulation device that mixes fluids supplied from at least two of the first supply port 9, the second supply port 10, and the third supply port 11 and discharges the mixed fluids from the discharge port 12. The first nozzle 21 connected to the supply port 9 opens toward the first mixing chamber 31, the second supply port 10 opens in the first mixing chamber 31, and is separated from the first mixing chamber 31 by the partition wall 24. A second nozzle 25 having a larger cross-sectional area than the first nozzle 21 opens toward the second mixing chamber 32, and the third supply port 1 is provided in the second mixing chamber 32.
1 is open and the second mixing chamber 32 is throat 2
9 and the diffuser 30 are sequentially connected to the outlet 12.

The parts constituting the ejector 7 are the first intake portion 22 in which the first nozzle 21 and the first connection port 9 for supplying the raw fuel gas communicate with each other, and the O-ring 23 connecting the first intake portion 22.
When assembled together, the second intake air configured so that the upstream side of the cylindrical tubular second nozzle 25 integrally provided in the partition wall 24 and the second supply port 10 for supplying the raw fuel gas or the exhaust circulation gas communicate with each other. O of the part 26 and the second intake part 26
By being assembled with the ring 27, the body portion 28 forms a space that connects the third supply port 11 and the discharge port 12 through which the exhaust circulation gas circulates.

The body portion 28 is provided with a throat 29 for mixing the raw fuel gas and the exhaust circulating gas and a diffuser 30 for reducing the flow velocity of the mixed flow to recover the pressure.

The second nozzle 25 is injected from the first nozzle 21 in the first state where the shutoff valve 18 is closed and the three-way valve 16 is controlled so as to communicate with the second supply port 10. The raw fuel gas flow is throttled in front of the second nozzle 25 to increase the flow velocity, and the cylindrical shape of the second nozzle 25 causes the first nozzle 2 to
It becomes a throat part for 1 and the second speed is increased by this flow velocity increase.
A negative pressure is generated with respect to the supply port 10, and the exhaust circulation gas is sucked by the flow from the first nozzle 21,
A mixed flow is generated inside the nozzle 25. This mixed flow passes through the throat 29 as it is, and is discharged from the discharge port 12 while recovering the pressure in the diffuser 30.

On the other hand, in the second state in which the shutoff valve 18 is opened and the three-way valve 16 is controlled so as to communicate with the third supply port 11 side, hydrogen gas is ejected from the second nozzle 25. And substantially acts as a nozzle portion, and the third supply port 11
The exhaust circulation gas is sucked from the throat 29, a mixed flow is generated at the throat 29, and the mixed flow is discharged from the discharge port 12 as in the first state.

FIG. 3 illustrates the difference in ejector characteristics between a small ejector and a large ejector in which the throat portion and the nozzle portion have different diameters. FIG. 3 (a) shows the supply gas flow rate Qin and the supply gas pressure Pin. In relation, FIG. 3B shows the circulation ratio R (the ratio of the circulation gas flow rate Qsu and the supply gas flow rate Qin) to the supply gas flow rate Qin with the thin ejector characteristic and the thick ejector characteristic with the large ejector characteristic.

FIG. 3 (b) is a diagram showing the relationship of the circulation ratio R to the supply gas flow rate Qin in the ejector.
The case of a small ejector having a small diameter nozzle and a small diameter throat is shown by a thin line, and the case of a large ejector having a large diameter nozzle and a large diameter throat is shown by a thick line. The supply gas flow rate Qin at which the circulation starts decreases as the diameter decreases, but the maximum value of the circulation rate R when the supply gas flow rate Qin increases tends to increase as the diameter increases.

Further, as shown in FIG. 3 (a), the supply pressure of the hydrogen gas supply system is regulated by the system, and the maximum pressure that can be supplied to the supply side connection port is Pinmax limited while ensuring the gas flow rate. Will be received. Therefore, from the viewpoint of lowering the supply flow rate at the start of circulation, the smaller the diameter, the better the characteristics, but the amount of gas that can be supplied cannot be secured sufficiently.

Therefore, the supply hydrogen gas flow rate Qmi at the time of the minimum load of the system which is required in the idle state such as when the vehicle is stopped.
When the flow rate range from n to the supply hydrogen gas flow rate Qmax at the maximum load of the system required at high speed running or acceleration is very wide, the circulation ratio necessary to maintain a good power generation state of the stack It is difficult to maintain Rmin with one nozzle.

FIG. 4 shows the characteristics of the ejector used in this embodiment as in FIG. First, from the gas flow rate Qmin corresponding to the minimum operation load of the system to the gas flow rate Q1 that can be supplied from the first nozzle 21 to the circulation system at the maximum pressure Pinmax that can be applied to the ejector upstream, the first state is set.
The circulation ratio R shown by the broken line in FIG. 4 is secured.

When the required power generation amount increases and the required supply amount of the raw fuel gas exceeds Q1, as the second state, the raw fuel gas is supplied to the second supply port 10, and the gas of the second supply port 10 is supplied. By controlling the pressure, the second nozzle 25 that acts as a large-diameter nozzle for the raw fuel gas that is insufficient in the first nozzle 21
Supplied from At this time, in the second nozzle 25, when both the pressures of the first supply port 9 and the second supply port 10 become Pinmax, the amount of raw fuel gas Q required for maximum power generation request Q
It has a diameter that can supply max.

Since the circulation ratio R in the second state is the value shown by the alternate long and short dash line, by switching between the first and second states in accordance with the load demanded by the system, all stack operating regions can be operated. The required circulation ratio Rmin can be secured.

Next, the control flow of the flow path switching valve and the pressure adjusting valve in this embodiment will be described with reference to FIGS. FIG. 5 shows how to control the valve downstream pressure tPrsHe of the pressure regulating valve 6 and the flow path switching state in order to realize the fuel cell power generation target value tPWR given from various vehicle conditions. 6 is a control flowchart shown in FIG.
Shows a graph showing examples of various tables referred to in the control flow.

First, in step S10, the generated power target value tPWR separately calculated based on the required load is read, and the measured value tPrsHO of the pressure sensor 19 and the measured value tPrsHeO of the pressure sensor 20 are read. Next, in step S12, the fuel gas pressure target value tPrsH at the fuel electrode of the fuel cell is calculated based on the power generation target value tPWR of the fuel cell.
Is calculated. In this calculation, the fuel gas pressure target value tPrsH with respect to the generated power target value tPWR as shown in FIG. 6 (a) is given in a table, and as the power generation target value of the fuel cell, that is, the load increases, the fuel gas at the fuel electrode is increased. The pressure is set to increase.

Next, in step S14, step S1
2. The fuel gas pressure target value tPrsH at the fuel electrode 2 obtained in 2 and the current fuel gas pressure tPrsHO at the fuel electrode 2 obtained from the pressure sensor 20 and the differential pressure tPrsHd = tPrsH-tPrsHO are calculated to adjust the pressure. The condition value is used to determine the basic pattern of control of the valve 6.

Step S16 is a step of determining whether or not the load demand on the fuel cell has rapidly increased. If the differential pressure tPrsHd is equal to or greater than a predetermined value tPrsHdH, it is determined as a rapid acceleration state and the process proceeds to step S18 to adjust the pressure. The target opening degree tArV of the valve 6 is set to a maximum value tArVmax that can be set, and then the signal tSV for controlling the opening / closing of the shutoff valve 18 is set as a state value to be an open command and the switching command value of the three-way valve 16 is set. Information is transmitted to the flow path switching sequence so as to be in the second state by using t3WV as a state value which is a command for communicating with the third supply port 11 side of the ejector 7.

When it is judged at step S16 that tPrsHd <tPrsHdH, the routine proceeds to step S22, where it is judged whether or not the load demand is reduced and it is necessary to control the opening of the purge valve 15. If tPrsHd is less than or equal to a predetermined negative value tPrsHdL, the process proceeds to step S24, where the target opening tArV of the pressure adjusting valve 6 is set to the settable minimum value tArVmin, and the purge valve 15 is controlled to open. Information is transmitted, and then the signal tSV for controlling the opening / closing of the shutoff valve 18 is set to the state value which is the closing command, and the switching command value t3WV of the three-way valve 16 is set to the second supply port 1 of the ejector 7 in step S26.
Information is transmitted to the flow path switching sequence so as to be in the first state as a state value which is a command to communicate with the 0 side.

When it is judged at step S22 that tPrsHd> tPrsHdL, it is judged as the normal control state, and step S2
In step 8, it is determined whether or not the flow path switching state is the first state. The first supply port 9 whose tPrsH is smaller than the predetermined switching pressure tPrsH1 and which is measured by the pressure sensor 19.
When the value tPrsHeO of the raw fuel gas pressure at is smaller than the maximum supplyable pressure tPrsHemax, it is determined that the gas flow path is in the first state, and the process proceeds to step S30.

In step S30, the generated power target value tPWR
The target pressure value tPrsHe at the first supply port 9 is calculated so that the target pressure value tPrsH at the fuel electrode necessary to achieve The target pressure value tPrsHe is calculated in advance according to the flow rate of the pressure loss in the fuel gas flow path from the pressure regulating valve 6 to the fuel electrode 2 cell of the stack 1, and the fuel cell fuel electrode targeting the pressure loss is calculated. It is necessary to calculate as a value added to the gas pressure, and it is better to use a form in which it is calculated in advance and referred to as a table value as shown in FIG.

Next, at step S32, the throttle area tArVm of the basic pressure regulating valve 6 is calculated according to tPrsHe so that the fuel gas flow rate according to the fuel load can be obtained. This calculation is given in the table as shown in FIG. 6C, and the throttle area tArVm increases as the target pressure value tPrsHe increases.
Also increases.

Next, at step S34, the signal tSV for controlling the opening / closing of the shutoff valve 18 is set to a state value which serves as a closing command, and the switching command value t3WV of the three-way valve 16 is communicated with the second supply port 10 side of the ejector 7. Information is transmitted to the flow path switching sequence so that the state value becomes the first state as the command state value, and the process proceeds to step S42 described later.

On the other hand, in step S28, tPrsH is tPrsH.
When it is determined that the value is 1 or more or tPrsHO is tPrsHemax, it is determined that the flow path switching state is the second state, and the process proceeds to step S36.

In step S36, similarly to step S30, tPrsH is calculated using a map, and the map used here has a large hydrogen gas supply nozzle diameter as shown in FIG. 6 (c). It corresponds to that. Next, in step S38, similarly to step S32, the throttle area tArVm of the basic pressure adjusting valve 6 is calculated according to tPrsHe so that the fuel gas flow rate according to the fuel load can be obtained. The table referred to here is shown in FIG. 6 (e) corresponding to the increase in the nozzle diameter.
It is a table like.

In step S40, as in step S20, the signal tSV for controlling the opening / closing of the shutoff valve 18 is set to a state value which is an open command, and the switching command value t3WV of the three-way valve 16 is set.
Is used as a state value which is a command to communicate with the third supply port 11 side of the ejector 7, and information is transmitted to the flow path switching sequence so as to be in the second state, and the process proceeds to step S42.

In step S42, the actual pressure tPrsHeO of the first supply port 9 measured by the pressure sensor 19 is compared with tArVm calculated in step S32 or step S36.
And a correction term α determined from the difference between the measured value of the pressure sensor 20 and the target value tPrsH determined in step S12, and the final throttle area tArV is set so that the pressure of the first supply port 9 becomes the target value. calculate.

Above, step S18, step S24,
The throttle area of the pressure adjusting valve 6 is determined by any of step S42, the control information of the pressure adjusting valve 6 is transmitted to the pressure adjusting mechanism controller in step S44, and the control flow ends.

In this embodiment, the valve 18 is a shutoff valve, but if this valve is used as a pressure regulating valve, it acts as a second pressure regulating valve according to claim 4, and the original nozzles of the first nozzle portion and the second nozzle portion are actuated. The fuel gas pressure can be controlled individually, and the exhaust gas circulation amount can be maintained in a wide operating range while maintaining good controllability of the raw fuel gas supply amount.

Next, a second embodiment of the present invention will be described with reference to FIG. In the first embodiment,
In contrast to the case where the shutoff valve 18 and the three-way valve 16 are used to switch the supply of the raw fuel gas and the exhaust circulation gas to the second supply port 10,
In the embodiment, by using one switching valve 39, the same flow passage switching as in the first embodiment is possible, and the flow passage switching control can be easily performed.

The switching valve 39 includes a body portion 40 having four connection ports, and two flow passages 42 and 43 formed therein, and a ball portion 41 rotatably included in the body portion 40. .

The four connection ports of the body portion 40 are connected to the branch portion 8
And a connection port 44a for supplying the raw fuel gas, a connection port 44b for supplying the exhaust circulation gas connected to the branch portion 14 located downstream of the fuel electrode 2, and a second supply port 10 of the ejector 7.
A gas discharge connection port 45a connected to the ejector 7
Connection port 45 for gas discharge connected to the third supply port 11 of
b and are provided.

In the first state, as shown in FIG. 7A, the flow path 42 of the ball portion 41 makes the connection port 44b and the connection port 45a communicate with each other, and the second supply port 10 of the ejector 7 is connected.
Supply the exhaust circulation gas to. At that time, the flow path 43 is arranged at a position so as to close the remaining connection ports 44a and 45b of the body portion 40.

On the other hand, in the second state, as shown in FIG. 7B, the ball portion 41 is controlled so as to be rotated to the left by 90 °. At this time, the flow path 42 is connected to the connection port 4
4a and the connection port 45a are communicated with each other, hydrogen gas is supplied to the second supply port 10 of the ejector 7, and the flow path 43 communicates the connection port 44b and the connection port 45b with each other.
The exhaust circulation gas can be supplied to the third supply port 11.

With the above configuration, the body portion 4 of the ball portion 41
Only by controlling the rotational position with respect to 0, the flow passage switching similar to that of the first embodiment can be performed by one operation.

As described above, according to the present invention, the required exhaust gas circulation amount can be secured for the supply gas flow rate corresponding to the wide load range, and the stable operation of the fuel cell becomes possible.

[Brief description of drawings]

FIG. 1 is a system configuration diagram illustrating a configuration of a first embodiment of a fuel cell system according to the present invention.

FIG. 2 is a cross-sectional view showing an internal structure of an ejector in the present embodiment.

FIG. 3A is a diagram illustrating supply gas pressure characteristics with respect to supply gas flow rates of a small ejector and a large ejector. (B) It is a figure explaining the circulation ratio characteristic with respect to the supply gas flow volume of a small ejector and a large ejector.

FIG. 4A is a diagram illustrating a supply gas pressure characteristic with respect to a supply gas flow rate in the ejector of the embodiment.
(B) It is a figure explaining the circulation ratio characteristic with respect to the supply gas flow rate in the ejector of embodiment.

FIG. 5 is a flow chart illustrating a first state / second state switching control of the pressure regulating valve and the gas passage according to the first embodiment.

FIG. 6 is a graph showing an example of various tables referred to in the control flow.

FIG. 7A is a configuration diagram illustrating a main part in a first state according to the second embodiment. (B) It is a block diagram explaining the principal part of the 2nd state in 2nd Embodiment.

[Explanation of symbols]

1 ... Fuel cell body (stack) 2 ... Fuel pole 3 ... Air electrode 4 ... Hydrogen storage tank 5 ... Pressure reducing valve 6 ... Pressure control valve 7 ... Ejector circulation device 9 ... First supply port 10 ... Second supply port 11 ... Third supply port 12 ... outlet 13 ... Humidifier 14 ... Branch 15 ... Purge valve 16 ... 3-way valve 17 ... Branch 18 ... Shut-off valve 19 ... Pressure sensor 20 ... Pressure sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 8/04 H01M 8/04 N

Claims (5)

[Claims] 1. A fuel cell main body having a fuel electrode and an air electrode, and an ejector circulation device that mixes an exhaust circulation gas discharged from the fuel electrode and a raw fuel gas having a high hydrogen concentration into a fuel gas. In a fuel cell system having a flow path for supplying the fuel gas mixed by the ejector circulation device to the fuel electrode, the ejector circulation device includes at least a first supply port, a second supply port, and a third supply port. The fluid supplied from the two is mixed and discharged from the discharge port. The first nozzle connected to the first supply port opens toward the first mixing chamber and the second supply port is provided in the first mixing chamber. And a second nozzle having a larger cross-sectional area than the first nozzle from the first mixing chamber toward the second mixing chamber is provided in front of the ejection direction of the first nozzle, and the third supply port is provided in the second mixing chamber. With the opening, the second mixing chamber The raw fuel gas is supplied to the first supply port, and either the raw fuel gas or the exhaust circulation gas is switchably supplied to the second supply port through the funnel part and the diffuser part in order to communicate with the discharge port. The fuel cell system is characterized in that when the raw fuel gas is supplied to the second supply port, the exhaust circulation gas is supplied to the third supply port. 2. The raw fuel gas is supplied from the first supply port when the load of the output of the fuel cell system is lower than a predetermined value,
When operating under the first condition in which the exhaust circulation gas is supplied from the second supply port and the pipe for supplying the exhaust circulation gas to the third supply port is cut off, and the output of the fuel cell system is a predetermined value or more, The fuel cell according to claim 1, wherein the fuel cell is operated in a second state in which the raw fuel gas is supplied from at least one of the first supply port and the second supply port and the exhaust circulation gas is supplied from the third supply port. system. 3. The fuel cell system is operated in the second state during a transition of increasing output of the fuel cell system.
The fuel cell system according to 1. 4. A first pressure adjusting valve is provided on a pipe for supplying raw fuel gas to the first supply port, and a second pressure adjusting valve is provided on a pipe for supplying raw fuel gas to the second supply port. 4. The pressure of the raw fuel gas supplied to the first supply port and the pressure of the raw fuel gas supplied to the second supply port can be controlled independently of each other. The fuel cell system according to item. 5. An ejector circulation device that mixes fluids supplied from at least two of a first supply port, a second supply port, and a third supply port and discharges the mixture from a discharge port. The connected first nozzle opens toward the first mixing chamber, the second supply port opens at the first mixing chamber, and the cross-sectional area from the first nozzle toward the second mixing chamber is larger than that of the first nozzle. A large second nozzle is opened, a third supply port is opened in the second mixing chamber, and the second mixing chamber is connected to the discharge port through the throat part and the diffuser part in order, and the ejector circulation. apparatus.