JP3879423B2 - Fuel cell system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to pressure control of a circulation system related to cooling water supply, gas supply, etc. of a fuel cell system.
[0002]
[Prior art and problems to be solved]
As a conventional technique related to the pressure control of the circulation system of the fuel cell, for example, in the fuel cell system disclosed in Japanese Patent Laid-Open No. 5-41232, the pressure is controlled by changing the pump rotation speed based on the pressure detection result of the circulation system. Correction is made. However, in this system, since the cooling water path is connected to the gas supply line by an air-water separator or the like, the pressure control of the cooling water and the supply gas cannot be performed, and thus the fuel cell is not necessarily operated efficiently. I can't.
[0003]
On the other hand, the one disclosed in Japanese Patent Laid-Open No. 9-320627 has a configuration in which cooling water is circulated through a pump in order to cool the fuel cell and the gas manufacturing apparatus, and each of the cooling water and the supply gas It is possible to control the pressure. However, in this system, sudden pressure fluctuations occur in the closed path when the pump rotation speed changes in the cooling water line, and the durability of the fuel cell itself and the cooling water supply line is impaired due to this pressure fluctuation. There is a fear.
[0004]
The present invention has been made paying attention to such a conventional problem, and in a fuel cell system, sudden pressure fluctuation due to a change in the number of revolutions of the pump or the like while appropriately controlling the supply pressure of a circulating system such as cooling water. The purpose is to suppress.
[0005]
[Means for Solving the Problems]
The first invention includes a circulation flow path provided in the fuel cell system, a circulation pump for circulating the fluid in the circulation passage, a bypass passage which bypasses the circulation pump, a valve for opening and closing said bypass passage An apparatus, a pressure fluctuation detection device for detecting pressure fluctuations in the circulation flow path, and the valve device so that the flow rate from the circulation flow path to the bypass flow path increases as the pressure fluctuation amount increases . And a control device for controlling the opening degree.
[0006]
According to a second aspect of the present invention, the valve device according to the first aspect of the present invention includes an upstream control valve that opens and closes a pump upstream side of the bypass flow path, and a downstream control valve that opens and closes a pump downstream side, and the circulation When the pressure on the downstream side of the pump is increased, the upstream control valve is opened after the downstream control valve is opened .
[0007]
According to a third aspect of the present invention, the valve device according to the first aspect of the present invention includes an upstream control valve that opens and closes a pump upstream side of the bypass flow path and a downstream control valve that opens and closes a pump downstream side, and the circulation When the pressure on the downstream side of the pump was lowered, the downstream control valve was opened after the upstream control valve was opened .
[0008]
In a fourth aspect of the invention, the pressure fluctuation detection device according to the first to third aspects of the invention is configured to detect a pressure fluctuation based on the rotational speed of the circulation pump .
[0009]
5th invention comprised the pressure fluctuation detection apparatus of the said 1st-3rd invention with the pressure sensor which detects the pressure of the said circulation pump outlet part .
[0010]
In a sixth aspect of the present invention, a water tank for storing condensed water in the gas flow path is connected to the bypass flow path of the first to fifth aspects of the invention .
[0011]
In a seventh aspect of the present invention, a gas-liquid separator that separates condensed water in the gas flow path is connected to the bypass flow path of the first to fifth aspects of the invention .
[0012]
In an eighth aspect of the invention, the circulation passage of the first to seventh aspects is a cooling water passage for circulating cooling water through the fuel cell .
[0013]
In a ninth aspect, the circulation flow path of the first to seventh aspects is a humidified water supply flow path for supplying water to the humidifier of the fuel cell .
[0014]
[Action / Effect]
According to each invention below, the rapid pressure fluctuation that occurs when the circulating pump is started, stopped, or transiently changed in the circulating flow path such as the cooling water flow path or the humidified water supply flow path is Since the valve device can be opened to escape from the bypass channel, it is possible to protect the circulation channel or the devices such as the fuel cell connected to the circulation channel.
[0015]
Note that the circulation channel may have a configuration in which a plurality of channels such as a cooling water channel and a humidified water supply channel are shared, and a single unit can be provided by providing a bypass channel and a valve device in the shared circulation channel. A plurality of circulation channels can be protected by the bypass channel and the valve device.
[0016]
The valve device, the second and third bypass channel, as shown as an invention of the inlet and each outlet portion upstream control valve may be a structure in which a downstream control valve, this case , it can be by the structure for connecting the pressure absorbing device in the middle of the bypass passage, enhance the relaxation effect of the pressure variation due to escape pressure in the bypass flow passage by opening the control valve.
[0017]
As the pressure absorbing device, the water tank for storing condensed water in the gas pipe of the fuel cell shown as the sixth invention or the gas-liquid separation device shown as the seventh invention can be applied. For this reason, it is not necessary to provide new parts, so that the system can be simplified, and the size and cost can be reduced. In addition, it is also possible to apply a structure in which the gas-liquid separator and the water tank are integrated as a pressure absorbing device. In this case, the gas pressure and the water pressure when the pressure fluctuation in the circulation flow path is reduced. The controllability of the fuel cell can be improved by reducing the differential pressure.
[0018]
The cooling water supply pipe or humidification water supply pipe pressure detected by the rotation variation of the circulation pump, by controlling the valve device downstream, it is possible to provide a good fuel cell system controllability in a simpler system .
[0019]
The pressure fluctuation in the circulation channel can be detected from the rotational speed of the circulation pump as shown as the fourth invention or by the pressure sensor provided at the outlet of the circulation pump as shown as the fifth invention. .
[0020]
As in the second invention, the upstream control valve is opened after the downstream control valve is opened when the pressure is increased, or the upstream control valve is opened when the pressure is lowered as in the third invention. By opening the valve, it is possible to more effectively absorb sudden pressure fluctuations before and after the circulation pump while preventing a pressure drop in the circulation flow path caused by idling of the circulation pump.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a system configuration of an embodiment in which the present invention is applied to a fuel cell cooling system. An air flow path 100, a fuel flow path 200, and a cooling water circulation flow path 300 are connected to the fuel cell 1, respectively. The air flow path 100 is provided with an air flow meter 2 that measures the supply flow rate from the upstream, a compressor 3 that pumps air, and a pressure sensor 4 that measures the fuel cell inlet air pressure, and a gas-liquid separation downstream of the fuel cell 1. 5 and a control valve 8 for pressure adjustment are provided, and the water separated by the gas-liquid separator 5 passes through the pipe 7 and is stored in the water tank 6.
[0022]
The fuel flow path 200 is provided with a fuel storage tank 9, an ejector pump 10 for fuel circulation, and a pressure sensor 11 for measuring fuel pressure at the fuel cell inlet from upstream. As the fuel circulation mechanism, a compressor may be provided in the fuel circulation path 14 without using an ejector. A gas-liquid separator 12 and a pressure adjusting control valve 13 are provided downstream of the fuel cell 1.
[0023]
The cooling water circulation passage 300 is provided with a radiator 15 having an electric fan and a circulation pump 16 capable of continuously adjusting the driving speed. The flow path 300 is provided with a bypass flow path 301 that bypasses the pump 16 and communicates with the water tank 6. The upstream control valve 18 and the downstream control valve are provided at the upstream end and the downstream end of the bypass flow path, respectively. 19 is provided, and a drain valve 17 is connected in front of the control valves 18 and 19.
[0024]
The control device (not shown) adjusts the fuel gas pressure and the air pressure with the pressure regulating valves 8 and 13 according to the power generation state of the fuel cell 1, respectively, and adjusts the air flow rate with the rotation speed of the compressor 3, Opening and closing of the control valves 18 and 19 is controlled according to the pressure fluctuation state of the cooling system circulation passage 300.
[0025]
FIG. 2 shows a system configuration of an embodiment in which the present invention is applied to a fuel cell system having a humidified water system. The difference from FIG. 1 is that instead of the cooling water circulation channel 300, a bypass channel 401 is formed so as to bypass the circulation pump 20 of the humidification water circulation channel 400 including the humidifier 20 and the humidification water tank 21, Control valves 18 and 19 are provided at the upstream end and the downstream end, respectively. FIG. 3 shows a system configuration of an embodiment in which the present invention is applied to a fuel cell system having a common circulation channel 500 for the cooling system and the humidification system. In this embodiment, cooling water is circulated in the fuel cell 1 and water is supplied to the humidifier 20 by the circulation flow path 500 having the radiator 15. The configuration of the bypass channel 501 and the control valves 18 and 19 with respect to the circulation channel 500 is the same as that in FIG. In FIG. 2 or FIG. 3, the same parts as those in FIG.
[0026]
In addition, in each said system, it is set as the structure connected with the pipe from the gas-liquid separator 5 provided in the air system flow path 100 to the water tank 6, but instead of doing in this way, the gas-liquid separator 5 and the water tank 6 are connected. The structure may be integrated, and as a result, absorption of pressure fluctuations in the circulation flow path can be efficiently performed by absorbing the air line. Further, when the circulation is formed in the cooling water flow path, it is possible to absorb the pressure fluctuation of the circulation flow path in a direction that eliminates the pressure difference between the pressure of the air line inside the fuel cell and the pressure of the cooling water.
[0027]
Next, control valve opening control executed by the control device under each system configuration will be described with reference to the flowchart shown in FIG. FIG. 4 shows a processing routine that is periodically executed by a microcomputer constituting the control device, and a symbol S in the figure indicates a processing step. This control is an example in which the pressure fluctuation in the cooling system flow path is represented by the fluctuation in the rotational speed of the pump 16 and the opening / closing of the control valves 18 and 19 is controlled based on the fluctuation in the rotational speed. In the following, description will be given in order.
S1: The rotational fluctuation amount H of the pump 16 is detected. The rotational fluctuation amount H is detected as, for example, a rotational speed change per unit time.
S2: It is determined whether the control valves 18 and 19 are opened or closed according to the rotation fluctuation H. Here, when the threshold value at the time of increasing the rotational speed is α and the threshold value at the time of decreasing the rotational speed is β, when α>H> β, the process proceeds to S6 and the control valves 18 and 19 are closed. This process is terminated. Even if the pump 16 is controlled under a certain condition, variations in rotation always occur. Therefore, the threshold value is set so as to remove rotation fluctuations that do not affect the pressure. If the condition is other than α>H> β, the process proceeds to S3.
S3: It is determined whether the rotational fluctuation is increasing or decreasing. When the rotational speed increases when H> α, the routine proceeds to the valve control process when the rotational speed increases at S4, and when the rotational speed decreases when H <β, the routine proceeds to the valve control process when the rotational speed decreases at S5. To do.
[0028]
FIGS. 5 and 6 show the opening control routines of the downstream control valve 19 and the upstream control valve 18 when the rotational speed is increased. Since the pressure rises on the pump discharge side (downstream side) when the rotational speed rises, the downstream control valve 19 is opened immediately by the processing of FIG. 5, and the upstream control valve 18 is opened after being delayed by a predetermined time by the processing of FIG. .
FIG. 5 Opening degree control S1 of the downstream side control valve 19: The rotation fluctuation amount H is read.
S2: Control valve opening data corresponding to the rotation fluctuation amount H is set. This is set, for example, by searching a table set in advance so as to give the valve opening according to the rotation fluctuation amount H as shown in FIG. Since the pressure fluctuation is considered to be larger as the rotation fluctuation amount is larger, the valve opening is set larger as the rotation fluctuation is larger as shown in FIG.
S3: The opening degree of the control valve 19 is controlled to be the opening degree set in S2.
FIG. 6 Opening control S1 of the upstream control valve 18: Read the rotation fluctuation amount H.
S2: The timer value T for setting the delay time is reset.
S3: Control valve opening data corresponding to the rotation fluctuation amount H is set. This is set, for example, by searching a table set in advance so as to give the valve opening according to the rotation fluctuation amount H as shown in FIG. Since the pressure fluctuation is considered to be larger as the rotation fluctuation amount is larger, the valve opening is set larger as the rotation fluctuation is larger as shown in FIG.
S4: The delay time γ is set based on the rotation fluctuation amount H. This is set, for example, by searching a table set in advance so as to give the delay time γ according to the rotation fluctuation amount H as shown in FIG. As shown in FIG. 11, the delay time is set shorter as the rotational fluctuation is larger as shown in FIG.
S5 to S6: The integration of the timer value T is repeated until the delay time γ is exceeded.
S7: When the timer value T exceeds the delay time γ, the opening degree of the control valve 18 is controlled so as to be the valve opening degree set in S3.
[0029]
Next, FIGS. 7 and 8 show the opening control routines of the downstream control valve 19 and the upstream control valve 18 when the rotational speed is lowered. Since the pressure drop occurs on the pump discharge side (downstream side) when the rotational speed is lowered, the upstream control valve 18 is immediately opened by the processing of FIG. 8, while the downstream control valve 19 is opened by being delayed by a predetermined time by the processing of FIG.
-FIG. 7 Opening degree control S1: Downstream fluctuation amount H of the downstream side control valve 19 is read.
S2: The timer value T for setting the delay time is reset.
S3: Control valve opening data corresponding to the rotation fluctuation amount H is set. This is set, for example, by searching a table set in advance so as to give the valve opening according to the rotation fluctuation amount H as shown in FIG.
S4: The delay time γ is set based on the rotation fluctuation amount H. This is set, for example, by searching a table set in advance so as to give the delay time γ according to the rotation fluctuation amount H as shown in FIG.
S5 to S6: The integration of the timer value T is repeated until the delay time γ is exceeded.
S7: When the timer value T exceeds the delay time γ, the opening degree of the control valve 19 is controlled so as to be the valve opening degree set in S3.
FIG. 8 Opening control S1 of the upstream control valve 18: Reads the rotation fluctuation amount H.
S2: Control valve opening data corresponding to the rotation fluctuation amount H is set. This is set, for example, by searching a table set in advance so as to give the valve opening according to the rotation fluctuation amount H as shown in FIG.
S3: The opening degree of the control valve 19 is controlled to be the opening degree set in S2.
[0030]
In this control, as described above, the pressure fluctuation is represented by the rotation fluctuation of the pump 16, but a pressure sensor 23 is provided in the vicinity of the outlet of the pump 16 or in the vicinity of the downstream control valve 19, and control is performed based on the detected value. If this is executed, the accuracy and controllability can be improved. Examples of control routines based on such pressure detection are shown in FIGS. FIGS. 12 and 13 are the opening control routines of the downstream control valve 19 and the upstream control valve 18 when the detected pressure is increased, respectively. FIGS. 14 and 15 are the downstream control valve 19 and the upstream when the detected pressure is decreased. This is an opening control routine of the side control valve 18. Since the control routine is different only in that the pressure deviation ΔP per unit time is detected instead of the rotation fluctuation amount H, description of each step is omitted.
[0031]
16 to 18 show the characteristics of the table used in the control routine. FIG. 16 or FIG. 17 is a table for giving valve opening data in accordance with the pressure deviation ΔP, and FIG. 18 is a table in accordance with the pressure deviation ΔP. Each table corresponds to a table giving delay time data.
[0032]
In any of the embodiments described so far, the timing for performing the second control after the first control is after a predetermined time has elapsed. However, the upstream control valve 18 and the downstream control valve 19 are respectively connected to the circulation flow path. Even when a pressure sensor is installed in the vicinity of the control valve and the pressure fluctuation detection value in the vicinity of the control valve in which the second control is performed is designated as the timing and the same control is performed, high control can be performed. .
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a first embodiment of the present invention.
FIG. 2 is a system configuration diagram of a second embodiment of the present invention.
FIG. 3 is a system configuration diagram of a third embodiment of the present invention.
FIG. 4 is a flowchart of the first embodiment relating to a control operation.
FIG. 5 is a flowchart of the first embodiment regarding the control operation;
FIG. 6 is a flowchart of the first embodiment relating to a control operation.
FIG. 7 is a flowchart of the first embodiment regarding the control operation;
FIG. 8 is a flowchart of the first embodiment regarding the control operation;
FIG. 9 is a characteristic diagram showing the relationship between the rotational fluctuation amount of the circulation pump and the control valve opening.
FIG. 10 is a characteristic diagram showing the relationship between the rotational fluctuation amount of the circulation pump and the control valve opening.
FIG. 11 is a characteristic diagram showing the relationship between the rotational fluctuation amount of the circulation pump and the delay time.
FIG. 12 is a flowchart of the second embodiment regarding the control operation;
FIG. 13 is a flowchart of the second embodiment regarding the control operation;
FIG. 14 is a flowchart of the second embodiment regarding the control operation;
FIG. 15 is a flowchart of the second embodiment regarding the control operation;
FIG. 16 is a characteristic diagram showing the relationship between pressure deviation and control valve opening.
FIG. 17 is a characteristic diagram showing the relationship between pressure deviation and control valve opening.
FIG. 18 is a characteristic diagram showing the relationship between pressure deviation and delay time.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Air flow meter 3 Compressor 4 Pressure sensor 5 Gas-liquid separator 6 Water tank 7 Piping 8 Pressure control valve 9 Fuel storage tank 10 Ejector pump 11 Pressure sensor 12 Gas-liquid separator 13 Pressure control valve 14 Fuel Circulation Path 15 Radiator 16 Circulation Pump 17 Drainage Valve 18 Upstream Control Valve 19 Downstream Control Valve

Claims (12)

A circulating passage provided in the fuel cell system,
A circulation pump for circulating fluid in the circulation channel ;
A bypass flow path bypassing the circulation pump ;
A valve device for opening and closing the bypass flow path;
A pressure fluctuation detection device for detecting pressure fluctuations in the circulation channel;
A fuel cell system comprising: a control device that controls an opening degree of the valve device so that a flow rate from the circulation flow path to the bypass flow path increases as the pressure fluctuation amount increases . The valve device comprises an upstream control valve that opens and closes the pump upstream side of the bypass flow path, and a downstream control valve that opens and closes the pump downstream side,
2. The fuel cell system according to claim 1, wherein when the pressure on the downstream side of the circulation pump is increased, the upstream control valve is opened after the downstream control valve is opened. The valve device comprises an upstream control valve that opens and closes the pump upstream side of the bypass flow path, and a downstream control valve that opens and closes the pump downstream side,
2. The fuel cell system according to claim 1, wherein when the pressure on the downstream side of the circulation pump is lowered, the downstream control valve is opened after the upstream control valve is opened.   The fuel cell system according to any one of claims 1 to 3, wherein the pressure fluctuation detection device is configured to detect a pressure fluctuation based on a rotational speed of the circulation pump.   The fuel cell system according to any one of claims 1 to 3, wherein the pressure fluctuation detection device includes a pressure sensor that detects a pressure at the outlet of the circulation pump. The fuel cell system according to any one of claims 1 to 5, wherein a water tank that stores condensed water in the gas flow path is connected to the bypass flow path . The fuel cell system according to any one of claims 1 to 5, wherein a gas-liquid separator that separates condensed water in the gas flow path is connected to the bypass flow path .   The fuel cell system according to any one of claims 1 to 7, wherein the circulation channel is a coolant channel that circulates coolant in the fuel cell.   The fuel cell system according to any one of claims 1 to 7, wherein the circulation channel is a humidified water supply channel for supplying water to a humidifier of the fuel cell. A coolant circulation path connected to the fuel cell;
A circulation pump for circulating cooling water through the cooling water circulation passage;
A bypass flow path bypassing the circulation pump;
An upstream control valve that opens and closes the bypass flow path on the upstream side of the circulation pump, and a valve device that includes a downstream control valve that opens and closes on the downstream side;
A pressure fluctuation detection device for detecting pressure fluctuations in the circulation channel;
A fuel cell system comprising: a control device that controls an opening degree of the valve device so that a flow rate from the circulation flow path to the bypass flow path increases as the pressure fluctuation amount increases. A humidified water circulation passage connecting the humidifier of the fuel cell and the water tank;
A circulation pump for circulating the humidified water in the humidified water circulation channel;
A bypass flow path bypassing the circulation pump;
An upstream control valve that opens and closes the bypass flow path on the upstream side of the circulation pump, and a valve device that includes a downstream control valve that opens and closes on the downstream side;
A pressure fluctuation detection device for detecting pressure fluctuations in the circulation channel;
A fuel cell system comprising: a control device that controls an opening degree of the valve device so that a flow rate from the circulation flow path to the bypass flow path increases as the pressure fluctuation amount increases. A water circulation passage connecting the fuel cell, the humidifier, and the water tank;
A circulation pump for circulating water in the water circulation channel;
A bypass flow path bypassing the circulation pump;
An upstream control valve that opens and closes the bypass flow path on the upstream side of the circulation pump, and a valve device that includes a downstream control valve that opens and closes on the downstream side;
A pressure fluctuation detection device for detecting pressure fluctuations in the circulation channel;
A fuel cell system comprising: a control device that controls an opening degree of the valve device so that a flow rate from the circulation flow path to the bypass flow path increases as the pressure fluctuation amount increases.

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