Fuel cell system

Abstract

To provide a fuel cell system capable of suppressing deviation of loads of a plurality of injectors.SOLUTION: A fuel cell system comprises: a fuel cell; a plurality of injectors for injecting fuel gas to be supplied to the fuel cell; and a controller for executing fuel gas injection control of performing opening / closing processing of making any one injector of the plurality of injectors repeat opening / closing and performing valve opening processing of keeping the remaining one or more injectors in a valve opening state. Each time a correlation value in correlation to the number of times of opening / closing from a start of the opening / closing processing of the injector during performing the opening / closing processing becomes equal to or higher than a threshold in the fuel gas injection control, the controller changes over the one injector on which the opening / closing processing is to be performed, from the plurality of injectors, in order.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fuel cell system. [Background technology]

[0002] In a fuel cell system equipped with a plurality of injectors, one of the injectors may repeatedly open and close while the remaining injectors are maintained in an open state (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-028510 Summary of the Invention [Problem to be solved by the invention]

[0004] If only the same specific injector repeatedly opens and closes, a continuous load is applied to that injector alone, which may result in the need to replace that specific injector more frequently.

[0005] Therefore, an object of the present invention is to provide a fuel cell system that can suppress uneven load distribution among a plurality of injectors. [Means for solving the problem]

[0006] The above object can be achieved by a fuel cell system comprising a fuel cell, a plurality of injectors that inject fuel gas supplied to the fuel cell, and a control device that executes fuel gas injection control, which performs an opening and closing process to repeatedly open and close one of the plurality of injectors, and performs a valve opening process to maintain the remaining injectors in an open state, wherein the control device sequentially switches from among the plurality of injectors to one of the injectors for which the opening and closing process is being performed, each time a correlation value correlating with the number of times the injector for which the opening and closing process is being performed has been performed since the opening and closing process began, becomes equal to or greater than a threshold value in the fuel gas injection control. [Effects of the Invention]

[0007] It is possible to provide a fuel cell system that can suppress uneven load distribution among a plurality of injectors. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of a fuel cell system. [Figure 2] 4 is a flowchart illustrating an example of fuel gas injection control. [Figure 3] 4 is a timing chart illustrating fuel gas injection control. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Fuel cell system configuration] Fig. 1 is a configuration diagram of a fuel cell system 1. The fuel cell system 1 is mounted on a vehicle and includes an ECU (Electronic Control Unit) 3, a fuel cell (hereinafter referred to as FC) 4, an oxidant gas supply system 10, and a fuel gas supply system 20. The fuel cell system 1 is mounted on the vehicle. Electric power generated by the FC 4 is supplied to a motor that is a drive source for running the vehicle.

[0010] The FC4 is composed of a stack of multiple solid polymer electrolyte unit cells that generate electricity when supplied with oxidant gas and fuel gas. The FC4 contains a cathode flow path 4c through which the oxidant gas flows and an anode flow path 4a through which the fuel gas flows. The unit cell is composed of a membrane electrode assembly and a cathode-side separator and an anode-side separator that sandwich the assembly. The cathode flow path 4c is defined primarily between the membrane electrode assembly and the cathode-side separator, and is a space through which the oxidant gas can flow. The anode flow path 4a is defined between the membrane electrode assembly and the anode-side separator, and is a space through which the fuel gas can flow. The membrane electrode assembly includes an electrolyte membrane and catalyst layers formed on both sides of the electrolyte membrane.

[0011] The oxidant gas supply system 10 supplies air containing oxygen as an oxidant gas to the FC4, and includes a supply pipe 11, a discharge pipe 12, a bypass pipe 13, an air compressor 14, a bypass valve 15, an intercooler 16, and a backpressure valve 17. The supply pipe 11 is connected to the inlet of the cathode flow path 4c of the FC4. The discharge pipe 12 is connected to the outlet of the cathode flow path 4c of the FC4. The bypass pipe 13 connects the supply pipe 11 and the discharge pipe 12. The bypass valve 15 is provided at the connection between the supply pipe 11 and the bypass pipe 13. The bypass valve 15 switches the communication state between the supply pipe 11 and the bypass pipe 13. The air compressor 14, the bypass valve 15, and the intercooler 16 are arranged on the supply pipe 11 in this order from upstream to downstream. The backpressure valve 17 is arranged on the discharge pipe 12, upstream of the connection between the discharge pipe 12 and the bypass pipe 13. The air compressor 14 supplies air containing oxygen as an oxidant gas to the FC4 via a supply pipe 11. The oxidant gas supplied to the FC4 is discharged via a discharge pipe 12. An intercooler 16 cools the oxidant gas supplied to the FC4. A back pressure valve 17 adjusts the back pressure on the cathode side of the FC4. The operation of the air compressor 14, bypass valve 15, and back pressure valve 17 is controlled by an ECU 3. The ECU 3 adjusts the opening of the bypass valve 15 and back pressure valve 17, thereby adjusting the flow rate of the oxidant gas supplied from the air compressor 14 to the FC4.

[0012] The fuel gas supply system 20 supplies hydrogen gas as fuel gas to the FC4, and includes a tank 20T, a supply pipe 21, a circulation pipe 22, a discharge pipe 23, a tank valve 24, a pressure regulating valve 25, three injectors (hereinafter referred to as INJs) 26a to 26c, a gas-liquid separator 27, and a discharge valve 28. The tank 20T and the inlet of the anode flow path 4a of the FC4 are connected by the supply pipe 21. Hydrogen gas, which is fuel gas, is stored in the tank 20T. The tank valve 24, the pressure regulating valve 25, and INJs 26a to 26c are arranged in this order from the upstream side of the supply pipe 21. The INJs 26a to 26c are respectively provided at portions of the supply pipe 21 where the supply pipe 21 partially branches off from one another. With the tank valve 24 open, the opening of the pressure regulating valve 25 is adjusted, and one of the INJs 26a to 26c is repeatedly opened and closed while the remaining two are maintained in an open state, thereby supplying the fuel gas to the FC4.

[0013] Each of the INJs 26a to 26c includes a valve seat with an injection hole for injecting fuel gas and a valve element driven by a solenoid to open and close the injection hole. Each of the INJs 26a to 26c injects fuel gas by separating the valve element from the valve seat for a predetermined time at predetermined intervals to open the valve, and then stops fuel gas injection by abutting the valve element against the valve seat for a predetermined time to close the valve. In this case, the amount of fuel gas injected per valve opening is changed by adjusting the duty ratio, which is the ratio of the valve opening period to the interval period. For example, when the duty ratio is 0%, the valve element always abuts against the valve seat, resulting in a fully closed state. When the duty ratio is 100%, the valve element always abuts against the valve seat, resulting in a fully open state. When the duty ratio is a predetermined value other than 0% and other than 100%, the valve element repeatedly abuts against and separates from the valve seat, repeatedly opening and closing the valve. The duty ratio is adjusted by duty controlling the voltage applied to each of the INJs 26a to 26c. The duty control of the voltage applied to each of the INJs 26a to 26c is executed by the ECU 3. In this embodiment, as will be described in detail later, an opening / closing process is executed for one of the INJs 26a to 26c, in which the INJs are repeatedly opened and closed, and an opening process is executed for the remaining two INJs, in which the INJs are maintained in an open state.

[0014] The circulation pipe 22 connects the outlet of the anode flow path 4a of the FC4 to a portion of the supply pipe 21 downstream of the INJs 26a to 26c. A gas-liquid separator 27 is provided in the circulation pipe 22. The circulation pipe 22 is a pipe for returning the fuel gas to the FC4.

[0015] A discharge pipe 23 is connected to the gas-liquid separator 27. A discharge valve 28 is provided in the discharge pipe 23. The gas-liquid separator 27 separates and stores water from the fuel gas discharged from the FC4. When the discharge valve 28 opens, the water stored in the gas-liquid separator 27 is discharged to the outside of the fuel cell system 1 via the discharge pipe 23. The operation of the tank valve 24, the pressure adjustment valve 25, the INJs 26a to 26c, and the discharge valve 28 is controlled by the ECU 3.

[0016] The ECU 3 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The ECU 3 is electrically connected to the accelerator position sensor 6, the air compressor 14, the bypass valve 15, the back pressure valve 17, the tank valve 24, the pressure regulating valve 25, the INJs 26a to 26c, and the discharge valve 28. The ECU 3 calculates the required output power for the FC4 based on the detection value of the accelerator position sensor 6 and the driving states of the vehicle accessories and the FC4 accessories. The ECU 3 also calculates a target current value for the FC4 according to the required output power for the FC4, and controls the flow rates of the oxidizer gas and fuel gas supplied to the FC4 by the air compressor 14 and the INJs 26a to 26c so that the output current value of the FC4 becomes the target current value.

[0017] [Fuel gas injection control] The ECU 3 controls the INJs 26a to 26c based on the required output to the FC 4. FIG. 2 is a flowchart illustrating the fuel gas injection control. FIG. 3 is a timing chart illustrating the fuel gas injection control. FIG. 3 shows the open / closed states of the INJs 26a to 26c. The ECU 3 performs an opening / closing process on the INJ 26a and an opening process on the INJs 26b and 26c (step S1a, time t1). Next, the ECU 3 counts the number of times the INJ 26a is opened and closed (step S2a). Next, the ECU 3 determines whether the number of times the INJ 26a is opened and closed is equal to or greater than a threshold (step S3a). If the result of step S3a is No, step S1a is executed again. If the result of step S3a is Yes, the ECU 3 resets the number of times the INJ 26a is opened and closed (step S4a).

[0018] Next, the ECU 3 performs an opening / closing process on the INJ 26b, and performs an opening process on the INJs 26a and 26c (step S1b, time t2). Next, the ECU 3 counts the number of times the INJ 26b is opened and closed (step S2b). Next, the ECU 3 determines whether the number of times the INJ 26b is opened and closed is equal to or greater than a threshold value (step S3b). The threshold value in step S3b is the same as the threshold value in step S3a. If the answer is No in step S3b, step S1b is executed again. If the answer is Yes in step S3b, the ECU 3 resets the number of times the INJ 26b is opened and closed (step S4b).

[0019] Next, the ECU 3 performs an opening / closing process on the INJ 26c, and performs a valve opening process on the INJs 26a and 26b (step S1c, time t3). Next, the ECU 3 counts the number of times the INJ 26c is opened and closed (step S2c). Next, the ECU 3 determines whether the number of times the INJ 26c is opened and closed is equal to or greater than a threshold value (step S3c). The threshold value in step S3c is the same as the threshold value in step S3a. If the answer is No in step S3c, step S1c is executed again. If the answer is Yes in step S3c, the ECU 3 resets the number of times the INJ 26c is opened and closed (step S4c). Note that after step S4c is completed, if a fuel injection request continues, step S1a and subsequent steps are executed again.

[0020] As described above, the injectors for which the opening and closing process is performed are switched sequentially. This reduces the unevenness in the number of times each of the INJs 26a to 26c is opened and closed, and reduces the unevenness in the load on the INJs 26a to 26c. This prevents, for example, repeated loads from being applied only to a specific INJ, which would otherwise require frequent replacement. Furthermore, if the INJs 26a to 26c are integrated into a unit, this prevents deterioration of only that specific INJ, which would require replacement of the entire unit. Furthermore, this reduces the generation of pressure pulsations caused by repeated opening and closing of only one of the INJs 26a to 26c. This also reduces the effects of pressure pulsations on other components.

[0021] In the above embodiment, the number of times the INJs are opened and closed during the opening and closing process is counted (steps S2a, S2b, and S2c). However, the operating time of the INJs during the opening and closing process may be measured. This is because the number of times the INJs are opened and closed increases as the operating time of the INJs during the opening and closing process increases, and such operating time is also a correlation value correlated with the number of times the INJs are opened and closed. In this case, too, by sequentially switching the injector for which the opening and closing process is performed each time the operating time reaches a threshold, the imbalance in the load on each of the INJs 26a to 26c is suppressed.

[0022] In the above embodiment, the fuel cell system 1 is described as having three injectors 26a to 26c, but the number of injectors may be two, or four or more.

[0023] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0024] 1. Fuel cell system 3 ECU (control unit) 4 fuel cell 26a, 26b, 26c injectors

Claims

[Claim 1] A fuel cell; a plurality of injectors for injecting fuel gas to be supplied to the fuel cell; a control device that executes fuel gas injection control by performing an opening / closing process to repeatedly open and close any one of the plurality of injectors and a valve opening process to maintain the remaining injectors in an open state, In the fuel gas injection control, the control device sequentially switches one of the injectors for which the opening and closing process is being performed from among the plurality of injectors each time a correlation value correlating with the number of times the injector has opened and closed since the opening and closing process was started for the injector for which the opening and closing process is being performed becomes equal to or greater than a threshold value.

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