Fuel cell module

Abstract

To suppress performance deterioration of a fuel battery stack due to an over cooling while warming the fuel battery stack at an early period.SOLUTION: A control part 64 performs a warming processing for making a fuel battery stack 30 be warming by causing the fuel battery stack 30 to generate power so as to satisfy a predetermined condition while controlling driving of a pump 32 so that a stack passing flow amount becomes a first flow amount with a condition that a temperature of the fuel battery stack 30 is a first temperature or less, performs a first processing for controlling the driving of the pump 32 so that the stack passing flow amount becomes a second flow amount that is larger than the first flow amount after a termination of the warming processing, reduces the stack passing flow amount from the second flow amount after the first processing, performs a second processing for determining whether or not a temperature of cooling water detected from a temperature sensor 63 is increased by a second temperature or larger by the time when a predetermined time passes from executing the first processing, and performs a third processing for controlling the driving of the pump 32 so as to gradually increase the stack passing flow amount in the case where the second processing is established.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to a fuel cell module.

Background Art

[0002] The fuel cell module described in Patent Document 1 includes a fuel cell stack, a circulation flow path, and a pump. The circulation flow path circulates cooling water for cooling the fuel cell stack between the fuel cell stack. The pump adjusts the flow rate of the cooling water circulated between the circulation flow path and the fuel cell stack.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When generating power from a fuel cell stack at a low temperature, it is desirable to warm up the fuel cell stack early in order to raise the temperature of the fuel cell stack to a temperature suitable for power generation. Further, after the warm-up of the fuel cell stack is completed, the fuel cell stack is cooled by supplying cooling water to the fuel cell stack. In this case, depending on the supply mode of the cooling water to the fuel cell stack, there is a risk that the performance of the fuel cell stack may deteriorate due to overcooling of the fuel cell stack.

Means for Solving the Problems

[0005] A fuel cell module that solves the above problems comprises a fuel cell stack, a circulation channel for circulating cooling water between the fuel cell stack and the fuel cell stack for cooling the fuel cell stack, a pump for adjusting the stack flow rate, which is the flow rate of the cooling water circulated between the circulation channel and the fuel cell stack, a temperature sensor for detecting the temperature of the cooling water flowing through the circulation channel, and a control unit for controlling the drive of the pump, wherein the control unit performs a warm-up process to warm up the fuel cell stack by generating electricity to satisfy predetermined conditions while controlling the drive of the pump so that the stack flow rate becomes a first flow rate, provided that the temperature of the fuel cell stack is below a first temperature, after which it performs a first process to control the drive of the pump so that the stack flow rate becomes a second flow rate which is greater than the first flow rate, after which it reduces the stack flow rate from the second flow rate and performs a second process to determine whether the temperature of the cooling water detected by the temperature sensor has risen to the second temperature or higher within a predetermined time since the execution of the first process, and if the second process is successful, it performs a third process to control the drive of the pump so that the stack flow rate is gradually increased.

[0006] With the above configuration, the stack flow rate is adjusted to a relatively low first flow rate during the warm-up process, allowing the fuel cell stack to be warmed up even when the flow rate of cooling water supplied to the fuel cell stack is low. Therefore, the fuel cell stack can be warmed up more quickly compared to when the fuel cell stack is warmed up while the stack flow rate is adjusted to a relatively high flow rate. Furthermore, the third process is performed only when the cooling water temperature has risen to a second temperature or higher within a predetermined time elapsed since the execution of the first process, allowing the third process to cool the fuel cell stack to be performed while the fuel cell module is functioning normally. In the third process, the stack flow rate is gradually increased, which suppresses performance degradation of the fuel cell stack due to overcooling. Thus, the fuel cell stack can be warmed up quickly while suppressing performance degradation of the fuel cell stack due to overcooling.

[0007] In a fuel cell module, the circulation channel includes a supply channel for supplying the cooling water to the fuel cell stack and a discharge channel for discharging the cooling water from the fuel cell stack. The fuel cell module also includes a bypass channel connecting the supply channel and the discharge channel, an ion exchanger provided in the bypass channel, and a control valve for adjusting the bypass flow rate, which is the flow rate of the cooling water circulating between the circulation channel and the bypass channel, and the stack passage flow rate. The control unit may, in the warm-up process, control the drive of the control valve so that the bypass flow rate is greater than the stack passage flow rate. In the first process, it may control the drive of the control valve so that the stack passage flow rate is greater than the bypass flow rate. In the second and third processes, it may control the drive of the control valve so that the cooling water circulates both between the circulation channel and the fuel cell stack and between the circulation channel and the bypass channel.

[0008] With the above configuration, cooling water can be introduced into the bypass channel during the warm-up, second, and third processes. This allows the ion exchanger installed in the bypass channel to remove electric charge from the cooling water flowing through it. Therefore, electric charge can be removed from the cooling water during the warm-up and cooling periods of the fuel cell stack.

[0009] In a fuel cell module, the control unit may, if it determines in the second process that the temperature of the cooling water detected by the temperature sensor has not risen to a second temperature or higher within the predetermined time elapsed since the execution of the first process, not perform the third process and may also perform an abnormality determination.

[0010] With the above configuration, it is possible to perform an abnormality detection when it can be estimated that the fuel cell module is not functioning properly. [Effects of the Invention]

[0011] According to this invention, it is possible to warm up the fuel cell stack quickly while suppressing the performance degradation of the fuel cell stack due to supercooling. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a fuel cell module. [Figure 2] This is a schematic diagram showing a fuel cell module. [Figure 3] This is a schematic diagram showing a fuel cell module. [Figure 4] This flowchart shows the control processing procedure performed by the control unit. [Figure 5] This is a timing chart showing the changes in the control valve, pump rotation speed, and cooling water temperature. [Modes for carrying out the invention]

[0013] Below, one embodiment of the fuel cell module will be described with reference to the drawings. <Overall configuration of the fuel cell module> As shown in Figure 1, the fuel cell module 10 comprises a fuel cell stack 30, a circulation channel 50, a pump 32, a temperature sensor 63, and a control unit 64. Furthermore, the fuel cell module 10 comprises a bypass channel 53, an ion exchanger 34, and a control valve 62. In this embodiment, the fuel cell module 10 comprises a fan 29, a radiator 31, an intercooler 33, a reserve tank 35, and a supply pipe 61. The fuel cell module 10 in this embodiment is mounted on an industrial vehicle such as a forklift.

[0014] The fan 29 is positioned adjacent to the radiator 31. By rotating, the fan 29 creates an airflow directed towards the radiator 31. Receiving this airflow, the radiator 31 exchanges heat between the coolant and the outside air.

[0015] The reserve tank 35 contains coolant to be supplied to the radiator 31. The reserve tank 35 and the radiator 31 are connected by a supply pipe 61. The circulation channel 50 circulates cooling water between the fuel cell stack 30 and the fuel cell stack 30 for cooling the fuel cell stack 30. The circulation channel 50 includes a supply channel 51 and a discharge channel 52. The fuel cell stack 30 and the radiator 31 are connected by the supply channel 51 and the discharge channel 52. The supply channel 51 is a channel through which cooling water that has undergone heat exchange in the radiator 31 flows toward the fuel cell stack 30. In other words, the supply channel 51 supplies cooling water to the fuel cell stack 30. The discharge channel 52 is a channel through which cooling water that has been heated by heat exchange with the heat-generating fuel cell stack 30 flows toward the radiator 31. In other words, the discharge channel 52 is through which cooling water is discharged from the fuel cell stack 30. The cooling water flowing through the supply channel 51 is cooling water that has been cooled by heat exchange with the outside air in the radiator 31. In the drawing, the flow of cooling water in the circulation channel 50 is indicated by black arrows.

[0016] Pump 32 is located in the supply channel 51. Pump 32 is located downstream of the radiator 31 and upstream of the fuel cell stack 30 in the direction of coolant flow in the supply channel 51. Pump 32 pumps coolant under pressure to deliver it to the supply channel 51 and the discharge channel 52. In this way, pump 32 adjusts the stack flow rate Fa, which is the flow rate of coolant circulating between the circulation channel 50 and the fuel cell stack 30.

[0017] The intercooler 33 is located in the supply channel 51. The intercooler 33 is located downstream of the pump 32 and upstream of the fuel cell stack 30 in the direction of coolant flow in the supply channel 51. The intercooler 33 cools the coolant after heat exchange in the radiator 31. The coolant cooled by the intercooler 33 flows into the fuel cell stack 30.

[0018] The bypass flow path 53 is connected to a position downstream of the intercooler 33 and upstream of the fuel cell stack 30 in the flow direction of the cooling water in the supply flow path 51. The bypass flow path 53 is connected to a position downstream of the fuel cell stack 30 and upstream of the radiator 31 in the flow direction of the cooling water in the discharge flow path 52. Therefore, the bypass flow path 53 connects the supply flow path 51 and the discharge flow path 52.

[0019] The ion exchanger 34 is provided in the bypass flow path 53. The ion exchanger 34 removes electric charges from the cooling water flowing through the bypass flow path 53. The regulating valve 62 adjusts the bypass flow rate Fb, which is the flow rate of the cooling water circulated between the circulation flow path 50 and the bypass flow path 53, and the stack passage flow rate Fa. The regulating valve 62 in the present embodiment is provided at the connection point of the bypass flow path 53 in the supply flow path 51. By driving the regulating valve 62, for example, the flow passage areas of the bypass flow path 53 and the supply flow path 51 are increased or decreased. The regulating valve 62 is, for example, a rotary valve. By rotating the rotary valve, the flow passage areas of the bypass flow path 53 and the supply flow path 51 are increased or decreased according to the rotational position of the rotary valve.

[0020] The temperature sensor 63 detects the temperature T of the cooling water flowing through the circulation flow path 50. The temperature sensor 63 in the present embodiment is provided at a position upstream of the connection point of the bypass flow path 53 to the discharge flow path 52 and downstream of the fuel cell stack 30 in the flow direction of the cooling water in the discharge flow path 52. Therefore, the temperature sensor 63 in the present embodiment detects the temperature T of the cooling water after being discharged from the fuel cell stack 30 into the discharge flow path 52. It can be said that the temperature of the cooling water after being discharged from the fuel cell stack 30 into the discharge flow path 52 is substantially equal to the temperature of the fuel cell stack 30.

[0021] The control unit 64 comprises a processor (not shown), such as a CPU or GPU, and a storage unit (not shown), such as RAM and ROM. The storage unit stores program code or instructions configured to cause the processor to execute processing. The storage unit, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The control unit 64 may be composed of hardware circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 64, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as an ASIC or FPGA, or a combination thereof.

[0022] The control unit 64 is electrically connected to the pump 32, the control valve 62, and the temperature sensor 63. The control unit 64 controls the operation of the pump 32. The control unit 64 receives the cooling water temperature T detected by the temperature sensor 63 as input.

[0023] The fuel cell stack 30 is supplied with oxygen-containing air from an air compressor (not shown) via an air channel (not shown). The fuel cell stack 30 is also supplied with hydrogen gas from a hydrogen tank (not shown) via a hydrogen channel (not shown). The hydrogen channel is equipped with, for example, a flow control valve to change the flow rate of hydrogen gas in the hydrogen channel.

[0024] The control unit 64 adjusts the amount of oxygen supplied to the fuel cell stack 30 by controlling the discharge rate of the air compressor. The control unit 64 also adjusts the amount of hydrogen gas supplied to the fuel cell stack 30 by controlling the opening degree of the flow rate change valve. In this way, the control unit 64 controls the amount of power generated by the fuel cell stack 30 by adjusting the amounts of oxygen and hydrogen gas supplied to the fuel cell stack 30, thereby switching between power generation and power generation stoppage in the fuel cell stack 30.

[0025] <Cooling water flow> The coolant cooled by the radiator 31 is cooled by the intercooler 33 before flowing into the fuel cell stack 30. The fuel cell stack 30 is cooled by heat exchange between the fuel cell stack 30 and the coolant. The coolant heated by heat exchange with the fuel cell stack 30 flows into the radiator 31. In the radiator 31, the coolant is cooled by the airflow from the fan 29.

[0026] When cooling water flows through the bypass channel 53, the charge of the cooling water is removed by the ion exchanger 34. The cooling water, from which the charge has been removed by the ion exchanger 34, flows from the bypass channel 53 into the discharge channel 52.

[0027] <Warm-up process> As shown in Figure 2, the control unit 64 performs a warm-up process. During the warm-up process, the control unit 64 performs the following process, provided that the temperature of the fuel cell stack 30, as obtained by the temperature sensor 63, is below the first temperature T1. That is, the control unit 64 controls the drive of the pump 32 so that the stack flow rate Fa becomes the first flow rate F1, and generates electricity to the fuel cell stack 30 to satisfy predetermined conditions and warm up the fuel cell stack 30.

[0028] In this embodiment, the control unit 64 continues the warm-up process for a certain period of time Ta, and then terminates the warm-up process. The certain period of time Ta is a predetermined value set in advance by experiments or other means as a predetermined condition. The certain period of time Ta is set such that, for example, the product of the amount of heat generated per unit time of the fuel cell stack 30 and the certain period of time Ta is smaller than the product of the heat capacity of the fuel cell stack 30 and the temperature of the fuel cell stack 30 immediately before overheating occurs. The certain period of time Ta may be set to the longest time within the range in which this relationship of multiplicative values ​​is satisfied. The above-mentioned "temperature of the fuel cell stack 30 immediately before overheating occurs" may be corrected according to the temperature of the fuel cell stack 30 immediately before the warm-up process is started. In this case, the control unit 64 may adjust the duration of the warm-up process by selecting one of the above-mentioned certain period of time Ta that has been set in advance to correspond to this corrected temperature.

[0029] During the warm-up process, the control unit 64 causes the fuel cell stack 30 to generate electricity by supplying oxygen and hydrogen gas to the fuel cell stack 30. In this embodiment, the control unit 64 determines that the temperature of the fuel cell stack 30 is below a first temperature T1 when the temperature T of the cooling water detected by the temperature sensor 63 is below a predetermined temperature Tp. The first temperature T1 is the temperature at which the cooling water in the fuel cell stack 30 may freeze if the temperature is below the first temperature T1. The first temperature T1 is, for example, 0 degrees. The predetermined temperature Tp is a value at which the temperature of the fuel cell stack 30 can be estimated to be below the first temperature T1 when the temperature of the cooling water flowing at the location of the circulation channel 50 where the temperature sensor 63 is provided is below the predetermined temperature Tp. The predetermined temperature Tp may be the same temperature as the first temperature T1, or it may be a different temperature from the first temperature T1.

[0030] In this embodiment, the control unit 64 controls the rotational speed of the pump 32 to a low first rotational speed P1 during the warm-up process. Furthermore, during the warm-up process, the control unit 64 controls the drive of the control valve 62 so that the bypass flow rate Fb is greater than the stack flow rate Fa. Specifically, during the warm-up process, the control unit 64 controls the drive state of the control valve 62 to a first state V1. When the control valve 62 is in the first state V1, no cooling water flows from the supply channel 51 to the fuel cell stack 30, and all of the cooling water flowing through the supply channel 51 flows into the bypass channel 53. As a result, during the warm-up process, the stack flow rate Fa becomes 0 (zero), so the bypass flow rate Fb is greater than the stack flow rate Fa. In this embodiment, the first flow rate F1 is 0 (zero). The first flow rate F1 may be about one-tenth of the second flow rate F2, which will be described later.

[0031] <Cooling water flow during warm-up process> During the warm-up process, the coolant flows through the radiator 31, supply channel 51, bypass channel 53, and discharge channel 52 in that order, before flowing back into the radiator 31 from the discharge channel 52. Thus, during the warm-up process, the coolant circulates between the circulation channel 50 and the bypass channel 53. On the other hand, during the warm-up process, the coolant does not flow from the supply channel 51 into the fuel cell stack 30. Therefore, the coolant is not discharged from the fuel cell stack 30 into the discharge channel 52. Consequently, during the warm-up process, the coolant does not circulate between the circulation channel 50 and the fuel cell stack 30. The coolant flowing through the circulation channel 50 does not experience a temperature increase due to power generation in the fuel cell stack 30.

[0032] During the warm-up process, the fuel cell stack 30 generates electricity in the state where cooling water does not circulate between the circulation channel 50 and the fuel cell stack 30. As a result, during the warm-up process, the fuel cell stack 30's temperature rises as time passes due to the power generation by the fuel cell stack 30.

[0033] <First Processing> As shown in Figure 3, the control unit 64 performs a first process after the warm-up process is completed. In the first process, the control unit 64 controls the drive of the pump 32 so that the stack passage flow rate Fa becomes a second flow rate F2 which is greater than the first flow rate F1.

[0034] In this embodiment, the control unit 64 controls the rotation speed of the pump 32 to a high second rotation speed P2 during the first process. Furthermore, in the first process, the control unit 64 controls the drive of the control valve 62 so that the stack passage flow rate Fa is greater than the bypass flow rate Fb. Specifically, in the first process, the control unit 64 controls the drive state of the control valve 62 to a second state V2. When the control valve 62 is in the second state V2, no cooling water flows into the bypass passage 53 from either the supply passage 51 or the discharge passage 52, and all of the cooling water flowing through the supply passage 51 flows into the fuel cell stack 30. As a result, in the first process, the bypass flow rate Fb becomes 0 (zero), so the stack passage flow rate Fa is greater than the bypass flow rate Fb. In this embodiment, the second flow rate F2 is the total flow rate of cooling water flowing through the circulation passage 50.

[0035] <Cooling water flow during the execution of the first process> During the execution of the first process, the cooling water flows in the following order: radiator 31, supply channel 51, fuel cell stack 30, and discharge channel 52, before flowing from the discharge channel 52 into the radiator 31. Thus, during the execution of the first process, the cooling water circulates between the circulation channel 50 and the fuel cell stack 30. On the other hand, during the execution of the first process, the cooling water does not flow from the supply channel 51 into the bypass channel 53. Therefore, the cooling water is not discharged from the bypass channel 53 into the discharge channel 52. Consequently, during the execution of the first process, the cooling water does not circulate between the circulation channel 50 and the bypass channel 53.

[0036] Cooling water circulates between the circulation channel 50 and the fuel cell stack 30. In the first process, the cooling water, which has been heated by the power generation in the fuel cell stack 30, flows from the fuel cell stack 30 into the circulation channel 50. By adjusting the stack passage flow rate Fa to the second flow rate F2, the fuel cell stack 30 is cooled by the cooling water supplied to it.

[0037] <Second Processing> As shown in Figure 1, the control unit 64 performs a second process to determine whether the cooling water temperature T detected by the temperature sensor 63 has risen to a second temperature T2 or higher within a predetermined time Tb since the execution of the first process. In the second process, the control unit 64 first controls the drive of the pump 32 so that the stack flow rate Fa becomes less than the second flow rate F2. As a result, in the second process, the control unit 64 reduces the stack flow rate Fa from the second flow rate F2 after the first process. After the first process, the control unit 64 reduces the stack flow rate Fa from the second flow rate F2 and determines that the cooling water temperature T detected by the temperature sensor 63 has risen to a second temperature T2 or higher within a predetermined time Tb since the execution of the first process, and determines that the second process has been completed.

[0038] In the first process, the stack flow rate Fa is set to the second flow rate F2, and the rotation speed of the pump 32 is controlled to the second rotation speed P2, causing the cooling water flowing through the circulation channel 50 to heat up relatively quickly. As a result, the cooling water temperature T detected by the temperature sensor 63 rises to the second temperature T2 or higher within a predetermined time Tb from the start of the first process. The predetermined time Tb and the second temperature T2 are set to values ​​such that the fuel cell module 10 is considered to be functioning normally if the cooling water temperature T detected by the temperature sensor 63 rises to the second temperature T2 or higher within a predetermined time Tb from the start of the first process. Here, the stack flow rate Fa becomes the second flow rate F2 at the start of the first process, and then decreases in the second process. That is, the amount of cooling water that was inside the fuel cell stack 30 is pushed out into the portion of the discharge channel 52 where the temperature sensor 63 is located, equal to the flow rate from when the stack flow rate Fa becomes the second flow rate F2 until it decreases. The pushed-out cooling water warms the temperature sensor 63. The cooling water flowing into the fuel cell stack 30 cools the fuel cell stack 30. When the fuel cell module 10 is functioning normally, for example, the cooling water in the circulation channel 50 is not frozen, the pump 32 and control valve 62 are operating normally, and the temperature sensor 63 is detecting temperature normally.

[0039] In this embodiment, the control unit 64 controls the rotational speed of the pump 32 to a medium third rotational speed P3 during the second process. Furthermore, during the second process, the control unit 64 controls the drive of the control valve 62 so that cooling water circulates both between the circulation passage 50 and the fuel cell stack 30, and between the circulation passage 50 and the bypass passage 53. Specifically, during the second process, the control unit 64 controls the drive state of the control valve 62 to a third state V3. When the control valve 62 is in the third state V3, cooling water flows from the discharge passage 52 to the bypass passage 53, and also flows from the supply passage 51 to the fuel cell stack 30. As a result, during the second process, neither the stack passage flow rate Fa nor the bypass flow rate Fb is 0 (zero). Consequently, the stack passage flow rate Fa is less than the second flow rate F2. In the second process of this embodiment, the stack passage flow rate Fa and the bypass flow rate Fb are set to the same value. In the second process, the stack flow rate Fa and the bypass flow rate Fb may be set to different values.

[0040] <Cooling water flow during the execution of the second process> During the execution of the second process, the cooling water flows in the following order: radiator 31, supply channel 51, fuel cell stack 30, and discharge channel 52, before flowing from the discharge channel 52 back into the radiator 31. Furthermore, the cooling water flows from the discharge channel 52 back into the supply channel 51 via the bypass channel 53. Thus, during the execution of the second process, the cooling water circulates between the circulation channel 50 and the fuel cell stack 30, as well as between the circulation channel 50 and the bypass channel 53.

[0041] In the second process, the stack flow rate Fa is adjusted to be less than the stack flow rate Fa in the first process. Although the cooling function of the fuel cell stack 30 by the cooling water temporarily decreases due to the reduction in the amount of cooling water supplied to the fuel cell stack 30, the cooling of the fuel cell stack 30 continues in the second process as well, by the cooling water supplied to the fuel cell stack 30, just as in the first process.

[0042] <Third Processing> The control unit 64 performs the third process if the second process is successful. In the third process, the control unit 64 controls the drive of the pump 32 so as to gradually increase the stack flow rate Fa.

[0043] In this embodiment, the control unit 64 gradually increases the rotational speed of the pump 32 from a medium rotational speed (third rotational speed P3) during the third process. Furthermore, in the third process, as in the second process, the control unit 64 controls the drive of the control valve 62 so that cooling water circulates both between the circulation passage 50 and the fuel cell stack 30, and between the circulation passage 50 and the bypass passage 53. Specifically, in the third process, the control unit 64 controls the drive state of the control valve 62 to a third state (third state V3). The term "gradually" here means that initially the target value of the rotational speed is set lower than the final rotational speed, and then it is slowly increased over a predetermined period of time to reach the final rotational speed.

[0044] <Cooling water flow during the execution of the third process> During the execution of the third process, the cooling water flows through the same path as in the second process. The stack flow rate Fa in the third process is gradually increased from the stack flow rate Fa set in the second process. As a result, the cooling function of the fuel cell stack 30 by the cooling water gradually improves during the execution of the third process due to the increase in the amount of cooling water supplied to the fuel cell stack 30.

[0045] <Abnormality determination> If the control unit 64 determines that the cooling water temperature T detected by the temperature sensor 63 in the second process has not risen to a second temperature T2 or higher within a predetermined time Tb since the execution of the first process, it will not perform the third process and will perform an abnormality determination.

[0046] When the control unit 64 determines an abnormality, it may also provide notification to the industrial vehicle equipped with the fuel cell module 10 using a notification means (not shown). Examples of such notification means include voice notification and illumination notification. This notification means can inform users of the industrial vehicle of the abnormality.

[0047] The control unit 64 stores the temperature T of the cooling water at the time the first process is started, and if it determines that the temperature does not rise by a second temperature T2 or more from the stored temperature T within a predetermined time Tb from the start of the first process, it performs an abnormality determination. In other words, if it determines that the temperature has risen by a second temperature T2 or more from the stored temperature T within a predetermined time Tb from the start of the first process, the control unit 64 executes the third process.

[0048] The predetermined time Tb and second temperature T2 are set to values ​​such that the fuel cell module 10 is deemed to be functioning normally if the cooling water temperature T detected by the temperature sensor 63 rises to or above the second temperature T2 within the predetermined time Tb elapsed from the execution of the first process. In other words, when the fuel cell module 10 is functioning normally, the predetermined time Tb is set based on the time required for the cooling water temperature T to rise to or above the second temperature T2 as the stack flow rate Fa is set to the second flow rate F2 in the first process.

[0049] When the fuel cell module 10 is functioning normally, cooling water circulates between the circulation channel 50 and the fuel cell stack 30. In the first process, the cooling water, heated by the power generation in the fuel cell stack 30, flows from the fuel cell stack 30 into the circulation channel 50. As a result, the temperature T of the cooling water detected by the temperature sensor 63 rises relatively quickly from the start of the first process. On the other hand, when the fuel cell module 10 is not functioning normally, the flow rate of cooling water circulating between the circulation channel 50 and the fuel cell stack 30 decreases compared to when the fuel cell module 10 is functioning normally. As a result, in the first process, the cooling water, heated by the power generation in the fuel cell stack 30, does not easily flow from the fuel cell stack 30 into the circulation channel 50. The temperature T of the cooling water detected by the temperature sensor 63 does not easily rise from the start of the first process. Therefore, the control unit 64 can estimate that the fuel cell module 10 is not functioning normally if the temperature T of the cooling water detected by the temperature sensor 63 does not rise to a second temperature T2 or higher within a predetermined time Tb from the start of the first process. If the fuel cell module 10 is not functioning properly, examples include the cooling water freezing in the circulation channel 50, the pump 32 and control valve 62 not operating properly, or the temperature sensor 63 not detecting properly.

[0050] <Processing procedure by the control unit> An example of the procedure performed by the control unit 64 will be described with reference to Figure 4. The procedure shown in Figure 4 is performed, for example, on the condition that power generation by the fuel cell stack 30 has started.

[0051] As shown in Figure 4, once processing begins, the control unit 64 determines whether the cooling water temperature T is less than or equal to the first temperature T1 (step S110). If it determines that the cooling water temperature T is higher than the first temperature T1 (step S110: NO), the control unit 64 terminates the process, determining that warm-up processing is unnecessary. If it determines that the cooling water temperature T is less than or equal to the first temperature T1 (step S110: YES), the control unit 64 performs warm-up processing (step S120).

[0052] Next, the control unit 64 performs the first process (step S130). After that, the control unit 64 starts the second process (step 140). If it is determined in the second process that the cooling water temperature T has risen to or above the second temperature T2 (step 150: YES), the control unit 64 performs the third process (step S160). Then the control unit 64 terminates the process.

[0053] If the control unit 64 determines that the cooling water temperature T has not risen above the second temperature T2 (step 150: NO), it performs an abnormality determination (step S170). Then, the control unit 64 terminates the process.

[0054] [Effect of the Embodiment] Next, the operation of this embodiment will be described. As shown in Figure 5, the control unit 64 performs a warm-up process until the first time t1. Figure 5 illustrates the case where the cooling water temperature T at the start of the warm-up process is the first temperature T1. During the warm-up process, the control unit 64 controls the rotation speed of the pump 32 to the first rotation speed P1 and controls the control valve 62 to the first state V1, thereby adjusting the stack flow rate Fa to the first flow rate F1. During the warm-up process, the control unit 64 generates electricity in the fuel cell stack 30 to warm it up. In this embodiment, since the stack flow rate Fa is adjusted to 0 (zero), the cooling water heated by the electricity generated by the fuel cell stack 30 does not flow into the circulation channel 50 until the first time t1 when the warm-up process is completed. As a result, the temperature T of the cooling water does not rise until the first time t1 when the warm-up process is completed.

[0055] After the warm-up process is completed, at a first time t1, the control unit 64 performs a first process to control the drive of the pump 32 so that the stack flow rate Fa becomes the second flow rate F2. In the first process, the control unit 64 controls the rotation speed of the pump 32 to the second rotation speed P2 and controls the control valve 62 to the second state V2, thereby adjusting the stack flow rate Fa to the second flow rate F2. In this embodiment, since the stack flow rate Fa is adjusted to the total flow rate of cooling water flowing through the circulation channel 50, when the first process is performed at a first time t1, the cooling water heated by the power generation from the fuel cell stack 30 flows into the circulation channel 50. As a result, when the first process is performed at a first time t1, the temperature T of the cooling water rises in a short time. When cooling water is supplied to the fuel cell stack 30, the fuel cell stack 30 is cooled by heat exchange with the cooling water.

[0056] Between the first time t1 and the second time t2, the control unit 64 starts the second process. Figure 5 illustrates a case where the difference between the first time t1 and the second time t2 is less than or equal to a predetermined time Tb, and the difference between the cooling water temperature T at the second time t2 and the cooling water temperature T at the first time t1 is the second temperature T2. In the second process, the control unit 64 controls the rotation speed of the pump 32 to the third rotation speed P3 and controls the control valve 62 to the third state V3, thereby reducing the stack flow rate Fa from the second flow rate F2. As a result, in the second process, the cooling function of the fuel cell stack 30 by the cooling water is reduced compared to when the first process is executed, due to the decrease in the amount of cooling water supplied to the fuel cell stack 30.

[0057] In the second process, after determining that the second temperature T2 has been reached at the second time t2, the control unit 64 performs the third process at the third time t3. In the third process, the control unit 64 gradually increases the stack flow rate Fa by gradually increasing the rotational speed of the pump 32 from the third rotational speed P3 and maintaining the control valve 62 in the third state V3. As a result, in the third process, the amount of cooling water supplied to the fuel cell stack 30 is gradually increased, and the cooling function of the fuel cell stack 30 by the cooling water gradually improves compared to when the second process is performed.

[0058] [Effects of the Embodiment] The effects of this embodiment will now be explained. (1) The control unit 64 performs a warm-up process on the condition that the temperature of the fuel cell stack 30 is below a first temperature T1. During the warm-up process, the control unit 64 controls the drive of the pump 32 so that the stack flow rate Fa becomes a first flow rate F1, and generates electricity in the fuel cell stack 30 to satisfy predetermined conditions and warm up the fuel cell stack 30. In this way, the stack flow rate Fa is adjusted to a first flow rate F1, which is a relatively low flow rate, during the warm-up process, so the fuel cell stack 30 can be warmed up even when the flow rate of cooling water supplied to the fuel cell stack 30 is low. Therefore, the fuel cell stack 30 can be warmed up earlier compared to when the fuel cell stack 30 is warmed up while the stack flow rate Fa is adjusted to a relatively high flow rate. After the warm-up process is completed, the control unit 64 performs a first process in which it controls the drive of the pump 32 so that the stack flow rate Fa becomes a second flow rate F2. The control unit 64 performs a second process after the first process by reducing the stack flow rate Fa from the second flow rate F2 and determining whether the cooling water temperature T detected by the temperature sensor 63 has risen to the second temperature T2 or higher within a predetermined time Tb from the execution of the first process. If the second process is successful, the control unit 64 performs a third process by controlling the drive of the pump 32 to gradually increase the stack flow rate Fa. Thus, the third process is performed on the condition that the cooling water temperature T has risen to the second temperature T2 or higher within a predetermined time Tb from the execution of the first process. Therefore, the third process for cooling the fuel cell stack 30 can be performed while the fuel cell module 10 is functioning normally. In the third process, since the stack flow rate Fa is gradually increased, performance degradation of the fuel cell stack 30 due to supercooling can be suppressed. Therefore, the fuel cell stack 30 can be warmed up early while performance degradation of the fuel cell stack 30 due to supercooling can be suppressed.

[0059] (2) During the warm-up process, the control unit 64 controls the drive of the control valve 62 so that the bypass flow rate Fb is greater than the stack flow rate Fa. During the second and third processes, the control unit 64 controls the drive of the control valve 62 so that cooling water circulates both between the circulation channel 50 and the fuel cell stack 30, and between the circulation channel 50 and the bypass channel 53. Therefore, cooling water can be introduced into the bypass channel 53 when the warm-up process, the second process, and the third process are being executed. This allows the ion exchanger 34 installed in the bypass channel 53 to remove charge from the cooling water flowing through the bypass channel 53. Thus, charge can be removed from the cooling water during the warm-up and cooling time of the fuel cell stack 30.

[0060] (3) In the second process, the control unit 64 determines that the temperature T of the cooling water detected by the temperature sensor 63 has not risen to a second temperature T2 or higher within a predetermined time Tb since the execution of the first process, and it does not perform the third process and makes an abnormality determination. Therefore, an abnormality determination can be made when it can be estimated that the fuel cell module 10 is not functioning normally.

[0061] [Example of changes] The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0062] ○ The control unit 64 may, if it determines in the second process that the cooling water temperature T detected by the temperature sensor 63 has not risen to a second temperature T2 or higher by the time Tc elapsed since the execution of the first process, not perform the third process and may also perform an abnormality determination. Note that the elapsed time Tc is different from the predetermined time Tb.

[0063] ○ The control unit 64 may omit the execution of abnormality determination. In this case, for example, if the control unit 64 determines in the second process that the cooling water temperature T has not risen to a second temperature T2 or higher within a predetermined time Tb since the execution of the first process, it may terminate the process without performing the third process.

[0064] ○ The bypass flow path 53 may be omitted from the fuel cell module 10. In this case, for example, an ion exchanger 34 may be provided in the middle of the circulation flow path 50. Also in this case, for example, the adjustment of the stack flow rate Fa to a first flow rate F1 in the warm air treatment and the adjustment of the stack flow rate Fa to a second flow rate F2 in the first treatment can be achieved by the drive control of the pump 32 by the control unit 64. The adjustment of the stack flow rate Fa to less than the second flow rate F2 in the second treatment and the increase of the stack flow rate Fa in the third treatment can be achieved by the drive control of the pump 32 by the control unit 64.

[0065] ○ The control unit 64 may determine whether the temperature of the fuel cell stack 30 is below the first temperature T1 based on parameters other than the cooling water temperature T detected by the temperature sensor 63. For example, the fuel cell module 10 may be equipped with an ambient temperature sensor that detects the ambient temperature. The control unit 64 may determine whether the temperature of the fuel cell stack 30 is below the first temperature T1 based on the ambient temperature detected by the ambient temperature sensor.

[0066] ○ The control unit 64 is not limited to terminating the warm-up process after continuing it for a certain period of time. For example, the control unit 64 may generate electricity at a predetermined amount for a predetermined time. The amount of electricity and the time should be determined experimentally. In this case, the control unit 64 controls the operation of the pump 32 so that cooling water is discharged from the fuel cell stack 30 into the discharge channel 52 during the warm-up process.

[0067] ○ The first flow rate F1 may be a value greater than 0 (zero). In this case, during the warm-up process, the control unit 64 controls the drive of the pump 32 so that the first flow rate F1, which is greater than 0 (zero), is the flow rate Fa passing through the stack, provided that the temperature of the fuel cell stack 30 is less than or equal to the first temperature T1.

[0068] ○ The control unit 64 may control the rotation speed of the pump 32 to 0 (zero) during the warm-up process. ○ The second flow rate F2 may be less than the total flow rate of the cooling water flowing through the circulation channel 50. In this case, the control unit 64 controls the drive of the pump 32 in the first process so that the stack passage flow rate Fa is greater than the first flow rate F1 and less than the total flow rate of the cooling water flowing through the circulation channel 50.

[0069] ○ The installation location of the temperature sensor 63 is not limited to a position upstream of the connection point of the bypass channel 53 to the discharge channel 52 and downstream of the fuel cell stack 30 in the direction of cooling water flow in the discharge channel 52. In short, the installation location of the temperature sensor 63 can be changed within a range in which the temperature T of the cooling water after it has been discharged from the fuel cell stack 30 into the discharge channel 52 can be detected.

[0070] ○ The fuel cell module 10 is not limited to being installed in industrial vehicles. For example, the fuel cell module 10 may be installed in automobiles, agricultural vehicles, construction machinery, stationary power generators, etc. [Explanation of Symbols]

[0071] F1...First flow rate, F2...Second flow rate, Fa...Stack flow rate, Fb...Bypass flow rate, T...Cooling water temperature, T1...First temperature, T2...Second temperature, Tb...Determined time, 10...Fuel cell module, 30...Fuel cell stack, 32...Pump, 34...Ion exchanger, 50...Circulation channel, 51...Supply channel, 52...Discharge channel, 53...Bypass channel, 62...Control valve, 63...Temperature sensor, 64...Control unit.

Claims

1. Fuel cell stack and A circulation channel for circulating cooling water between the fuel cell stack and the fuel cell stack for cooling the fuel cell stack, A pump that adjusts the stack passage flow rate, which is the flow rate of the cooling water circulating between the circulation channel and the fuel cell stack, A temperature sensor for detecting the temperature of the cooling water flowing through the circulation channel, A fuel cell module comprising a control unit for controlling the drive of the pump, The control unit, Provided that the temperature of the fuel cell stack is below a first temperature, a warm-up process is performed to warm up the fuel cell stack by generating electricity while controlling the drive of the pump so that the flow rate through the stack becomes a first flow rate, thereby satisfying predetermined conditions. After the warm-up process is completed, a first process is performed to control the drive of the pump so that the flow rate through the stack becomes a second flow rate which is greater than the first flow rate. After the first process, the stack flow rate is reduced from the second flow rate, and a second process is performed to determine whether the temperature of the cooling water detected by the temperature sensor has risen to the second temperature or higher within a predetermined time elapsed since the execution of the first process. A fuel cell module characterized by performing a third process, which, when the second process is completed, controls the drive of the pump to gradually increase the flow rate through the stack.

2. The circulation channel includes a supply channel for supplying the cooling water to the fuel cell stack and a discharge channel for discharging the cooling water from the fuel cell stack. The aforementioned fuel cell module is A bypass channel connecting the supply channel and the discharge channel, An ion exchanger is provided in the bypass channel, The system includes a control valve that adjusts the bypass flow rate, which is the flow rate of the cooling water circulating between the circulation channel and the bypass channel, and the stack passage flow rate. The control unit, In the warm-up process, the drive of the control valve is controlled so that the bypass flow rate is greater than the stack flow rate. In the first process, the drive of the control valve is controlled so that the flow rate through the stack is greater than the bypass flow rate. The fuel cell module according to claim 1, wherein in the second and third processes, the drive of the control valve is controlled so that the cooling water circulates both between the circulation channel and the fuel cell stack and between the circulation channel and the bypass channel.

3. The fuel cell module according to claim 1 or 2, wherein the control unit determines that the temperature of the cooling water detected by the temperature sensor in the second process has not risen to a second temperature or higher within the predetermined time elapsed since the execution of the first process, and does not perform the third process, and performs an abnormality determination.

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