JP5891863B2 - Fuel gas supply device - Google Patents

Description

  The present invention relates to a fuel supply device for supplying hydrogen as a fuel to a fuel cell.

  In a vehicle that travels using electric power generated by a fuel cell, hydrogen stored in a tank at a high pressure is decompressed using a pressure regulating valve and supplied to the fuel cell. Generally, the remaining amount of hydrogen in the hydrogen tank is calculated from the detected value of the pressure sensor, and when the detected value of the pressure sensor falls to a predetermined value, the system is stopped assuming that the remaining amount of hydrogen is exhausted. .

  By the way, as a pressure sensor for detecting the pressure in the hydrogen tank, there is a trade-off between cost and a sensor having an error range of about 3% of the detectable range (full scale) is often used. For example, if a pressure sensor that detects a pressure in a hydrogen tank for 70 [MPa] that is generally used for vehicles has a full scale exceeding 100 [MPa], an error of about ± 4 [MPa] is generated. Become.

  When the error is ± 4 [MPa], if the detected value of the pressure sensor decreases to 4 [MPa], the hydrogen tank internal pressure may be 0 [MPa], so the system needs to be stopped. is there. However, in practice, hydrogen that can still travel may remain in the tank. That is, as the error range of the pressure sensor increases, the amount of hydrogen remaining in the hydrogen tank when the system is stopped (hereinafter referred to as an invalid remaining amount) increases, and the cruising distance of the vehicle becomes shorter.

  As a configuration for improving the detection accuracy of the pressure in the hydrogen tank, Patent Document 1 discloses that the detected value of the upstream pressure sensor provided between the hydrogen tank and the pressure regulating valve is the downstream pressure provided on the downstream side of the pressure regulating valve. A configuration for correcting based on the detection value of the sensor is described. More specifically, at the time of system startup or idle stop, the upstream pressure and downstream pressure of the pressure regulating valve are made uniform, and the deviation between the detected values of the upstream pressure sensor and downstream pressure sensor is calculated. The detection value of the upstream pressure sensor is corrected based on the deviation.

JP 2006-140132 A

  However, even in the configuration of Patent Document 1, the pressure in the hydrogen tank is detected by the pressure sensor. Therefore, in the low pressure region that becomes the boundary of whether or not to stop the system, the influence of the error of the pressure sensor becomes large, and it is difficult to sufficiently reduce the invalid remaining amount in the hydrogen tank.

  Accordingly, an object of the present invention is to provide a fuel supply device that can detect the pressure in the hydrogen tank with higher accuracy and reduce the ineffective remaining amount in the hydrogen tank.

  The fuel gas supply apparatus of the present invention is a fuel gas supply apparatus that supplies fuel gas to a fuel cell stack that generates power using fuel gas and oxidant gas. And it has a fuel tank which stores fuel gas, a fuel gas passage which connects a fuel tank and a fuel cell stack, and a control valve which is provided in the fuel gas passage and controls the supply amount of fuel gas. Further, the downstream pressure estimating means for estimating the pressure of the fuel gas downstream from the control valve, the current detecting means for detecting the control current of the control valve, and the control based on the detected control current and the estimated downstream pressure. And a controller having first pressure detection means for detecting the pressure of the fuel gas upstream of the valve.

  According to the present invention, the pressure of the fuel gas upstream of the control valve, that is, the pressure in the hydrogen tank is detected based on the control current of the control valve and the pressure downstream of the control valve. Can be detected with higher accuracy. As a result, the system can be operated until the pressure in the hydrogen tank becomes lower, and the ineffective remaining amount in the hydrogen tank can be reduced.

It is a lineblock diagram of the fuel supply system concerning a 1st embodiment. It is a schematic block diagram which shows an example of a flow regulating valve. It is a characteristic view of the control current with respect to the pressure of a primary port. It is a characteristic view of a pressure sensor detection value when hydrogen decreases at a constant rate. It is the figure which expanded a part of FIG. 4A. It is a figure which shows the error range of the upstream pressure estimated value based on control current, and the upstream pressure detection value by a pressure sensor. It is a flowchart which shows the control routine for the upstream pressure detection which the controller 6 performs in 1st Embodiment. It is a characteristic view of the upstream pressure with respect to the control current. It is a block diagram of the fuel supply system which concerns on 2nd Embodiment. It is a characteristic view of the downstream pressure with respect to the electric power generation amount of a fuel cell stack. It is a block diagram of the fuel supply system which concerns on 3rd Embodiment. It is a characteristic view of the electric power generation amount of the fuel cell stack with respect to the vehicle speed. It is a block diagram of the fuel supply system which concerns on 4th Embodiment. It is a flowchart which shows the control routine for the upstream pressure detection which the controller 6 performs in 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of a fuel supply system 100 for a fuel cell according to the first embodiment.

  The fuel supply system 100 is a system that supplies hydrogen to the fuel cell stack 1, and includes a hydrogen tank 2, a hydrogen supply passage 3, a flow rate adjustment valve 4, a downstream pressure sensor 7, and a controller 6. .

  The hydrogen tank 2 is provided on the upstream side of the hydrogen supply passage 3. The hydrogen tank 2 stores the hydrogen supplied to the fuel cell stack 1 in a high pressure state of, for example, 70 [MPa]. The hydrogen tank 2 includes an on-off valve 5 that controls the communication state with the hydrogen supply passage 3. The on-off valve 5 is electromagnetically operated and shuts off the communication between the hydrogen tank 2 and the hydrogen supply passage 3 when the power is off.

  The flow rate adjustment valve 4 operates electromagnetically, adjusts the amount of hydrogen supplied from the hydrogen tank 2 to the fuel cell stack 1, and controls the hydrogen pressure at the fuel electrode of the unit cell.

  In the hydrogen supply passage 3, the hydrogen tank 2 side (hereinafter referred to as the upstream side) from the flow rate adjustment valve 4 is the high-pressure pipe 3 </ b> A, and the fuel cell stack 1 side from the flow rate adjustment valve 4 (hereinafter referred to as the downstream side). Is formed by the low-pressure pipe 3B.

  The controller 6 is a device that controls the entire fuel cell system including the fuel supply system 100, and includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). ). In the present embodiment, the function of detecting the pressure in the high-pressure pipe 3A (hereinafter referred to as upstream pressure) of the controller 6 will be mainly described.

  The controller 6 receives signals from the downstream pressure sensor 7 that detects the pressure in the low-pressure pipe 3B (hereinafter referred to as downstream pressure) and the current sensor 8 that detects the control current of the flow rate adjustment valve 4. A signal from the downstream pressure sensor 7 is input to the downstream pressure detection unit 6A of the controller 6, and a control current value of the flow rate adjusting valve 4 is input to the current detection unit 6B of the controller 6.

  Here, the flow rate adjusting valve 4 will be described.

  FIG. 2 is a schematic configuration diagram showing an example of the flow rate adjusting valve 4. The flow rate adjusting valve 4 has a configuration similar to that of a known electromagnetic control valve, for example, disclosed in JP-A-2002-295712.

  A primary port 11, a valve chamber 18, a passage 16, a secondary port 12, a pressure equalizing passage 17, a spring chamber 19, and a valve port 20 are formed in the housing 10 of the flow rate adjusting valve 4.

  The valve chamber 18 communicates with the outside through the primary port 11 and communicates with the outside through the passage 16 and the secondary port 12.

  The pressure equalizing passage 17 is a branch of the passage 16 and connects the passage 16 and the spring chamber 19.

  The primary port 11 is connected to the high pressure pipe 3A, and the secondary port 12 is connected to the low pressure pipe 3B.

  Inside the valve chamber 18, a valve body 13 for controlling the communication state between the valve chamber 18 and the passage 16 is arranged. The valve body 13 has a tapered portion along a tapered valve seat 16 </ b> A provided at the end of the passage 16 on the valve chamber 18 side.

  A shaft 14 is formed integrally with the valve body 13, and the shaft 14 is disposed so as to be able to advance and retract within the valve port 20. The shaft 14 also serves as a plunger rod of the electromagnetic solenoid device 22, and moves in the left-right direction in the figure according to the magnitude of current supplied to the electromagnetic solenoid device 22. When the power is off, the tapered surface of the valve element 13 and the valve seat are moved. The valve chamber 18 and the passage 16 are blocked from communicating with each other.

  A spring 15 is disposed in the spring chamber 19. The elastic force of the spring 15 acts so as to press the valve body 13 toward the passage 16 side.

  The spring chamber 19 and the valve chamber 18 are hermetically separated by a diaphragm seal 21 in which the shaft 14 passes through the center portion and the outer edge portion is hermetically connected to the housing 10.

  A differential pressure between the valve chamber 18 and the spring chamber 19 acts on the diaphragm seal 21, and the area of the portion where the differential pressure acts is determined by the effective pressure receiving diameter. On the other hand, the differential pressure between the valve chamber 18 and the spring chamber 19 also acts on the valve body 13, and the area is determined by the effective pressure receiving diameter of the valve seat 16A. The effective pressure receiving diameter of the diaphragm seal 21 and the effective pressure receiving diameter of the valve seat 16A are set to the same size. With this setting, the force acting on the valve body 13 due to the differential pressure between the pressure of the primary port 11 and the pressure of the secondary port 12 cancels out the force acting on the diaphragm seal 21. As a result, the influence of the differential pressure between the pressure of the primary port 11 and the pressure of the secondary port 12 on the opening and closing of the valve body 13 is eliminated.

  According to the above configuration, when the valve body 13 is opened, the hydrogen flowing into the valve chamber 18 from the high pressure pipe 3A via the primary port 11 passes to the low pressure pipe 3B via the passage 16 and the secondary port 12. And flow. The flow rate to the low-pressure pipe 3B is determined by the positional relationship between the valve body 13 and the valve seat 16A, and the positional relationship is determined by the electromagnetic force for moving the valve body 13, that is, the energized current (hereinafter referred to as control current). .

  There is a relationship as shown in FIG. 3 between the control current required to move the valve body 13 in the valve opening direction, that is, the left direction in FIG. 2 and the pressure of the primary port 11.

  In FIG. 3, the vertical axis represents the magnitude of the control current, and the horizontal axis represents the pressure of the primary port 11. EMAX in the figure indicates a current necessary for moving the valve body 13 to a position where the maximum gas amount required by the fuel cell stack 1 can flow. EMIN in the figure indicates the minimum current value required to move the valve body 13, that is, the current value required to separate the valve body 13 seated on the valve seat 16A from the valve seat 16A.

  As shown in FIG. 3, the current value EMAX and the current value EMIN change according to the pressure change in the region where the pressure of the primary port 11 is P1 or less, but in the region higher than P1, the pressure of the primary port 11 is Even if it changes, it hardly changes. This is because the influence of the differential pressure between the pressure of the primary port 11 and the pressure of the secondary port 12 is eliminated as described above.

  The pressure P1 is, for example, about 5 [MPa] in the case of a fully filled tank of 70 [MPa].

  By the way, when the internal pressure of the hydrogen tank 2 is detected by a pressure sensor, one having an error of about 3% of full scale is generally used. For example, when the full scale exceeds 100 [MPa], an error of about ± 4 [MPa] occurs. As shown in FIG. 4A, this error is constant from a fully filled hydrogen tank 2 to an empty state. FIG. 4A is a diagram showing pressure sensor detection values when hydrogen decreases at a constant rate until the hydrogen tank 2 is fully filled to empty. The vertical axis represents the hydrogen tank pressure, and the horizontal axis represents time. In the figure, a solid line indicates a pressure sensor detection value, and a broken line indicates an error range with respect to the pressure sensor detection value.

  4B is an enlarged view of a circled portion of FIG. 4A. Here, the error range is set to ± 4 [MPa].

  When the pressure sensor detection value is 4 [MPa], considering the error range of the pressure sensor, the actual hydrogen tank pressure is zero [MPa], that is, the tank may be empty. There is a need to. However, in reality, it may still be 8 [MPa]. Thus, when it is determined that the hydrogen tank 2 is empty and the system is stopped, there is a possibility that an invalid remaining amount exists in the hydrogen tank 2.

  The ineffective remaining amount increases as the detection accuracy of the hydrogen tank pressure decreases, and the cruising distance in the hydrogen tank 2 having the same capacity decreases. If a pressure sensor with high detection accuracy is used, the remaining amount of invalidity can be reduced, but this leads to an increase in cost.

  FIG. 5 shows the pressure of the hydrogen tank 2 estimated based on the control current of the flow rate adjusting valve 4 and the error range of 3% of full scale when hydrogen decreases at a constant rate as in FIG. 4A. It is a figure which shows the relationship with the pressure of the hydrogen tank 2 detected by (1). As in FIG. 4A, the vertical axis represents pressure, and the horizontal axis represents time. The two solid lines indicate the maximum and minimum pressure estimation values based on the control current, the one-dot chain line indicates the pressure sensor detection value, and the two dashed lines indicate the maximum and minimum values in the error range of the pressure sensor detection value. Are shown respectively.

  As shown in FIG. 5, when the timing t1 is exceeded, the error value is narrower for the estimated value based on the control current than for the pressure sensor detection value. Before the timing t1, the estimated value based on the control current has a wider error range than the pressure sensor detection value, but in this region, hydrogen remains to the extent that it is not necessary to determine whether or not to stop the system. The influence of the difference in error range on the remaining amount of invalidity is small.

  That is, if the amount of hydrogen in the hydrogen tank 2 is estimated based on the control current of the flow regulating valve 4, the hydrogen tank is more accurate than using a pressure sensor, particularly in a region where the amount of hydrogen in the hydrogen tank 2 is small. Since the amount of hydrogen in 2 can be estimated, the remaining amount of invalidity can be reduced.

  Therefore, in the present embodiment, the amount of hydrogen in the hydrogen tank 2 is estimated based on the control current of the flow rate adjustment valve 4. Hereinafter, the hydrogen amount estimation control in the hydrogen tank 2 will be described.

  FIG. 6 is a flowchart showing a control routine executed by the controller 6 for estimating the amount of hydrogen in the hydrogen tank 2 based on the control current of the flow rate adjusting valve 4. This routine is repeatedly executed at a cycle of, for example, about 10 milliseconds.

  In step S100, the downstream pressure detector 6A of the controller 6 reads the detection value of the downstream pressure sensor 7. By using the downstream pressure sensor 7, the downstream pressure can be easily detected.

  In step S110, the current detector 6B of the controller 6 reads the detection signal of the current sensor 8 and converts it into a control current. Then, the maximum value of the control current is read when the fuel cell stack 1 starts generating power or during power generation and the downstream pressure reaches a predetermined target value. The predetermined target value of the downstream pressure is set by the controller 6 according to the traveling state of the vehicle, the request from the driver, and the like.

  Here, the reason for reading the maximum value will be described with reference to FIG. If the control current is the same, the primary port pressure, that is, the pressure in the hydrogen tank 2 is lower when the control current corresponds to the current value EMAX than when the control current corresponds to the current value EMIN. When deciding whether or not to stop the power generation of the fuel cell system, if the pressure of the hydrogen tank 2 is selected to be lower, the fuel cell system is operated in a state where hydrogen cannot be supplied from the hydrogen tank 2 You can avoid continuing. Therefore, in this embodiment, the maximum value is read.

  In step S120, the characteristic map selection unit 6C of the controller 6 selects a characteristic map indicating the pressure in the hydrogen tank 2, that is, the relationship between the upstream pressure and the control current, based on the downstream pressure. The characteristic map selection unit 6C has a characteristic map created for each target value of the downstream pressure, and selects a characteristic map corresponding to the detected value of the downstream pressure from these. The characteristic map is created for each target value because, if the downstream pressure is different, the differential pressure from the upstream pressure is also different, and the relationship between the control current of the flow regulating valve 4 and the upstream pressure is also different. is there.

  An example of the characteristic map is shown in FIG. In FIG. 7, the vertical axis represents the upstream pressure, and the horizontal axis represents the control current.

  In step S130, the upstream pressure detector 6D of the controller 6 calculates the upstream pressure corresponding to the control current detected in step S110 using the characteristic map selected in step S120, and estimates the upstream pressure. Value. For example, when the map of FIG. 7 is used, since the upstream pressure corresponding to the maximum value E1 of the control current is P1, the upstream pressure estimated value is P1. The upstream pressure estimated value estimated in this way has a narrower error range than the detected value of the pressure sensor as the amount of hydrogen in the hydrogen tank 2 decreases, so that the ineffective remaining amount can be reduced.

  When the upstream pressure estimated value becomes zero, the controller 6 stops the fuel cell system. It should be noted that a control current value at which the upstream pressure estimated value becomes zero, for example, the current value E2 in the case of FIG. 7, is obtained in advance, and if the current value detected in step S110 is lower than this, the fuel immediately The battery system may be stopped. Further, a warning may be issued to the driver when the upstream pressure estimated value becomes a predetermined value, for example, P1 or less.

  In step S110, the average value or rate of change of the control current while the downstream pressure is maintained at a predetermined target value may be read.

  When the downstream pressure is changed to a predetermined target value, the control current tends to have a maximum value overshooting at a timing when the downstream pressure starts to change, and then changes at a value lower than the maximum value. Accordingly, the average value of the control current approaches the value corresponding to the actual downstream pressure as the time during which the downstream pressure is maintained constant as in the case of traveling on the highway at a constant vehicle speed, and the hydrogen tank 2 The amount of hydrogen in the inside can be detected more accurately. If the detection accuracy of the remaining amount of hydrogen increases, the cruising distance with hydrogen remaining in the hydrogen tank 2 can be estimated more accurately.

  Since the interval between places where refueling stations are installed on the expressway is wider than ordinary roads, it is possible to continue to determine whether refueling is necessary immediately or whether it is possible to travel to the next refueling station Distance estimation accuracy is important. On the other hand, in the method of estimating the amount of hydrogen in the hydrogen tank 2 using the average value of the control current, the detection accuracy increases as the traveling time at a constant vehicle speed increases as in traveling on a highway. That is, the estimation using the average value of the control current is an estimation method suitable for traveling on a highway or the like.

  As described above, according to the first embodiment, the following effects can be obtained.

  (1) The fuel supply system 100 includes a controller 6 including detection means 6A-6D (first detection means) for detecting the upstream pressure based on the control current detected by the current sensor 8 and the detection value of the downstream pressure sensor 7. Therefore, it is possible to detect the remaining amount of hydrogen in the hydrogen tank 2 with higher accuracy than that detected by the pressure sensor.

  (2) The controller 6 detects the upstream pressure using the maximum value of the control current detected during the period until the downstream pressure reaches the predetermined target value. That is, since the upstream pressure is detected using the control current value at which the pressure of the hydrogen tank 2 becomes lower, it is possible to avoid continuing to operate the fuel cell system in a state where hydrogen cannot be supplied from the hydrogen tank 2. .

(Second Embodiment)
In the present embodiment, the upstream pressure is estimated in a state where the fuel cell stack 1 is generating power at a constant output. Since only the downstream pressure detection method is different from the first embodiment, the description will focus on the downstream pressure detection method.

  The control routine for estimating the upstream pressure executed by the controller 6 is the same as that in FIG. 6 except that the downstream pressure detection method in step S100 in FIG. 6 is different.

  FIG. 8 is a configuration diagram of a fuel supply system 100 for a fuel cell according to the second embodiment.

  As shown in FIG. 8, in this embodiment, the downstream pressure sensor 7 is not provided, and the power generation amount of the fuel cell stack 1 is input to the downstream pressure detector 6A.

  The current detection unit 6B calculates the average value of the control current of the flow rate adjustment valve 4 while the fuel cell stack 1 is generating power at a constant output, based on the signal of the input current sensor 8.

  The downstream pressure detection unit 6A has a map showing the relationship between the power generation amount of the fuel cell stack 1 and the downstream pressure, and calculates the downstream pressure from this map and the input power generation amount. An example of the map is shown in FIG. The vertical axis in FIG. 9 is the downstream pressure, and the horizontal axis is the power generation amount. The larger the power generation amount, the larger the target value of the downstream pressure.

  When the fuel cell stack 1 generates power at a constant output, that is, when the power generation amount is maintained constant, the downstream pressure is maintained at a target value set to realize the power generation amount. Therefore, the downstream pressure calculated by the downstream pressure detection unit 6A through the map search is a target value of the downstream pressure. Therefore, in a step corresponding to step S120 in FIG. 6, the characteristic map selection unit 6C selects a characteristic map according to the downstream pressure calculated here.

  As described above, when the power generation amount of the fuel cell stack 1 is kept constant, the downstream pressure can be detected without using the downstream pressure sensor 7. Except when traveling on a highway or the like, a vehicle is more frequently generated in a situation where it is accelerating or decelerating than a situation where it travels at a constant speed. Therefore, when the fuel cell system is used as a vehicle drive source, the frequency of occurrence is higher in the situation where the power generation amount changes than in the situation where the power generation amount is maintained constant. However, when used in a stationary state, for example, a household power supply, the frequency of occurrence is higher in a situation where the amount of power generation is maintained constant than in a situation where it changes, so the downstream pressure sensor 7 should be used. This embodiment that can estimate the upstream pressure without any problem is particularly effective.

  Note that both the detection of the downstream pressure by the downstream pressure sensor 7 and the estimation of the downstream pressure based on the power generation amount may be performed. Specifically, the detected value of the downstream pressure sensor 7 is compared with the estimated value of the downstream pressure based on the power generation amount, and the difference is periodically confirmed, for example, every time the vehicle is started or stopped, Remember. If the difference is equal to or greater than a predetermined threshold value, whether the detection value of the downstream pressure sensor 7 is abnormal or the output of the fuel cell stack 1 is reduced by comparing with the detection value and the estimated value at the previous confirmation. Carve out

  When the detected value of the downstream pressure sensor 7 is abnormal, the flow rate adjustment valve 4 is controlled using an estimated value based on the power generation amount of the fuel cell stack 1. When the output of the fuel cell stack 1 is reduced, the flow rate adjustment valve 4 is controlled using the detection value of the downstream pressure sensor 7.

  Thus, by having two values of the detection value by the downstream pressure sensor 7 and the estimated value based on the power generation amount, it is possible to continue the control using the other value even if one of the problems occurs. Therefore, the detection accuracy is improved as compared with the case where the control is performed with only one detection value.

  As described above, according to the present embodiment, in addition to the same effects as those of the first embodiment, the following effects are further obtained.

  (3) Since the downstream pressure detection unit 6A detects the downstream pressure based on the state of the fuel cell stack 1, specifically, the amount of power generation, it detects the downstream pressure without using the downstream pressure sensor 7. be able to. This is particularly useful when there are many opportunities to operate with a constant power generation amount, such as a stationary fuel cell stack.

(Third embodiment)
In the present embodiment, the upstream pressure is estimated in a state where a vehicle using a fuel cell system as a drive source is traveling at a constant vehicle speed. Since only the downstream pressure detection method is different from the first embodiment and the second embodiment, the description will focus on the downstream pressure detection method.

  The current detector 6B calculates an average value of the control current of the flow rate adjustment valve 4 while the vehicle is traveling at a constant vehicle speed.

  FIG. 10 is a configuration diagram of a fuel supply system 100 mounted on a vehicle using the fuel cell system as a drive source.

  As shown in FIG. 10, the fuel supply system 100 basically has the same configuration as that in FIG. 8, but the downstream pressure detection unit 6 </ b> A receives not the power generation amount of the fuel cell stack 1 but the signal of the vehicle speed sensor 30. Is different.

  When the vehicle is traveling at a constant speed, the power generation amount of the fuel cell stack 1 is also maintained at a target value set based on the traveling state and can be regarded as constant. When the power generation amount of the fuel cell stack 1 is constant, it can be considered that the downstream pressure is also constant. That is, when the vehicle speed is constant, it can be considered that the downstream pressure is also constant. Therefore, in the present embodiment, the upstream pressure is estimated as described below.

  The downstream pressure detection unit 6A has a map showing the relationship between the vehicle speed and the power generation amount of the fuel cell stack 1, and calculates the power generation amount of the fuel cell stack 1 from this map and the input vehicle speed. An example of the map is shown in FIG. The vertical axis in FIG. 11 represents the power generation amount of the fuel cell stack 1, and the horizontal axis represents the vehicle speed. The higher the vehicle speed, the larger the power generation amount.

  Then, after calculating the power generation amount of the fuel cell stack 1, the downstream pressure detection unit 6A calculates the downstream pressure using a map indicating the relationship between the power generation amount and the target value of the downstream pressure, as in the second embodiment. calculate. The calculation contents of the characteristic map selection unit 6C and the upstream pressure detection unit 6D are the same as those in the second embodiment.

  As described above, the upstream pressure can be estimated without detecting the downstream pressure sensor by the pressure sensor or detecting the power generation amount of the fuel cell stack 1.

  Note that both the estimation of the downstream pressure using the directly detected power generation amount and the estimation of the downstream pressure using the vehicle speed may be performed.

  As described above, according to the present embodiment, in addition to the same effects as those of the first embodiment and the second embodiment, the following effects can be further obtained.

  (4) Since the downstream pressure detection unit 6A detects the downstream pressure based on the state of the moving body, specifically, the vehicle speed, the downstream pressure can be detected without using a pressure sensor.

(Fourth embodiment)
As described above, the detected value of the pressure sensor has a certain error range regardless of the magnitude of the upstream pressure. On the other hand, the estimated value based on the control current of the flow regulating valve 4 has a characteristic that the error range is widened when the upstream pressure increases.

  Therefore, in the present embodiment, as means for detecting the upstream pressure, means for detecting based on the signal of the pressure sensor and means for estimating based on the control current of the flow rate adjusting valve 4 are provided, and hydrogen in the hydrogen tank 2 is provided. Which means is to be used is determined according to the remaining amount.

  FIG. 12 is a configuration diagram of the fuel supply system according to the present embodiment.

  The hydrogen tank 2 and the fuel cell stack 1 are connected by a hydrogen supply passage 3, and a flow rate adjusting valve 4 is interposed in the hydrogen supply passage 3. From the flow rate adjustment valve 4 of the hydrogen supply passage 3, the hydrogen tank 2 side is a high-pressure pipe 3A, and the downstream side is a low-pressure pipe 3B. An upstream pressure sensor 40 is disposed in the high-pressure pipe 3A. The flow rate adjusting valve 4 is provided with a current sensor 8 for detecting a control current. Further, for example, there is provided means for detecting state information such as the power generation amount of the fuel cell stack 1 or the speed of the vehicle on which the system is mounted and inputting it to the controller 6. That is, the upstream pressure sensor 40 is added to the configuration shown in FIG. 8 according to the second embodiment or FIG. 10 according to the third embodiment.

  The controller 6 includes a first detection unit 6E1, a second detection unit 6E2, a comparison unit 6F, and an upstream pressure detection unit 6G.

  The first detector 6E1 includes the downstream pressure detector 6A, the current detector 6B, the characteristic map selector 6C, and the upstream pressure detector 6D shown in FIGS. That is, the state information and the signal of the current sensor 8 are input to the first detection unit 6E1, the downstream pressure is estimated based on the input state quantity, a characteristic map is selected according to the downstream pressure, and the characteristic map And the control current detected by the current sensor 8 are used to estimate the upstream pressure.

  The second detector 6E2 detects the pressure of the high-pressure pipe 3A, that is, the pressure of the hydrogen tank 2 based on the signal from the upstream pressure sensor 40.

  The comparison unit 6F selects one of the estimated value of the upstream pressure estimated by the first detection unit 6E1 or the detection value of the upstream pressure sensor 40 detected by the second detection unit 6E2 as the upstream pressure detection means.

  The upstream pressure detection unit 6G determines the value estimated or detected by the detection means selected by the comparison unit 6F as the detected value of the upstream pressure.

  FIG. 13 is a flowchart showing a control routine of the controller 6.

  In step S200, the controller 6 estimates the upstream pressure. Specifically, the estimation of the upstream pressure based on the state information such as the power generation amount or the vehicle speed of the fuel cell stack 1 and the control current of the flow regulating valve 4 described in the second embodiment or the third embodiment is performed as a subroutine. Run as.

  In step S210, the controller 6 reads the detection value of the upstream pressure sensor 40.

  In step S220, the controller 6 compares the detection value read in step S210 with a preset threshold value. The threshold value is, for example, a detection value of the upstream pressure sensor 40 when the error range of the upstream pressure sensor 40 and the error range of the estimated value based on the control current of the flow rate adjusting valve 4 have the same width. Each error range is obtained by experiments.

  As already described, the error range of the detected value of the pressure sensor is constant regardless of the pressure, and the estimated value based on the control current increases as the remaining amount of hydrogen in the hydrogen tank 2 increases. That is, in the region where the detected value of the upstream pressure sensor 40 is larger than the threshold value, the upstream pressure sensor 40 is more accurate than the estimated value based on the control current. In the region where the detected value of the upstream pressure sensor 40 is equal to or less than the threshold value, the estimated value based on the control current is more accurate than the detected value of the upstream pressure sensor 40.

  Therefore, the controller 6 selects the first detection unit 6E1 in step S230 when the detection value of the upstream pressure sensor 40 is equal to or smaller than the threshold value, and selects the second detection unit 6E2 in step S240 when the detection value is larger than the threshold value. . In either case, the one with higher detection accuracy is selected.

  In step S240, the controller 6 sets the upstream pressure detected by the detection means selected in step S230 or S240 as the upstream pressure detection value.

  Thus, by selecting the higher detection accuracy from the two detection means according to the remaining amount of hydrogen in the hydrogen tank 2 and determining the upstream pressure detection value, the upstream pressure, that is, in the hydrogen tank 2 is determined. It is possible to accurately detect the amount of hydrogen in a wider range.

  Note that the threshold value is not limited to the value described above. The second detector 6E2 is selected in a predetermined region on the fully filled side of the hydrogen tank 2, and the first detector 6E1 is in a region where the remaining amount of hydrogen in the hydrogen tank 2 is small enough to determine whether or not to stop the system. If the condition that is selected is satisfied, the value may deviate from the above-described value.

  As described above, in the present embodiment, in addition to the same effects as those of the first to third embodiments, the following effects are further obtained.

  (5) The controller 6 sets the detection value of the second detection unit 6E2 when the detection value of the second detection unit 6E2 is equal to or greater than a predetermined threshold, and sets the detection value of the first detection unit 6E1 when the detection value is less than the threshold. Since each upstream pressure detection value is used, even if the upstream pressure changes within a wide range, it can be accurately detected.

  (6) The fuel gas supply apparatus according to claim 8, wherein the predetermined value is a pressure at which detection accuracy of the first pressure detection means and that of the second pressure detection means are equal.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

1 Fuel cell stack 2 Hydrogen tank (fuel tank)
3 Fuel supply piping (fuel gas passage)
4 Flow control valve (control valve)
5 On-off valve 6 Controller 7 Downstream pressure sensor (downstream pressure estimation means)
8 Current sensor (current detection means)
30 Vehicle speed sensor (moving body state detection means)
40 Upstream pressure sensor (second pressure detection means)
100 Fuel supply system

Claims (7)

In a fuel gas supply device that supplies fuel gas to a fuel cell stack that generates power using fuel gas and oxidant gas,
A fuel tank for storing fuel gas;
A fuel gas passage connecting the fuel tank and the fuel cell stack;
A control valve provided in the fuel gas passage for controlling the supply amount of the fuel gas;
Downstream pressure estimating means for estimating the pressure of the fuel gas downstream of the control valve;
Current detecting means for detecting a control current of the control valve;
A controller having first pressure detection means for detecting the pressure of the fuel gas upstream of the control valve based on the control current detected by the current detection means and the downstream pressure estimated by the downstream pressure estimation means. When,
A fuel gas supply device comprising:   The first pressure detecting means is upstream of the control valve using the maximum value of the control current detected during the period until the pressure of the fuel gas downstream of the control valve reaches a predetermined target value. The fuel gas supply apparatus according to claim 1, wherein the pressure of the fuel gas is detected.   3. The fuel gas supply device according to claim 1, wherein the downstream pressure estimation means is a pressure sensor provided downstream of the control valve in the fuel gas passage. Comprising a state detecting means for detecting the state of the fuel cell stack;
2. The fuel gas supply device according to claim 1, wherein the downstream pressure estimation unit estimates a pressure of the fuel gas downstream of the control valve based on a state of the fuel cell stack. A moving body state detecting means for detecting a state of a moving body that travels using the electric power generated by the fuel cell stack;
The fuel gas supply device according to claim 1, wherein the downstream pressure estimation unit estimates the pressure of the fuel gas downstream of the control valve based on the state of the moving body. The controller includes a pressure sensor that detects a pressure of the fuel gas upstream of the control valve as a second pressure detection unit,
When the detection value of the second pressure detection means is greater than or equal to a predetermined value, the detection value of the second pressure detection means is the pressure of the fuel gas upstream of the control valve,
2. The fuel gas according to claim 1, wherein when the detection value of the second pressure detection unit is less than the predetermined value, the detection value of the first pressure detection unit is used as the pressure of the fuel gas upstream of the control valve. Feeding device.   The fuel gas supply apparatus according to claim 6, wherein the predetermined value is a pressure at which detection accuracy of the first pressure detection means and the second pressure detection means is equal.

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