Fuel cell vehicle

Abstract

To provide a fuel cell vehicle having improved estimation accuracy of a temperature inside a tank filled with hydrogen.SOLUTION: A fuel cell vehicle 1 includes: a tank 2 filled with hydrogen; a control part 3 for calculating a tank temperature of the tank 2; a temperature sensor 4 arranged inside the tank 2; and a temperature sensor 5 arranged outside the tank 2. The control part 3 estimates a temperature inside the tank 2 on the basis of a value T1 of the temperature sensor 4, a value T2 of the temperature sensor 5, and a consumption amount ΔH of hydrogen inside the tank 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to fuel cell vehicles. [Background technology]

[0002] In the hydrogen tank included in the fuel cell mounted on a fuel cell vehicle, the temperature inside the tank is generally measured to monitor the temperature drop during power generation by the fuel cell and the temperature rise during charging. Conventionally, as described in Patent Document 1, for example, one temperature sensor is installed inside one tank, and the information detected by this temperature sensor is used to calculate a temperature (tank temperature) that reflects the temperature of the hydrogen gas filled in the tank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-149533 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional fuel cell vehicles, the tank temperature is calculated based on the detection information from a single temperature sensor installed inside one tank, so there are cases where the reliability of the temperature sensor's detection information decreases, for example, when some abnormality occurs in the temperature sensor.

[0005] An object of the present disclosure is to provide a fuel cell vehicle that can improve the accuracy of estimating the temperature inside a tank filled with hydrogen. [Means for solving the problem]

[0006] A fuel cell vehicle according to one aspect of an embodiment of the present invention comprises a tank filled with hydrogen, a control unit that calculates the tank temperature of the tank, a first temperature sensor arranged inside the tank, and a second temperature sensor arranged outside the tank, and the control unit estimates the temperature inside the tank based on the value of the first temperature sensor, the value of the second temperature sensor, and the amount of hydrogen consumed in the tank. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a fuel cell vehicle that can improve the accuracy of estimating the temperature inside a tank filled with hydrogen. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a fuel cell vehicle according to a first embodiment; [Figure 2] FIG. 10 is a diagram illustrating a tank temperature estimation method in the first embodiment. [Figure 3] FIG. 10 is a diagram showing a schematic configuration of a fuel cell vehicle according to a second embodiment; [Figure 4] FIG. 10 is a diagram illustrating a tank temperature estimation method in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0010] [First embodiment] 1 is a diagram showing a schematic configuration of a fuel cell vehicle 1 according to a first embodiment. The fuel cell vehicle 1 is a vehicle equipped with a fuel cell system that uses this fuel cell system to supply power to a drive motor, which is the vehicle drive source.

[0011] As shown in FIG. 1, a fuel cell vehicle 1 includes a tank 2, a control unit 3, a temperature sensor 4 (first temperature sensor), and a temperature sensor 5 (second temperature sensor).

[0012] Tank 2 is one element of the fuel cell system. The fuel cell system includes a fuel cell stack. The fuel cell stack outputs electricity generated in the process of converting hydrogen and oxygen into water to the motor that drives the vehicle. Tank 2 is filled with hydrogen to be supplied to the fuel cell stack.

[0013] The control unit 3 controls the operation of the fuel cell system. In particular, in this embodiment, the control unit 3 calculates a tank temperature corresponding to the temperature of the hydrogen gas stored inside the tank 2. Furthermore, based on the calculated tank temperature, the control unit 3 can control the cooling or heating of the tank 2 so that the hydrogen temperature does not rise or fall outside the operating temperature range of the tank 2.

[0014] The temperature sensor 4 is disposed inside the tank 2 and detects temperature information corresponding to the temperature of the hydrogen stored in the tank 2 .

[0015] The temperature sensor 5 is disposed outside the tank 2. In the first embodiment, the temperature sensor 5 is disposed near the tank 2 and detects temperature information corresponding to the temperature near the tank 2.

[0016] The control unit 3 calculates the temperature inside the tank T1 based on temperature information detected by the temperature sensor 4, and calculates the temperature near the tank T2 based on temperature information detected by the temperature sensor 5. In the first embodiment, the control unit 3 estimates the temperature inside the tank 2 (estimated tank temperature Te) based on the value of the temperature sensor 4 (i.e., the temperature inside the tank T1), the value of the temperature sensor 5 (i.e., the temperature near the tank T2), and the amount of hydrogen consumed in the tank 2 ΔH.

[0017] Figure 2 is a diagram illustrating the tank temperature estimation method in the first embodiment. Figure 2(A) shows an example of the time progression of the consumption amount ΔH of hydrogen stored in the tank 2. Figure 2(B) shows an example of the time progression of the estimated temperature Te of the hydrogen tank 2 corresponding to the time progression of the hydrogen consumption amount ΔH illustrated in Figure 2(A). Here, the hydrogen consumption amount ΔH represents, for example, the hydrogen consumption rate, and is expressed in units of, for example, (L / second).

[0018] As shown in Figure 1, if the temperature T2 around the tank can be measured using temperature sensor 5, the control unit 3 can estimate the temperature Te inside the tank 2 from the data on fluctuations in hydrogen consumption ΔH up to now. For example, if the ambient temperature T2 is 25°C and a long enough time has passed since the fuel cell system started operating so that the temperature T1 inside the tank 2 is roughly the same as the outside air temperature T2, the control unit 3 can estimate the temperature Te inside the tank 2 from the hydrogen consumption ΔH and consumption time using the outside air temperature T2. However, because the estimation formula differs depending on the structure and arrangement of the tank 2, data must be stored for each vehicle.

[0019] For example, by using the temperature T2 around the tank 2 when hydrogen consumption in the tank 2 begins and the hydrogen consumption rate ΔH shown in FIG. 2A, the control unit 3 can estimate the tank temperature Te as shown in FIG. 2B. In the example of FIG. 2, a constant amount of hydrogen is consumed from time t1 to time t2 as shown in FIG. 2A. In this case, the estimated tank temperature Te decreases in proportion to the hydrogen consumption rate ΔH from time t1 to time t2 as shown in FIG. 2B. The slope coefficient of the time transition of the estimated tank temperature Te at this time differs from vehicle to vehicle.

[0020] In addition, the control unit 3 can always ensure the reliability of the temperature sensor 4 by checking whether the value of the temperature sensor 4 that actually measures the tank temperature T1 is far from such an estimated value Te.

[0021] In the first embodiment, the control unit 3 can estimate the tank temperature, for example, in the following procedure. (1) Calculate the tank temperature T1 based on the information detected by the temperature sensor 4. (2) Calculate the temperature T2 near the tank based on the information detected by the temperature sensor 5. (3) Obtain information on the hydrogen consumption rate ΔH of Tank 2 (4) Calculate the estimated tank temperature Te from the temperature near the tank T2 and the hydrogen consumption rate ΔH. (5) The estimated tank temperature Te is compared with the tank internal temperature T1 to determine whether the temperature sensor 4 is abnormal.

[0022] In the abnormality determination in (5) above, for example, when there is a difference between the estimated tank temperature Te and the internal tank temperature T1 that is equal to or greater than a predetermined threshold, it can be determined that some abnormality has occurred in the temperature sensor 4. In this case, the control unit 3 can notify the driver or a mechanic of the occurrence of the sensor abnormality by, for example, turning on a warning light in the driver's seat of the vehicle.

[0023] On the other hand, if the deviation between the estimated tank temperature Te and the internal tank temperature T1 is less than a predetermined threshold, it can be determined that the temperature sensor 4 is operating normally. In this case, the control unit 3 can use the estimated tank temperature Te or the internal tank temperature T1 to control the cooling or heating of the tank 2 so that the hydrogen temperature does not rise or fall outside the operating temperature range of the tank 2.

[0024] Thus, the fuel cell vehicle 1 according to the first embodiment includes a tank 2 that is filled with hydrogen, a control unit 3 that calculates the tank temperature of the tank 2, a temperature sensor 4 that is disposed inside the tank 2, and a temperature sensor 5 that is disposed outside the tank 2. The control unit 3 estimates the temperature inside the tank 2 based on a value T1 from the temperature sensor 4, a value T2 from the temperature sensor 5, and the amount of hydrogen consumed in the tank 2 ΔH.

[0025] In conventional fuel cell vehicles, it has been difficult to increase the size of hydrogen tanks, so multiple tanks have been installed to ensure sufficient hydrogen capacity. In this configuration, even if one temperature sensor is installed in one tank, multiple temperature sensors are installed in the system as a whole, so even if some abnormality occurs in one of the temperature sensors, the impact on the estimation of tank temperature can be reduced by using the measurement values of the other sensors, ensuring the reliability of the temperature sensors.

[0026] On the other hand, in recent years, it has become possible to increase the size of hydrogen tanks, and a fuel-cell vehicle could be configured with only one hydrogen tank. In this configuration, if one temperature sensor is installed per tank, the entire system would only have one sensor. Therefore, if any abnormality occurs in this single temperature sensor, accurate temperature measurement may not be possible, which could lead to problems with the reliability of the temperature sensor. With only one temperature sensor for measuring the temperature of a hydrogen tank, there is a concern that the measured value may deviate from the actual temperature in the event of a sensor failure. Therefore, to safely use a hydrogen tank within its operating temperature range, it is necessary to improve the reliability of the temperature sensor. To solve this problem, a method of installing multiple temperature sensors within a single tank is considered. However, unlike conventional hydrogen tanks, this would require the manufacture of a special tank with a structure that allows for the installation of multiple temperature sensors within a single tank.

[0027] Incidentally, a typical fuel cell vehicle has traditionally been equipped with a temperature sensor for measuring the outside air temperature. If this temperature sensor can directly measure the temperature around the tank, the temperature inside the tank can be estimated from the temperature sensor and the amount of hydrogen consumed. In the first embodiment, the temperature sensor 5 shown in Figure 1 corresponds to such a temperature sensor.

[0028] Therefore, in the first embodiment, as configured above, the control unit 3 can estimate the temperature inside the tank 2 by calculating the estimated tank temperature Te, which is estimated based on the near-sensor temperature T2 measured by the temperature sensor 5 and the hydrogen consumption rate ΔH in the tank 2. Furthermore, by comparing the calculated estimated tank temperature Te with the sensor-internal temperature T1 measured by the temperature sensor 4, it is possible to determine whether an abnormality has occurred in the temperature sensor 4 or the temperature sensor 5. This eliminates the need to manufacture a special tank structured to accommodate multiple temperature sensors within a single tank. Even with an existing configuration in which a single temperature sensor is installed per tank, the reliability of the temperature sensor can be improved at low cost. As a result, the fuel cell vehicle 1 of the first embodiment can improve the accuracy of estimating the temperature inside the tank 2 when it is filled with hydrogen. Furthermore, improving the accuracy of estimating the temperature inside the tank 2 makes it possible to accurately control the tank temperature based on the estimated temperature so that the tank temperature falls within the operating temperature range of the tank 2, thereby reducing the occurrence of problems with the tank 2, such as damage to the tank 2.

[0029] Furthermore, the configuration of this first embodiment can achieve particularly remarkable effects when the fuel cell vehicle is equipped with only one large hydrogen tank, since the entire fuel cell system installed in the vehicle is equipped with only one temperature sensor.

[0030] Furthermore, unlike conventional metal tanks, the tank 2 provided in the fuel cell vehicle 1 of the first embodiment is preferably a tank with a structure in which the inside is made of resin and the outside is made of carbon. This allows for a reduction in the weight of the fuel cell system and the vehicle weight. In this case, the tank 2 is required to have higher thermal reliability than a metal tank, and this reliability can be ensured by using the sensor internal temperature T1 and the tank estimated temperature Te in combination as in the first embodiment.

[0031] [Second embodiment] Fig. 3 is a diagram showing a schematic configuration of a fuel cell vehicle 1A according to the second embodiment. As shown in Fig. 3, the fuel cell vehicle 1A according to the second embodiment includes a temperature sensor 6 (second temperature sensor) instead of the temperature sensor 5 according to the first embodiment.

[0032] The temperature sensor 6 is disposed outside the tank 2. The temperature sensor 6 is installed at a position inside the vehicle that is farther from the tank 2 than the temperature sensor 5. The temperature sensor 6 detects temperature information corresponding to the outside air temperature.

[0033] The control unit 3A calculates the outside air temperature T3 inside the vehicle based on temperature information detected by the temperature sensor 6. Then, the control unit 3A estimates the estimated temperature T2e around the tank based on the calculated outside air temperature T3 and various information such as the installation position of the temperature sensor 6 and the vehicle running conditions. Furthermore, the control unit 3A calculates the inside-tank temperature T1 based on the temperature information detected by the temperature sensor 4, as in the first embodiment.

[0034] In the second embodiment, the control unit 3A estimates the temperature inside the tank 2 (estimated tank temperature TeA) based on the value of the temperature sensor 4 (i.e., the tank temperature T1), the value of the temperature sensor 6 (i.e., the estimated tank ambient temperature T2e), and the hydrogen consumption amount ΔH in the tank 2.

[0035] Figure 4 is a diagram illustrating a tank temperature estimation method in the second embodiment. Figure 4(A) shows an example of the time progression of an estimated temperature T2e around the tank estimated based on information detected by the temperature sensor 6. Figure 4(B) shows an example of the time progression of the consumption rate ΔH of hydrogen stored in the tank 2. Figure 4(C) shows an example of the time progression of an estimated temperature TeA of the hydrogen tank 2 corresponding to the time progression of the hydrogen consumption rate ΔH illustrated in Figure 4(B). Figures 4(B) and (C) respectively illustrate time progressions similar to those in Figures 2(A) and (B) of the first embodiment.

[0036] As described above, the temperature sensor 5 in the first embodiment is an existing temperature sensor that has been conventionally installed in vehicles to measure the outside air temperature. However, although the temperature sensor 5 in the first embodiment is configured to be installed near the tank 2, in reality, the position where the existing temperature sensor measures the outside air temperature is near drivetrain components such as the motor, and the existing temperature sensor is often not installed near the tank 2. In this case, if it is desired to know the temperature around the tank 2, it is possible to consider adding a new temperature sensor in addition to the existing temperature sensor. However, this would require increasing the number of temperature sensors installed in the vehicle.

[0037] On the other hand, once the vehicle shape and the location of tank 2 are determined, the ambient temperature of tank 2 can be estimated using measurements from an existing temperature sensor, taking into account the effects of wind tunnel travel. For example, if the ambient temperature of tank 2 is estimated based on information such as the outside air temperature and vehicle speed, and the internal tank temperature Te is then estimated, there is no need to add a new temperature sensor around the tank. Estimation is difficult using a general formula, and depends on the location of the temperature sensor and tank, as well as the wind conditions during travel. Therefore, it is convenient to estimate the temperature using, for example, a vehicle speed-temperature map. Alternatively, coefficients from actual measurement data can be used, or the ambient temperature of the tank can be estimated based on vehicle speed. Once the ambient temperature of the tank can be estimated, the hydrogen consumption rate can be estimated relatively easily using a physical formula (Boyle's law). However, because the heat dissipation rate changes depending on the piping and tank shapes, it is also a good idea to use a map to calculate this.

[0038] In the second embodiment, the temperature sensor 6 for measuring the outside air temperature is not installed near the tank 2, as in the above-described configuration example, but is installed near drive system components such as the motor. In the second embodiment, the control unit 3A applies the same method as in the above-described configuration example to calculate the outside air temperature T3 at the installation position of the temperature sensor 6 based on temperature information detected by the temperature sensor 6. Then, based on the calculated outside air temperature T3 and various conditions such as the installation position of the temperature sensor 6, the vehicle traveling conditions, and the tank structure, it calculates an estimated tank-surrounding temperature T2e as shown in FIG. 4(A) as an example.

[0039] The control unit 3A can correct and calculate the estimated tank temperature TeA as shown in Figure 4(C) by taking into account the estimated tank ambient temperature T2e as shown in Figure 4(A) based on the hydrogen consumption rate ΔH as shown in Figure 4(B).

[0040] In the second embodiment, the control unit 3A can estimate the tank temperature, for example, in the following procedure. (1) Calculate the tank temperature T1 based on the information detected by the temperature sensor 4. (2) The outside air temperature T3 inside the vehicle is calculated based on the information detected by the temperature sensor 6. (3) Calculate the estimated temperature around the tank T2e based on the outside air temperature T3 inside the vehicle and various conditions. (4) Obtain information on the hydrogen consumption rate ΔH of Tank 2 (5) Calculate the estimated tank temperature TeA from the estimated tank surrounding temperature T2e and the hydrogen consumption rate ΔH. (6) The estimated tank temperature TeA is compared with the tank internal temperature T1 to determine whether the temperature sensor 4 is abnormal (the specific process for determining abnormality is the same as in the first embodiment).

[0041] The fuel cell vehicle 1A of the second embodiment is configured to use both the sensor internal temperature T1 and the estimated tank temperature TeA in the same manner as the first embodiment, and therefore can achieve the same effects as the first embodiment.

[0042] The control unit 3 of the first embodiment and the control unit 3A of the second embodiment can be physically configured as a computer system including a CPU (Central Processing Unit), a main storage device such as RAM (Random Access Memory) and ROM (Read Only Memory), an input device, an output device, a communication module, an auxiliary storage device such as a hard disk, etc. The functions of the above-mentioned control units 3 and 3A are realized by loading predetermined computer software onto hardware such as the CPU and RAM, thereby operating the communication module, input device, and output device under the control of the CPU and reading and writing data from and to the RAM and auxiliary storage device. Furthermore, the control units 3 and 3A may be implemented as part of an ECU mounted on a vehicle.

[0043] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0044] 1. 1A Fuel Cell Vehicle 2 Tanks 3, 3A control section 4 Temperature sensor (first temperature sensor) 5, 6 Temperature sensor (second temperature sensor) T1 Tank temperature T2 Temperature near the tank T2e Estimated temperature around the tank Te, TeA Tank estimated temperature ΔH Hydrogen consumption

Claims

[Claim 1] a tank filled with hydrogen; a control unit that calculates the tank temperature of the tank; a first temperature sensor disposed within the tank; a second temperature sensor disposed outside the tank; Equipped with The control unit a value of the first temperature sensor; the value of the second temperature sensor and the amount of hydrogen consumed in the tank; and estimating the temperature in the tank based on the Fuel cell vehicle.

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