Hydrogen release control system and hydrogen release control method for hydrogen engine vehicle

Abstract

The present invention relates to a hydrogen release control system and a hydrogen release control method for a hydrogen-powered vehicle. The hydrogen release control system controls the hydrogen release flow rate in a hydrogen-powered vehicle that releases hydrogen from a hydrogen tank having a resin lining laminated on the inner wall to a hydrogen engine according to an accelerator operation amount. The hydrogen release control system includes a control device. When the accelerator is turned on, the control device estimates the reaching temperature in the hydrogen tank after a prescribed time when the accelerator operation amount is maximum based on the time-temperature gradient in the hydrogen tank and the temperature in the hydrogen tank, and when the reaching temperature is below a first prescribed temperature, the control device performs a release limit control that limits the maximum value of the hydrogen release flow rate from the hydrogen tank to a prescribed flow rate.

Description

Technical Field

[0001] The invention relates to a hydrogen release control system and a hydrogen release control method for a hydrogen engine vehicle. Background Art

[0002] Japanese Patent Application Laid-Open No. 2003-013765 describes a hydrogen engine vehicle that uses hydrogen as fuel. In the hydrogen engine vehicle, hydrogen stored in a hydrogen tank is supplied to a combustion chamber of a hydrogen engine, and the hydrogen engine is operated. Summary of the invention

[0003] In a hydrogen engine vehicle, hydrogen is released from a hydrogen tank formed by laminating a resin lining on the inner wall to a hydrogen engine according to the amount of operation of an accelerator such as an accelerator pedal. In this case, compared with a fuel cell vehicle that uses the hydrogen released from the hydrogen tank as fuel for power generation, in a hydrogen engine vehicle, the release flow rate of hydrogen released from the hydrogen tank according to the amount of operation of the accelerator is large. In addition, the higher the residual pressure in the hydrogen tank, the greater the temporal temperature gradient in the hydrogen tank, and therefore the more the temperature in the hydrogen tank drops when hydrogen is released.

[0004] Therefore, according to the current temperature and internal residual pressure in the hydrogen tank, if the state of the maximum accelerator operation amount continues or the frequency of this state increases, it is possible that the temperature drop caused by the hydrogen release in the hydrogen tank will immediately reach the allowable lower limit temperature of the resin lining of the hydrogen tank. In this case, the hydrogen release is stopped in order to protect the resin lining, so the vehicle stops running. Therefore, the vehicle cannot continue to run until the temperature in the tank rises.

[0005] The present invention provides a hydrogen release control system and a hydrogen release control method for a hydrogen engine vehicle, which can protect a resin lining of a hydrogen tank while realizing continued driving of the vehicle.

[0006] A hydrogen release control system for a hydrogen-powered vehicle according to one embodiment of the present invention is a system for controlling the hydrogen release flow rate in a hydrogen-powered vehicle that releases hydrogen from a hydrogen tank having a resin lining laminated on the inner wall to a hydrogen engine according to an accelerator operation amount, wherein the system is provided with a control device. The control device is configured to estimate the reaching temperature in the hydrogen tank after a prescribed time has passed when the accelerator operation amount is maximum based on the time-temperature gradient in the hydrogen tank during hydrogen release determined by the residual pressure in the hydrogen tank and the temperature in the hydrogen tank when the accelerator operation amount is turned on, and when the reaching temperature is below a first prescribed temperature, perform release limiting control to limit the maximum value of the hydrogen release flow rate from the hydrogen tank to a prescribed flow rate.

[0007] According to the hydrogen emission control system of the hydrogen-powered vehicle of the present invention, even if the current temperature in the hydrogen tank is low or the internal residual pressure is high, and the state of the maximum accelerator operation continues or the frequency of this state increases, the vehicle can continue to travel while preventing the temperature in the hydrogen tank from immediately reaching below the allowable lower limit temperature. Thus, the resin lining of the hydrogen tank can be protected.

[0008] In addition, in the hydrogen release control system of the hydrogen-powered vehicle of the above-mentioned scheme, the control device can be configured to release the restriction on the hydrogen release flow rate when the temperature in the hydrogen tank becomes above a second specified temperature that is higher than the temperature in the hydrogen tank at the start of the release restriction control after the release restriction control is performed.

[0009] According to the above structure, after the limiting control of hydrogen release is performed, when the temperature in the hydrogen tank rises to above the second specified temperature due to an increase in the number of accelerator-off states or a higher frequency of small accelerator operation, normal operation can be restored, thereby shortening the time during which the user feels uncomfortable with the driving performance.

[0010] A hydrogen release control method for a hydrogen-powered vehicle according to another embodiment of the present invention is a control method for controlling the hydrogen release flow rate in a hydrogen-powered vehicle that releases hydrogen from a hydrogen tank having a resin lining laminated on the inner wall to a hydrogen engine according to an accelerator operation amount, wherein the method comprises the following steps: when the accelerator is turned on, estimating the reaching temperature in the hydrogen tank after a prescribed time has passed when the accelerator operation amount is maximum based on a time-temperature gradient in the hydrogen tank during hydrogen release determined by the residual pressure in the hydrogen tank and the temperature in the hydrogen tank; and when the reaching temperature is below a first prescribed temperature, performing a release limiting control to limit the maximum value of the hydrogen release flow rate from the hydrogen tank to a prescribed flow rate.

[0011] The hydrogen release control method of the above aspect may further include the step of: releasing the restriction on the hydrogen release flow rate when the temperature inside the hydrogen tank becomes equal to or higher than a second predetermined temperature higher than the temperature inside the hydrogen tank at the start of the release restriction control after the release restriction control is performed.

[0012] According to the hydrogen emission control system of the hydrogen-powered vehicle of the present invention, it is possible to protect the resin lining of the hydrogen tank while continuing to travel the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

[0014] Figure 1It is a schematic configuration diagram of a hydrogen release control system for a hydrogen engine vehicle according to an embodiment of the present invention.

[0015] Figure 2 This is a diagram showing an example of the permissible range of the pressure and temperature in the hydrogen tank.

[0016] Figure 3 This is a diagram showing the relationship between the residual pressure P1 in the hydrogen tank at the current time and the time temperature gradient A in the hydrogen tank when the accelerator operation amount is maximized.

[0017] Figure 4 The diagram shows a method of estimating the tank internal temperature Tx that reaches a predetermined time after time t1 when the accelerator operation amount is assumed to be maintained at a maximum, in the relationship between the tank internal temperature and time.

[0018] Figure 5 This is a flowchart showing a hydrogen release restriction control method in an embodiment.

[0019] Figure 6 This is a schematic diagram showing an example of changes in the temperature inside the tank during driving of the vehicle and during hydrogen filling. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of a hydrogen emission control system for a hydrogen-powered vehicle according to the present invention will be described. Figure 1 The schematic structure of the hydrogen release control system 20 of the embodiment is shown. The hydrogen release control system 20 is mounted on a hydrogen engine vehicle that runs with the hydrogen engine 10 as a driving source. The hydrogen engine vehicle includes the hydrogen engine 10, a hydrogen tank 12, an accelerator 16 such as an accelerator pedal operated by the driver to instruct acceleration and deceleration, and a control device 40 that controls the driving of the hydrogen engine 10 according to the operation of the accelerator 16. The hydrogen engine vehicle releases hydrogen from the hydrogen tank 12 through the hydrogen pipe 17 and the injector 18 to the combustion chamber of the hydrogen engine 10 according to the operation amount of the accelerator 16 (hereinafter referred to as "accelerator operation amount").

[0021] The hydrogen engine 10 causes a mixture of hydrogen and air to burn in a combustion chamber by ignition of a spark plug, etc. The hydrogen engine 10 rotates a crankshaft by reciprocating a piston using the combustion energy. Therefore, hydrogen is injected from a hydrogen tank 12 through a hydrogen pipe 17 and a delivery pipe (not shown) to the combustion chamber of the hydrogen engine 10 from an injector 18 connected to the combustion chamber.

[0022] The hydrogen tank 12 stores hydrogen in a high-pressure state. The hydrogen tank 12 is a hollow container, and a resin lining 13 is laminated on the inner wall. The resin lining 13 is formed of a resin having gas barrier properties with respect to hydrogen, such as a polyamide resin. A reinforcement layer 14 is provided on the outer wall of the hydrogen tank 12. The reinforcement layer 14 is provided to increase the strength of the hydrogen tank, and is formed, for example, of a carbon fiber reinforced resin (CFRP). A metal joint 15 is provided at one end of the hydrogen tank 12, and a valve 19 is provided at the joint 15. The joint 15 is provided with a hydrogen discharge path connected to the hydrogen pipe 17 and a hydrogen filling path used to fill hydrogen into the hydrogen tank at a hydrogen station.

[0023] A temperature sensor 21 and a pressure sensor 22 are connected to the joint 15 of the hydrogen tank 12. The temperature sensor 21 detects the internal temperature of the hydrogen tank 12, and the pressure sensor 22 detects the residual pressure in the hydrogen tank 12. Detection signals of the temperature sensor 21 and the pressure sensor 22 are sent to the control device 40.

[0024] The accelerator 16 is provided in front of the driver's seat, and the accelerator operation amount is detected by the accelerator sensor 24. The detection signal of the accelerator sensor 24 is sent to the control device 40. The accelerator sensor 24 also detects the case where the accelerator 16 is stepped on by the driver (i.e., the accelerator 16 is on) because the accelerator operation amount is greater than a prescribed amount, and the case where the accelerator 16 is not stepped on (i.e., the accelerator 16 is off) because the accelerator operation amount is less than a prescribed amount.

[0025] The hydrogen release control system 20 includes the injector 18, a temperature sensor 21, a pressure sensor 22, an accelerator sensor 24, and a control device 40. The hydrogen release control system 20 controls the hydrogen release flow rate in the hydrogen-powered vehicle.

[0026] The control device 40 is configured to include a microcomputer having a CPU or other computing unit and a memory or other storage unit. The control device 40 controls the hydrogen discharge flow rate ejected from the injector 18 to the hydrogen engine 10 according to the accelerator operation amount when the vehicle is driven. If the accelerator operation amount is large, the hydrogen discharge flow rate is increased, and if the accelerator operation amount is small, the hydrogen discharge flow rate is reduced. When the accelerator 16 is closed, the hydrogen discharge from the injector 18 to the hydrogen engine 10 is stopped.

[0027] The internal temperature of the hydrogen tank 12 decreases due to the reduction of the internal pressure of the tank by the release of hydrogen. On the contrary, if the hydrogen tank 12 is filled with hydrogen by hydrogen filling at a hydrogen station, the internal pressure of the tank increases and the temperature rises. In addition, if the accelerator 16 is turned off or the operation amount of the accelerator 16 is small, the internal temperature of the tank gradually rises in a manner close to the ambient temperature according to the ambient temperature around the hydrogen tank 12.

[0028] Figure 2An example of the permissible range of the tank internal temperature and tank internal pressure is shown. Figure 2 In the figure, the allowable range is shown by the oblique grid portion. The temperature inside the tank needs to be maintained at an allowable lower limit temperature set in the range of, for example, -80°C to -50°C, that is, above the first prescribed temperature T1 and below the third prescribed temperature T3. If the temperature inside the tank is too low, it may not be possible to ensure the required mechanical properties of the resin lining 13. Therefore, the control device 40 controls the temperature inside the tank to be maintained above the first prescribed temperature T1. Specifically, if the temperature inside the tank reaches below the first prescribed temperature T1, the release of hydrogen from the injector 18 is stopped. Before the temperature inside the tank is about to reach the first prescribed temperature T1 or when it reaches the first prescribed temperature T1, the control device 40 generates a warning display or a warning sound, i.e., reports to notify the driver that the temperature inside the tank is approaching the first prescribed temperature T1 or has reached the first prescribed temperature T1.

[0029] On the other hand, if the release of hydrogen from the injector 18 is stopped during the driving of the vehicle, the vehicle stops running, and thus the vehicle cannot continue running until the temperature in the tank rises. In order to eliminate such an undesirable situation, in the embodiment, when the accelerator 16 is turned on, the control device 40 estimates the reaching temperature in the hydrogen tank 12 after a prescribed time has passed when the accelerator operation amount is maximum, and when the reaching temperature is below the first prescribed temperature T1, a release limiting control is performed to limit the maximum value of the hydrogen release flow rate from the hydrogen tank 12 to a prescribed flow rate. In this way, the vehicle can continue running while protecting the resin lining 13 of the hydrogen tank 12.

[0030] The following describes the release restriction control of the hydrogen release control system in detail. As described above, the temperature inside the tank decreases due to the release of hydrogen. On the other hand, the degree of the temperature drop inside the tank due to the release of hydrogen varies depending on the residual pressure inside the hydrogen tank 12 (residual pressure inside the tank). Specifically, the greater the residual pressure inside the tank, the greater the time temperature gradient inside the hydrogen tank 12.

[0031] Figure 3 The figure shows the relationship between the residual pressure in the tank at the current time and the time temperature gradient A in the hydrogen tank 12 when the accelerator operation amount is maximized, that is, the temperature drop per unit time. Figure 3 As shown in FIG. 1 , the time-temperature gradient A when the accelerator operation amount is the largest increases in a linear proportional relationship with respect to the residual pressure in the tank. More specifically, when the temperature drop per unit time at the maximum discharge flow rate of hydrogen from the hydrogen tank 12 is set to K (constant), the current residual pressure in the tank is set to P1, and the pressure in the tank when the hydrogen tank 12 is full is set to P (constant), the time-temperature gradient A is calculated by

[0032] A=K×P1 / P…(1)

[0033] By using the time temperature gradient A, the tank internal temperature Ta at the current time t1 and the tank internal residual pressure P1, it is possible to estimate the tank internal temperature Tx at time t2 after a predetermined time assumed when the accelerator operation amount is maintained at the maximum from time t1.

[0034] Figure 4 The method of estimating the tank internal temperature Tx at time t2 after a predetermined time from time t1, assuming that the accelerator operation amount is maintained at a maximum, is shown in the relationship between the tank internal temperature and time. Figure 4 In FIG. 1 , the horizontal axis shows time, and the vertical axis shows the tank internal temperature. The relationship between the temperature drop from the tank internal temperature Ta at the current time t1 and time is represented by a solid line L1.

[0035] As described above, the time temperature gradient A of the tank temperature when the accelerator operation amount is the maximum is obtained by equation (1), so the temperature drop ΔT at time t2 after the specified time (t2-t1) is obtained as

[0036] ΔT=A×(t2-t1)=K×P1 / P×(t2-t1)...(2).

[0037] Therefore, if the tank internal temperature Ta and the tank internal residual pressure P1 at time t1 are known, the tank internal temperature Tx at time t2 can be calculated by

[0038] Tx=Ta-ΔT=Ta-K×P1 / P×(t2-t1)…(3)

[0039] To presume.

[0040] In the embodiment, using this relationship, when the accelerator is turned on, the control device 40 estimates the tank temperature Tx after the prescribed time when the accelerator operation amount is maximum based on the tank temperature Ta and the time temperature gradient A of the tank temperature when hydrogen is released determined by the residual pressure P1 in the tank. And, when it is estimated that the tank temperature Tx is below the allowable lower limit temperature, that is, the first prescribed temperature T1, the control device 40 performs a release restriction control that limits the maximum value of the hydrogen release flow rate from the hydrogen tank 12 to the prescribed flow rate. Thus, even when the driver operates the accelerator and the operation amount becomes maximum or close to maximum, the hydrogen release flow rate from the hydrogen tank 12 is smaller than the maximum flow rate in the normal state when the release restriction control is not performed. Therefore, it is possible to suppress the temperature drop caused by the release of hydrogen in the hydrogen tank 12 from becoming sharp. Therefore, even if the current temperature in the hydrogen tank 12 is low or the internal residual pressure is large, the state of the maximum accelerator operation amount continues or the frequency of this state becomes high, it is possible to achieve the continued driving of the vehicle while preventing the tank temperature from immediately reaching the allowable lower limit of the first prescribed temperature T1. Therefore, the resin liner 13 of the hydrogen tank 12 can be protected while the vehicle continues to travel.

[0041] On the other hand, Figure 4 As shown by the single-dot chain line L2, when the time-temperature gradient A determined by the residual pressure P1 in the tank becomes gentle due to the small residual pressure P1 in the tank, and the estimated reaching temperature Tx1 in the tank at time t2 exceeds the first prescribed temperature T1, and the release restriction control is not currently being performed, the control device 40 does not start the release restriction control.

[0042] It should be noted that if hydrogen is released from the hydrogen tank 12, the residual pressure in the tank actually decreases gradually with the passage of time. Therefore, if the specified time until the estimated temperature Tx in the tank is longer, the time-temperature gradient of the actual temperature in the tank may become smaller than the time-temperature gradient calculated based on the current residual pressure in the tank. In this regard, in the embodiment, it is assumed that the time-temperature gradient A is maintained during the specified time and the temperature Tx in the tank after the specified time is estimated. When the estimated temperature of the temperature Tx in the tank is below the first specified temperature T1, the release restriction control is performed. Therefore, it is possible to prevent the actual temperature in the tank from becoming below the first specified temperature T1 with sufficient margin.

[0043] Moreover, in the embodiment, when the temperature inside the tank becomes higher than the second predetermined temperature T2 which is higher than the temperature inside the tank Ta at the start of the release limiting control after the release limiting control is performed, the control device 40 releases the restriction on the hydrogen release flow rate. For example, when the accelerator is closed more frequently or the frequency of the accelerator operation amount is small after the release limiting control is performed, the tank temperature inside the hydrogen tank 12 sometimes gradually rises according to the ambient temperature around the hydrogen tank 12. When the restriction on the hydrogen release flow rate is released because the tank temperature becomes higher than the second predetermined temperature T2 as described above, when the temperature of the hydrogen tank 12 rises after the hydrogen release limiting control is performed, it is possible to return to normal operation, thereby shortening the time for the user to feel uncomfortable with the driving performance.

[0044] Figure 5 This is a flowchart showing a hydrogen release restriction control method in an embodiment. Figure 5 The processing of each step is performed by the control device 40. In step S10, it is determined whether the accelerator is turned on after the start of the hydrogen engine 10. If the determination of step S10 is an affirmative determination (yes), the process moves to step S12. When the determination of step S10 is a negative determination (no), the processing of step S10 is repeated.

[0045] In step S12, the temperature inside the tank is measured by the temperature sensor 21, and the residual pressure inside the tank is measured by the pressure sensor 22. In step S14, it is determined whether the hydrogen release flow rate is restricted and whether the current temperature Ta inside the tank is above the second specified temperature T2 for determining the release of the release restriction control. In the case where the determination in step S14 is affirmative (yes), the process proceeds to step S18, releases the release restriction control, and returns to normal operation. In this way, the time during which the restriction on hydrogen release is performed can be shortened, thereby shortening the time during which the user feels uncomfortable with the driving performance. After processing step S18, the process proceeds to step S16.

[0046] In the case where the determination of step S14 is a negative determination (No), in step S16, as a determination process of whether to execute the hydrogen release flow rate restriction, it is determined whether the temperature Tx (=Ta-ΔT) reached in the tank after a specified time when the accelerator operation amount is maintained at the maximum is below the first specified temperature T1. In the case where the determination of step S16 is an affirmative determination (Yes), the process moves to step S20, and the restriction control of the hydrogen release flow rate from the hydrogen tank 12 is executed. In this way, it is possible to prevent the temperature in the tank from immediately reaching below the first specified temperature T1, thereby ensuring the continued driving of the vehicle and protecting the resin lining 13. After the processing of step S20, the process moves to step S22, and it is determined whether the hydrogen engine 10 is stopped. In the case where the determination of step S22 is an affirmative determination (Yes), the execution of the release restriction control and the determination process are stopped.

[0047] On the other hand, if the determination in step S22 is a negative determination (No), the process returns to step S12, and the process of step S12 to step S22 is repeated until the determination in step S22 is a positive determination (Yes). In addition, if the determination in step S16 is a negative determination (No), the process returns to step S12 and the process is repeated.

[0048] Figure 6 An example of the change in the temperature in the tank when the vehicle is driving and when hydrogen is filled is shown. Figure 6 In the figure, the vehicle state is shown as the relationship between time and the temperature inside the tank. The vehicle state moves from point A0 at time t0 to points A1, A2...A9 in sequence. The first hydrogen filling is being carried out at point A0, and the temperature inside the tank gradually rises. From point A1, the vehicle starts to move, and as hydrogen is released from the hydrogen tank 12, the temperature inside the tank gradually decreases. From point A1 to point A2, in fact, the vehicle accelerates, decelerates, and stops, so the temperature inside the tank fluctuates, but as a whole, the state with a large accelerator operation amount occurs more often, and the temperature inside the tank gradually decreases from point A1 toward point A2 in a roughly linear manner. In the movement of the vehicle later than point A2, the tendency of the change in the temperature inside the tank between two points (for example, between point A3 and point A4, between point A4 and point A5, etc.) is also roughly shown as a straight line.

[0049] At point A2, the second hydrogen filling is being performed, and the tank temperature gradually rises to point A3. From point A3, the vehicle starts to travel again, but at this time, it is determined that the tank temperature Tx reached after the predetermined time when the accelerator operation amount is the maximum is less than the first predetermined temperature T1. Specifically, Figure 6 As shown by the dotted line α, when it is assumed that the accelerator operation amount is the maximum and the temperature inside the tank drops, it is estimated that the temperature Tx inside the tank reaches point B below the first prescribed temperature T1 after a prescribed time from point A3. Therefore, from point A3, the maximum value of the hydrogen release flow rate from the hydrogen tank 12 is limited to the prescribed flow rate. The temperature drop in the tank temperature becomes gentler from point A3 to point A4. On the other hand, after point A4, the temperature inside the tank gradually rises from point A4 due to the increased frequency of accelerator closing in the vehicle. Then, the release restriction control is released by reaching point A5 where the temperature inside the tank becomes the second prescribed temperature T2. Therefore, even if the temperature inside the tank drops again from point A6, the restriction on the amount of hydrogen released from the hydrogen tank 12 is still lifted. As a result, the state of high accelerator operation amount increases, and the temperature inside the tank drops sharply from point A6 to point A7.

[0050] From point A7 to point A8, the tank temperature rises due to the third hydrogen filling, and from point A8 to point A9, the tank temperature drops due to the increase in the number of high accelerator operation amounts. At point A9, the drop in tank temperature becomes moderate due to the execution of release restriction control.

[0051] from Figure 6 As a result, it is known that when the emission restriction control of the embodiment is executed, the tank temperature is unlikely to reach or fall below the first predetermined temperature T1 during multiple hydrogen fillings. Therefore, it is known that the resin liner of the hydrogen tank 12 can be protected while the vehicle continues to travel.

[0052] In the above, in order to estimate the temperature inside the tank after a predetermined time, as described using equations (1) and (2), the temperature drop ΔT of the temperature inside the tank when the accelerator operation amount is maximum is obtained by multiplying the time temperature gradient A inside the tank by the predetermined time (t2-t1). On the other hand, the embodiment is not limited to this, and the temperature drop amount after a predetermined time at the maximum discharge flow rate based on the time temperature gradient A inside the tank may be obtained in advance, and the temperature inside the tank after a predetermined time may be estimated using the current temperature inside the tank, the residual pressure inside the tank, and the above temperature drop amount.

Claims

1. A hydrogen release control system configured to control a hydrogen release flow rate in a hydrogen engine vehicle that releases hydrogen from a hydrogen tank having a resin lining laminated on an inner wall to a hydrogen engine in accordance with an accelerator operation amount, wherein the hydrogen release control system is characterized in that: Including control devices, in, The control device is composed of: When the accelerator is turned on, the temperature in the hydrogen tank that is reached after a predetermined time has passed when the accelerator operation amount is maximum is estimated based on the time-temperature gradient in the hydrogen tank when hydrogen is released, which is determined by the residual pressure in the hydrogen tank, and the temperature in the hydrogen tank. When the reaching temperature is equal to or lower than a first predetermined temperature, a release limiting control is performed to limit a maximum value of a hydrogen release flow rate from the hydrogen tank to a predetermined flow rate.

2. The hydrogen release control system according to claim 1, characterized in that: The control device is configured to release the restriction on the hydrogen release flow rate when the temperature inside the hydrogen tank becomes equal to or higher than a second predetermined temperature higher than the temperature inside the hydrogen tank at the start of the release restriction control after the release restriction control is performed.

3. A method for controlling hydrogen release flow rate in a hydrogen engine vehicle that releases hydrogen from a hydrogen tank having a resin lining laminated on an inner wall to a hydrogen engine according to an accelerator operation amount, the method comprising the following steps: When the accelerator is turned on, based on the time-temperature gradient in the hydrogen tank when hydrogen is released determined by the residual pressure in the hydrogen tank and the temperature in the hydrogen tank, the temperature in the hydrogen tank is estimated to reach after a predetermined time has passed when the accelerator operation amount is maximum; and When the reaching temperature is equal to or lower than a first predetermined temperature, a release limiting control is performed to limit a maximum value of a hydrogen release flow rate from the hydrogen tank to a predetermined flow rate.

4. The hydrogen release control method according to claim 3, characterized in that: The following steps are also included: When the temperature in the hydrogen tank becomes equal to or higher than a second predetermined temperature after the release limiting control is performed, which is higher than the temperature in the hydrogen tank at the start of the release limiting control, the restriction on the hydrogen release flow rate is released.

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