JP4033376B2 - Fuel supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel supply device that supplies fuel gas, and more particularly to a fuel supply device that includes means for detecting leakage of fuel gas.
[0002]
[Prior art]
Conventionally, a vehicle driven by a fuel gas such as hydrogen or compressed natural gas mainly has a tank for storing the fuel gas and a fuel supply pipe for supplying the fuel gas from the tank to a fuel cell, an engine, or the like. The fuel supply apparatus comprised is provided. Such a fuel supply apparatus is provided with an overflow prevention valve that shuts off the fuel supply pipe when gas leaks as a countermeasure against gas leakage. Specifically, this overflow prevention valve is provided with a shut-off mechanism that closes the fuel supply pipe when an excessive flow rate flows using the increase in the flow rate of the gas flowing through the fuel supply pipe as the gas leaks. It has a structure.
As another gas leakage countermeasure, there is a fuel supply device that includes a pressure sensor that detects the pressure of the fuel gas flowing through the fuel supply pipe, and a shutoff valve that shuts off the supply of the fuel gas based on the detected value of the pressure sensor. . Specifically, in this fuel supply device, when the pressure of the fuel gas flowing through the fuel supply pipe is constantly detected by a pressure sensor, and the amount of pressure drop calculated from this detected value is equal to or greater than a predetermined pressure drop amount, the shut-off valve It has a structure that can be closed.
[0003]
[Problems to be solved by the invention]
However, in the conventional structure with an overflow prevention valve, the set flow rate for closing the overflow prevention valve is set to the maximum consumption of a gas engine such as a fuel cell so that the overflow prevention valve does not operate during normal operation. Since it was set higher than this, it was difficult to detect a slight gas leak, and the shut-off mechanism sometimes did not operate.
In addition, in a structure with a pressure sensor that detects the pressure of the fuel gas flowing through the fuel supply pipe and a shutoff valve that shuts off the fuel gas supply based on the detected value of the pressure sensor, the shutoff valve operates during normal operation. Therefore, it was difficult to detect a slight gas leak because the set pressure drop for closing the shut-off valve was set higher than the pressure drop corresponding to the maximum consumption of fuel cells. It was.
In order to detect this slight gas leak, there is a method of providing a sensor at the place where gas leak is expected, but this method is sensitive to the temperature of the external air, etc. It was difficult to detect well.
[0004]
Therefore, an object of the present invention is to provide a fuel supply device that can accurately detect a slight gas leak.
[0005]
[Means for Solving the Problems]
The hydrogen supply device according to claim 1, which has been made to solve the above problem, includes a hydrogen tank filled with hydrogen, and supplies fuel from the hydrogen tank to the fuel cell via a hydrogen supply path. In the apparatus, a circulation path for returning hydrogen discharged from the fuel cell to the hydrogen supply path, a purge valve provided in the circulation path, and an amount of unused hydrogen discharged from the fuel cell a purge amount of hydrogen is purged by opening the depletion amount of hydrogen and the purge valve of the inner, pressure drop in the hydrogen supply path from the total amount of hydrogen corresponding to the sum of the consumed hydrogen amount by the power generation of the fuel cell Pressure drop amount calculating means for calculating the pressure drop amount detecting means for detecting the pressure drop amount in the hydrogen supply path, and when the detected pressure drop amount is larger than the calculated pressure drop amount by a predetermined value or more. A hydrogen leak judging means for judging that the hydrogen is leaking; a sensor installed in the circulation path for detecting pressure and temperature; and a sensor for detecting the opening time of the purge valve; The amount of hydrogen is calculated based on the opening time of the purge valve and the pressure and temperature, and the amount of depleted hydrogen is calculated based on the pressure and temperature.
[0006]
According to the first aspect of the present invention, the pressure drop amount calculation means calculates the amount of unused hydrogen discharged from the fuel cell and the total amount of hydrogen corresponding to the sum of the amount of hydrogen consumed by the fuel cell from the total hydrogen amount in the hydrogen supply path. The amount of pressure drop is calculated. On the other hand, the actual pressure drop amount in the hydrogen supply path is detected by the pressure drop amount detecting means. Then, when the actual pressure drop detected by the pressure drop detecting means is larger than the pressure drop calculated by the pressure drop calculating means by a predetermined value or more by the hydrogen leak judging means, it is determined that hydrogen is leaking. Is done. When it is determined by the hydrogen leak determination means that hydrogen is leaking, for example, the hydrogen leak is notified by the notification means, and the supply of hydrogen from the hydrogen tank is shut off by closing the shutoff valve.
In addition, since the amount of unused hydrogen is calculated separately for the amount of depleted hydrogen and the amount of purge hydrogen in the fuel cell, a slight hydrogen leak can be detected with higher accuracy.
[0009]
According to a second aspect of the present invention, in the configuration of the first aspect of the present invention, there is provided correction means for correcting the total hydrogen amount according to the state of hydrogen in the hydrogen supply path.
[0010]
According to the invention described in claim 2 , in addition to the operation of the invention described in claim 1 , for example, the total hydrogen amount is corrected according to the pressure and temperature of hydrogen in the hydrogen supply path.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details of the fuel supply device according to the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a fuel supply device that supplies hydrogen to a fuel cell.
[0016]
As shown in FIG. 1, the fuel supply apparatus 1 mainly includes a hydrogen tank 11 filled with hydrogen (fuel gas) as a fuel, and a hydrogen supply path 12 connected to the hydrogen tank 11. In this fuel supply device 1, hydrogen in a hydrogen tank 11 is supplied to a fuel cell (gas engine) 2 through a hydrogen supply path 12.
[0017]
The hydrogen tank 11 is provided with an in-tank valve 11a, and hydrogen is supplied and shut off by opening and closing the in-tank valve 11a. In the hydrogen supply path 12, a first regulator 12b, a shut-off valve 12a, a second regulator 12c, and an ejector 12d are provided at appropriate positions in this order from the hydrogen tank 11 side. The ejector 12d is connected to a circulation path 12e for reusing unused hydrogen that has not contributed to power generation in the fuel cell 2. The circulation path 12e is provided with a purge valve 12f that is opened by a purge command from a monitoring means (not shown) that monitors the operating state of the fuel cell 2. The purge valve 12f is provided for the purpose of refreshing the state of the fuel cell 2 on the hydrogen electrode side. For example, the purge valve 12f is opened when water generated by power generation of the fuel cell 2 is accumulated in the circulation path 12e. The generated water is discharged together with the hydrogen in the circulation path 12e.
[0018]
And between the in-tank valve 11a and the 1st regulator 12b in the hydrogen supply path 12, the 1st sensor (pressure drop amount detection) which always detects the pressure (pressure drop amount) P1 and temperature T1 of the hydrogen in the inside. Means) 3 is provided. In addition, a second sensor 4 is provided between the ejector 12d and the fuel cell 2 in the hydrogen supply path 12 to constantly detect the pressure P2 and the temperature T2 therein. Further, the purge valve 12f of the circulation path 12e is provided with a third sensor 5 for detecting the opening time. Incidentally, when the in-tank valve 11 a is open, the pressure detected by the first sensor 3 is the same as the pressure inside the hydrogen tank 11.
[0019]
On the other hand, the accelerator pedal AP is provided with an opening sensor 6 for detecting an accelerator opening corresponding to the depression amount. The opening sensor 6 transmits a command value based on the accelerator opening to the fuel cell 2 to generate a predetermined amount of current from the fuel cell 2. The opening sensor 6 and the first to third sensors 3 to 5 are connected to an ECU (control microcomputer) 7. The ECU 7 has a hydrogen leak determination means 71 incorporated therein as a program, and a notification means 8 such as an alarm buzzer or an alarm lamp connected to an external connection terminal. The “pressure drop amount calculating means” in the present embodiment is configured by first to third sensors 3 to 5, an opening sensor 6 of the accelerator pedal AP, and an ECU 7.
[0020]
As shown in FIG. 2, the hydrogen leak determination means 71 of the ECU 7 includes a power generation amount setting means 71a, a consumed hydrogen amount setting means 71b, a purge hydrogen amount setting means 71c, a depletion hydrogen amount setting means 71d, a total hydrogen amount calculation means 71e, It includes density correction value setting means 71f, pressure drop amount calculation means 71g and 71h, and leak determination means 71i. In the present embodiment, the hydrogen leak determination means 71 is configured as a program that functions inside the ECU 7, but it goes without saying that it may be configured in hardware.
[0021]
Hereinafter, each structure of the hydrogen leak judgment means 71 is demonstrated.
The power generation amount setting means 71 a inputs the command value from the opening sensor 6 and sets the power generation amount of the fuel cell 2. For this reason, this power generation amount setting means 71a has a map for setting the power generation amount from the command value.
[0022]
The hydrogen consumption amount setting means 71b inputs the power generation amount set by the power generation amount setting means 71a, and sets the hydrogen consumption amount consumed by the fuel cell 2. For this reason, this hydrogen consumption amount setting means 71b has a map for setting the hydrogen consumption amount from the power generation amount.
[0023]
The purge hydrogen amount setting means 71c receives the purge valve 12f opening time detected by the third sensor 5, the pressure P2 and the temperature T2 detected by the second sensor 4, and purge hydrogen purged to the outside. Set the amount. Therefore, the purge hydrogen amount setting means 71c has a map for setting the purge hydrogen amount from the valve opening time, the pressure P2, and the temperature T2. That is, in this embodiment, the density of the purged hydrogen amount is corrected by the pressure P2 and the temperature T2 in the circulation path 12e detected by the second sensor 4. By doing so, it becomes possible to set the amount of unused hydrogen more accurately, and the determination accuracy of the leak determination means 71i described later is improved.
[0024]
The depleted hydrogen amount setting means 71d inputs the pressure P2 and temperature T2 detected by the second sensor 4, and sets the depleted hydrogen amount other than the consumed hydrogen amount and purge hydrogen amount. For this reason, this depleted hydrogen amount setting means 71d has a map for setting the depleted hydrogen amount from the pressure P2 and the temperature T2. That is, in this embodiment, the amount of depleted hydrogen is density-corrected by the pressure P2 and the temperature T2 in the circulation path 12e detected by the second sensor 4. By doing so, it becomes possible to set the amount of unused hydrogen more accurately, and the determination accuracy of the leak determination means 71i described later is improved.
[0025]
Here, as the amount of depleted hydrogen, in the case of a fuel cell in which a plurality of cells are stacked, hydrogen leaking out from the gaps between the cells can be used. In this case, the amount of depleted hydrogen tends to increase as the pressure increases and decrease as the temperature increases. Incidentally, the fuel cell has a structure in which a membrane electrode structure (MEA) in which an electrolyte membrane is sandwiched between a hydrogen electrode and an oxygen electrode is stacked while being partitioned by a metal separator.
During normal operation of the fuel cell 2, the relationship among the amount of hydrogen consumed, the amount of purge hydrogen, the amount of depleted hydrogen, and the amount of hydrogen supplied to the fuel cell 2 (total hydrogen amount) is as follows.
<Supply hydrogen amount> = <Consumption hydrogen amount> + <Purge hydrogen amount> + <Depleted hydrogen amount>
[0026]
The total hydrogen amount calculating means 71e adds the consumed hydrogen amount, the purge hydrogen amount and the depleted hydrogen amount set by the consumed hydrogen amount setting means 71b, the purge hydrogen amount setting means 71c and the depleted hydrogen amount setting means 71d. Calculate the amount. For this reason, the total hydrogen amount calculating means 71e has an addition function of adding the consumed hydrogen amount, the purge hydrogen amount, and the depleted hydrogen amount.
[0027]
The density correction value setting means 71f receives the temperature T1 and pressure P1 detected by the first sensor 3, and sets a density correction value for bringing the total hydrogen amount calculated as an ideal gas close to the amount as a real gas. Set. For this reason, the density correction value setting means 71f has a map for setting the density correction value from the temperature T1 and the pressure P1.
[0028]
Based on the density correction value and the total hydrogen amount, the pressure drop amount calculating unit 71g calculates a pressure drop amount indicating an amount by which the pressure in the hydrogen supply path 12 drops during a predetermined time. Here, the calculated pressure drop amount is determined between the in-tank valve 11a and the first regulator 12b when hydrogen supplied to the fuel cell 2 passes from the hydrogen tank 11 without leaking through the hydrogen supply path 12. Pressure drop amount (calculated pressure drop amount, hereinafter also referred to as “calculated pressure drop amount”). On the other hand, the pressure drop amount calculating means 71h is based on the actual pressure drop amount (hereinafter referred to as “detection”) between the in-tank valve 11a and the first regulator 12b based on the pressure P1 detected by the first sensor 3. Calculated pressure drop amount).
[0029]
The leak determination means 71i inputs the detected pressure drop amount and the calculated pressure drop amount, and if this detected pressure drop amount is larger than the calculated pressure drop amount by a predetermined value or more, that is, detects If the difference between the calculated pressure drop amount and the calculated pressure drop amount is equal to or greater than a predetermined value, it is determined that hydrogen is leaking, and an alarm signal is output. In other words, as shown in FIG. 3, the leak determination means 71i sets a predetermined value in consideration of errors and the like in the hydrogen amount remaining in the hydrogen tank 11 estimated from the consumed hydrogen amount, purge hydrogen amount and depleted hydrogen amount. If the amount of hydrogen actually remaining in the hydrogen tank 11 is less than the subtracted amount, it is determined that there is a hydrogen leak and an alarm signal is output. For this reason, the leakage determination means 71i has a comparison determination function for determining a hydrogen leak by comparing the difference between the detected pressure drop amount and the calculated pressure drop amount with a predetermined value, and operates the notification means 8. For generating a warning signal. The predetermined value for determining hydrogen leak has a significance for detecting a leak or a dead zone. This predetermined value is determined from experimental values and theoretical calculation values in consideration of the system volume and the like. Here, if this predetermined value is reduced, a small amount of hydrogen leakage can be detected, and if it is increased, erroneous notification can be prevented.
[0030]
Next, the operation of the fuel supply device 1 will be described.
First, as shown in FIG. 1, the in-tank valve 11 a and the shut-off valve 12 a are opened to release hydrogen from the hydrogen tank 11. The hydrogen sent from the hydrogen tank 11 is depressurized to an appropriate pressure by the first and second regulators 12b and 12c, and supplied to the fuel cell 2 via the ejector 12d. The fuel cell 2 supplies a current output by the power generation to the electric motor M. Then, the hydrogen that has not been consumed by the power generation of the fuel cell 2 is returned to the ejector 12d through the circulation path 12e. The purge valve 12f provided in the circulation path 12e is opened by a purge command from the monitoring means to purge hydrogen to the outside, and is closed when the pressure in the circulation path 12e reaches a predetermined value. Thus, while hydrogen is supplied from the hydrogen tank 11 to the fuel cell 2, detection values detected by the first to third sensors 3 to 5 and the opening sensor 6 are constantly sent to the ECU 7.
[0031]
In the ECU 7, as shown in FIG. 2, the power generation amount setting means 71a sets the power generation amount of the fuel cell based on the command value transmitted from the opening sensor 6, and based on this power generation amount, the hydrogen consumption amount setting means 71b. Sets the amount of hydrogen consumed. The purge hydrogen amount setting means 71c sets the purge hydrogen amount based on the opening time of the purge valve 12f transmitted from the third sensor 5 and the pressure P2 and temperature T2 transmitted from the second sensor 4. Based on the pressure P2 and temperature T2 transmitted from the second sensor 4, the depleted hydrogen amount setting means 71d sets the depleted hydrogen amount. Then, the total hydrogen amount is calculated by adding the purged hydrogen amount and the depleted hydrogen amount, which are the unused hydrogen amount discharged from the fuel cell, by the total hydrogen amount calculating means 71e.
[0032]
Based on the pressure P1 and temperature T1 transmitted from the first sensor 3, that is, according to the state of hydrogen, the density correction value setting unit 71f sets the density correction value. The density correction value becomes a value for correcting the total hydrogen amount to be larger as the pressure P1 detected by the first sensor 3 is higher, and becomes a value for correcting the total hydrogen amount to be smaller as the temperature T1 is lower. Based on the density correction value and the total hydrogen amount, the pressure drop amount calculation means 71g calculates the pressure drop amount. On the other hand, based on the pressure P1 transmitted from the first sensor 3, the pressure drop amount calculating means 71h calculates the actual pressure drop amount.
[0033]
In this way, the pressure drop amount calculated by the pressure drop amount calculating means 71g and the actual pressure drop amount (detected pressure drop amount) calculated by the pressure drop amount calculating means 71h are compared by the leak determining means 71i. The If the difference between the detected pressure drop amount and the calculated pressure drop amount is equal to or greater than a predetermined value, the leak determination unit 71i determines that hydrogen is leaking.
[0034]
Thus, when it is judged by the hydrogen leak judgment means 71 (leak judgment means 71i) of ECU7 that hydrogen is leaking, the signal is sent to the notification means 8, as shown in FIG. 8 indicates that hydrogen is leaking. Further, the ECU 7 sends a hydrogen shut-off signal for shutting off the supply of hydrogen to the in-tank valve 11a and the shut-off valve 12a, and these valves 11a and 12a are closed.
[0035]
According to the above, the following effects can be obtained in the present embodiment.
Since the calculated pressure drop, that is, the pressure drop representing the value when hydrogen passes through the hydrogen supply path 12 without leaking is compared with the detected pressure drop representing the actual value, the detected pressure drop It can be determined that hydrogen is leaking when the difference between the drop amount and the calculated pressure drop amount is equal to or greater than a predetermined value. In addition, by comparing the actual pressure drop amount with the pressure drop amount calculated from the total hydrogen amount of the fuel cell 2 in this way, the set value for closing the valve corresponds to the maximum consumption amount of the fuel cell as in the past. Since it is not necessary to set the pressure drop higher than the amount of pressure drop to be performed, a slight hydrogen leak can be detected with high accuracy.
[0036]
As mentioned above, this invention is implemented in various forms, without being limited to the said embodiment.
In the present embodiment, in order to set the amount of hydrogen consumption of the fuel cell 2, the command value from the opening sensor 6 is used. However, the present invention is not limited to this. For example, a current value and a voltage value taken out from the fuel cell may be detected by a sensor, and the hydrogen consumption amount of the fuel cell may be calculated based on the detected value. In the present embodiment, the purge hydrogen amount is calculated based on the opening time of the purge valve 12f detected by the third sensor 5, but the present invention is not limited to this. For example, the purge hydrogen amount may be calculated based on a purge command value such that the purge valve is opened for a predetermined time at the time of the purge command, and the amount of hydrogen discharged from the purge valve is directly detected and based on the detected value It may be calculated.
In this embodiment, the total hydrogen amount is calculated using the purge hydrogen amount and the depleted hydrogen amount discharged from the fuel cell. However, the present invention is not limited to this, for example, either purge hydrogen or depleted hydrogen. May be negligible and negligible, the total hydrogen amount may be calculated using one of the unused hydrogen amounts.
[0037]
【The invention's effect】
According to the first aspect of the present invention, by comparing the calculated pressure drop amount with the detected pressure drop amount indicating the actual value, the set value for closing the valve as in the conventional case is set. Since it is not necessary to set higher than the flow rate or pressure drop corresponding to the maximum consumption, a slight hydrogen leak can be accurately detected.
[0038]
According to the invention described in claim 1, For example other, to calculate separately the amount of hydrogen unutilized in depletion of hydrogen amount and the purge amount of hydrogen in the fuel cell, to more accurately detect a slight hydrogen leakage Can do.
[0039]
According to the invention described in claim 2 , in addition to the effect of the invention described in claim 1 , for example, since the total hydrogen amount is corrected according to the pressure and temperature of hydrogen in the hydrogen supply path, Leakage can be detected with higher accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a fuel supply device according to an embodiment.
FIG. 2 is a block diagram showing hydrogen leak determination means according to the present embodiment.
FIG. 3 is a conceptual diagram illustrating a concept of a determination method of a leak determination unit according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel supply apparatus 11 Hydrogen tank 12 Hydrogen supply path 2 Fuel cell 3 1st sensor (pressure drop amount detection means)
4 Second sensor 5 Third sensor 6 Opening sensor 7 ECU
71 Hydrogen leak judgment means

Claims (2)

A hydrogen tank filled with hydrogen,
In the fuel supply device that supplies hydrogen from the hydrogen tank to the fuel cell via the hydrogen supply path,
A circulation path for returning hydrogen discharged from the fuel cell to the hydrogen supply path;
A purge valve provided in the circulation path;
The amount of depleted hydrogen in the fuel cell, which is the amount of unused hydrogen discharged from the fuel cell, the amount of purge hydrogen purged by opening the purge valve, and the amount of hydrogen consumed by power generation of the fuel cell A pressure drop amount calculating means for calculating a pressure drop amount in the hydrogen supply path from a total hydrogen amount corresponding to the sum;
Pressure drop amount detecting means for detecting a pressure drop amount in the hydrogen supply path;
Hydrogen leakage determination means for determining that the hydrogen is leaking when the detected pressure drop amount is larger than the calculated pressure drop amount by a predetermined value or more;
A sensor installed in the circulation path for detecting pressure and temperature, and a sensor for detecting the opening time of the purge valve;
The purge hydrogen amount is calculated based on the purge valve opening time and the pressure and temperature,
The depleted hydrogen amount is calculated based on the pressure and temperature.   The fuel supply apparatus according to claim 1, further comprising a correction unit that corrects the total hydrogen amount according to a state of hydrogen in the hydrogen supply path.

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