JP6650194B2 - Detection device and detection method - Google Patents

Description

  The present invention relates to a detection device and a detection method for detecting a gas leak in a vehicle using gaseous fuel as a fuel.

  Conventionally, as a technology for improving the fuel efficiency and environmental protection performance of vehicles, liquid fuel such as gasoline and gaseous fuel such as compressed natural gas (CNG) are selectively switched and supplied to a single engine. A bifuel system is known (for example, see Patent Document 1). In a vehicle equipped with such a gaseous fuel, a detection device for detecting gaseous fuel leak (gas leak) is mounted as a safety measure.

  The above-described detection device generally monitors the gas pressure in the tank via a pressure sensor that detects the pressure of the tank filled with compressed natural gas. Then, when the amount of decrease in the gas pressure per unit time exceeds a specified value, the detection device determines that a gas leak has occurred, and outputs a signal notifying the fact.

JP 2001-234814 A

  On the other hand, when the compressed natural gas is charged while the engine is driven, the gas pressure in the tank may fluctuate peculiarly. Then, during the filling of the compressed natural gas into the tank, a drop in gas pressure that exceeds a predetermined value happens to be detected, and the occurrence of gas leak may be erroneously detected.

  The present invention has been made in view of the above problems, and has as its object to suppress occurrence of erroneous detection of gas leak during filling of a gaseous fuel into a tank.

  One aspect of the present invention is a leak determination unit that notifies the occurrence of a gas leak when the amount of change in the pressure of the gas charged in the tank falls below a predetermined leak determination threshold, and the gas charged in the tank. When the fluctuation amount of the pressure exceeds a predetermined filling determination threshold, a filling determining unit that notifies that the tank is being filled with gas, and the leak determining unit, from the filling determining unit When receiving notification that the tank is being filled with gas, even if the amount of change in the pressure falls below a predetermined leak determination threshold value, the occurrence of gas leak is not notified. It is a detection device.

  In one embodiment of the present invention, in the above-described detection device, the filling determination unit sets the filling determination threshold to a larger value as the pressure of the gas filled in the tank is higher. .

  Further, according to one aspect of the present invention, in the above-described detection device, after a predetermined period has elapsed from a time when the leak determination unit has received a notification that the tank is being filled with gas, the pressure is not changed. Is characterized in that when a variation amount of the gas falls below a predetermined leak determination threshold value, occurrence of a gas leak is notified.

  Further, one aspect of the present invention, when the variation amount of the pressure of the gas filled in the tank exceeds a predetermined filling determination threshold, notifies that the tank is being filled with gas, the tank If the notification that the gas is being charged to the tank has not been received, when the amount of change in the pressure falls below a predetermined leak determination threshold, the occurrence of a gas leak is notified, and the gas is charged into the tank. The detection method is characterized in that, when the notification that the gas is in the middle is received, the occurrence of the gas leak is not notified even when the fluctuation amount of the pressure falls below the leak determination threshold value.

  According to the above-described detection device and detection method, it is possible to suppress occurrence of erroneous detection of gas leak during filling of the gaseous fuel into the tank.

It is a figure showing the whole gas supply system composition concerning a 1st embodiment. FIG. 8 is a graph showing a change in gas pressure when gaseous fuel is charged during startup of the engine. It is a flow chart figure showing the processing flow of the detecting device concerning a 1st embodiment. FIG. 4 is a graph illustrating contents of a filling determination table according to the first embodiment.

<First embodiment>
Hereinafter, the gas supply system according to the first embodiment will be described in detail.
FIG. 1 is a diagram illustrating the overall configuration of the gas supply system according to the first embodiment. The gas supply system 1 is mounted on a vehicle that runs with power from gaseous fuel such as CNG.

As shown in FIG. 1, the gas supply system 1 includes a detection device 10, a tank 20, and a pressure sensor 21.
The detection device 10 is realized by an ECU (Engine Control Unit) of a vehicle on which the gas supply system 1 is mounted. The detection device 10 acquires the pressure (hereinafter simply referred to as “gas pressure”) of the gas (gas fuel) filled in the tank 20 via the pressure sensor 21. When the acquired gas pressure satisfies a predetermined condition, the detection device 10 determines that a gas leak has occurred, and outputs a signal (leak detection signal) for notifying the occurrence. When a separately mounted safety device (not shown) receives the leak detection signal, the safety device is activated. The detection device 10 operates as a leak determination unit 11 and a filling determination unit 12 by reading and executing a prepared program.
The tank 20 is a fuel tank that stores gaseous fuel filled from a filling port. The gaseous fuel in the tank 20 is sent to an engine mechanism (not shown) via a pipe according to the driving of the vehicle.
The pressure sensor 21 is a detector that detects the gas pressure in the tank 20. The pressure sensor 21 is installed on a pipe transported to the engine mechanism. The pressure sensor 21 converts the detected gas pressure into an electric signal and outputs the electric signal to the detection device 10 which is an ECU.

Next, each functional configuration of the detection device 10 will be described.
The detection device 10 includes a leak determination unit 11, a filling determination unit 12, and a filling determination table 13.
Leak determination unit 11 outputs a signal (leak detection signal) for notifying the occurrence of a gas leak when variation amount ΔP of gas pressure in tank 20 falls below predetermined leak determination threshold ΔPL. Immediately after this leak detection signal is output to a predetermined safety device, a safety operation such as shutting off a gas flow is executed.
When the filling of the gaseous fuel is started through the filling port, the filling determination unit 12 detects that fact. Specifically, when the variation amount ΔP of the gas pressure in the tank 20 exceeds a predetermined filling determination threshold value ΔPi, a signal (filling detection signal) for notifying that the tank 20 is being filled with gas. Is output. The filling determination unit 12 outputs this filling detection signal to the leak determination unit 11.
The filling determination table 13 is a storage table used by the filling determining unit 12 to make the above-described filling determination. The filling determination table 13 is defined in advance according to the results of a separate experiment performed separately. The filling determination table 13 defines the value of a filling determination threshold value ΔPi to be employed for each gas pressure in the tank 20. The filling determination table 13 is stored in a storage unit (not shown) in advance, and the detection device 10 as an ECU reads and holds the filling determination table 13 stored in the storage unit at the time of startup.

FIG. 2 is a graph showing a change in gas pressure when gaseous fuel is charged during startup of the engine.
In the graph shown in FIG. 2, the vertical axis represents the gas pressure P in the tank 20, and the horizontal axis represents time t. FIG. 2 shows a change in the gas pressure P when the charging (injection) of the gaseous fuel is started at the time t0.
When gas fuel filling is started while the engine is running, the gas pressure P in the tank 20 rises while pulsating, as shown in FIG. Then, as the charging start time t0 elapses, the pulsation width gradually decreases, and the pulsation disappears at a time t1 after a predetermined time Δt (for example, Δt = 120 sec) has elapsed, and the gas pressure P is stabilized.

At this time, the detection device 10 detects, for example, an increase in the gas pressure P (positive fluctuation amount ΔP1) corresponding to the filling of the gaseous fuel (see FIG. 2). Similarly, the detection device 10 detects a decrease in the gas pressure P due to the pulsation (a negative fluctuation amount ΔP2) (see FIG. 2). Here, when the decrease amount ΔP2 of the gas pressure P based on the pulsation is lower than the leak determination threshold value ΔPL, the detection device 10 determines that the gas leak has occurred even though the gas leak has not actually occurred. Outputs a leak detection signal. That is, the detection device 10 may erroneously detect a gas leak during the charging of the gaseous fuel.
Therefore, when the detection device 10 according to the present embodiment detects an increase in the gas pressure P in response to the filling of the gaseous fuel, the leak occurrence notification processing is performed for a predetermined time Δt (for example, Δt = 120 sec) thereafter. (Output of leak detection signal) is not performed. Hereinafter, the specific method will be described.

FIG. 3 is a flowchart illustrating a processing flow of the detection device according to the first embodiment.
FIG. 3A is a flowchart illustrating a processing flow of the filling determination unit 12 in the detection device 10, and FIG. 3B is a flowchart illustrating a processing flow of the leak determination unit 11 in the detection device 10. The processing flows shown in FIGS. 3A and 3B are both started from the stage where power is supplied to the detection device 10 and the operation as the ECU is started.

First, the processing flow of the filling determination unit 12 will be described with reference to FIG.
As shown in FIG. 3A, the filling determination unit 12 acquires the gas pressure P in the tank 20 at the present time through the pressure sensor 21 (Step S01). Next, the filling determination unit 12 sets a predetermined filling determination threshold ΔPi according to the gas pressure P at the current time with reference to the filling determination table 13 (step S02). Next, the filling determination unit 12 obtains the gas pressure P again, and obtains a fluctuation amount ΔP that is a difference between the gas pressure P obtained the second time and the gas pressure P obtained the first time (step S03). .

  Next, the filling determination unit 12 determines whether or not the variation ΔP exceeds the filling determination threshold ΔPi (> 0) set in step S02 (step S04). Here, the filling determination threshold ΔPi is a threshold used by the detection device 10 to determine whether or not gas fuel is currently being filled. Specifically, when the variation amount ΔP exceeds the filling determination threshold value ΔPi, the filling determination unit 12 performs the current filling process because there is no other rise variation than the filling determination threshold value ΔPi other than the filling process. It can be determined that. The specific setting value of the filling determination threshold value ΔPi will be described later.

  When the fluctuation amount ΔP is greater than the filling determination threshold value ΔPi (step S04: YES), the filling determining unit 12 sends a filling detection signal indicating that the gas fuel is currently being filled to the leak determining unit 11. Output (Step S05). At this time, the filling determination unit 12 continues to output the filling detection signal for a predetermined time Δt (for example, 120 seconds). On the other hand, when the fluctuation amount ΔP is equal to or smaller than the filling determination threshold value ΔPi (Step S04: NO), the filling determining unit 12 ends the process without outputting the filling detection signal.

  The filling determination unit 12 repeatedly executes the processing of steps S01 to S05 described above. At this time, in the processing of step S02 after the second time, the filling determination threshold value ΔPi may be obtained based on the gas pressure P obtained in step S03 one cycle before, and the processing of step S01 may be omitted. In this case, in the second and subsequent processes of step S03, the variation ΔP is obtained from the difference between the gas pressure P obtained in step S03 one cycle before and the gas pressure P obtained in step S03 this time. Is also good.

Next, a processing flow of the leak determination unit 11 will be described with reference to FIG.
As shown in FIG. 3B, the leak determination unit 11 acquires the gas pressure P in the tank 20 at the present time through the pressure sensor 21 (Step S11). Next, the leak determination unit 11 obtains the gas pressure P again, and obtains a variation ΔP that is a difference between the gas pressure P obtained the second time and the gas pressure P obtained the first time (step S12). .
Next, the leak determination unit 11 determines whether the fluctuation amount ΔP is less than a leak determination threshold ΔPL (<0) (Step S13). When the fluctuation amount ΔP is equal to or larger than the leak determination threshold ΔPL (step S13: NO), the leak determination unit 11 ends the processing without performing any special processing. On the other hand, when the fluctuation amount ΔP is smaller than the leak determination threshold value ΔPL (<0) (step S13: YES), the leak determination unit 11 subsequently determines whether or not a filling detection signal is input. (Step S14). Here, if there is an input of the filling detection signal from the filling determining unit 12 in the processing of step S05 (FIG. 4A) (step S14: YES), the processing ends without performing any special processing. On the other hand, when there is no input of the filling detection signal from the filling determining unit 12 (step S14: NO), the leak determining unit 11 outputs a leak detection signal assuming that a gas leak has occurred (step S15). As a result, the safety device that has received the input of the leak detection signal operates, and processing such as shutting off the gas flow of the gas leak is performed.

  The leak determination unit 11 also repeatedly executes the processing of steps S11 to S15 as in the case of the filling determination unit 12. At this time, in the processing of step S11 after the second time, the filling determination threshold value ΔPi is obtained from the difference between the gas pressure P obtained in step S12 one cycle before and the gas pressure P obtained in this step S12. , The processing of step S11 may be omitted.

According to the above-described processing, when the leak determining unit 11 receives a notification (filling detection signal) that the tank 20 is being filled with the gaseous fuel from the filling determining unit 12, the leak determining unit 11 performs the charging for a predetermined period (filling time). For a predetermined time Δt from the start, even when the fluctuation amount ΔP of the gas pressure P falls below the leak determination threshold value ΔPL, the occurrence of gas leak is not notified (leak detection signal).
For example, according to the example shown in FIG. 2, the filling determination unit 12 detects the rise of the gas pressure P (the rise amount ΔP1> ΔPi) immediately after the start of the filling of the gaseous fuel from the time t0, and the filling detection signal. Is output to the leak determination unit 11 for a predetermined time Δt (Δt = 120 sec). Then, leak detecting section 11 does not output a leak detection signal even when detecting a decrease in gas pressure P (decrease amount ΔP2 <ΔPL) generated immediately thereafter due to pulsation.
As described above, even when the fluctuation amount ΔP of the gas pressure that is lower than the leak determination threshold ΔPL is detected during the charging and the pulsation of the gas pressure P is occurring, the detection device 10 detects the leak. Do not notify the occurrence of Therefore, erroneous detection of gas leak due to pulsation of gas pressure P generated during filling can be suppressed.

FIG. 4 is a graph illustrating the contents of the filling determination table according to the first embodiment.
As described above, when the fluctuation amount ΔP of the gas pressure exceeding the filling determination threshold ΔPi is detected, the detection device 10 (filling determination unit 12) determines that the filling has been started. Therefore, in order to prevent the erroneous detection of “filling” in a situation where the gaseous fuel has not been filled, the filling determination threshold ΔPi is set to a value corresponding to the fluctuation of the gas pressure assumed in a situation other than the filling. Must be set to a value above the amount. Further, the filling determination unit 12 should always detect “filling” when the filling is started, and therefore the filling determination threshold ΔPi is set to be equal to or less than the increase ΔP of the gas pressure P assumed at the start of the filling. Need to be

As described above, the filling determination unit 12 according to the present embodiment sets the filling determination threshold ΔPi based on the filling determination table 13 in step S02. As shown in FIG. 4, the filling determination table 13 used here defines a correlation between the filling determination threshold value ΔPi and the gas pressure (original gas pressure) P in the tank 20 immediately before detecting the variation ΔP. are doing. The “gas pressure P in the tank 20 immediately before detecting the variation ΔP” is, specifically, the gas pressure P obtained in step S01 (or step S03 one cycle before).
The filling determination table 13 stores the filling determination threshold ΔPi and the original gas pressure P in association with each other based on the correlation defined by the straight line α shown in FIG. The straight line α is a straight line α ′ (ΔPi = a × P, where the proportional coefficient a is, for example, a = 1/20) indicating a proportional relationship based on the proportional coefficient a between the filling determination threshold value ΔPi and the original gas pressure P. , A straight line obtained by adding a predetermined offset pressure ΔPq (for example, ΔPq = 10 kPa). That is, the filling determination table 13 defines a correlation between the filling determination threshold ΔPi based on ΔPi = a × P + ΔPq (1) and the original gas pressure P.

  According to the straight line α, when the gas pressure (original gas pressure) P obtained in step S01 (or step S03 one cycle before) is Pm (= 4000 kPa), the filling determination threshold value set in step S02. ΔPi is set to ΔPim (= 110 kPa). Further, when the original gas pressure P is Pn (= 8000 kPa), the filling determination threshold value ΔPi set in step S02 is set to ΔPin (= 210 kPa) (see equation (1)). Therefore, according to the filling determination table 13, the filling determining unit 12 sets the filling determination threshold ΔPi to a larger value as the pressure P of the gas filled in the tank 20 is higher. Hereinafter, the reason for this will be described.

  Fluctuations in the gas pressure P assumed in situations other than during the filling of the tank 20 with the gaseous fuel are mainly caused by the temperature. That is, the temperature of the gaseous fuel in the tank 20 fluctuates due to external factors such as the environmental temperature and the exhaust heat of the driven engine. Generally, when the volume V of the gas is constant, the pressure P of the gas increases in proportion to the temperature T. Then, since the volume V of the gaseous fuel (the volume of the tank 20) is constant, the fluctuation amount ΔPT of the gas pressure P caused by the temperature change ΔT based on the above-mentioned external factor is equal to the gas pressure P (the original gas pressure) before the fluctuation. P) increases or decreases in proportion to itself. That is, the variation ΔPT of the gas pressure P caused by the temperature change satisfies the relationship ΔPT∝P.

  For example, let us consider a case where there is a temperature increase of ΔT in each of the case where the gas pressure P of the tank 20 is Pm = 4000 kPa and the case where Pn = 8000 kPa. At this time, since Pn is twice the gas pressure of Pm (Pn = 2 × Pm), the fluctuation amount ΔPTn generated based on the temperature increase ΔT when the gas pressure P is Pn is the same as the gas pressure P (ΔPTn = 2 × ΔPTm). Therefore, assuming that the filling determination threshold ΔPi is constant, the increase in the gas pressure P caused by the temperature increase when the gas pressure P is 8000 kPa is “filling” compared to when the gas pressure P is Pm = 4000 kPa. Is likely to be erroneously detected.

  Therefore, as described above, the filling determination unit 12 according to the present embodiment defines the original gas pressure P and the filling determination threshold ΔPi in a correlation based on the equation (1), so that the higher the original gas pressure P is, The filling determination threshold value ΔPi is set to a large value. By doing so, the higher the original gas pressure P, the larger the margin until the amount of increase ΔPT of the gas pressure P caused by the temperature rise reaches the filling determination threshold ΔPi. However, erroneous detection can be reduced.

  Further, the offset pressure ΔPq is an offset provided to prevent the fluctuation of the fluctuation amount ΔPe caused by the characteristic variation of the detection device 10 as the ECU, the detection error of the pressure sensor 21 and the like from being erroneously detected as “charging”. That is, the offset pressure ΔPq is set to a value (ΔPq> ΔPe) that exceeds the variation ΔPe based on the ECU characteristic variation and the detection error of the pressure sensor 21 obtained by a preliminary experiment or the like.

  The detection device 10 according to the present embodiment determines whether or not the filling determination unit 12 causes the gas pressure P in the tank 20 to increase during “filling” based on the above-described filling determination table 13. Since the determination is performed, it is possible to prevent the increase in the gas pressure P from being erroneously detected as “charging”. Therefore, when a gas leak actually occurs, it is possible to prevent a situation in which the rise of the gas pressure P is erroneously detected as “filling” and the occurrence of the gas leak is not notified.

  As described above, according to the detection device according to the first embodiment, it is possible to suppress occurrence of erroneous detection of gas leak during filling of a tank with gaseous fuel such as compressed natural gas.

  Although the above-described filling determination unit 12 has been described based on the filling determination table 13 to set the filling determination threshold ΔPi to be larger as the original gas pressure P is larger, other embodiments are limited to this mode. Not done. For example, the filling determination unit 12 may determine whether or not filling is being performed based on a preset fixed filling determination threshold ΔPic.

  Further, after a lapse of a predetermined period (predetermined time Δt) from the timing determined as “filling”, the filling determination unit 12 according to the present embodiment automatically stops the output of the filling detection signal and detects the gas leak. Return to the normal processing for notification. This predetermined time Δt is desirably set to a period from the start of filling until the pulsation stops. According to the example shown in FIG. 2, the pulsation falls at time t1 after elapse of 120 seconds from the filling start time t0, so in the snare of this embodiment, the predetermined time Δt is set to 120 seconds. By doing so, at least during the occurrence of the pulsation, the notification of the detection of the gas leak is not always made, so that the occurrence of the erroneous detection of the gas leak can be suppressed with higher accuracy. In addition, since the detection device 10 automatically returns to the normal process (the process of notifying the detection of the gas leak) as time passes, no special signal or configuration for returning to the normal process is required.

  Note that, even after returning to the above-described normal processing, the filling determination unit 12 repeatedly performs the processing of detecting whether or not “filling” (the processing of steps S01 to S05), and again performs the fluctuation exceeding the charging determination threshold ΔPi. When the amount ΔP is detected, the filling detection signal is output again for the predetermined period Δt.

  Note that other embodiments are not limited to the above-described embodiment. For example, the filling determination unit 12 according to another embodiment outputs a separate signal (for example, a filling end signal for notifying the end of the filling process) after determining that the filling is in progress and outputting a filling determination signal. When it is received, the output of the filling detection signal may be stopped. By doing so, the notification of the gas leak detection is not always sent during the filling, so that the erroneous detection of the gas leak during the filling can be suppressed more reliably.

  In the above-described embodiment, when the variation ΔP (> 0) of the gas pressure P exceeds the filling determination threshold ΔPi, the filling determination unit 12 determines that the filling determination signal is “filling” with the output of the filling determination signal. Although the notification has been described, the process of the “notification” is not limited to the above mode. That is, the “notification” by the filling determination unit 12 may be performed, for example, by turning on / off a determination flag indicating whether or not a predetermined storage area is “filling”.

  In addition, in order to more reliably determine the start of filling, the filling determination unit 12 notifies the user that “gas is being charged”, for example, when the increase exceeding the determination threshold ΔPi is continued twice or more consecutively. It may be an aspect. Similarly, the leak determination unit 11 may be configured to notify that “a gas leak has occurred”, for example, when the decrease below the determination threshold value ΔPL is continuously performed twice or more.

In the above-described embodiment, a program for realizing the function of the detection device 10, which is an ECU, is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by a computer system. Each procedure is performed by executing. Here, the process of each process of the above-described detection device 10 is stored in a computer-readable recording medium in the form of a program, and the various processes are performed by reading and executing the program by the computer. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer that has received the distribution may execute the program.
Further, the functional configuration of the detection device 10 may be provided over a plurality of devices connected via a network.

  Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

1 gas supply system 10 detection device (ECU)
11 Leak determination unit 12 Fill determination unit 13 Fill determination table 20 Tank 21 Pressure sensor

Claims (3)

A leak determining unit that notifies the occurrence of a gas leak when the variation amount of the pressure of the gas filled in the tank is lower than a predetermined leak determination threshold;
When the fluctuation amount of the pressure of the gas filled in the tank exceeds a predetermined filling determination threshold two or more times continuously, a filling determination unit that notifies that the tank is being filled with gas,
With
When the leak determination unit receives a notification from the filling determination unit that the tank is being filled with gas, the pressure pulsation of the gas filled in the tank starts at the time when the notification is received. A detection device that does not notify the occurrence of a gas leak during a predetermined period until the time is satisfied. The detection device according to claim 1, wherein the filling determination unit sets the filling determination threshold to a larger value as the pressure of the gas filled in the tank is higher. When the fluctuation amount of the pressure of the gas filled in the tank exceeds a predetermined filling determination threshold two or more times continuously, notifies that the gas is being filled into the tank,
If the notification that the tank is being filled with gas has not been received, when the amount of change in the pressure falls below a predetermined leak determination threshold, the occurrence of a gas leak is notified,
When a notification that the tank is being filled with gas is received, a predetermined period of time from when the notification is received to the time when the pressure pulsation of the gas filled in the tank stops is reduced. A detection method which does not notify the occurrence of a gas leak even when the amount of change falls below a leak determination threshold.

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