JP2001234814A - Abnormality detector of gas fuel feed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably detect any ON failure of a shutoff valve in a gas fuel feed device having the shutoff valve in the middle of a gas fuel feed passage. SOLUTION: The compressed natural gas in a gas cylinder 1 is fed via the shutoff valve 5 and reduced in pressure to a predetermined value by a regulator 6 and fed to an injection fuel feed pipe 11, and the natural gas is injected from an injector 10 into a CNG engine 9. When a vehicle is in an idling condition after the CNG engine 9 is started, the shutoff valve OFF output signal to close the shutoff valve 5 is outputted from an ECU 8 to the shutoff valve 5. Then, the pressure of the natural gas in the injection fuel feed pipe 11 is monitored by a fuel pressure sensor 7, and if the fuel pressure is not higher than the predetermined reference value for judgment, the shutoff valve 5 is judged to be normal. On the other hand, if the fuel pressure is not below the reference value for judgment even after the predetermined time is elapsed, it is judged that the shutoff valve 5 cannot be closed by the control signal from the ECU 8, i.e., the shutoff valve 5 is ON-failed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas fuel supply apparatus for supplying gaseous fuel such as compressed natural gas to a gas internal combustion engine or the like.

[0002]

2. Description of the Related Art Conventionally, gas fuels such as compressed natural gas (CNG) and liquefied petroleum gas (LPG) have been widely used in various fields such as home use and vehicle use. In particular, vehicles using gas fuel have the problem that the vehicle weight is heavier and the cruising range is shorter than gasoline-powered vehicles.However, due to the advantages of fuel economy, for example, taxis that use LPG as fuel are used. Has been put to practical use.

[0003] CNG also has clean fuel properties, has abundant reserves and is easy to secure stably, has a higher octane number than LPG, and has extremely low harmful substances in exhaust gas. Therefore, it has attracted attention as an alternative fuel to conventional gasoline, and so-called natural gas vehicles using CNG as fuel have already been put to practical use.

In gas appliances and gas-fueled vehicles using these gas fuels, the gas fuel stored in the gas cylinder at a high pressure is reduced to a predetermined pressure via a gas fuel supply device, and then the combustion device or the internal combustion engine is used. Generally supplied to institutions and the like. For example, in a gas-fueled vehicle using a gas such as CNG as a fuel, a gas cylinder compressed and filled with a gas fuel is provided.
Generally, there is provided a gas fuel supply device including a gas pipe for supplying gas fuel from a gas cylinder to an internal combustion engine, and a shutoff valve and a regulator provided in the middle of the gas pipe. . In the gas fuel supply device configured as described above, the pressure of the high-pressure gas fuel supplied from the gas cylinder via the shut-off valve is reduced to a predetermined pressure by the regulator and supplied to the internal combustion engine. Also,
A fuel pressure sensor provided downstream of the regulator in the gas pipe constantly monitors the gas fuel pressure (hereinafter, referred to as "fuel pressure") reduced by the regulator.

In the above gas fuel supply device, the shutoff valve is mainly for shutting off the gas fuel supply from the gas cylinder when the regulator is abnormal, and is always open during normal running. The regulator adjusts the pressure of gaseous fuel to a predetermined fuel pressure. When the fuel pressure rises abnormally due to some reason, such as an abnormality in the regulator, a function of releasing gaseous fuel to the atmosphere (mechanical guard) Also have. However, normally, when the fuel pressure rises abnormally, the shutoff valve is closed before the mechanical guard is activated (when the fuel pressure rises to a level slightly lower than the fuel pressure at which the mechanical guard is activated) to shut off the fuel supply from the gas cylinder. ing.

Further, in the above gas-fueled vehicle, when the shut-off valve is turned OFF (meaning that the valve is always closed and cannot be opened; the same applies hereinafter), gas fuel is supplied to the internal combustion engine. In this case, the engine cannot be started, but in this case, the user can immediately know that some abnormality has occurred. on the other hand,
If the shut-off valve has an ON failure (it means that it is always open and cannot be closed, the same applies hereinafter)
There is no particular problem since the supply of gas fuel is continued.

That is, there is no particular problem in terms of safety performance whether the shut-off valve is turned OFF or ON, and no abnormality is detected in the shut-off valve.

[0008]

However, when the ON failure of the shut-off valve and the abnormality of the regulator (abnormal increase in fuel pressure) occur simultaneously, there is a possibility that the gas fuel is continuously released from the regulator to the atmosphere.

That is, if the shut-off valve fails to turn on, the shut-off valve cannot be closed even if the regulator malfunctions and the fuel pressure of the gas fuel supplied to the internal combustion engine rises abnormally. The gas will continue to be supplied from the gas cylinder, and the mechanical guard of the regulator will operate. And as long as the supply of high-pressure gas fuel from the gas cylinder continues
Gas fuel continues to be released from the regulator into the atmosphere.

If the release of gaseous fuel into the atmosphere continues for a long time, the gaseous fuel is wasted, and it is not preferable from the environmental point of view. Therefore, when an ON failure occurs in the shut-off valve, it is necessary to detect the failure and notify the user to promptly deal with the failure. The present invention has been made in view of the above problems, and has as its object to reliably detect an ON failure of a shutoff valve in a gas fuel supply device having a shutoff valve in the middle of a gas fuel supply path.

[0011]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, there is provided an abnormality detecting apparatus, comprising: a fuel supply path; a fuel pressure adjusting means; a fuel pressure detecting means; Means for detecting an abnormality of the fuel cut-off means in the gas fuel supply device provided with the means and the cut-off control means. When the fuel cut-off means is normally open, the forced cut-off control means A forced cut-off signal (a control signal for forcibly closing the fuel supply path by the fuel cut-off means) is output, and after the forced cut-off signal is output to the fuel cut-off means by the forced cut-off control means, adjustment is performed even if a predetermined time has elapsed. When the pressure of the pressurized gas fuel does not become lower than the predetermined reference value, the abnormality determining means determines the abnormality of the fuel cutoff means.

In the above-described gas fuel supply device, the gas fuel supplied from the fuel tank passes through the fuel cut-off means provided in the middle of the fuel supply path, and is supplied by the fuel pressure adjusting means also provided in the fuel supply path. After being adjusted to a predetermined pressure,
The pressure-regulated gas fuel whose pressure has been adjusted is supplied to predetermined combustion equipment. Here, the "predetermined pressure" refers to a pressure suitable for normal operation of the combustion equipment (in other words, normal pressure gas fuel burns normally in the combustion equipment).

The fuel shut-off means is for shutting off the fuel supply path when the fuel pressure adjusting means is abnormal, for example, and stopping the supply of gaseous fuel to the fuel pressure adjusting means. (During fuel combustion) is usually open. Such operation of the fuel cutoff means is performed based on a cutoff control signal input to the fuel cutoff means. Specifically, for example, when the pressure of the pressure-regulated gas fuel detected by the fuel pressure detecting means exceeds a predetermined upper limit, the cutoff control means outputs a cutoff control signal for cutting off the fuel supply path. Further, for example, when the pressure of the pressure-regulated gas fuel does not exceed the predetermined upper limit, the shutoff control unit outputs a shutoff control signal for opening the fuel shutoff unit.

Incidentally, the "predetermined upper limit value" is set to a value slightly larger than a predetermined fuel pressure (considering variation) which should be originally adjusted by the fuel pressure adjusting means, and does not normally reach the value. For example, the value may be set appropriately in consideration of the performance of the combustion device to be used and the fuel pressure adjusting means, for example, to a value that may interfere with the normal operation of the combustion device if it exceeds the value.

In the abnormality detecting device according to the present invention, when the fuel shut-off means is normally open (that is, when the combustion apparatus is operating and the combustion of the regulated gas fuel is performed normally),
The forced cutoff control means outputs a forced cutoff signal to the fuel cutoff means. If the fuel cut-off means operates normally, the fuel cut-off means cuts off the fuel supply path in response to the forced cut-off signal from the forced cut-off control means, so that the downstream side of the fuel cut-off means (fuel pressure adjusting means, combustion equipment, etc.) Is no longer supplied with gaseous fuel. Therefore, the pressure of the pressure-regulated gas fuel flowing out from the fuel pressure adjusting means also gradually decreases.

Therefore, after the forced cutoff signal is output to the fuel cutoff means by the forced cutoff control means, the pressure of the pressure-regulated gas fuel is monitored by the fuel pressure detection means, and when the pressure becomes lower than a predetermined judgment reference value. , The fuel cutoff means is determined to be normal. Note that this determination reference value can be appropriately determined within a range that does not hinder normal operation of the combustion equipment.

On the other hand, if the pressure of the pressure-regulated gas fuel does not become lower than a predetermined reference value even though a predetermined time has elapsed after the output of the forced cutoff signal, the fuel cutoff means cannot be closed. Then, an abnormality determination is made to the effect that the fuel cut-off means has an ON failure. The "predetermined time" is, for example, when the fuel cutoff means is normal, the pressure of the pressure-regulated gas fuel drops to a predetermined determination reference value after the fuel supply path is cut off by the forced cutoff signal. The time may be set as appropriate by actually measuring or estimating a sufficient time, and setting a time that allows for a margin.

That is, in the abnormality detecting device according to the present invention, after outputting the forced shutoff signal for forcibly closing the fuel shutoff means, it is checked whether or not the pressure of the pressure-regulated gas fuel drops. This is to detect abnormalities in the data. Therefore, according to the abnormality detection device described above, a control signal (forcible shutoff signal) for temporarily shutting off gas fuel flowing into the fuel pressure adjusting unit during gas fuel supply is output to the fuel shutoff unit,
The abnormality (ON failure) of the fuel cut-off means can be determined only by determining whether or not the pressure of the pressure-regulated gas fuel decreases, so that the ON failure of the fuel cut-off means can be reliably detected.

Here, the abnormality detection device according to the present invention includes, for example, an internal combustion engine as a combustion device, and the internal combustion engine is driven by supplying a pressure-regulated gas fuel to the internal combustion engine. It can be applied to gas-fueled vehicles. In addition, when the abnormality detection device of the present invention is applied to a gas fuel supply device of a gas-fueled vehicle that travels by driving the internal combustion engine, for example, the internal combustion engine may be in an idle state. At the time, that is, when the internal combustion engine is stably driven by the supply of the pressure-regulated gas fuel but the gas-fueled vehicle does not run and is stopped, a forced cutoff signal for forcibly closing the fuel cutoff means is forcibly issued. It is desirable to output from the shutoff control means.

That is, while the internal combustion engine is running, the gas-fueled vehicle can be either running or stopped. For example, when the internal combustion engine is running at high speeds requiring a large amount of pressure-regulated gas fuel, When a forced shutoff signal is output to the fuel shutoff means during acceleration or the like to shut off the fuel supply path, it may be impossible to supply sufficient gas fuel to the internal combustion engine depending on the fuel consumption of the internal combustion engine at that time. .

Therefore, when the internal combustion engine is in an idling state in which the internal combustion engine is rotating at a relatively low speed and the rotation speed is stable with little fluctuation, if the forced cut-off signal is output, the driving of the internal combustion engine is not hindered and the fuel is not hindered. Abnormality of the shutoff means can be detected. Also, during the running of a gas-fueled vehicle, the frequent cutoff of the fuel supply path by the forced cutoff signal output to the fuel cutoff means only for judging whether the fuel cutoff means is normal or not during the running of the car. Not very good. Therefore, as in the abnormality detection device according to the fourth aspect, it is desirable that the abnormality determination of the fuel cutoff unit by the forced cutoff unit and the abnormality determination unit be performed only once every time the internal combustion engine is started.
With this configuration, the abnormality determination is performed only once after the internal combustion engine is started, for example, at the time of idling immediately before traveling.
Thereafter, the abnormality determination is not performed, so that there is no possibility that the driving of the automobile will be affected.

Further, as in the abnormality detecting device according to the fifth aspect, the abnormality judging means makes the fuel cut-off means abnormal (O).
It is preferable to include an abnormality notification unit that notifies a driver or the like that an abnormality has occurred when it is determined to be (N failures). In this way, the driver or the like can immediately know that the fuel cut-off means has an ON failure, and can promptly deal with the failure.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a configuration of a gas fuel supply device of a CNG vehicle to which the present invention is applied. CNG vehicles are compressed natural gas (CNG)
This is an automobile driven by an internal combustion engine using the fuel as a fuel, and is attracting attention as one of future automobiles against the background of social demands such as promotion of introduction of alternative energy to petroleum and reduction of exhaust gas.

As shown in FIG. 1, the gas fuel supply device of the present embodiment includes a first high-pressure gas pipe 2 for supplying high-pressure natural gas filled in a gas cylinder 1 to an injection fuel supply pipe 11. A second high-pressure gas pipe 3 and a low-pressure gas pipe 4; a shutoff valve 5 for shutting off natural gas supply from the gas cylinder 1 to the injection fuel supply pipe 11 when shutoff conditions described later are satisfied; and a shutoff valve from the gas cylinder 1 A regulator 6 for reducing the high-pressure natural gas flowing through the valve 5 to a predetermined pressure, and a natural gas (hereinafter referred to as “pressure-regulated natural gas”) reduced to a predetermined pressure by the regulator 6. Operation (opening / closing) of a shutoff valve 5 based on a fuel pressure sensor 7 for detecting pressure (fuel pressure) and a fuel pressure signal or the like input from the fuel pressure sensor 7
And an electronic control unit (hereinafter, referred to as “ECU”) 8 that performs a shut-off valve abnormality determination process.

The gas cylinder 1 uses one all-composite (composite material) tank, and natural gas as a gas fuel is in a high pressure state (for example, about 19.6 MPa).
Filled with. The gas cylinder 1 is provided with a manual valve 1a for blocking outflow and inflow of natural gas inside. Also, a CNG filling port 1b for injecting high-pressure natural gas from the outside is provided so that the natural gas can be repeatedly used by refilling with natural gas.

The shut-off valve 5 is connected to the first high-pressure gas pipe 2 and the second high-pressure gas pipe 3, and natural gas flowing through the first high-pressure gas pipe 2 passes through the shut-off valve 5 through the second high-pressure gas pipe 2. Flow to high pressure gas pipe. The shutoff valve 5 is electrically connected to the ECU 8, and its opening and closing are controlled by a shutoff valve control signal from the ECU 8. Thereby, the supply of the natural gas to the downstream side of the shutoff valve 5 is controlled. The main purpose of providing the shutoff valve 5 is to shut off the supply of natural gas when the regulator 6 is abnormal.

The regulator 6 is connected to the second high-pressure gas pipe 3 on the upstream side and the low-pressure gas pipe 4 on the downstream side, and is configured to control the pressure of the high-pressure natural gas flowing through the second high-pressure gas pipe 3. At a predetermined pressure (for example, 400 kP) suitable for the injector 10 to inject fuel into the CNG engine 9.
The pressure is reduced to a). Then, the pressure-regulated natural gas reduced to a predetermined pressure flows out to the low-pressure gas pipe 4 and is supplied to the injection fuel supply pipe 11. In addition, regulator 6
When the fuel pressure exceeds a predetermined second upper limit value (for example, 800 kPa), a relief valve 6a for releasing the pressure-regulated natural gas to the outside (mechanical guard) is provided.
For this reason, when an abnormality occurs in the regulator 6 due to some factor, the fuel pressure cannot be reduced to a predetermined pressure, and when the fuel pressure rises abnormally, the regulated natural gas is discharged into the atmosphere, so that the low-pressure gas pipe 4 The influence on the downstream side of the regulator 6 such as the fuel supply pipe 11 is prevented, and fail-safe when the regulator 6 is abnormal is achieved.

The pressure-regulated natural gas supplied to the injection fuel supply pipe 11 is injected from the injector 10 into the combustion chamber of the CNG engine 9 based on the injector drive signal from the injector driver 13. This injection fuel supply pipe 11
Is mounted with a fuel pressure sensor 7 and a fuel temperature sensor 12. The fuel pressure sensor 7 detects the fuel pressure of the pressure-regulated natural gas supplied to the injector 10, and the fuel temperature sensor 12 controls the pressure supplied to the injector 10. The temperature of natural gas (hereinafter referred to as "fuel temperature") is detected. Then, the detected fuel pressure and fuel temperature are input to the ECU 8.

The ECU 8 operates using a voltage of a battery 15 (hereinafter, referred to as "battery voltage") applied through an ignition switch (hereinafter, referred to as "IG switch") 14 as a power source, and includes a CPU 8a, a ROM 8b,
It includes an input circuit, an output circuit, a power supply device and the like (not shown) in addition to the RAM 8c.

The ECU 8 outputs a shutoff valve control signal for controlling the opening and closing of the shutoff valve 5 to the shutoff valve 5 based on the fuel pressure detected by the fuel pressure sensor 7 and other various input signals. For example, when the IG switch 14 is ON or the CNG engine 9 is rotating, a control signal (opening valve ON output) for opening the shutoff valve 5 is output. On the other hand, regulator 6
When the fuel pressure exceeds a predetermined first upper limit value (for example, 680 kPa) due to a failure due to some factor, the shut-off valve 5
A signal for shutting off (a shutoff valve OFF output) is output.

That is, the fuel pressure of the pressure-regulated natural gas is constantly monitored by the ECU 8. If the fuel pressure of the pressure-regulated natural gas rises abnormally, the shut-off valve 5 is closed before the mechanical guard of the regulator 6 is activated. This stops the supply of natural gas. Then, when the fuel pressure decreases, the shut-off valve is turned on again.
An output signal is output to open the shutoff valve 5, and the supply of natural gas is restarted. Thus, even if the fuel pressure of the pressure-regulated gas fuel cannot be properly controlled, the vehicle can continue to run by opening and closing the shutoff valve 5.

The ECU 8 also controls the amount of natural gas injected from the injector 10 to the CNG engine 9 as in a well-known gasoline engine. Specifically, EC
In U8, besides fuel pressure and fuel temperature, for example, engine speed, vehicle speed, crank position, air flow rate, throttle opening, etc.
Various signals are input, the amount of fuel required for operation of the CNG engine 9 is calculated from these input signals, and the result is used as an injector drive signal as an injector driver 13.
Output to In the injector driver 13, the ECU 8
Injector 1 based on the injector drive signal from
0 controls the injection of natural gas properly. Specifically, for example, if the fuel pressure of the pressure-regulated natural gas detected by the fuel pressure sensor 7 is high, the energization time of the injector 10 is shortened to shorten the injection time, and if the fuel pressure is low, the injector 1
The energization time of 0 is lengthened to lengthen the injection time. Further, for example, the energization time of the injector is corrected according to the fuel temperature detected by the fuel temperature sensor 12.

Further, the ECU 8 also corresponds to the abnormality detecting device of the present invention, and executes a shut-off valve abnormality determining process for detecting an abnormality of the shut-off valve 5. If it is determined that the shut-off valve 5 is abnormal by executing the shut-off valve abnormality determination process, the non-volatile RAM (backup RA
M) 8c is recorded to that effect, and the warning light 16 provided in the instrument panel on the front of the cab is also turned on. The details of the shutoff valve abnormality determination process will be described later.

Next, the operation of the gas fuel supply device of this embodiment will be described with reference to FIGS. CPU8
a, after turning on the IG switch 14 (ON position ON, the same applies hereinafter), at predetermined time intervals (for example, 8 msec.), a ROM 8b in which a plurality of programs are recorded stores a shut-off valve control processing program and a shut-off valve abnormality detection processing program. reading,
The processing is executed according to this program. FIG. 2 is a flowchart of the shut-off valve control process, FIG. 3 is a flowchart showing details of the shut-off valve abnormality determination process in the shut-off valve control process shown in FIG. 2, and FIG. 5 is a time chart showing the operation of the device (when the shut-off valve 5 is normal), and FIG. 5 is a time chart showing the operation of the gas fuel supply device of FIG. 1 (when the shut-off valve 5 is abnormal).

Hereinafter, a description will be given of a state in which the engine remains stopped only by turning on the IG switch 14 (t = t _{0 to} t ₂ in FIGS. 4 and 5). FIG.
And, regarding the state of each flag in FIG. 5, “1” indicates a state where the flag is set, and “0” indicates a state where the flag is reset.

When the IG switch 14 is turned on (t = t ₀ in FIGS. 4 and 5), the determination end flag and the normal flag are reset, and the shutoff valve control process starts. At this time, the regulated natural gas is already at a predetermined pressure (about 400 kP
This indicates that the pressure-regulated natural gas from the previous run remains in the injected fuel supply pipe 11 as it is. That is, in the CNG vehicle of the present embodiment, the regulated natural gas is always supplied to the injection fuel supply pipe 11 during traveling, and the fuel is injected by the injector 10 from there. At this time, when the engine is stopped, fuel injection is not performed, and the shutoff valve 5 is also closed as described later, so that the pressure-regulated natural gas in the injection fuel supply pipe 11 remains almost as it is. . Also, as shown in FIGS. 4 and 5, before the IG switch 14 is turned on, the normal flag is set and the abnormal flag is reset. Is determined.

Then, as shown in FIG. 2, first, in S110, the IG on counter is incremented. The IG on counter is for checking the elapsed time after the IG switch 14 is turned on, and a fixed time (8 msec.) Elapses every time the IG on counter is incremented.

After incrementing the IG on counter in S110, the process proceeds to S120, in which it is determined whether the fuel pressure of the pressure-regulated natural gas is equal to or lower than a predetermined first upper limit (680 kPa) (that is, whether the regulator 6 is normal). to decide. As described above, in the regulator 6, the high-pressure (about 19.6 MPa) natural gas filled in the gas tank 1 is reduced to a predetermined pressure (about 400 kPa). Therefore, if the regulator 6 is normal, the fuel pressure of the regulated natural gas will not exceed the first upper limit (680 kPa).

Therefore, as long as the fuel pressure of the pressure-regulated natural gas does not exceed the predetermined first upper limit (680 kPa), it is determined that the regulator 6 is normal and the process proceeds to S130. If so, it is determined that the regulator 6 is abnormal, and the process proceeds to S160, where the normal control cutoff valve ON flag is reset. Here, FIGS. 4 and 5
As shown in the figure, since the fuel pressure is maintained at the predetermined pressure (about 400 kPa), an affirmative determination is made in S120, and S13
Go to 0.

In S130, it is determined whether or not the CNG engine 9 is rotating. Starting the CNG engine 9
As is well known, the operation is performed by setting the IG switch 14 to the start position STA and starting a starter (not shown). Here, since the CNG engine 9 has not been started yet, C
It is determined that the NG engine 9 has not yet rotated (that is, the IG switch 14 is on, but the starter has not been started yet), and the process proceeds to S140.

In S140, the IG is determined based on the count value of the IG on counter incremented in S110.
After the switch 14 is turned on, a predetermined ON duration (for example, 2
Seconds). If it is within the predetermined ON duration, the process proceeds to S150 and the normal control cutoff valve O
Although the N flag is set, if the predetermined ON duration has been exceeded, the routine proceeds to S160, where the normal control cutoff valve ON flag is reset. Here, since the IG switch 14 has just been turned on, an affirmative determination is made in S140, and the process proceeds to S150. Then, in S150, the normal control cutoff valve ON flag is set. After the normal control cutoff valve ON flag is set in S150, the process proceeds to S170, and a cutoff valve abnormality determination process (see FIG. 3 for details) is performed. Then, after the end of the shutoff valve abnormality determination processing, the process proceeds to S180.

In the shutoff valve abnormality judging process (see FIG. 3), the state of the judgment end flag is first judged in S310. This flag is set only in S390 after the abnormality or the normality of the shutoff valve 5 is judged. Because it is
Here, a negative determination is made and the process proceeds to S320. In S320, it is determined whether the vehicle is in a stable state. Here, the “stable state” refers to a state in which the rotation of the CNG engine 9 is in a steady state and is stable, and a vehicle stability condition such as a decrease in rotation speed is satisfied (for example, a stable idle state). State). Therefore, in this case, since the CNG engine 9 has not been started yet, S3
At 20, a negative determination is made and the routine proceeds to S400 and subsequent steps. S400
Then, the determination flag is reset, and in S410, the abnormality detection counter is reset. Then, the process proceeds to S180 of the normal shutoff valve control process (see FIG. 2). The determination flag and the abnormality detection counter will be described later in detail.

In S180, it is determined whether or not the determination flag is being set. However, since the determination flag has been reset in S400, a negative determination is made and the process proceeds to S190. That is, as described later, when the CNG engine 9 is not rotating, the abnormality determination of the shutoff valve 5 is not performed, and the determination in-progress flag is not set, so that the process proceeds to S190.

In S190, the state of the normal control cutoff valve ON flag is determined. Normal control shut-off valve ON at S150
If the flag has been set, the process proceeds to S210,
A shutoff valve ON output signal is output from the ECU 8 to the shutoff valve 5. Thereby, the shut-off valve 5 is opened, and the supply of the natural gas is started. If a negative determination is made in S120 and the normal control shutoff valve ON flag is reset, a negative determination is made in S190 and the routine proceeds to 220, where a shutoff valve OFF output signal is output from the ECU 8 to the shutoff valve 5. That is, in this case,
The closed state of the shutoff valve 5 will be continuously maintained.

That is, when the IG switch 14 is turned on (t = t ₀ ), the shut-off valve control is executed as described above, and the shut-off valve 5 is opened. The shut-off valve control process is executed every predetermined time (for example, 8 msec.) As described above. However, after the IG switch 14 is turned on, a predetermined on-duration (for example, 2 seconds) is performed according to the above-described flow. Will be repeated.

However, if a predetermined ON continuation time (for example, 2 seconds) elapses after the IG switch 14 is turned on (t = t ₁ in FIGS. 4 and 5), a negative determination is made in S140, and the process proceeds to S160. move on. In S160, the normal control cutoff valve ON flag is reset. Therefore, S19
In the determination process of 0, a negative determination is made and the process proceeds to S220. Then, in S220, the shut-off valve OFF output signal becomes E
The signal is output from the CU 8 to the shutoff valve 5, and the shutoff valve is closed.
Thereafter, as long as the CNG engine 9 does not start, the shut-off valve 5 remains closed.

That is, in the control of the shut-off valve 5 as described above (control before starting the engine), the IG switch 14
Is turned on, the normal control cutoff valve ON flag is set and the cutoff valve 5 is turned on for at least the ON duration (for example, 2 seconds).
Is opened to supply high-pressure natural gas in the gas cylinder 1. During this time, the natural gas passes through the shut-off valve 5 and is regulated by the regulator 6, and then is injected into the injection fuel supply pipe 11.
And the injector 10 is ready for natural gas injection. Then, after the lapse of the ON duration, C
When the NG engine 9 has not been started, the shutoff valve 5 is closed and the supply of the natural gas is temporarily stopped. At this time, although the shutoff valve 5 is closed, the injection fuel supply pipe 11 is already supplied with pressure-regulated natural gas having an appropriate fuel pressure.
That is, the NG engine 9 can be started.

Next, by starting the further starter from the state where the IG switch 14 is turned on, if the CNG engine 9 is started for (see t ₂ later in FIGS. 4 and 5) will be described. At t = t ₂ , when the rotation of the CNG engine 9 starts due to the starter start, thereafter, it is determined that there is an input of the engine speed in the determination of S130 in the shut-off valve control process (see FIG. 2) (positive). Judgment), the process proceeds from S130 to S150, and the normal control shutoff valve is turned on.
Set a flag. Then, the process proceeds to a shutoff valve abnormality determination process in S170.

In the shutoff valve abnormality determination process (see FIG. 3), C
Nevertheless NG engine 9 is started, such as immediately after start-up there is a variation in engine speed, since the vehicle is not in a stable state, the vehicle until the stable state (up to t ₃ in FIG. 4 and FIG. 5) is, As before the engine is started, a negative determination is continuously made in S320. Therefore, in this shutoff valve abnormality determination processing, the same processing as before the engine start is performed, and then S1
Go to step 80 (see FIG. 2). In S180, as described above, since the determination is not yet made, a negative determination is made, and the process proceeds to S190. At this time, since the normal shut-off valve ON flag is set again (S150) by the start of the CNG engine 9 as described above, an affirmative determination is made in S190, the process proceeds to S210, and the shut-off valve ON output signal is sent from the ECU 8 to the shut-off valve 5 Output to As a result, after the IG switch 14 is turned on, the shut-off valve 5 which has been once closed due to the elapse of the ON duration is opened again, and the supply of the natural gas is restarted.

Thereafter (after t = t ₂ ), the same processing is repeated until the vehicle is in a stable state, but when the vehicle is in a stable state (t = t ₃ in FIGS. 4 and 5),
As described below, abnormality determination of the shutoff valve 5 is started.
That is, when the vehicle is in a stable state at t = t ₃ , an affirmative determination is made in S320 in the shutoff valve abnormality determination process (see FIG. 3) in S170 during the shutoff valve control process, and the process proceeds to S330. S3
In S30, the state of the determination flag is determined. However, when the process proceeds to S330 for the first time after the vehicle is in a stable state, the determination flag is not set as a matter of course.
The process proceeds to 0, where the determination flag is set for the first time.
This means that the abnormality determination of the shutoff valve 5 has been started.

Then, the process proceeds to S180 of the normal shutoff valve control process (see FIG. 2). In S180, since the determination flag is set, the flow proceeds to S240 to turn off the shutoff valve.
The ECU 9 outputs the output to the shutoff valve 5, and the supply of the natural gas to the downstream side of the shutoff valve 5 is stopped. That is, once the determination flag is set, the cutoff valve 5 is always closed regardless of the state of the normal control cutoff valve ON flag.

This shut-off valve control processing is repeatedly performed at predetermined time intervals (for example, 8 msec.) After the IG switch 14 is turned on until a certain determination result is obtained, as described above.
In After determination flag is set as the blocking valve abnormality determining process (t = t ₂ later in FIGS. 4 and 5) (see FIG. 3), as long as the vehicle is stable state S3
An affirmative determination is made in 30 and the process proceeds to S340 and thereafter.

In S340, it is determined whether the fuel pressure of the pressure-regulated natural gas is equal to or lower than a predetermined reference value (for example, 300 kPa). The determination reference value is not limited to the above value, and is a value that does not hinder normal traveling even if the fuel pressure decreases to that value (in other words, a value that allows the fuel injection amount from the injector 10 to be appropriately controlled). Any value is acceptable.

Here, if the shut-off valve 5 is normal, the shut-off valve 5 is in a closed state during the judgment.
The natural gas inside will not be supplied. Therefore, if the rotation of the CNG engine 9 continues in this state, the pressure-regulated natural gas in the injection fuel supply pipe 11 gradually decreases, and the fuel pressure also decreases.

Therefore, in S340, it is determined whether or not the fuel pressure of the pressure-regulated natural gas drops to the reference value.
Immediately after the shut-off valve 5 is closed, usually, the fuel pressure does not suddenly decrease but gradually decreases. Therefore, for a while after the shut-off valve 5 is closed, the state in which the fuel pressure is higher than the determination reference value continues. Therefore, in this state (t = t ₃ to
t ₄ ) is negative at S340 and proceeds to S350.
The abnormality detection counter is incremented. This abnormality detection counter is for checking the elapsed time after the shut-off valve 5 is closed by the start of the determination.

Then, the flow proceeds to S360, and determines whether or not the value of the counter incremented in S350 is equal to or more than a predetermined value.
That is, the elapsed time after the shut-off valve is closed is the predetermined determination time t.
_j (see FIG. 4) This determination time t _j is the time sufficient to fuel pressure regulating natural gas fuel cutoff valve 5 to close the shut-off valve 5, if it is normal is reduced to the determination reference value, a slight margin Is anticipated. If the predetermined time t _j has not elapsed, the process proceeds to S430 and subsequent steps again. That is, after the determination flag is set again (S430), the process proceeds to S180 of the normal shut-off valve control process, and the affirmative determination is made in S180, and the process proceeds to S240. Output to As a result, the shutoff valve 5 is kept closed.

Accordingly, the above-described processing is repeated until the determination time t _j elapses after the start of the determination of the shut-off valve 5, but when the fuel pressure falls below the determination reference value (FIG. 4). At t ₄ ), S3 is performed in the shutoff valve abnormality determination process of FIG.
The process proceeds from S40 to S380, and the normal flag is set.
In other words, shut-off valve OF for closing the shut-off valve 5 at t = t ₃
After the output of F is output from the ECU 8, the fuel pressure of the pressure-regulated natural gas has become equal to or less than the determination reference value. Therefore, the shutoff valve 5 is normal (that is, it can be reliably closed by the control signal from the ECU 8). Therefore, the normality flag is set based on the result, and the normality of the shutoff valve 5 is determined. This normal flag is reset every time the IG switch 14 is turned on.

On the other hand, when the shut-off valve 5 has an ON failure,
Even if the shut-off valve OFF output signal is output from the ECU 8 to the shut-off valve 5, the shut-off valve 5 is not closed. Therefore, (t = t ₃ subsequent steps in FIG. 5) determined after the start of the shut-off valve 5, the fuel pressure even after the lapse of the determination time t _j is does not become the determination reference value (e.g. 300 kPa) or less. Therefore, the judgment time t _j elapses (t = t _{5 in} FIG. ₅ ).
Then, an affirmative determination is made in S360 (see FIG. 3) and S37
The process proceeds to 0, an abnormality flag is set, and it is determined that the shut-off valve 5 has an ON failure (abnormality determination). The history of the ON failure is stored in the backup RAM 8c. The warning light 16 is turned on together with the setting of the abnormality flag, thereby notifying the driver of the vehicle that an abnormality has occurred.

An abnormality determination (S370) or a normal determination (S
After one of the determinations in step 380) is performed, the process proceeds to S390, in which a determination end flag indicating that the abnormality determination of the shutoff valve 5 has been completed is set. Thereafter, the determination flag is reset in S400, and the abnormality detection counter is reset in S410.

Then, the process proceeds to S180 of the normal shut-off valve control process (see FIG. 2). At this time, since the determination has already been completed and the determination flag has been reset, S190
Proceed to. In S190, as described above, the state of the normal control cutoff valve ON flag is determined. As long as the regulator 6 is normal and the CNG engine 9 is rotating, the normal control cutoff valve ON flag is always set (S150). Therefore, the process proceeds to S210, and the ECU 8 outputs the shut-off valve ON output to the shut-off valve 5. As a result, the shutoff valve 5 is opened again, and the supply of the natural gas is restarted.

Thereafter, the shutoff valve control process is repeated every predetermined time (for example, 8 msec.). However, as described above, the regulator 6 is normal (YES in S120) and the CNG engine 9 is rotating (S130). As long as the determination is affirmative, the normal control cutoff valve ON flag is set (S150).
Then, in the shutoff valve abnormality determination processing (S170: see FIG. 3), since the determination end flag is set, an affirmative determination is always made in S310, and S310 to S40.
0, and then S in the normal shut-off valve control process.
The processing proceeds in the order of 180, S190, and S210. In other words, even after the determination of the shutoff valve 5 is completed, the shutoff valve control process is continuously performed, and the process proceeds to the shutoff valve abnormality determination process of S170 (see FIG. 3) each time the execution is performed, but the abnormality determination process is not substantially performed. . Then, since a negative determination is always made in S180, the state of the normal control cutoff valve ON flag is determined, and the operation of the cutoff valve 5 is controlled.

When the CNG engine 9 is stopped, a negative determination is made in S130 and the routine proceeds to S140, where the IG
If it is determined that the ON duration (for example, 2 seconds) has elapsed after the switch 14 is turned on, a negative determination is made in S140, and the process further proceeds to S160 to reset the normal control cutoff valve ON flag. Therefore, in the subsequent processing,
A negative determination is made in S190, and the process proceeds to S220, in which a shutoff valve OFF output is output, and the shutoff valve 5 is closed.
Thus, when the CNG engine 9 is stopped, the shutoff valve 5 is also closed.

Even if the CNG engine 9 is rotating, if the fuel pressure exceeds a predetermined first upper limit value (680 kPa) due to an abnormality of the regulator 6 (No in S120), the routine proceeds to S160, where normal control is performed. By resetting the shut-off valve ON flag, the shut-off valve 5 is controlled to be closed.

That is, in the abnormality detecting device of the present embodiment,
As shown in FIGS. 4 and 5, after the CNG engine 9 is started (t = t ₂ ), when the vehicle is in an idling state and the vehicle is in a stable state (t = t ₃ ), the shutoff valve 5 is forcibly turned on. A shut-off valve OFF output signal is output to close the valve, and it is determined whether or not the fuel pressure of the regulated natural gas decreases. And the shutoff valve 5
Is normal and the shut-off valve is securely closed by the shut-off valve OFF output signal, the fuel pressure gradually decreases. Therefore, it is determined that the shut-off valve 5 is normal when the fuel pressure falls below a predetermined reference value (FIG. 4). T ₄ ). On the other hand, when the shut-off valve 5 is on-failed, the shut-off valve 5 is not completely closed despite the output of the shut-off valve OFF output signal, so that the supply of natural gas is continued and the fuel pressure does not decrease. . for that reason,
After the output of the shut-off valve OFF output signal, it is determined that the shut-off valve 5 is abnormal based on the fact that the fuel pressure does not decrease even after the determination time t _j has elapsed (t _{5 in} FIG. ₅ ).

As described above, the determination of the normal or abnormal state of the shut-off valve 5 is made only once each time the IG switch 14 is turned on in order to minimize the influence on the vehicle running.
Although the fuel pressure of the pressure-regulated natural gas is lowered by forcibly turning off the shut-off valve 5 during the determination, as described above, this fuel pressure reduction is performed within a range that does not hinder normal traveling. However, it is not preferable for traveling to reduce the fuel pressure only for the purpose of determining the shutoff valve 5 many times during traveling. Therefore, it is desirable that the determination process of the shutoff valve 5 be performed only once each time the IG switch 14 is turned on.

In step S32 in the shut-off valve abnormality determination process,
In the process of 0, it is determined whether or not the vehicle is in a stable state because, for example, immediately after the CNG engine 9 starts, the rotation of the CNG engine 9 has just started, and the shut-off valve 5 is forcibly closed. This is because, for example, when the level of the fuel pressure before starting the engine is not sufficient, the rotation of the CNG engine 9 may be stopped.

Therefore, according to the above gas fuel supply device, the shut-off valve OFF output signal is supplied to the shut-off valve 5 during the supply of natural gas.
The abnormality (ON failure) of the shutoff valve 5 can be determined only by determining whether or not the fuel pressure of the pressure-regulated natural gas falls below the determination reference value. Therefore, it is possible to reliably detect the ON failure of the shut-off valve 5 with the component configuration of the conventional gas fuel supply device without newly adding a component or the like to determine the abnormality of the shut-off valve 5.

Further, whether the shutoff valve 5 is normal or abnormal is determined as follows.
When the vehicle is in a stable state, that is, in an idling state in which the CNG engine 9 is rotating stably with a relatively low speed and little change in the number of revolutions, the shut-off valve OFF output signal is output. 9 is performed only once each time the engine is started, and is not repeatedly performed after the result of the determination of normal or abnormal, so that the ON failure of the shut-off valve 5 is detected without hindering the running of the CNG vehicle. It can be performed.

Further, when it is determined that the shut-off valve 5 has an ON fault, the warning light 16 notifies the driver or the like that the ON fault has occurred. This allows the person or the like to know immediately, and to promptly cope with the failure.

In this embodiment, each of the first high-pressure gas pipe 2, the second high-pressure gas pipe 3, and the low-pressure gas pipe 4 corresponds to the fuel supply path of the present invention, and the regulator 6 corresponds to the fuel pressure of the present invention. The fuel pressure sensor 7 corresponds to the fuel pressure detecting means of the present invention, the shutoff valve 5 corresponds to the fuel shutoff means of the present invention, the ECU 8 corresponds to the shutoff control means, the forced shutoff means, and the abnormality determination of the present invention. The shutoff valve ON output signal and the shutoff valve OFF output signal correspond to a shutoff control signal or a forced shutoff signal of the present invention.

The embodiments of the present invention are not limited to the above-described embodiments at all, and it goes without saying that various embodiments can be adopted as long as they fall within the technical scope of the present invention. For example, the gas cylinder 1 may have a configuration in which a shutoff device capable of controlling the supply and cutoff of CNG to the outside by a control signal from the ECU 8 is provided. The abnormality detecting device of the present invention may be configured to detect the abnormality of the shutoff device inside the gas cylinder 1 configured as described above, similarly to the shutoff valve 5.

The abnormality detection device of the present invention is not limited to CNG vehicles, but can be applied to all types of gas-fueled vehicles such as vehicles using LNG (liquefied natural gas) or LPG (liquefied petroleum gas) as fuel. In any case, the same operation and effect as those of the above-described embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of a gas fuel supply device of a CNG vehicle to which the present invention is applied.

FIG. 2 is a flowchart of a shutoff valve control process.

FIG. 3 is a flowchart showing details of a shutoff valve abnormality determination process in the shutoff valve control process shown in FIG. 2;

FIG. 4 is a time chart showing the operation of the gas fuel supply device of FIG. 1 (when the shut-off valve is normal).

FIG. 5 is a time chart showing the operation of the gas fuel supply device of FIG. 1 (when the shut-off valve is abnormal).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Gas cylinder 1a ... Manual valve 1b ... CNG filling port 2 ... 1st high pressure gas pipe 3 ... 2nd high pressure gas pipe 4 ... Low pressure gas pipe 5 ... Shutoff valve 6 Regulator 6a Relief valve 7 Fuel pressure sensor 8 ECU 9 CNG engine 10 Injector 11 Injected fuel supply pipe 12 Fuel temperature sensor 13 Injector driver 14 IG switch, 15 Battery 16 Warning light

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 21/02 311 F02M 21/02 311L F02B 43/00 F02B 43/00 A F02M 37/00 F02M 37/00 J 341 341D

Claims (5)

[Claims] 1. A fuel supply path for supplying gaseous fuel from a fuel tank to a predetermined combustion device, and a fuel supply path provided in the middle of the fuel supply path and controlling a pressure of the gaseous fuel supplied from the fuel tank to a predetermined value. Fuel pressure adjusting means for adjusting pressure, fuel pressure detecting means for detecting the pressure of the pressure-regulated gas fuel downstream of the fuel pressure adjusting means in the fuel supply path, and upstream of the fuel pressure adjusting means in the fuel supply path A fuel shutoff means for shutting off the gas fuel flowing into the fuel pressure adjusting means based on a shutoff control signal; and a pressure of the pressure regulated gas fuel detected by the fuel pressure detecting means being a predetermined upper limit value. And a shut-off control means for outputting the shut-off control signal to the fuel shut-off means to shut off the fuel supply path when An abnormality detection device for detecting an abnormality of a stage, wherein a forced shutoff signal for forcibly closing the fuel supply path is output to the fuel shutoff means when the fuel shutoff means is controlled to an open state. Shut-off control means, when the pressure of the pressure-regulated gas fuel does not become lower than a predetermined determination reference value even after a predetermined time has elapsed after the forced shut-off signal is output to the fuel cut-off means by the forced cut-off control means. Abnormality detecting means for determining that the fuel cutoff means is abnormal. 2. The gas fuel supply device is provided in a gas-fueled vehicle equipped with an internal combustion engine driven by the gas fuel, and the pressure-regulated gas fuel is supplied to the internal combustion engine. Item 2. An abnormality detection device for a gas fuel supply device according to Item 1. 3. The abnormality detection device for a gas fuel supply device according to claim 2, wherein said forced cutoff control means outputs said forced cutoff signal when said internal combustion engine is in an idle state. 4. The fuel supply system according to claim 2, wherein the determination of the abnormality of the fuel cut-off unit by the operation of the forced cut-off control unit and the abnormality determination unit is performed only once every time the internal combustion engine is started. Abnormality detection device for gas fuel supply device. 5. An abnormality notifying means for notifying a driver or the like that an abnormality has occurred when the abnormality determining means determines that the fuel cutoff means is abnormal. 4. An abnormality detection device for a gas fuel supply device according to any one of 4).