JP2003286903A - Fuel control device for fuel gas vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel control device for a fuel gas vehicle capable of preventing an error determination on fuel leakage caused by a close failure of a container main valve. <P>SOLUTION: When the close failure of either of the container main valves of two fuel vessels is detected, a determination value α is increased (step S150). Even if a lowering speed of fuel pressure is increased due to the close failure of either of the container main valves at a state that an engine is operated at the same fuel consumption speed, the determination on the fuel leakage is accurately performed. Accordingly, the error determination of presence of the fuel leakage due to the close failure of the container main valve can be prevented. As a result, an occurrence of situations such as giving an unneeded warning to a passenger lighting on a warning lamp owing to the error determination on the fuel leakage and unnecessarily halting the vehicle can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for a gas fuel vehicle capable of supplying a gas fuel such as compressed natural gas (CNG) stored in a plurality of fuel containers to an internal combustion engine.

[0002]

2. Description of the Related Art Generally, in a gas-fueled vehicle equipped with a plurality of fuel containers, the gas fuel in the fuel container of the plurality of fuel containers whose container main valve is open is delivered through a fuel supply path to a delivery pipe. And is injected by the injector of each cylinder. Further, in this gas fuel vehicle, it is possible to detect the closing failure of the container main valve provided in each of the plurality of fuel containers, and when the fuel pressure decrease speed in the fuel supply path exceeds a preset determination value, It is determined that there is a fuel leak. For example, in the gas fuel leak detection device disclosed in Japanese Unexamined Patent Publication No. 9-242614, when the pressure change amount of the gas fuel during traveling of the vehicle is equal to or larger than a predetermined value (determination value), there is a gas fuel leak. judge. The term "close failure" as used herein means that the container valve does not open due to a failure.

Further, the above judgment value for judging fuel leakage is
Although it depends on the vehicle and engine, the maximum fuel consumption rate of the engine is generally used as a guide. That is, it is determined that there is fuel leakage when the fuel pressure reduction rate is greater than the fuel pressure reduction rate when the engine is operating at the maximum fuel consumption rate. Further, normally, when it is determined that there is a fuel leak, the warning lamp is turned on, the fuel is not supplied to the engine, and the vehicle is stopped.

[0004]

By the way, in the above-mentioned prior art, when a fuel container out of a plurality of fuel containers has a closing failure, the gas fuel in the fuel container is not supplied to the engine. Since the effective volume of the fuel system (container effective volume) decreases, the fuel pressure decrease rate increases even when the engine is operating at the same fuel consumption rate.
Therefore, when a certain fuel container has a closing failure, there is a possibility that the fuel pressure decrease rate exceeds the determination value and a fuel leak is erroneously determined, although there is no fuel leakage. When the fuel leak is erroneously determined in this way, the warning lamp is turned on to give an unnecessary warning to the occupant even if there is no fuel leakage, and the vehicle is stopped unnecessarily.

The present invention has been made in view of such conventional problems, and an object thereof is to prevent a gas fuel from being erroneously determined due to a closing failure of a container valve. It is to provide a fuel control device for a vehicle.

[0006]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. The invention according to claim 1 is applied to a gas fuel vehicle capable of supplying a gas fuel stored in each of a plurality of fuel containers to an internal combustion engine. In the fuel control device for a gas fuel vehicle, which can be individually detected, and is determined to have fuel leakage when the fuel pressure decrease rate exceeds a preset fuel leakage determination value, one of the plurality of fuel containers The gist is to provide a judgment value changing means for increasing the judgment value when a closing failure of the container valve is detected.

According to this structure, when the closing failure of the container valve of any one of the plurality of fuel containers is detected, the judgment value changing means increases the judgment value of the fuel leakage. Therefore, the fuel leak determination can be performed accurately even if the fuel pressure decrease rate increases while the engine is operating at the same fuel consumption rate due to the closing failure of the container source valve. Therefore, it is possible to prevent erroneous determination that there is fuel leakage due to the closing failure of the container valve. As a result, it is possible to avoid a situation in which a warning lamp is turned on to give an unnecessary warning to an occupant or the vehicle is stopped unnecessarily due to an erroneous determination of fuel leakage.

According to a second aspect of the present invention, in the fuel control system for a gas fuel vehicle according to the first aspect, the judgment value changing means is a fuel container in which the container valve is normal among the plurality of fuel containers. The gist is to increase the judgment value of the fuel leak as the container effective volume, which is the sum of the volumes of, becomes smaller.

According to this structure, the fuel leak determination value is increased as the container effective volume, which is the sum of the volumes of the fuel containers in which the container valve is normal among the plurality of fuel containers, becomes smaller. Therefore, the fuel leak determination value can be changed according to the container effective volume. That is, as the number of fuel containers in which the container valve has a failure increases and the container effective volume decreases, the determination value increases. Therefore, the fuel leak determination can be accurately performed according to the state of the fuel system, that is, the container effective volume that is the sum of the normal volume of the fuel container.

According to a third aspect of the present invention, in the fuel control system for a gas fueled vehicle according to the first or second aspect, a closed valve for sequentially determining whether or not there is a closing failure of the container valve for all of the plurality of fuel containers. The determination value changing means includes a failure determination means and a container effective volume calculation means for calculating a container effective volume that is the sum of the volumes of the fuel containers determined by the determination means to be not a closing failure of the container source valve. The gist is to change the judgment value of the fuel leakage according to a value obtained by dividing the total volume of the plurality of fuel containers by the container effective volume.

According to this structure, the presence or absence of the closing failure of the container main valve is sequentially determined for all of the plurality of fuel containers, and the container effective is the sum of the volumes of the fuel containers determined not to have the closing failure of the container main valve. The volume is calculated, and the judgment value of the fuel leakage is changed according to the value obtained by dividing the total volume of the plurality of fuel containers by the container effective volume. As a result, it is possible to accurately detect the container effective container, which is the sum of the volumes of the fuel containers determined to have no closing failure of the container source valve, and divide the total volume of the plurality of fuel containers by the container effective container. It is possible to accurately change the judgment value of fuel leakage according to the value. Therefore, the fuel leak determination can be performed accurately according to the effective container volume.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a fuel control device for a gas fuel vehicle embodying the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a fuel control device for a gas fuel vehicle according to one embodiment. This fuel control device is applied to a gas fuel vehicle equipped with a 6-cylinder engine that uses compressed natural gas (CNG) as fuel. This gas-fueled vehicle has two fuel containers 11 and 12 each storing compressed natural gas (hereinafter, simply referred to as “gas fuel”).
Is installed. The fuel containers 11 and 12 are respectively provided with container main valves 13 and 14, and when the container main valves 13 and 14 are opened, the fuel containers 11 and 12 and the pipe 15 communicate with each other. The gas fuel inside is supplied to the pipes 15, respectively. Further, both container main valves 13 and 14 are connected to a filling coupler 19 via a pipe 16, a three-pronged connector 17, and a pipe 18, and the filling coupler 19 supplies the gas fuel to the fuel container 1.
1 and 12 can be filled respectively.

The container main valves 13 and 14 are electromagnetic valves, respectively. The container main valves 13 and 14 are opened and closed by the ECU 20.
Are controlled respectively. Further, the fuel containers 11 and 12 are respectively provided with container fuel temperature sensors 21 and 22 for detecting the temperature of the gas fuel on the outlet side of each container. The temperatures of the gas fuel detected by the container fuel temperature sensors 21 and 22 are respectively taken into the ECU 20.

The gas fuel supplied from the fuel containers 11 and 12 to the pipe 15 is supplied to the regulator main body 26 via the three-pronged connector 23, the pipe 24 and the regulator cutoff valve 25. In addition, the pipes 15, 16,
The 18 and the three-pronged connecting tool 23 form a high-pressure pipe 27.

The regulator body 26 includes a fuel container 11,
The pressure of the gas fuel supplied from 12 through the high pressure pipe 27 is reduced to a constant pressure. The regulator cutoff valve 25 is composed of a solenoid valve or the like, and the opening and closing thereof is performed by the ECU 2
It is controlled by 0. In addition, the regulator body 26 includes an inlet side of the regulator shutoff valve 25,
That is, the primary side fuel pressure sensor 28 for detecting the primary side fuel pressure is provided. The fuel pressure detected by the primary fuel pressure sensor 28 is taken into the ECU 20.

The gas fuel depressurized to a constant pressure by the regulator main body 26 is supplied to the low pressure pipe 29 and the delivery cutoff valve 30.
It is adapted to be supplied to the delivery pipe 31 via. The gas fuel supplied to the delivery pipe 31 is sent to each of the six injectors 33 provided for each cylinder, and each injector 33 supplies each intake air of the engine 10 in an appropriate amount at an appropriate timing according to the engine operating state. It is injected into the passage or each combustion chamber. The injection timing and the injection amount are obtained by the ECU 20 controlling the electromagnetic solenoid of each injector 33 according to the engine operating state.

The delivery pipe 31 has a fuel temperature sensor 34 for detecting the fuel temperature inside the pipe and a fuel pressure sensor 35 for detecting the fuel pressure at the inlet side or inside the pipe.
And are provided.

A microcomputer or the like is mounted on the ECU 20. The microcomputer is configured as a logical operation circuit including an A / D converter (not shown), a CPU that executes various arithmetic processes, a ROM that stores various control programs, and a RAM that stores various data. .

Further, the ECU 20 uses the container main valves 13, 14
The above-mentioned closing failure is detected by detecting disconnection of the coil. In addition, the ECU 20 determines the fuel pressure at the inlet side of the regulator cutoff valve 25 detected by the primary fuel pressure sensor 28, that is, the fuel pressure decrease rate in the high-pressure pipe 27 (fuel pressure decrease rate), in which fuel leakage is determined in advance. When the value is exceeded, it is determined that there is a fuel leak.

That is, the fuel pressure decrease rate is calculated by the following equation 1.

[0022]

[Formula 1] Further, the fuel pressure decrease rate dPcnggh becomes maximum when the fuel consumption rate Gf becomes maximum. The maximum value of the fuel pressure decrease rate dPcngh is calculated by the following equation 2.

[0023]

[Formula 2] Here, dPcnghmax is the fuel pressure decrease rate dPc
The maximum value of ngh, Gfmax is the maximum value of the fuel consumption speed Gf.

Therefore, the fuel pressure decrease rate dPcng
When h exceeds the maximum value dPcnghmax, there is a suspicion of fuel leakage. On the other hand, when the container valve of the i-th fuel container (volume Vi) of the plurality of fuel containers (two fuel containers 11 and 12 in this example) has a closing failure, the fuel pressure decrease rate is It is calculated by the following Equation 3. The fuel pressure decrease rate dPcngh at this time becomes larger than that when none of the container source valves have a closing failure.

[0025]

[Formula 3] For this reason, when the container valve 13 or 14 of either of the two fuel containers 11 and 12 has a closing failure, it is necessary to change the fuel leak determination value.

Next, the "fuel leakage determination value changing process" executed by the ECU 20 will be described with reference to the flowchart shown in FIG. This process is repeatedly executed at a predetermined control cycle.

First, in step S100, the initial value of the fuel container number i and the initial value of the container effective volume V are set to "0". Next, in step S110,
Increment the number i.

Next, in step S120, the container main valve 1 of the i-th fuel container, here the first fuel container 11, is placed.
It is determined whether or not 3 has a closing failure. If the container source valve 13 is not closed, the process proceeds to step S130, where the container volume V1 of the fuel container 11 is set to the container effective volume V.
Set as. That is, since the initial value of the container effective volume V is set to "0", the container effective volume V set at this time is equal to the container volume V1.

On the other hand, in step S120, if the first (i-th) container valve 13 has a closing failure, step S130 is skipped and the process proceeds to step S140. This is because the first (i) th container valve 1
This is because the gas volume in the first fuel container 11 is not supplied to the high-pressure pipe 27 when the valve 3 has a closed failure, so that the container volume V1 is not added to the container effective volume V.

In step S140, it is determined whether i has reached n. In this example, since the number of fuel containers is two (n = 2), it is determined whether i has reached 2. If not reached, the process returns to step S110 to continue the routine. If i has reached 2, the process proceeds to step S150,
A fuel leak determination value α is calculated. Here, when the system is normal, that is, when the container main valves 13 and 14 do not have a closing failure, the fuel leak determination value α0 is set to the total volume of the fuel system (total volume of the fuel container). S13
A fuel leakage determination value α is calculated by multiplying the value by dividing the container effective volume V set at 0. The determination value α0 is determined and set in advance by experiments or the like.

By executing such "fuel leak determination value changing processing", when neither of the container main valves 13 and 14 has a closing failure, the container effective volume V is the total volume of the fuel system, that is, Volume sum of fuel containers 11 and 12 (V1
+ V2), and the fuel leak determination value α remains unchanged and is equal to the determination value α0. Also, the first fuel container 11
In the case where the container main valve 13 has a closing failure, the container effective volume V becomes equal to the container volume V2 of the fuel container 12, and the determination value α becomes the determination value α0 and the total volume of the fuel system (V1
+ V2) / volume V2 (container effective volume V) is multiplied. That is, the determination value α is the container main valve 13, 1
In each of the four cases, the value is set to be larger than that in the case where no closing failure occurs.

Further, the container main valve 1 of the second fuel container 12
4 has a closing failure, the container effective volume V becomes equal to the container volume V1 of the fuel container 11, and the judgment value α
Is changed to a value obtained by multiplying the determination value α0 by the value of the total volume of the fuel system (V1 + V2) / volume V1 (container effective volume V). That is, the determination value α is changed to a value larger than that in the case where neither the container valve 13 or 14 has a closing failure.

When both the container main valves 13 and 14 have a closing failure, it is not necessary to judge the fuel leakage. Incidentally, the determination value α at this time becomes “0”. Note that step S120 corresponds to the closing failure determination means. Further, step S130 corresponds to the container effective volume calculating means. Then, step S150 corresponds to the judgment value changing means.

According to one embodiment configured as described above, the following operational effects are exhibited. (A) When the closing failure of the container valve 13 or 14 of one of the two fuel containers 11 and 12 is detected, the fuel leak determination value α is increased (step S150). Therefore, even if the fuel pressure decrease rate dPcngh becomes large while the engine 10 is operating at the same fuel consumption rate Gf due to the closing failure of either of the container main valves 13 and 14, the fuel leak determination can be performed accurately. You can Therefore, it is possible to prevent erroneous determination that there is fuel leakage due to the closing failure of the container valve.

As a result, it is possible to avoid a situation in which a warning lamp is turned on to give an unnecessary warning to an occupant or the vehicle is stopped unnecessarily due to an erroneous determination of fuel leakage.

(B) The smaller the container effective volume V, which is the sum of the volumes of the fuel containers whose normal valves 13 and 14 are normal among the two fuel containers 11 and 12, becomes smaller, the larger the fuel leak determination value α becomes. . Therefore, the fuel leak determination value α can be changed according to the container effective volume V. That is, as the number of fuel containers in which the container valve has failed increases and the container effective volume V decreases, the determination value increases. Therefore, the fuel leak determination can be accurately performed according to the state of the fuel system, that is, the container effective volume V that is the sum of the volumes of the normal fuel containers.

(C) For the two fuel containers 11 and 12, the presence / absence of the closing failure of the container source valve is sequentially determined, and the sum of the volume of the fuel containers (V1 + V2) determined to have no closing failure of the container source valve.
The effective container volume V is calculated, and the fuel leakage determination value α is changed according to the value obtained by dividing the total volume of the two fuel containers by the effective container volume V. As a result, the container effective volume, which is the sum of the volume of the fuel containers, can be accurately detected, and the fuel leakage determination value is determined according to the value obtained by dividing the total volume (V1 + V2) of the two fuel containers by the container effective volume V. It is possible to change α accurately. Therefore, the fuel leak determination can be accurately performed according to the container effective volume V.

[Modification] The present invention can be modified and embodied as follows. In the above-described one embodiment, an example in which it is applied to a gas-fueled vehicle using compressed natural gas (CNG) as a fuel has been shown.
Gas fuel other than NG, such as liquefied petroleum gas (LPG),
It is also applicable to gas fueled vehicles using dimethyl ether (DME), hydrogen, etc. as fuel.

In the above-mentioned one embodiment, an example in which it is applied to a gas fuel vehicle equipped with a 6-cylinder engine is shown, but the present invention is also applicable to a multi-cylinder engine other than the 6-cylinder engine. The present invention is also applicable to a bifuel vehicle that uses both the above-mentioned various types of gas fuel and gasoline.

In the above embodiment, two fuel containers 1
Although the example in which the present invention is applied to the gas fuel vehicle in which 1 and 12 are mounted is shown, the present invention is also applicable to the gas fuel vehicle in which a plurality of fuel containers other than 2 are mounted.

In the above-described embodiment, the rate of decrease in fuel pressure at the inlet side of the regulator shutoff valve 25 detected by the primary fuel pressure sensor 28 (fuel pressure decrease rate) exceeds a preset fuel leak determination value α. However, the present invention is not limited to such a configuration. If the rate of decrease in fuel pressure on the inlet side or inside the delivery pipe 31 detected by the fuel pressure sensor 35 exceeds a preset fuel leakage determination value α, it may be determined that there is fuel leakage.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an entire fuel control device for a gas fuel vehicle according to an embodiment.

FIG. 2 is a flowchart showing a fuel leak determination value changing process executed by the fuel control device.

[Explanation of symbols]

10 ... Engine as internal combustion engine, 11, 12 ... Fuel container, 13, 14 ... Vessel main valve.

Claims (3)

[Claims] 1. A gas fuel vehicle capable of supplying a gas fuel stored in each of a plurality of fuel containers to an internal combustion engine, and individually detecting a closing failure of a container source valve provided in each of the plurality of fuel containers. In the fuel control device for a gas fuel vehicle, which is possible and determines that there is fuel leakage when the fuel pressure decrease rate exceeds a preset fuel leakage determination value, a container source valve of any one of the plurality of fuel containers is provided. A fuel control device for a gas fuel vehicle, comprising: a judgment value changing means for increasing the judgment value when the closing failure is detected. 2. The determination value changing means increases the determination value of the fuel leakage as the container effective volume, which is the sum of the volumes of the fuel containers in which the container source valve is normal among the plurality of fuel containers, becomes smaller. The fuel control device for a gas fueled vehicle according to claim 1, wherein 3. A closure failure determination means for sequentially determining whether or not there is a closure failure of the container source valve for all of the plurality of fuel containers, and a fuel container for which the determination means determines that the container source valve is not a closure failure. And a container effective volume calculating means for calculating a container effective volume that is the sum of the volumes of the plurality of fuel containers, the determination value changing means, according to a value obtained by dividing the total volume of the plurality of fuel containers by the container effective volume. The fuel control device for a gas fueled vehicle according to claim 1 or 2, wherein a judgment value of fuel leakage is changed.