JP3480108B2 - Gas engine fuel leak detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting fuel leakage from a fuel supply line of a gas engine that uses a gaseous fuel such as CNG (compressed natural gas).

[0002]

2. Description of the Related Art As a conventional gas engine, for example, the one shown in FIG. 8 is known (Actual exploitation 63-12).
5155, etc.).

This is to store a plurality of fuel cylinders (fuel tanks) 1 as a gas fuel supply source in a vehicle trunk room or the like, and to supply the fuel from the fuel cylinders 1 to an emergency shutoff valve 3 provided in a fuel pipe 2 and fuel. It is sent to the fuel injector 7 installed in the intake pipe 6 of the engine through the cut valve 4 and the regulator 5 for reducing the pressure of the fuel to a predetermined pressure.

The fuel injector 7 is drive-controlled by a drive signal from the control unit 8 to control the fuel injection amount.

A catalyst 10 is interposed in the exhaust pipe 9, and engine exhaust gas is purified by the catalyst 10 and released to the atmosphere.

[0006]

However, in such a conventional device, even if a fuel leak occurs in the fuel supply line from the fuel cylinder 1 to the fuel injector 7, it cannot be detected. It was.

When the fuel leak is slight, the driver may not notice the leak, and if the driver continues driving as it is, there is a problem that fuel consumption deteriorates.

An object of the present invention is to provide a detection device capable of accurately detecting such a fuel leak.

[0009]

A first aspect of the present invention is directed to a regulator 5 for supplying gas fuel from a fuel tank 50 as shown in FIG.
The fuel temperature on the fuel tank 50 side is detected in a gas engine that includes a fuel supply line that reduces the pressure via 1 and sends it to the fuel injector 52, and an injection control unit 53 that outputs a drive signal for injecting fuel to the fuel injector 52. A temperature sensor 54, a pressure sensor 55 that also detects the fuel pressure, a tank fuel consumption amount calculation unit 56 that calculates the fuel amount of the fuel tank 50 that has been consumed in a predetermined period based on these detected values, and a synchronization period. Injected fuel amount calculation means 57 for calculating the amount of fuel injected from the fuel injector 52, fuel leakage determination means 58 for determining the presence or absence of fuel leakage from the fuel supply line based on these calculated values, and the temperature sensor
54 of the fuel tank 50 based on the detection values of 54 and the pressure sensor 55.
The volume change is calculated, and based on this calculated value, the fuel tank 50
And means for correcting the fuel amount .

[0010]

[0011]

[0012]

A second aspect of the invention is to add gas fuel from a fuel tank.
Fuel that is decompressed via the regulator and sent to the fuel injector
To inject fuel into the fuel supply line and fuel injectors.
Gas engine having injection control means for outputting a motion signal
Temperature sensor for detecting the fuel temperature on the fuel tank side at
And a pressure sensor that also detects fuel pressure,
Based on the detected value of the
In the same period as the tank fuel consumption amount calculation means for calculating the amount of fuel
Injection that calculates the amount of fuel injected from the fuel injector
Fuel amount calculation means and the fuel supply line based on these calculated values
Fuel leakage determining means for determining the presence or absence of fuel leakage from the engine
If the calculated outlet pressure of the regulator on the basis of the detection value of the pressure sensor is provided and means for correcting the fuel injection amount of the fuel injector based on the calculated value.

[0014]

A third aspect of the invention is to add gas fuel from a fuel tank.
Fuel that is decompressed via the regulator and sent to the fuel injector
To inject fuel into the fuel supply line and fuel injectors.
Gas engine having injection control means for outputting a motion signal
At the temperature sensor that detects the fuel temperature on the fuel tank side.
And a pressure sensor that also detects fuel pressure,
Based on the detected value of the
In the same period as the tank fuel consumption amount calculation means for calculating the amount of fuel
Injection that calculates the amount of fuel injected from the fuel injector
Fuel amount calculation means and the fuel supply line based on these calculated values
Fuel leakage determining means for determining whether or not there is fuel leakage from the
In addition to the above, the fuel leakage determination means has a stop time determination means for determining fuel leakage based on the fuel amount in the fuel tank when the engine is stopped and the fuel amount in the fuel tank when restarted.

[0016]

In the first aspect of the invention, the fuel consumption amount of the tank is calculated by the fuel consumption amount calculation means of the tank on the basis of the fuel temperature and the fuel pressure, and the fuel consumption amount calculation means of the injection fuel amount is calculated by the injection fuel amount calculation means. The amount of fuel injected from the fuel injector is calculated, and the fuel leakage is determined by comparing the consumed fuel amount and the injected fuel amount. In this case, warm
Fuel tank volume based on the values detected by the temperature sensor and pressure sensor
The change is calculated, and the fuel amount in the fuel tank is calculated based on this calculated value.
As it is corrected, the fuel can be accurately
The fuel quantity in the tank is calculated.

[0017]

[0018]

[0019]

According to the second aspect of the present invention, the tank fuel consumption amount calculation
Depending on the stage, the fuel is
The amount of fuel consumed from the tank is calculated, and the amount of injected fuel is calculated.
Is injected from the fuel injector during the same period by the output means.
Fuel amount is calculated and the consumed fuel amount and injected fuel
Fuel leakage is determined by comparison with the charge. This place
In this case, the outlet pressure of the regulator is calculated based on the detected value of the pressure sensor, and the injected fuel amount is corrected based on this calculated value. That is, when the pressure on the fuel tank side changes, the outlet pressure of the regulator fluctuates and affects the injection amount of the fuel injector, but since the fluctuation of the outlet pressure is corrected, the injected fuel amount can be calculated accurately. .

[0021]

In the third invention, the consumed fuel amount and the injected fuel amount
The fuel leakage is determined by comparing the fuel amount in the fuel tank when the engine is stopped and the fuel amount in the fuel tank when restarting the engine.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 20 is an engine body, 21
Is a fuel tank as a supply source for accumulating gas fuel such as CNG, and 22 is a fuel injector installed in an intake pipe 23 of the engine.

The fuel from the fuel tank 21 is supplied to the fuel pipe 2
The fuel is sent to the fuel injector 22 via the emergency cutoff valve 25, the fuel cut valve 26, and the regulator 27 provided in FIG.

The fuel cut valve 26 is closed by the control unit 28 when the engine is stopped. The regulator 27 is set to reduce the pressure of the fuel sent to the fuel injector 22 to a predetermined pressure.

The fuel tank 21 or the fuel pipe 24 near the fuel tank 21 is provided with a temperature sensor 30 for detecting the fuel temperature and a pressure sensor 31 for detecting the fuel pressure. The control unit 28 together with signals from respective sensors for detecting engine operating conditions such as rotation speed and accelerator opening (engine load) and an engine key switch (not shown).
Entered in.

Based on these signals, the control unit 28 controls the fuel injection amount of the fuel injector 22 and monitors the fuel leakage of the fuel supply line from the fuel tank 21 to the fuel injector 22.

A catalyst 33 for purifying the exhaust gas and an oxygen sensor 34 for feeding back the oxygen concentration in the exhaust gas to the injection amount control of the fuel injector 22 are installed in the exhaust pipe 32 of the engine. The fuel pipe 21 is connected to the fuel tank 21.
A gas fuel inlet 35 is formed in the vicinity of, and an opening / closing valve 36 and a check valve 37 are provided in the middle thereof.

Fuel injection amount gi of the fuel injector 22
Is controlled by determining the pulse width wi of the drive pulse signal based on the operating conditions of the engine, the signal of the oxygen sensor 34, and the like, and outputting the drive pulse signal to the fuel injector 22.

The pulse width wi and the injection amount gi have a relationship as shown in FIG. 2 when the fuel supply pressure is constant. Therefore, data of the injection amount gi can be obtained from the pulse width wi.

The fuel leakage in the fuel supply line is monitored by checking the fuel amount G injected from the fuel injector 22 in a predetermined period.
i is compared with the fuel amount (fuel consumption amount) Gt of the fuel tank 21 consumed in the same period.

Fuel amount in fuel tank 21 (remaining fuel amount) Gt
i is calculated from the fuel temperature Ti, the fuel pressure Pi, and the volume Vi of the fuel tank 21, and the fuel consumption amount Gt of the fuel tank 21 in a predetermined period is the remaining fuel amount Gt0 at the beginning of the period and the remaining fuel amount at the end of the period. It is calculated from the difference from Gt1.

In this case, the volume Vi of the fuel tank 21 is
Since it changes depending on the fuel temperature Ti and the fuel pressure Pi, the residual fuel amount Gti in the fuel tank 21 is corrected based on the volume change.

The volume Vi of the fuel tank 21 is calculated by the following equation (1).
Calculated by (3) (for a cylindrical tank).

Vi = V ₀ + ΔVp + ΔVt (1) = V ₀ {(1 + αΔT) ³ + (5-4ν) rPi / 2Et} (2) = f (Pi, Ti) (3) However, V ₀ ; reference tank volume ΔVp; Volume change due to pressure ΔVt; Volume change due to temperature α; Linear expansion coefficient ΔT; Temperature change ν; Poisson's ratio r; Tank radius E; Young's modulus t; Thick fuel tank tank residual fuel amount Gti Is calculated by the following equation (4) from the volume Vi, the fuel temperature Ti, and the fuel pressure Pi.

Gti = Pi × Vi / R × Ti (4) where R: total gas amount G of fuel injected from the fuel injector 22 during a predetermined gas constant period
i is obtained by integrating the pulse width wi of the drive pulse signal output to the fuel injector 22 during the period and converting it into an injection amount. Alternatively, the pulse width wi may be converted into the injection amount and then integrated.

In this case, the fuel whose pressure has been reduced to a predetermined pressure by the regulator 27 is sent to the fuel injector 22, but the inlet pressure of the regulator 27 (fuel tank 21
Side pressure) and outlet pressure (fuel injector 22 side pressure)
Has a correlation as shown in FIG. 3 due to the characteristic of the regulator 27. Therefore, based on the fuel pressure Pi, the fuel injector 2
The injection amount gi of 2 (when converting the pulse width wi into the injection amount gi) is corrected.

The pressure on the fuel injector 22 side, that is, the supply pressure Pinj to the fuel injector 22 is obtained from the characteristic of the regulator 27 by the fuel pressure Pi, and the injection amount gi is corrected by the following equation (5).

Gi = gi [before correction] × (Pinj / P ₀ inj) (5) where P ₀ inj; reference set pressure by regulator 27 Next, detection of fuel leakage by control unit 28 in FIGS. A flow of processing will be shown and described.

In steps 1 and 2, the fuel pressure Pi and the fuel temperature Ti are read from the sensors 31 and 30 on the fuel tank 21 side.

In steps 3 and 4, the remaining fuel amount Gt0 (remaining amount of the measurement start tank) of the fuel tank 21 is calculated in the initial stage of engine startup (formulas (1) to (4)).

In steps 5 and 6, the fuel injector 2
The pulse width wi of the drive pulse signal output to 2 is read, and this is converted into the injection amount gi.

In steps 7 and 8, the supply pressure Pinj to the fuel injector 22, which is set to be reduced by the regulator 27, is calculated from the fuel pressure Pi, and the supply pressure Pinj is calculated.
Thus, the injection amount gi is corrected (formula (5)).

In step 9, the injection amount gi of the fuel injector 22 is integrated to calculate the total injection fuel amount Gi.

In step 10, it is judged whether or not it is the fuel leak judgment timing, and if it is the judgment timing, the routine proceeds to step 11. The judgment timing is after starting the engine,
It is set every time a predetermined time has elapsed.

At step 11, the current remaining fuel amount Gt1 in the fuel tank 21 is calculated (formula (1)-
(4)).

In steps 12 and 13, the fuel tank 21
Call the remaining fuel amount Gt0 at the beginning of the
From the difference between 0 and the current remaining fuel amount Gt1, the fuel tank 21
The fuel consumption amount Gt is calculated.

In step 14, the fuel consumption amount Gt of the fuel tank 21 and the fuel injector 2 obtained in step 10
2 is compared with the total injected fuel amount Gi of the fuel injector 21 and the consumed fuel amount Gt of the fuel tank 21 is calculated as follows.
When it is larger than i, it is determined that there is a fuel leak from the fuel supply line.

If it is determined that there is a fuel leak, the process proceeds to step 15 to warn the driver of the fuel leak. this is,
The driver installed in the vehicle blinks or the driver recognizes the sound.

In steps 16 and 17, when the determination is completed, the fuel injector 22 is started to start the next detection.
The total injected fuel amount Gi is cleared and the remaining fuel amount Gt1 in the fuel tank 21 is rewritten to the initial remaining fuel amount Gt0.

As described above, by calculating the total injected fuel amount of the fuel injector 22 and the consumed fuel amount of the fuel tank 21 for a predetermined period and comparing them, whether or not there is fuel leakage from the fuel supply line. Can be determined.

Further, since the fuel amount in the fuel tank 21 is corrected according to the change in the volume of the fuel tank 21 and the injection amount of the fuel injector 22 is corrected according to the characteristic of the regulator 27, the total injected fuel of the fuel injector 22 is corrected. The amount and the amount of fuel consumed in the fuel tank 21 can be accurately calculated, and the fuel leakage can be accurately determined.

Therefore, when there is a fuel leak, a warning is given by an indicator or voice so that the driver does not continue driving without noticing the fuel leak and it is possible to prevent deterioration of fuel consumption. The property is improved.

The fuel leakage may be monitored during a predetermined period during high speed traveling. Since there is little change in the pulse width of the drive signal of the fuel injector 22 during steady operation such as high-speed traveling, the injection amount of the fuel injector 22 can be accurately obtained and high accuracy can be secured.

Further, it is possible to determine the fuel leak by measuring the residual fuel amount in the fuel tank 21 when the engine is stopped and the residual fuel amount in the fuel tank 21 at the time of restart and comparing them. You can In this case, fuel leakage can be detected while the engine is stopped, so reliability is further improved.

FIG. 6 shows another embodiment of the present invention. This is because the fuel supply pressure (Pin to the fuel injector 22 is between the regulator 27 and the fuel injector 22).
The supply pressure sensor 40 for detecting j) is provided, and the injection amount of the fuel injector 22 is obtained from the pulse width of the drive pulse signal based on the detected value.

When the fuel supply pressure changes, the injection amount of the fuel injector 22 changes as shown in FIG. 7. By doing so, a more accurate injection amount of the fuel injector 22 can be obtained. In addition, an accurate injection amount can be obtained even with a pressure change at the time of transition such as sudden acceleration, and the fuel leak detection accuracy is further improved.

[0059]

According to the first invention as described above, according to the present invention, in a gas engine using a gaseous fuel, the fuel leakage can be detected, it is possible to prevent the deterioration of fuel efficiency, in this case, the fuel
The amount of fuel consumed in the tank can be measured accurately, and fuel leakage can be detected.
The output accuracy is improved .

[0060]

[0061]

[0062]

According to the second aspect of the present invention, the injection amount of the fuel injector can be accurately obtained, and the fuel leak detection accuracy is improved.

[0064]

According to the third invention, it is possible to detect fuel leakage even when the engine is stopped.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a characteristic diagram of a pulse width of a fuel injector and an injection amount.

FIG. 3 is a characteristic diagram of a regulator.

FIG. 4 is a flowchart of a detection process.

FIG. 5 is a flowchart of a detection process.

FIG. 6 is a configuration diagram of another embodiment.

FIG. 7 is a characteristic diagram of a pulse width and an injection amount of a fuel injector depending on a difference in fuel supply pressure.

FIG. 8 is a configuration diagram of a conventional example.

FIG. 9 is a block diagram of the invention.

[Explanation of symbols]

20 engine body 21 Fuel tank 22 Fuel injector 24 Fuel piping 25 Emergency shutoff valve 26 Fuel cut valve 27 Regulator 28 Control unit 30 temperature sensor 31 Pressure sensor 40 Supply pressure sensor

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toyoaki Nakagawa 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Ryuichi Idoguchi 2 Takara-cho, Kanagawa-ku, Yokohama, Japan Nissan Motor Co., Ltd. In-company (56) References JP-A-8-93564 (JP, A) Actual development 63-190555 (JP, U) Actual development 62-165458 (JP, U) (58) Fields investigated (Int.Cl . ⁷ , DB name) F02M 21/02 F02B 77/08 F02M 37/00

Claims (3)

(57) [Claims] 1. A gas engine comprising a fuel supply line for depressurizing gas fuel from a fuel tank via a regulator and sending it to a fuel injector, and an injection control means for outputting a drive signal for injecting fuel to the fuel injector. A temperature sensor for detecting the fuel temperature on the side, a pressure sensor for similarly detecting the fuel pressure, and a tank fuel consumption amount calculation means for calculating the fuel amount of the fuel tank consumed in a predetermined period based on these detected values, , An injection fuel amount calculation means for calculating the amount of fuel injected from the fuel injector during the same period, a fuel leakage determination means for determining the presence or absence of fuel leakage from the fuel supply line based on these calculated values, and the temperature sensor.
Change in fuel tank volume based on sensor and pressure sensor detection values
Is calculated, and the fuel amount in the fuel tank is corrected based on this calculated value.
A fuel leak detection device for a gas engine, which is provided with: 2. A regulator for gas fuel from a fuel tank
Supply line that reduces pressure via the fuel and sends it to the fuel injector
And output a drive signal for fuel injection to the fuel injector
In a gas engine equipped with injection control means
Same as the temperature sensor that detects the fuel temperature on the fuel tank side
A pressure sensor that detects the fuel pressure and the detected values
To calculate the amount of fuel in the fuel tank that was consumed in a given period
Tank fuel consumption amount calculation means and the fuel injection
Fuel amount calculator that calculates the amount of fuel injected from the engine
And the fuel from the fuel supply line based on these calculated values.
A fuel leak judging means for judging whether or not there is a leak, and the pressure sensor
Calculate the outlet pressure of the regulator based on the detected value of the sensor.
Correct the fuel injection quantity of the fuel injector based on the calculated value of
A fuel leak detection device for a gas engine, which is provided with a means for 3. A regulator for gas fuel from a fuel tank
Supply line that reduces pressure via the fuel and sends it to the fuel injector
And output a drive signal for fuel injection to the fuel injector
In a gas engine equipped with injection control means
Same as the temperature sensor that detects the fuel temperature on the fuel tank side
A pressure sensor that detects the fuel pressure and the detected values
To calculate the amount of fuel in the fuel tank that was consumed in a given period
Tank fuel consumption amount calculation means and the fuel injection
Fuel amount calculator that calculates the amount of fuel injected from the engine
And the fuel from the fuel supply line based on these calculated values.
A fuel leak determining means for determining the presence or absence of a leak is provided together.
To the fuel leakage determining hands stage, when the engine is stopped
Fuel Tank Fuel Volume and Fuel Tank Fuel Volume at Restart
A fuel leak detection device for a gas engine having a stop time determination means for determining a fuel leak based on the above .