JPH0882250A - Gas fuel leakage preventing device for vehicle - Google Patents

Abstract

PURPOSE: To realize a gas fuel leakage preventing device for vehicle which can cope in case that a fuel supplying system is damaged by a vehicle collision. CONSTITUTION: In a control unit 30, a vehicle collision is detected on the basis of an acceleration change signal of a prescribed value or more from an acceleration sensor 60 provided on a vehicle, and when such an acceleration change of the prescribed value or more is detected, it is judged that an engine 1 received a damage of the extent of damage or more, and fuel supply cutoff valves 52, 53 are controlled to be immediately closed. Thus, at a vehicle collision, high pressure gas fuel can be prevented from being leaked into the engine room or to the outside of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas fuel leakage prevention device for a vehicle equipped with a gas fuel engine.

[0002]

2. Description of the Related Art As a conventional vehicle fuel gas leakage prevention device, there is, for example, a device disclosed in Japanese Utility Model Laid-Open No. 62-21459. This is a liquefied petroleum gas (LP
G) is a fuel leakage prevention device for a spark ignition type engine, and an opening / closing valve 11 is provided in a fuel supply passage 108 as shown in FIG.
2 is provided and the on-off valve 112 is opened during engine operation, and the on-off valve 112 is closed at the same time when the engine is stopped to prevent gas fuel from leaking to the engine intake system and to the outside. Is to prevent. Further, 101 is a mixer main body, 102 is an intake passage, 103 is a venturi, 104 is a choke valve, 105 is a throttle valve, 106 is a main nozzle, 107 is a lower body, 109 is a fuel inlet port, 110 is a main adjusting screw, 111 is a needle valve and 122 is a solenoid.

Further, as disclosed in Japanese Utility Model Application Laid-Open No. 60-188862, the fuel is inserted in a fuel supply passage from a cylinder storing LPG fuel and a gas fuel return passage to the cylinder under predetermined conditions. Close the supply shutoff valve,
Some are designed to prevent fuel leakage.

[0004]

However, in such a conventional gas fuel leakage prevention device for a vehicle, for example, the occurrence of gas leakage due to damage to the fuel supply system at the time of a vehicle collision is immediately detected. There was no consideration regarding urgent measures to prevent leakage. In other words, conventionally,
The target gas fuel is liquefied petroleum gas (LPG) in most cases, and compressed natural gas (CN) has been actively developed in recent years.
This is because the problem in the case of using G) as a gas fuel was not so remarkable.

That is, the gas pressure of compressed natural gas (CNG) when it is mounted on a vehicle is often less than 10 atm in the case of liquefied petroleum gas (LPG), but often reaches 200 atm. Therefore, for example, when a fuel supply passage or the like is damaged at the time of a vehicle collision and gas fuel leaks, a large amount of gas leaks rapidly.
An air-fuel mixture having a concentration that is easily ignited is easily formed (in the case of LPG, the air-fuel mixture is often diffused before the air-fuel mixture having a concentration that is easily ignited is diffused), and compressed natural gas (CNG) is used as a gas fuel. In such a case, countermeasures for fuel leakage that can be dealt with will be required.

Even when LPG is used as fuel, it is necessary to immediately detect the occurrence of gas leakage due to damage to the fuel supply system in the event of a vehicle collision and urgently prevent the leakage. Further, conventionally, when the engine was started, it was not possible to distinguish whether the gas fuel was leaking due to cranking or the gas fuel was actually leaking due to damage or the like. There is a possibility that the fuel supply cutoff valve may be closed due to a failure.

The present invention has been made in view of such a conventional situation, and prevents the leakage of gas fuel when the vehicle or engine is damaged due to a vehicle collision and the fuel supply system is damaged. An object of the present invention is to provide a gas fuel leakage prevention device for a vehicle that is made possible. It is also an object of the present invention to further increase the certainty of preventing fuel leakage, improve the accuracy of fuel leakage prevention control, or simplify the configuration. Further, it is an object of the present invention to distinguish between leakage of gas fuel due to cranking at engine startup and leakage of gas fuel due to damage or the like so that highly accurate fuel leakage prevention control can be performed.

[0008]

For this reason, the vehicle gas fuel leakage prevention apparatus according to the first aspect of the invention is shown in FIG.
As shown in FIG. 3, a fuel supply cutoff valve A provided in the gas fuel supply system for cutting off the supply of gas fuel, damage detection means B for detecting damage to the vehicle or engine, and damage detection means B for the vehicle or engine. A first for cutting off the supply of gas fuel through the fuel supply cutoff valve A when damage is detected;
The gas fuel supply cutoff means C is provided.

According to the second aspect of the invention, as shown in FIG. 2, the vehicle gas fuel leakage prevention device according to the first aspect further comprises a gas leakage detection means D for detecting a gas fuel leakage. Second gas fuel supply cutoff means E for cutting off the supply of gas fuel through the fuel supply cutoff valve A when the gas leak detection means D detects a leak of gas fuel;
I was prepared.

According to the third aspect of the invention, the damage detecting means B is configured to detect damage to the vehicle or the engine based on a change in vehicle acceleration. In the invention according to claim 4, the damage detecting means B is configured to detect damage to the vehicle or the engine based on the operation of the airbag device. In the invention according to claim 5, the fuel supply cutoff valve A
Is configured to shut off the supply of gas fuel by stopping energization and close the valve, and the damage detection means B is connected to the fuel supply cutoff valve A.
Is configured to detect damage to the vehicle or the engine based on the disconnection of a part of the drive circuit, and the first gas fuel supply cutoff means C is connected to a part of the drive circuit of the fuel supply cutoff valve. When the power supply is stopped, the fuel supply cutoff valve is automatically closed to cut off the gas fuel supply.

According to the sixth aspect of the invention, as indicated by the broken line in FIG. 2, when the engine is started, even if the gas leak detection means D detects a leak of gas fuel for a predetermined period from the start of cranking. The starting fuel supply cutoff prohibiting means F for prohibiting the cutoff of the gas fuel supply by the second gas fuel supply cutoff means E is provided. In the invention according to claim 7, as shown by a broken line in FIG. 2, at the time of starting the engine, for a predetermined period from the start of cranking, a judgment reference value for judging the presence or absence of leakage of gas fuel in the gas leakage detection means D. The gas leak judgment reference value setting changing means G for setting the high value is provided.

According to an eighth aspect of the present invention, there is provided a gas fuel leakage prevention device for a vehicle equipped with an engine equipped with a gas fuel supply system for supplying gas fuel, wherein A fuel supply cutoff valve A for cutting off the supply,
Gas leak detecting means D for detecting leak of gas fuel, and secondly shutting off the supply of gas fuel through the fuel supply shutoff valve A when the leak of gas fuel is detected by the gas leak detecting means D. Even if the gas fuel supply cutoff means E and the gas leak detection means D detect a leak of the gas fuel for a predetermined period from the start of cranking when the engine is started,
Starting fuel supply cutoff prohibiting means F for prohibiting cutoff of the gas fuel supply by the second gas fuel supply cutoff means E;
It is configured to include.

According to a ninth aspect of the present invention, there is provided a gas fuel leakage prevention device for a vehicle equipped with an engine equipped with a gas fuel supply system for supplying gas fuel, wherein A fuel supply cutoff valve A for cutting off the supply,
Gas leak detecting means D for detecting leak of gas fuel, and secondly shutting off the supply of gas fuel through the fuel supply shutoff valve A when the leak of gas fuel is detected by the gas leak detecting means D. The gas fuel supply cutoff means E and the gas leak judgment reference value setting for setting a high judgment reference value for judging the presence or absence of the gas fuel leakage in the gas leak detection means D for a predetermined period from the start of cranking at the time of engine startup. And a changing unit G.

In a tenth aspect of the present invention, when the gas fuel supply system includes a pressure reducing valve for reducing the pressure of the high pressure gas fuel supplied from the fuel tank, the fuel supply cutoff valve A is used as a fuel tank. It is arranged between the pressure reducing valve. In the invention according to claim 11, a plurality of gas fuel supply cutoff valves A are provided from the upstream side to the downstream side of the gas fuel supply system,
When the supply of gas fuel is cut off, the plurality of fuel supply cutoff valves A
Of these, the supply of the gas fuel is shut off in order from the fuel supply shutoff valve A on the upstream side of the gas fuel supply.

[0015]

In the gas fuel leakage prevention system for a vehicle according to the present invention having the above-mentioned structure, the damage detection means is used to predict that the gas fuel supply system will be damaged. When the damage is detected and the damage of the vehicle or the engine is detected, the fuel supply cutoff valve is immediately cut off through the first gas fuel supply cutoff means to cut off the supply of the gas fuel. As a result, for example, when the vehicle or the engine is damaged due to a vehicle collision or the like, and the gas fuel supply system is damaged, the supply of the gas fuel can be immediately shut off via the fuel supply shutoff valve. Therefore, it is possible to reliably prevent the leakage of gas fuel.

The invention according to claim 2 is further provided with gas leakage detection means for detecting the leakage of the gas fuel, and when the leakage of the gas fuel is detected by this means, the second gas fuel supply cutoff means is provided. The fuel supply shut-off valve is shut off via the fuel cell to shut off the gas fuel supply. Thereby, for example, even if the gas fuel supply system is cracked due to something other than a vehicle collision and the gas fuel leaks,
Since the supply of gas fuel can be cut off, the leakage of gas fuel can be prevented more reliably.

According to the third aspect of the present invention, the damage to the vehicle or the engine is detected based on the change in the vehicle acceleration. Therefore, the above-described operation can be performed with high accuracy by a relatively simple structure. In the invention according to claim 4, the damage of the vehicle or the engine is detected based on the operation of the airbag device. Therefore, in the vehicle equipped with the airbag device, a separate special damage detecting means is not provided. Therefore, the configuration can be simplified. Further, since it is based on the operation of the airbag, the determination as to whether or not the vehicle has been damaged is made on the side of the airbag device. Therefore, for example, as in the invention according to claim 3, Therefore, it is not necessary to judge whether the vehicle is damaged or not, so that the configuration can be simplified also in terms of control logic.

In a fifth aspect of the present invention, when the fuel supply cutoff valve is configured to shut off the supply of gas fuel by shutting off the energization, the fuel supply is cut off at the same time when the vehicle or the engine is damaged. Since a part of the drive circuit of the supply cutoff valve is divided, the fuel supply cutoff valve can be closed automatically, which simplifies the structure, reduces the cost, and eventually provides an emergency cutoff. The responsiveness can be improved.

In a sixth aspect of the present invention, when the engine is started, for a predetermined period from the start of cranking, the supply of the gas fuel is shut off even if the gas leak detection means detects the leak of the gas fuel. Try not to. As a result, it is possible to prevent the supply of the gas fuel from being interrupted due to the leakage of the gas fuel from the intake system and the exhaust system during cranking, which prevents the engine from starting.

In a seventh aspect of the present invention, when the engine is started, for a predetermined period from the start of cranking, the determination reference value for determining the presence / absence of gas fuel leakage in the gas leakage detection means is set high. . This makes it possible to consider that leakage of gas fuel from the intake system and exhaust system during cranking is not abnormal gas fuel leakage due to damage to the fuel supply system. It is possible to prevent the supply from being interrupted and thus the engine from being unable to start.

According to an eighth aspect of the present invention, there is provided a fuel supply cutoff valve provided in the gas fuel supply system for cutting off the supply of the gas fuel, and a gas leak detection means for detecting the leakage of the gas fuel. In the case of a gas fuel leakage prevention device for a vehicle, at the time of starting the engine, the supply of gas fuel should be cut off for a predetermined period from the start of cranking even if the leakage of gas fuel is detected by the gas leakage detection means. Try not to. As a result, the intake system during cranking,
It is possible to prevent the engine from being unable to start because the supply of the gas fuel is interrupted due to the leakage of the gas fuel from the exhaust system.

According to a ninth aspect of the present invention, there is provided a fuel supply cutoff valve provided in the gas fuel supply system for cutting off the supply of the gas fuel, and a gas leak detection means for detecting the leakage of the gas fuel. In the case of a gas fuel leakage prevention device for a vehicle, at the time of starting the engine, a high judgment reference value is set for a predetermined period from the start of cranking to determine whether or not the gas fuel leakage is present in the gas leakage detection means. . This makes it possible to consider that leakage of gas fuel from the intake system and exhaust system during cranking is not abnormal gas fuel leakage due to damage to the fuel supply system. It is possible to prevent the supply from being interrupted and thus the engine from being unable to start.

According to the tenth aspect of the present invention, since the fuel supply cutoff valve is provided between the fuel tank and the pressure reducing valve, the fuel supply between the fuel tank and the pressure reducing valve at the time of a collision or the like. It is possible to reliably prevent the high-pressure gas fuel from being supplied to the system, thereby reducing the possibility of gas fuel leakage. . According to the invention of claim 11,
When a plurality of gas fuel supply cutoff valves are provided from the upstream side to the downstream side of the gas fuel supply system, when the supply of gas fuel is cut off, among the plurality of fuel supply cutoff valves, from the fuel supply cutoff valve on the gas fuel supply upstream side in order Since the supply of the gas fuel is cut off, the pressure of the gas fuel remaining in the system can be reduced toward the downstream side of the fuel supply system. That is, if both are shut off at the same time, the high-pressure gas fuel remains in the system, and the leakage of the gas fuel easily occurs, but this can be suppressed.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 3 showing the configuration of the first embodiment, an air cleaner 3 is provided in an intake passage 2 of an engine 1, an air flow meter 4 for detecting an intake air flow rate Q, and a throttle for controlling the intake air flow rate Q in conjunction with an accelerator pedal. A valve 5 is interposed, and an intake manifold 6 is connected downstream of the valve 5. A branch portion 7 that distributes air to each cylinder is provided in the intake manifold 6.
A fuel injection valve 11 for injecting and supplying gas fuel is provided for each. The throttle valve 5 is provided with a throttle sensor 5A that detects the opening degree of the throttle valve 5. Further, the fuel injection valve 11 is valve-opening controlled according to a valve-opening drive pulse signal transmitted from a control unit 30 described later, whereby a predetermined amount of fuel can be injected and supplied.

The fuel used in the engine 1 is, for example,
High-pressure natural gas (CNG), and this high-pressure gas fuel is supplied from the fuel tank 50 mounted on the vehicle 70 to the fuel injection valve 11 via a fuel supply passage 51 such as a pipe. In the middle of the fuel supply passage 51, the fuel supply cutoff valve 5
2, 53 are interposed, and a pressure adjusting valve 54 for adjusting the supply pressure of the gas fuel is provided downstream thereof (see FIG. 4).
reference). The fuel supply cutoff valves 52, 53 are electromagnetic type opening / closing valves (for example, solenoid valves) that are energized to open and then deenergized to close, but the invention is not limited to this, and for example, opening / closing speed may be changed. An opening control valve using a changeable step motor or the like may be used. Further, it is particularly preferable to provide the fuel supply cutoff valve 53 near the outlet of the fuel tank 50 from the viewpoint of reducing the number of leak points.

A distribution passage 55 for distributing fuel to each cylinder is provided on the downstream side of the fuel supply passage 51, and a tip portion of each distribution passage 55 and each branch portion 7 are provided. The fuel injection valve 11 is connected. By the way, the cylinder head 12 of the engine 1 is equipped with a spark plug 13 for each cylinder. The spark plug 13 is ignition-controlled based on an ignition signal from the control unit 30, and the cylinder inside the cylinder at an optimum timing. The air-fuel mixture introduced into is ignited by spark ignition.

The exhaust passage 14 is provided with an air-fuel ratio sensor 15 for detecting the air-fuel ratio of the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas, and further on the downstream side to purify harmful components in the exhaust gas. As an exhaust gas purification catalyst, which is the exhaust gas purification catalyst in the present embodiment, CO and HC in the exhaust gas and NO _x
Although the three-way catalyst 16 that reduces and purifies the catalyst is provided, the present invention is not limited to this, and may be, for example, an oxidation catalyst or a lean catalyst.

In FIG. 3, an auxiliary air introducing valve 8 for maintaining the engine speed at idle optimally, a fast idle adjusting valve 9 for adjusting the engine speed when a load such as an air conditioner is applied, and the like. Air regulator 10
Although it is provided in the intake bypass passage that bypasses the throttle valve 5, these may not be provided in particular.

An ignition coil 18 is connected to the distributor 17 that rotates in synchronization with the cam shaft of the engine 1, and the ignition coil 18 and the spark plug 13 are connected to each other. The distributor 17 includes a crank angle sensor 20.
The control unit 30 counts the crank unit angle signal output from the crank angle sensor 20 in synchronization with the engine rotation for a certain period of time, or measures the cycle of the crank reference angle signal to determine the engine rotation. The speed N can be detected. A water temperature sensor 21 for detecting the cooling water temperature Tw in the cooling jacket of the engine 1 is provided.

Various signals from the above-mentioned sensors necessary for engine control are fetched into the control unit 30 including a microcomputer and the like. In the present embodiment, in addition to the various signals described above, as shown in FIG. 4, an acceleration sensor 60 for detecting a vehicle collision or the like based on the magnitude of a change in the vehicle acceleration is provided in a part of the vehicle body 70. Gas leak sensors 61 and 62 for detecting a gas leak by detecting a gas concentration and the like are provided in the engine room 71 and in the middle of the fuel supply passage 51 while being attached. Signals are also being input.

In the above structure, the air sucked from the air cleaner 3 is measured by the air flow meter 4,
It is introduced into each cylinder through the throttle valve 5 and the intake manifold 6 and the branch portion 7. On the other hand, regarding the supply of gas fuel, when the engine key switch is turned on, the fuel supply cutoff valve 5 is supplied via the control unit 30.
2 and 53 are energized and opened, and the high-pressure gas fuel stored in the fuel tank 50 flows out of the fuel tank 50 and fills the fuel supply passage 51. The fuel tank
The pressure inside 50 reaches over 200 atm,
Up to 54, the same pressure as that in the fuel tank 50 is reached.

This high-pressure gas fuel is decompressed by the pressure adjusting valve (pressure reducing valve) 54 and always has a substantially constant pressure (usually set to 10 atm or less) regardless of the pressure on the upstream side. It is supposed to be maintained. As a result, the injection amount control from the fuel injection valve 11 can be performed with high accuracy. The gas fuel that has been decompressed and has reached the distribution passage 9 is injected and supplied into the branch portion 7 by the fuel injection valve 11, is mixed with air, and is introduced into each cylinder.

The fuel injection amount is set in the control unit 30 as described below. That is,
The intake air flow rate Q is detected by the air flow meter 3, and the engine rotation speed N is detected by the detection signal from the crank angle sensor 20.
Is detected, the basic fuel injection pulse width (corresponding to the basic fuel injection amount) Tp (= k × Q / N, k is a constant) is calculated. Then, the water temperature correction coefficient Kw is determined by referring to a map or the like stored in advance in the control unit 30 based on the signal from the water temperature sensor 21. In addition, the load correction coefficient K _MR is determined based on the signal from the throttle sensor 5A (or the above Tp) and the engine speed N, and various correction coefficients (for example, a wall flow rate correction coefficient, etc.) according to the transient operation or the like. ) Is determined. Further, by detecting the oxygen concentration in the exhaust gas by the air-fuel ratio sensor 15, the air-fuel ratio of the intake air-fuel mixture is detected, and the feedback correction coefficient α set based on the detected air-fuel ratio by another routine.
It is also supposed to be corrected by. It should be noted that a correction according to the supply pressure or the supply temperature of the gas fuel may be included.

Based on the above Tp and various correction terms,
The final fuel injection pulse width (fuel supply amount) Ti is calculated according to the following formula. Ti = Tp × (1 + Kw + K _MR + ...) × α + T
s (Ts is the voltage correction amount of the fuel injection valve 11)] A valve opening drive pulse signal according to the finally determined fuel injection pulse width Ti is sent from the control unit 30 to the fuel injection valve 11 and the engine 1 Gas fuel will be injected and supplied to. The injection timing and the ignition timing are set by the control unit 30 so that the most appropriate timing is selected according to operating conditions and the like. Further, in the present embodiment, a knock sensor 22 is provided, and, for example, when knocking of the engine 1 is detected under a high load or the like, the control unit 30 sets the ignition timing to a predetermined timing in order to prevent occurrence of knocking. Although it is possible to perform delayed knock prevention control, the knock prevention control device need not be provided in particular.

Exhaust gas burned in the cylinder and discharged from an exhaust valve (not shown) is purified by the three-way catalyst 16, silenced through a silencer (not shown), and then discharged into the atmosphere. Will be. Next, the operation stop of the engine 1 (fuel supply stop) will be described. When the engine 1 is stopped, the fuel supply cutoff valves 52 and 53 are closed at the same time when the engine key switch is turned off, so that the fuel supply to the engine 1 is stopped.

The fuel supply shutoff valves 52 and 53 are not closed at the same time, but the fuel supply shutoff valve 52 and the fuel supply cutoff valve 53 are slightly closed.
It is preferable that the high pressure gas does not remain in the fuel supply passage 51. That is, if the upstream fuel supply cutoff valve 52 is closed a little earlier than the downstream fuel supply cutoff valve 53 by adjusting the closing timing (or the closing speed of the fuel supply cutoff valve 52 is The fuel supply cutoff valve 53 is set to be faster than the closing speed, and the fuel supply cutoff valve 52 is set.
The valve closing completion timing may be earlier than the valve closing completion timing of the fuel supply cutoff valve 53), and the residual amount of high-pressure gas in the fuel supply passage 51 can be reduced. In other words, if both are shut off at the same time, high pressure gas fuel will remain in the system, but this can be suppressed.

Next, a case will be described in which the fuel supply shutoff valves 52, 53 are urgently closed in order to prevent the leakage of gas fuel and the occurrence of fire and the like in the event of a vehicle collision or the like. In many cases, the vehicle 70 is damaged and the engine 1 and the fuel supply passage 51 are also damaged due to a vehicle collision or the like.

When a liquid fuel of a gasoline engine or the like is used as a fuel, a material having large elasticity such as a rubber tube is partially used as the fuel supply passage, so that the impact at the time of a collision, the deformation of the fuel supply passage, etc. Because it can absorb
It is possible to reduce the possibility that cracks or the like will occur in the fuel supply passage at the time of a vehicle collision or the like. However, in an engine that uses gas fuel as fuel, particularly in an engine that injects and supplies gas fuel with a fuel injection valve, the pressure in the fuel supply passage is considerably higher than atmospheric pressure, so a material with high elasticity such as a rubber tube is used in the fuel supply passage However, metal pipes and the like are often used. However, since cracks and the like are likely to occur in this metal pipe due to vibrations and the like, it is necessary to firmly fix it to the vehicle or the like, so it is relatively weak against momentary impact and the like.

That is, in the case of the gas fuel engine as in this embodiment, the fuel supply passage 51 is likely to be cracked or broken due to the impact or deformation of the vehicle at the time of collision. Therefore, the control unit 30 detects an acceleration change of a predetermined value or more that occurs at the time of a collision based on the signal from the acceleration sensor 60, and when the acceleration change of the predetermined value or more is detected, the engine 1 is damaged. When it is determined that the impact is greater than the amount to be received (the function corresponds to the damage detection means according to the present invention), the fuel supply cutoff valves 52 and 53 are controlled to be immediately closed (the function is It corresponds to the first gas fuel supply cutoff means according to the present invention).

Thus, it is possible to prevent the high-pressure gas fuel from leaking into the engine room 71 or the outside of the vehicle 70 in the event of a collision. If the vehicle or the engine 1 is not seriously damaged, that is, if the signal from the acceleration sensor 60 does not reach a certain level, the control unit
The 30 does not instruct the fuel supply cutoff valves 52 and 53 to close according to the signal from the acceleration sensor 60, but even in such a case, the fuel supply passage 51 is damaged and the gas fuel leaks. Possibility is considered.

Therefore, the control unit 30 detects the presence / absence of leakage of the gas fuel based on the output signals of the gas leakage sensors 61 and 62, and when it determines that the gas leakage has occurred (the relevant function is , Which corresponds to the gas leak detection means according to the present invention), and controls so that the fuel supply cutoff valves 52 and 53 are immediately closed even if the signal from the acceleration sensor 60 does not reach a certain level (the relevant function is Corresponds to the second gas fuel supply cutoff means according to the present invention).

That is, in addition to damage to the fuel supply passage 51 due to a shock such as a vehicle collision, if the vehicle 70 is used for a long period of time, the fuel supply passage 51 may be corroded or the fuel supply passage 51 may be damaged. If gas fuel leaks due to loosening of the joint part of the gas leak sensor 61, 62
Control unit 30 so that can be detected
Then, irrespective of the signal from the acceleration sensor 60, when any one of the gas leak sensors 61 and 62 detects a gas leak, the fuel supply cutoff valves 52 and 53 are controlled to be closed. On the other hand, when the engine cannot be started easily even after cranking with a starter motor (not shown) at the time of starting the engine (for example, defective spark plug 13),
The gas fuel injected from the fuel injection valve 11 into the branch portion 7 of the intake manifold 6 does not burn, but flows backward in the intake passage 2 and leaks from the air cleaner 3 to the outside, or is exhausted to exhaust the catalyst 16 or noise reduction. May leak to the outside from the vessel.

Therefore, in the control unit 30, in order to prevent the gas fuel from leaking due to a start failure, and to perform a good start in a normal state, a predetermined time (that is, the engine key switch is ON) from cranking start (that is,
Even if the gas leak sensors 61, 62 detect the gas leak, the fuel supply cutoff valve 52, until the start of the normal operation is completed normally and the leaked gas fuel is likely to diffuse)
While prohibiting the valve closing control of 53 (to ensure starting.
This function corresponds to the fuel supply cutoff prohibition means at startup according to the present invention. ), If the gas leak sensors 61, 62 still detect the gas leak after the lapse of the predetermined time, the fuel supply cutoff valves 52, 53 are closed to prevent the gas leak due to a start failure. Control to instruct. Alternatively, control may be performed such that the determination reference value (slice level) for closing the fuel supply cutoff valves 52, 53 is set high within the predetermined time (the function is
It corresponds to the gas leakage determination reference value setting changing means according to the present invention. ) If the acceleration sensor 60 and the gas leak sensors 61, 62 simultaneously send signals to the control unit 30 at a level for closing the fuel supply cutoff valves 52, 53, the acceleration sensor 60 The signal is given the highest priority, and the fuel supply cutoff valves 52 and 53 are promptly closed to surely prevent the occurrence of gas leakage due to a collision or the like.

Now, the valve closing control of the fuel supply cutoff valve as described above will be described with reference to the flowchart of FIG. Step (denoted as S in the figure. The same applies hereinafter) 1
Then, it is detected that the engine key switch is turned on. In step 2, the fuel supply cutoff valves 52 and 53 are opened.

In step 3, it is determined whether or not the starter motor is turned on. The determination can be made based on the presence or absence of voltage supply to the starter motor or the engine key switch being returned from the start position. If YES, it is determined that cunking is being performed, and the process proceeds to step 4. On the other hand, if NO, it is determined that the engine 1 is in operation after the start is completed, and the process proceeds to step 7.

In step 4, it is determined whether or not the detection value (TAS) of the acceleration sensor 60 is larger than a predetermined value (TA). If YES, it is determined that a vehicle collision or the like has occurred, the process proceeds to step 9, the fuel supply cutoff valves 52 and 53 are immediately closed, and this flow ends. If NO, it is determined that a vehicle collision or the like has not occurred, and the process proceeds to step 5.

In step 5, it is judged whether or not the detected value (TGS) of either of the gas leak sensors 61 and 62 is larger than a predetermined value (TG). If YES, go to step 6. If NO, the process returns to step 3 to continue cranking. In step 6, it is judged whether or not the elapsed time from the start of cranking has exceeded a predetermined time. If not, the cranking is continued as it is. It is highly possible that a relatively large amount of gas fuel is exhausted as raw gas or flows backward and leaks to the outside.
Close valves 2 and 53 to end this flow.

Instead of determining whether the elapsed time from the start of cranking exceeds a predetermined time, it is determined whether the number of rotations of the engine from the start of cranking exceeds a predetermined number. Even if it does so, the same effect can be obtained. On the other hand, if NO in step 4, that is, if it is determined that the engine is operating, the process proceeds to step 7. However, in step 7, the detection value (TAS) of the acceleration sensor 60 is equal to a predetermined value (T
A) Judge whether it is larger than or not.

If YES, it is determined that a vehicle collision or the like has occurred, and the routine proceeds to step 9, where the fuel supply cutoff valve 5 is immediately started.
Close valves 2 and 53 to end this flow. If NO, it is determined that a vehicle collision or the like has not occurred, and the process proceeds to step 8 and the detection values (TGS) of the gas leak sensors 61 and 62.
Is larger than a predetermined value (TG). YE
If it is S, it is determined that gas leakage has occurred due to some influence (for example, deterioration of sealability, corrosion, cracking, etc.), and the process proceeds to step 9, and the fuel supply cutoff valves 52, 53 are closed. Then, this flow ends.

If NO, it is determined that the operation can be continued normally, and this flow is ended. By the way, the fuel supply cutoff valves 52 and 53 are connected to the acceleration sensor 60 and the gas leak sensor 6
After the engine is closed urgently based on the signals 1 and 62, once the engine key switch is turned off, the fuel supply cutoff valve 52,
The judgment of the emergency closing of 53 is itself canceled. Thus, if there is no abnormality in the vehicle 70 and the electrical system of the engine 1, the fuel supply cutoff valves 52 and 53 will be opened when the engine key switch is turned on next time.
That is, for example, in order to prevent restarting when the valve is urgently closed due to erroneous diagnosis.

Further, the damage to the vehicle 70 and the engine 1 is great,
Even if the battery or wiring is instantly destroyed and the control unit 30 cannot control the closing of the fuel supply cutoff valves 52, 53, the current that holds the fuel supply cutoff valves 52, 53 in the open state is Since the fuel supply cutoff valves 52 and 53 are closed at the same time, the gas fuel will not leak into the engine room 71 or outside the vehicle even in such a case.

In the above embodiment, the case where one acceleration sensor 60 is used has been described, but a plurality of sensors (a lateral collision or the like can be detected if the acceleration detection direction is changed) are used in the engine room 71 or in the engine room 71. It can be installed in the vehicle 70. In this case, if the collision signal is detected from one sensor, the above control is performed, whereby the detection accuracy is further improved and the leakage of gas fuel is further reduced. Wear. It is also possible to use a signal from a crash sensor or the like in the airbag device.

The gas leak sensors were installed in the lower part of the engine hood in the engine room 71 and in the vicinity of the fuel supply passage 51 below the vehicle 70. However, natural gas has a smaller specific gravity than air, and therefore tends to rise. Therefore, it is needless to say that it is possible to find a place where natural gas easily accumulates and appropriately change the installation positions, or to increase the installation positions.

By the way, in this embodiment, the acceleration sensor 60
However, the present invention is also applicable to the case where only the gas leak sensor is provided for the sake of simplification of the configuration, and in this case, the steps 4 and 7 can be omitted. Such a case corresponds to the invention described in claims 8 and 9. Next, a second embodiment will be described.

In the second embodiment, the operation of an airbag is used as a means for detecting a vehicle collision or the like, instead of the acceleration sensor described in the first embodiment.
The other structure is similar to that of the first embodiment, and the description thereof is omitted. The outline of the circuit diagram according to the second embodiment will be described below with reference to FIG. Three crash zone sensors 108-11 provided on the left, right, and center in front of the vehicle 70
0 and at least one of the tunnel sensors 107 (collision detection in the passenger compartment) provided in the tunnel portion of the vehicle floor, and the safing sensor 103 (misidentified as collision detection in the center portion of the vehicle) provided in the tunnel portion of the vehicle floor. The sensor for preventing the operation) simultaneously operates, so that the inflator (in the airbag module 111) provided in the central portion of the steering wheel (or the instrument panel in front of the passenger seat) is provided via the spiral cables 105 and 106. That is, an ignition current flows through a unit containing an electric igniter, an igniting agent, a nitrogen gas generating agent, etc. (not shown), and an airbag is activated. In addition,
Reference numeral 101 is a battery, and 102 is an engine key switch.

At the same time when the airbag is energized,
By the control unit 104 of the airbag system, the current supplied to the fuel supply cutoff valves 52, 53 is instantaneously cut off, and the supply of gas fuel is cut off. As a result, even when a vehicle collision occurs, it is possible to prevent the gas fuel from leaking into the engine room or outside the vehicle.

Next, the third embodiment will be described. In the third embodiment, as shown in FIG. 7, a part (indicated by a broken line in the figure) 80 of a circuit (harness) for driving and controlling the fuel supply cutoff valves 52, 53 is wired in the engine room 71. So, when the engine room 71 is heavily damaged,
A part 80 of the drive circuit of the fuel supply cutoff valve is damaged at the same time, that is, a part 80 of the drive circuit of the fuel supply cutoff valve is positively damaged (broken), It is designed such that the conduction to 52, 53 is cut off and the valve is closed. Part of the drive circuit for the fuel supply cutoff valve 80
However, it further functions as the damage detection means according to the present invention and the first gas fuel supply cutoff means.

More specifically, FIG. 7 is a view of the engine room 71 as observed from above, showing the fuel supply cutoff valve.
A part 80 of the circuit that drives 52, 53 is wired so as to extend around the inside of the engine room 71. This wiring is firmly fixed to the vehicle and is designed to be broken immediately when the vehicle is deformed. For example, the wiring 80 is divided, and the divided portion is arranged in a container filled with an electrically conductive liquid to ensure continuity, while at the time of a collision, the container is damaged so that the electric conduction from the container is reduced. It is possible to use a material in which the conductive liquid is discharged to disconnect the electrical connection of the wiring 80. Further, the wiring 80 is divided, and the conductive material is pressed across the divided portion via a spring or the like to ensure conduction, while the spring is disengaged during a collision and the electric conductivity is maintained. It is also possible to interrupt the electrical connection of the wiring 80 by cutting off the contact between the material and the dividing portion.

In each of the above embodiments, the fuel injection valve 15 is provided in each cylinder, but the invention is not limited to this.
The present invention is also applicable to a vehicle equipped with an engine configured to supply gas fuel via a mixer or the like, and further has a liquid fuel supply device for supplying gasoline fuel and a gas fuel supply device. It is also applicable to a vehicle equipped with an engine (dual fuel engine) that switches between these types of use. And the gas fuel is compressed natural gas (CNG)
However, it is applicable to a vehicle equipped with an engine using liquefied petroleum gas (LPG), and in this case, a more reliable engine can be used. Moreover, the occurrence of gas leakage can be suppressed. Further, although the fuel supply cutoff valve has been described as having two valves, one fuel supply shutoff valve may be provided, or two or more fuel supply shutoff valves may be provided.

In the above embodiments, the spark ignition type internal combustion engine using gas fuel as the fuel has been described. Of course, if the engine uses gas fuel as the fuel, the compression ignition system and other systems are used. Engine (external combustion engine, etc.)
It is also applicable in.

[0061]

As described above, according to the gas fuel leak prevention system for a vehicle according to the first aspect of the invention, the vehicle or the engine is damaged due to a vehicle collision or the like, and the gas fuel supply system is extended. If the gas is damaged, the supply of the gas fuel can be immediately shut off, so that the leakage of the gas fuel can be reliably prevented.

According to the second aspect of the present invention, the supply of the gas fuel can be interrupted even when the leakage of the gas fuel is detected. Even if a crack or the like occurs and the gas fuel leaks, the supply of the gas fuel can be cut off, so that the leak of the gas fuel can be more reliably prevented. According to the invention of claim 3, damage to the vehicle or the engine is detected based on the change in the vehicle acceleration.
It is possible to prevent leakage of gas fuel with a relatively simple structure and with high accuracy.

According to the fourth aspect of the present invention, the damage to the vehicle or the engine is detected based on the operation of the air bag device. Therefore, in the vehicle equipped with the air bag device, a separate special damage is caused. Since the detection means need not be provided, the structure can be simplified. Further, since it is based on the operation of the airbag, the determination as to whether or not the vehicle has been damaged is made on the side of the airbag device. Therefore, for example, as in the invention according to claim 3, Therefore, it is not necessary to judge whether the vehicle is damaged or not, so that the control logic can be simplified.

According to the fifth aspect of the present invention, when the fuel supply cutoff valve is configured to shut off the supply of gas fuel by shutting off the energization to shut off the supply of the gas fuel, at the same time when the vehicle or the engine is damaged, Since a part of the drive circuit of the fuel supply cutoff valve is divided, the fuel supply cutoff valve can be automatically closed, which simplifies the structure, reduces the cost, and eventually makes an emergency. The blocking response can be improved.

According to the sixth aspect of the present invention, when the engine is started, the leakage of gas fuel is detected by the gas leakage detection means for a predetermined period from the start of cranking,
Since the supply of gas fuel is not cut off, it is possible to prevent the engine from being unable to start because the supply of gas fuel is cut off due to leakage of gas fuel from the intake system and exhaust system during cranking. it can.

According to the seventh aspect of the present invention, when the engine is started, for a predetermined period from the start of cranking, the judgment reference value for judging the presence / absence of leakage of the gas fuel in the gas leakage detection means is set high. Therefore, it is possible to consider that the leakage of gas fuel from the intake system and the exhaust system during cranking is not an abnormal leakage of gas fuel due to damage to the fuel supply system, etc. It is possible to prevent that the fuel supply is cut off and the engine cannot be started.

According to an eighth aspect of the present invention, there is provided a fuel supply cutoff valve provided in the gas fuel supply system for cutting off the supply of the gas fuel, and a gas leakage detection means for detecting the leakage of the gas fuel. In the case of the gas fuel leakage prevention device for a vehicle, the supply of gas fuel is shut off for a predetermined period from the start of cranking even if the gas leakage detection means detects the leakage of gas fuel when the engine is started. Since the operation is not performed, it is possible to prevent the engine from being unable to start because the supply of the gas fuel is interrupted due to the leakage of the gas fuel from the intake system and the exhaust system during cranking.

According to a ninth aspect of the present invention, there is provided a fuel supply cutoff valve provided in the gas fuel supply system for cutting off the supply of the gas fuel, and a gas leakage detection means for detecting the leakage of the gas fuel. In the case of a gas fuel leak prevention device for a vehicle, at the time of engine start, a high judgment reference value is set for a predetermined period from the start of cranking to determine the presence or absence of gas fuel leak in the gas leak detection means. Therefore, leakage of gas fuel from the intake system and exhaust system during cranking can be considered not to be abnormal gas fuel leakage due to damage to the fuel supply system. It is possible to prevent the engine from being cut off and thus preventing the engine from starting.

According to the tenth aspect of the invention, since the fuel supply cutoff valve is provided between the fuel tank and the pressure reducing valve, the fuel supply system between the fuel tank and the pressure reducing valve is provided. Therefore, it is possible to reliably prevent supply of high-pressure gas fuel. According to the invention of claim 11, when the plurality of gas fuel supply cutoff valves are provided from the upstream side to the downstream side of the gas fuel supply system, when the supply of the gas fuel is cut off, the gas fuel supply Since the supply of the gas fuel is cut off in order from the fuel supply cutoff valve on the supply upstream side, the pressure of the gas fuel remaining in the system can be reduced toward the downstream side of the fuel supply system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration according to a first aspect of the invention.

FIG. 2 is a block diagram showing a configuration according to a second aspect of the invention.

FIG. 3 is an overall configuration diagram showing the configuration of the first embodiment.

FIG. 4 is a layout diagram of a fuel supply system including a vehicle in the above embodiment.

FIG. 5 is a flowchart illustrating fuel cutoff control performed by the control unit according to the embodiment.

FIG. 6 is a circuit configuration diagram according to a second embodiment.

FIG. 7 is a layout diagram of an engine room according to a third embodiment.

FIG. 8 is a diagram showing a gas fuel leakage prevention device in a conventional example.

[Explanation of symbols]

 1 engine 2 intake passage 11 fuel injection valve 30 control unit 50 fuel tank 51 fuel supply passage 52 fuel supply cutoff valve 53 fuel supply cutoff valve 54 pressure reducing valve 60 acceleration sensor 61 gas leak sensor 62 gas leak sensor 70 vehicle 80 fuel supply cutoff valve A part of the drive circuit of 103 Safing sensor 104 Control unit for airbag system 107 Tunnel sensor 108 to 110 Crash zone sensor 111 Airbag module

Claims (11)

[Claims] 1. A gas fuel leakage prevention device for a vehicle equipped with an engine having a gas fuel supply system for supplying gas fuel, the fuel supply cutoff being provided in the gas fuel supply system for cutting off the supply of gas fuel. A valve, damage detection means for detecting damage to the vehicle or engine, and a first fuel supply cutoff valve for interrupting the supply of gas fuel when the damage detection means detects damage to the vehicle or engine A gas fuel leakage prevention device for a vehicle, comprising: a gas fuel supply cutoff means. 2. A gas leak detecting means for detecting a leak of gas fuel, and when the leak of gas fuel is detected by said gas leak detecting means, the supply of gas fuel is shut off through said fuel supply shutoff valve. The gas fuel leakage prevention device for a vehicle according to claim 1, further comprising: a second gas fuel supply cutoff means. 3. The gas fuel leakage of a vehicle according to claim 1, wherein the damage detecting means is means for detecting damage to the vehicle or the engine based on a change in vehicle acceleration. Prevention device. 4. The gas fuel for a vehicle according to claim 1 or 2, wherein the damage detecting means is means for detecting damage to the vehicle or the engine based on the operation of the airbag device. Leakage prevention device. 5. The fuel supply cutoff valve is configured so as to shut off the supply of gas fuel by stopping energization to close the supply of gas fuel, and the damage detection means has a part of a drive circuit of the fuel supply cutoff valve cut off. Based on the fact, damage to the vehicle or the engine is detected, and the first gas fuel supply cutoff means is configured such that a part of the drive circuit of the fuel supply cutoff valve is cut off to stop energization, thereby supplying the fuel. The gas fuel leak prevention device for a vehicle according to claim 1 or 2, wherein the shutoff valve is automatically closed to shut off the supply of the gas fuel. 6. When the engine is started, the gas fuel supply is cut off by the second gas fuel supply cutoff means for a predetermined period from the start of cranking even if the gas leak detection means detects a leak of gas fuel. The vehicle fuel gas leakage prevention device according to any one of claims 2 to 5, further comprising a start-up fuel supply cutoff prohibition means for prohibiting the start-up. 7. A gas leak judgment reference value setting changing means for setting a high judgment reference value for judging whether or not there is a leak of gas fuel in the gas leak detecting means for a predetermined period from the start of cranking when the engine is started. The gas fuel leakage prevention device for a vehicle according to any one of claims 2 to 5, characterized in that. 8. A gas fuel leakage prevention device for a vehicle, which is equipped with an engine having a gas fuel supply system for supplying gas fuel, the fuel supply cutoff being provided in the gas fuel supply system for cutting off the supply of gas fuel. A valve, a gas leak detecting means for detecting a leak of the gas fuel, and a second means for shutting off the supply of the gas fuel through the fuel supply shutoff valve when the leak of the gas fuel is detected by the gas leak detecting means. The gas fuel supply cutoff means and the second fuel gas supply cutoff means for supplying the gas fuel for a predetermined period from the start of cranking even if the gas leak detection means detects a leak of the gas fuel at the engine start. A fuel gas leakage prevention device for a vehicle, comprising: a start fuel supply cutoff prohibition means for prohibiting the cutoff. 9. A gas fuel leakage prevention device for a vehicle, which is equipped with an engine having a gas fuel supply system for supplying gas fuel, the fuel supply cutoff being provided in the gas fuel supply system for cutting off the supply of gas fuel. A valve, a gas leak detecting means for detecting a leak of the gas fuel, and a second means for shutting off the supply of the gas fuel through the fuel supply shutoff valve when the leak of the gas fuel is detected by the gas leak detecting means. Gas fuel supply cutoff means, and gas leakage determination reference value setting change means for setting a high determination reference value for determining whether or not gas fuel has leaked in the gas leakage detection means for a predetermined period from the start of engine cranking. A gas fuel leakage prevention device for a vehicle, comprising: 10. When the gas fuel supply system includes a pressure reducing valve for reducing the pressure of high-pressure gas fuel supplied from a fuel tank, the fuel supply cutoff valve is provided between the fuel tank and the pressure reducing valve. The gas fuel leakage prevention device for a vehicle according to any one of claims 1 to 9, wherein 11. A plurality of gas fuel supply cutoff valves are provided from an upstream side to a downstream side of the gas fuel supply system, and when the supply of the gas fuel is cut off, the fuel on the gas fuel supply upstream side of the plurality of fuel supply cutoff valves is provided. 11. The vehicle gas fuel leakage prevention device according to claim 1, wherein the supply of the gas fuel is shut off in order from the supply shutoff valve.