JP2002235571A - Fuel supply control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve safety when large impact is applied due to a collision of a vehicle of a bi-fuel system using gas fuel and, liquid fuel jointly. SOLUTION: When the collision of the vehicle is detected by an impact sensor 43, both of a gas fuel cut-off valve 27 and a liquid fuel cut-off valve 40 are closed and both of a gas fuel pipe 26 and a liquid fuel pipe 31 are interrupted. When an ignition switch 42 is turned off, the presence or absence of fuel leakage of a liquid fuel supply system 24 is detected. When leakage of liquid fuel does not exist, the liquid fuel cut-off valve 40 is opened and only liquid fuel can be supplied. When leakage of liquid fuel exists, the presence or absence of fuel leakage of a gas fuel supply system 23 is detected. When leakage of gas fuel does not exist, the gas fuel cut-off valve 27 is opened and only gas fuel can be supplied. When fuel leakage exists in both of the liquid fuel supply system 24 and the gas fuel supply system 23, the fuel cut-off valves 27 and 40 are maintained in closed states.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine having a gas fuel supply system for supplying gaseous fuel and a liquid fuel supply system for supplying liquid fuel.

[0002]

2. Description of the Related Art In recent years, vehicles using gaseous fuel such as compressed natural gas (CNG), which is inexpensive and has low exhaust emissions, as fuel for internal combustion engines have been proposed. For vehicles using gaseous fuel, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. 189789, when an impact sensor detects an impact equal to or more than a predetermined impact, a gas fuel supply system is shut off by an shutoff valve. As a result, in the event of a vehicle collision, the supply of gaseous fuel is stopped immediately to stop the engine, and even if a part of the gaseous fuel supply system is damaged by the impact of the vehicle collision, the fuel is removed from the damaged portion. The high-pressure gaseous fuel in the tank is prevented from leaking into the atmosphere.

[0003]

As a vehicle using gaseous fuel, a bifuel vehicle using both gaseous fuel and liquid fuel (such as gasoline) as disclosed in Japanese Patent Application Laid-Open No. 11-166432 is also available. Is being developed.
In this bifuel type vehicle, a gaseous fuel supply system for supplying gaseous fuel to the engine and a liquid fuel supply system for supplying liquid fuel are separately provided, as described in JP-A-7-189789 described above. The liquid fuel supply system is not shut off even if the gas fuel supply system is shut off by the shut-off valve when the shock sensor detects an impact equal to or greater than a predetermined value.
For this reason, even if a vehicle collision occurs while the engine is being driven using liquid fuel, the supply of liquid fuel is continued and the engine continues to rotate, or, in the unlikely event of a vehicle collision, Therefore, when a part of the liquid fuel supply system is damaged, there is a possibility that the liquid fuel leaks out from the damaged portion.

[0004] The present invention has been made in view of such circumstances, and accordingly, an object of the present invention is to apply a large impact due to a vehicle collision or the like to a bifuel type vehicle using both gaseous fuel and liquid fuel. An object of the present invention is to provide a fuel supply control device for an internal combustion engine that can improve safety at the time.

[0005]

According to a first aspect of the present invention, there is provided a fuel supply control apparatus for an internal combustion engine, comprising a gas fuel supply system and a liquid fuel supply system. In the vehicle, an impact sensor for detecting an impact applied to the vehicle is provided, and gas fuel shutoff means for shutting off gas fuel supply and liquid fuel shutoff means for shutting off liquid fuel supply are provided. When the impact is detected, both the gaseous fuel shutoff means and the liquid fuel shutoff means are switched to a state in which the supply of the gaseous fuel and the liquid fuel is interrupted by the fuel supply control means.

With this configuration, when a large impact is applied to the vehicle, such as at the time of a vehicle collision, the impact can be detected by the impact sensor to shut off the supply of both gaseous fuel and liquid fuel. Thus, regardless of whether the engine is operated using gaseous fuel or liquid fuel, when the impact is detected, the fuel supply can be stopped immediately to stop the engine, and in the unlikely event of a vehicle collision, etc. Even if the gaseous fuel supply system or liquid fuel supply system is partially damaged by the impact of the gas, the leakage of gaseous fuel or liquid fuel from the damaged part can be prevented beforehand, and safety can be improved. it can.

In this case, when the ignition switch is turned off while the gaseous fuel and the liquid fuel are shut off, if there is no abnormality in the liquid fuel supply system, only the liquid fuel shutoff means is turned off. You may make it switch to the state which can be supplied. In other words, when the driver turns off the ignition switch once to restart the engine while the gaseous fuel and the liquid fuel are shut off after the impact is detected, if there is no abnormality in the liquid fuel supply system, only the liquid fuel is discharged. It is made possible to supply. Thus, when the driver turns on the ignition switch again, the engine can be driven with liquid fuel having a relatively high degree of safety, and the vehicle can be evacuated to a safe place. In addition, since it is confirmed that there is no abnormality in the liquid fuel supply system, the cutoff state of the liquid fuel is released, so that the liquid fuel does not leak.

Further, when the ignition switch is turned off while the gaseous fuel and the liquid fuel are shut off, the liquid fuel supply system has an abnormality. Alternatively, only the gaseous fuel cutoff means may be switched from the cutoff state to a supplyable state. With this, even if the liquid fuel supply system is damaged by an impact such as a vehicle collision, if there is no abnormality in the gas fuel supply system,
The vehicle can be evacuated to a safe place by driving the engine with the gaseous fuel.

Further, when both the gaseous fuel supply system and the liquid fuel supply system are abnormal, the gaseous fuel shutoff means and the liquid fuel shutoff means are shut off even after the ignition switch is turned off. It is good to keep it in a state. In this way, if both the gaseous fuel supply system and the liquid fuel supply system fail due to an impact such as a vehicle collision, the shutoff state of both the gaseous fuel and the liquid fuel is continued even after the ignition switch is turned off. Thus, leakage of gaseous fuel and liquid fuel can be reliably prevented.

By the way, after a large impact is applied to a vehicle, even if no abnormality is detected in the fuel supply system, there is a possibility that a crack or deformation may occur in the fuel supply pipe due to the impact. When the fuel supply pressure is increased to the same level as normal when resuming fuel supply, the fuel supply pressure may cause cracks in the fuel supply pipe to expand, or new cracks may occur in deformed parts of the fuel supply pipe. There is
Fuel leakage may occur during evacuation travel.

As a countermeasure, when supplying the gaseous fuel or the liquid fuel by switching the gaseous fuel shutoff means or the liquid fuel shutoff means from the cutoff state to the supplyable state (that is, the fuel supply after the impact is detected), When resuming)
The supply fuel pressure may be limited to a predetermined limit range. With this configuration, when the fuel supply is restarted after the impact is detected, it is possible to reduce the load on the fuel supply system by restricting the supplied fuel pressure to a range necessary for the limp-home running,
It is possible to prevent the occurrence of fuel leakage during the limp-home operation.

After a large impact is applied to the vehicle,
Since the steering and running stability of the vehicle may be degraded, the throttle opening may be limited to a predetermined limit range when fuel supply is restarted after the impact is detected (claim 6). Alternatively, the engine speed may be limited to a predetermined limit range (claim 7). With this configuration, the throttle opening and the engine rotation speed can be limited to the ranges required for the limp-home running, and the safety during the limp-home running can be improved.

In general, the greater the impact applied to a vehicle during a collision, the greater the damage to the vehicle and the fuel supply system, and the greater the effect on the vehicle's handling and running stability. Tends to occur.

In consideration of this point, the limiting ranges for the supplied fuel pressure, the throttle opening, and the engine speed at the time of restarting the fuel supply after detecting the impact are determined by the impact detected by the impact sensor. You may make it set according to a magnitude | size. In this way, the limits of the supplied fuel pressure, throttle opening, and engine speed after the impact is detected are set to appropriate values according to the degree of damage to the vehicle and the fuel supply system due to the impact of a vehicle collision or the like. The engine can be operated within a range that can ensure the maneuverability, running stability, and fuel leakage prevention of the vehicle.

The technical ideas of claims 5 to 8 described above can also be applied to a system that shuts off only one of gaseous fuel and liquid fuel when an impact is detected. That is, when the shock sensor detects a shock equal to or more than a predetermined amount, the fuel cut-off means is switched to a state in which the supply of the gaseous fuel or the liquid fuel is cut off. At the time of supply, at least one of the supply fuel pressure, the throttle opening, and the engine speed may be limited to a predetermined limit range. Furthermore, the limit range may be set according to the magnitude of the impact detected by the impact sensor. With this configuration, a system that shuts off only one of the gaseous fuel and the liquid fuel when an impact is detected,
The same effects as those of the above-described claims 5 to 8 can be obtained.

In the system for shutting off only one of the gaseous fuel and the liquid fuel upon detection of an impact, the supply of the fuel which is not interrupted after the impact is detected may be performed. At least one of the fuel pressure, the throttle opening, and the engine speed may be limited to a predetermined limit range. In other words, with regard to the fuel supply system that is not interrupted at the time of impact detection, there is a possibility that cracks or deformation may occur somewhere, or the handling and running stability of the vehicle may be reduced, Even if the fuel that is not shut off is used after the impact is detected, if at least one of the supplied fuel pressure, the throttle opening, and the engine speed is limited to a predetermined limit range, the fuel leakage during the limp-home running can be prevented. It is possible to prevent the occurrence of such a situation and to restrict the throttle opening and the engine rotation speed to a range necessary for the evacuation traveling, thereby improving safety during the evacuation traveling. Also in this case, it goes without saying that the limit range during the limp-home running may be set according to the magnitude of the impact detected by the impact sensor (claim 11).

[0017]

[Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine.
An air flow meter 14 for detecting an intake air amount is provided downstream of the air cleaner 13. A throttle valve 15 is provided downstream of the air flow meter 14, and the opening of the throttle valve 15 (throttle opening) is detected by a throttle opening sensor 16.

The intake air that has passed through the throttle valve 15 is drawn into each cylinder of the engine 11 through an intake manifold 17. The combustion gas of each cylinder joins the exhaust pipe 19 through the exhaust manifold 18 and is discharged into the atmosphere. In the middle of the exhaust pipe 19, an air-fuel ratio sensor 20 (A / F sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or lean / rich of the exhaust gas, a catalyst (not shown) for purifying the exhaust gas, and the like are provided. Have been. A water temperature sensor 21 for detecting a cooling water temperature is provided on a cylinder block of the engine 11.
And a crank angle sensor 22 for detecting an engine rotation speed.
Is attached.

In this case, two fuel supply systems for supplying fuel to the engine 11 are provided, one of which is a gas fuel supply system 23 for supplying gaseous fuel such as compressed natural gas (CNG).
The other is a liquid fuel supply system 24 for supplying a liquid fuel such as gasoline. The gaseous fuel supply system 23 includes a gaseous fuel tank 25 filled with a gaseous fuel at a high pressure. A fuel shutoff valve 27 (gas fuel shutoff means) is provided.

A fuel pressure regulator 28 is provided downstream of the gas fuel cutoff valve 27. Gas fuel whose fuel pressure has been adjusted by the fuel pressure regulator 28 is supplied to a gas fuel injection valve attached to the intake manifold 17 of each cylinder. 29. On the downstream side of the fuel pressure regulator 28, a gas fuel pressure sensor 39 for detecting a gas fuel supply pressure is provided. The gas fuel tank 25 has a fuel pressure sensor 3 for detecting the pressure of the gas fuel filled in the tank 25.
The remaining amount of gaseous fuel is determined based on the fuel pressure detected by the fuel pressure sensor 35.

On the other hand, the liquid fuel supply system 24 includes a liquid fuel tank 30 storing liquid fuel, and a fuel pump 32 for pumping liquid fuel is provided upstream of a liquid fuel pipe 31 connected to the liquid fuel tank 30. A liquid fuel cutoff valve 40 (liquid fuel cutoff means) including an electromagnetic valve or the like is provided. A fuel pressure regulator 33 is provided downstream of the liquid fuel cutoff valve 40.
The liquid fuel whose fuel pressure has been adjusted in 3 is distributed to the liquid fuel injection valve 34 attached to the intake manifold 17 of each cylinder. On the downstream side of the fuel pressure regulator 33, a liquid fuel pressure sensor 41 for detecting a supply pressure of the liquid fuel is provided. The liquid fuel tank 30 is provided with a fuel remaining meter 36 for measuring the remaining amount of the liquid fuel.

Further, an engine 1 is provided on the driver's seat side in the vehicle interior.
An ignition switch 42 for starting the vehicle 1 is provided, and an impact sensor 43 for detecting an impact applied to the vehicle is provided at a predetermined position of the vehicle. This shock sensor 4
3 may also serve as an impact sensor for operating an airbag or the like.

The outputs of these various sensors are input to an engine control circuit (hereinafter referred to as "ECU") 37.
The ECU 37 controls the fuel supply operation of the gaseous fuel supply system 23 and the liquid fuel supply system 24 by executing various control programs stored in a built-in ROM (storage medium), mainly composed of a microcomputer. It functions as fuel supply control means.

A fuel changeover switch 38 is connected to the ECU 37, and a driver changes over the fuel changeover switch 38 to output a fuel changeover signal to the ECU 37.
The fuel supplied to the engine 11 is switched between gas fuel and liquid fuel. Furthermore, ECU3
7 determines the remaining amount of gaseous fuel based on the fuel pressure detected by the fuel pressure sensor 35, and automatically switches the injected fuel to liquid fuel when the remaining amount of gaseous fuel becomes smaller than a specified amount. When the remaining amount of liquid fuel detected by the fuel remaining meter 36 becomes smaller than a specified amount, the injected fuel is automatically switched to gaseous fuel.

Normally, when gaseous fuel is selected, the ECU 37 determines whether the gaseous fuel shutoff valve 2 of the gaseous fuel supply system 23
7 is opened, and the gaseous fuel in the gaseous fuel tank 25 is supplied to the gaseous fuel injection valve 29 of each cylinder through the gaseous fuel pipe 26. In this case, the fuel pump 3 of the liquid fuel supply system 24
2 is stopped, and the liquid fuel cutoff valve 40 is closed. still,
The liquid fuel cutoff valve 40 may be left open. On the other hand, when the liquid fuel is selected, the liquid fuel cutoff valve 40 of the liquid fuel supply system 24 is opened, and the fuel pump 32 is driven to supply the liquid fuel in the liquid fuel tank 30 to the liquid fuel pipe 3.
1 to the liquid fuel injection valve 34 of each cylinder. In this case, the gaseous fuel cutoff valve 27 of the gaseous fuel supply system 23 is closed.

Further, the ECU 37 detects the engine operating state based on the output signals of the various sensors described above, and calculates the fuel injection amount (fuel injection time) and the injection timing according to the type of the injected fuel at that time. An injection signal having a pulse width corresponding to the calculation result is output to the gas fuel injection valve 29 or the liquid fuel injection valve 34 to control these injection operations.

The ECU 37 executes the fuel supply cutoff control program shown in FIG. 2 and the fuel leak detection program shown in FIGS. 3 and 4 so that the impact sensor 43 detects a predetermined or more impact due to a vehicle collision or the like. , Gas fuel shutoff valve 2
7 and the liquid fuel cutoff valve 40 are both closed to shut off both the gas fuel pipe 26 and the liquid fuel pipe 31. afterwards,
The presence / absence of fuel leakage in the liquid fuel supply system 24 and the gaseous fuel supply system 23 is detected. If there is no fuel leakage in the liquid fuel supply system 24, the liquid fuel cutoff valve 40 is opened to supply only liquid fuel. If the liquid fuel supply system 24 has a fuel leak, if the gas fuel supply system 23 has no fuel leak,
The gaseous fuel shutoff valve 27 is opened so that only gaseous fuel can be supplied.

The specific processing of each program executed by the ECU 37 will be described below. The fuel supply cutoff control program shown in FIG. 2 is repeatedly executed at every predetermined time or every predetermined crank angle. When this program is started,
First, in step 101, it is determined whether or not the vehicle has collided based on whether or not the impact detected by the impact sensor 43 is equal to or more than a predetermined value. If the vehicle has not collided, the program ends without executing the subsequent fuel supply stop processing (steps 102 to 112).

If it is determined in step 101 that the vehicle has collided, the fuel supply stop processing in step 102 and thereafter is executed as follows. First, step 102
Then, both the gas fuel shutoff valve 27 and the liquid fuel shutoff valve 40 are closed to shut off both the gas fuel pipe 26 and the liquid fuel pipe 31. As a result, no matter which gas fuel or liquid fuel has been supplied to the engine 11 until then, the fuel supply is immediately stopped and the engine 11 is stopped.

Thereafter, the routine proceeds to step 103, where it is determined whether or not the ignition switch 42 has been switched from on to off. If the ignition switch 42 remains ON, the state where both the fuel cutoff valves 27 and 40 are closed is continued.

Thereafter, when the ignition switch 42 is turned off, the routine proceeds from step 103 to step 104, in which a fuel leakage detection program for the liquid fuel supply system shown in FIG. The presence or absence is detected, and the routine proceeds to the next step 105, where it is determined whether or not there is a fuel leak in the liquid fuel supply system 24. If there is no fuel leakage in the liquid fuel supply system 24, it is determined that the liquid fuel may be supplied, and the process proceeds to step 106, where FIG.
The maps (a) to (c) are searched and the maximum permissible engine speed, the maximum permissible throttle opening, and the maximum permissible supply fuel pressure when supplying liquid fuel are determined by the impact sensor 4.
3 is calculated according to the detection signal level (impact magnitude).

In general, as the impact applied to the vehicle at the time of the collision increases, the damage to the vehicle and the fuel supply systems 23 and 24 increases, and the influence on the steering and running stability of the vehicle increases, or the fuel supply system 23 , 24 tend to crack or deform. In consideration of this point, FIGS.
Is set such that the larger the detection signal of the impact sensor 43, the smaller the maximum allowable engine speed, the maximum allowable throttle opening, and the maximum allowable supply fuel pressure.

Thereafter, the routine proceeds to step 107, where the liquid fuel shut-off valve 40 is opened so that only liquid fuel can be supplied.
Thus, when the driver turns on the ignition switch 42 again, liquid fuel is supplied to the engine 11 so that the engine can be operated. At this time, the engine speed, the throttle opening, and the supply fuel pressure of the liquid fuel are limited to the maximum allowable engine speed, the maximum allowable throttle opening, and the maximum allowable supply fuel pressure, respectively.

On the other hand, if it is determined in step 105 that there is a fuel leak in the liquid fuel supply system 24, the process proceeds to step 108, where a gas leak detection program for the gas fuel supply system shown in FIG. The presence or absence of fuel leakage in the fuel supply system 23 is detected, and in the next step 109, it is determined whether or not there is a fuel leakage in the gaseous fuel supply system 23. if,
If there is no fuel leak in the gaseous fuel supply system 23, it is determined that gaseous fuel may be supplied, and the routine proceeds to step 110, where maps similar to those shown in FIGS. The maximum permissible engine rotation speed, the maximum permissible throttle opening, and the maximum permissible supply fuel pressure when the power supply is supplied are calculated in accordance with the detection signal level (impact magnitude) of the impact sensor 43.

The map of the maximum permissible engine speed and the maximum permissible throttle opening in FIG. 5 may be a common map for the liquid fuel supply and the gas fuel supply. Two types of maps for fuel are set, and a map for liquid fuel is used in step 106,
At 10, a map for gaseous fuel may be used.

Thereafter, the routine proceeds to step 111, where the gaseous fuel shutoff valve 27 is opened to allow only gaseous fuel to be supplied.
Thus, when the driver turns on the ignition switch 42 again, the engine 11 can be operated by supplying gaseous fuel to the engine 11. At this time, the engine speed, the throttle opening, and the supplied fuel pressure of the gaseous fuel are limited to the maximum allowable engine speed, the maximum allowable throttle opening, and the maximum allowable supplied fuel pressure, respectively.

In step 105, the liquid fuel supply system 24
It is determined that there is a fuel leak and
If it is determined that there is a fuel leak in the gaseous fuel supply system 23, it is determined that it is better not to restart the fuel supply, and the routine proceeds to step 112, where both the fuel cutoff valves 27 and 40 are kept closed. Thus, the supply cutoff state of both the gaseous fuel and the liquid fuel is maintained.

Next, the processing contents of the fuel leak detection program for the liquid fuel supply system shown in FIG. 3 will be described. The fuel leakage detection program for the liquid fuel supply system in FIG.
4 and plays a role corresponding to the liquid fuel supply system abnormality detecting means described in the claims. This program
This is executed immediately after the ignition switch 42 is turned off. When this program is started, first, step 2
01, the liquid fuel shutoff valve 40 is opened, and the next step 2
At 02, the detection pressure Pa (the fuel pressure in the liquid fuel pipe 31) of the liquid fuel pressure sensor 41 is read after a predetermined time has elapsed. Thereafter, in step 203, the liquid fuel cutoff valve 40 is closed to close the liquid fuel pipe 31 from the liquid fuel cutoff valve 40 to the liquid fuel injection valve 34 in the next step 2
At 04, after a predetermined time has elapsed, the detected pressure Pb of the liquid fuel pressure sensor 41 is read.

Thereafter, the routine proceeds to step 205, where it is determined whether or not the difference between the detected pressure Pa when the liquid fuel shutoff valve 40 is open and the detected pressure Pb when the liquid fuel shutoff valve 40 is closed is larger than a predetermined determination value T1. If the difference between the detected pressure Pa and the detected pressure Pb is larger than the predetermined determination value T1, the process proceeds to step 206, where it is determined that the liquid fuel supply system 24 has a fuel leak. On the other hand, if the difference between the detected pressure Pa and the detected pressure Pb is equal to or smaller than the predetermined determination value T1, the process proceeds to step 207, where it is determined that the liquid fuel supply system 24 has no fuel leakage.

Next, the processing contents of the fuel leakage detection program for the gaseous fuel supply system shown in FIG. 4 will be described. The fuel leakage detection program for the gaseous fuel supply system in FIG.
8 and plays a role corresponding to the gas fuel supply system abnormality detecting means described in the claims. This program also
This is executed immediately after the ignition switch 42 is turned off. First, the gaseous fuel shutoff valve 27 is opened, and after a lapse of a predetermined time, the detected pressure Pc of the gaseous fuel pressure sensor 39 (the fuel pressure in the gaseous fuel pipe 26) is read (step 301,
302).

Thereafter, the gaseous fuel cutoff valve 27 is closed to close the gaseous fuel cutoff valve 27 of the gaseous fuel pipe 26 from the gaseous fuel injection valve 29 in a sealed state. (Step 3
03, 304). Then, the detected pressure Pc and the detected pressure Pd
If the difference between the detected pressure Pc and the detected pressure Pd is equal to or smaller than the predetermined determination value T2, the gas fuel supply system 23 determines that there is a fuel leak. It is determined that there is no fuel leakage in the supply system 23 (steps 305 to 307).

In the embodiment (1) described above, when the collision sensor 43 detects a collision of the vehicle (impact of a predetermined value or more), both the gas fuel shutoff valve 27 and the liquid fuel shutoff valve 40 are closed. Because both the gaseous fuel pipe 26 and the liquid fuel pipe 31 are shut off, regardless of which gaseous fuel or liquid fuel has been supplied to the engine 11, the fuel supply is immediately stopped when an impact is detected. The engine can be stopped, and even if a part of the gaseous fuel supply system 23 or the liquid fuel supply system 24 is damaged by the impact at the time of the collision, the gaseous fuel or the liquid fuel leaks from the damaged part. This can be prevented beforehand, and safety at the time of a vehicle collision can be improved.

In this embodiment (1), after the fuel supply is cut off, if the driver once turns off the ignition switch 42 to restart the engine 11, it is first determined whether or not there is a fuel leak in the liquid fuel supply system 24. If there is no fuel leak in the liquid fuel supply system 24, the liquid fuel cutoff valve 40 is opened and only the liquid fuel can be supplied. Therefore, when the driver turns on the ignition switch 42 again,
The vehicle can be evacuated to a safe place by restarting the engine 11 by preferentially supplying liquid fuel having a relatively high degree of safety. Moreover, since it is confirmed that there is no fuel leakage in the liquid fuel supply system 24, the liquid fuel cutoff valve 40 is opened, so that the liquid fuel does not leak.

Further, in the present embodiment (1), if it is determined that there is a fuel leak in the liquid fuel supply system 24, then the presence or absence of fuel leak in the gas fuel supply system 23 is detected, and the gas fuel supply system 23 is detected. If there is no fuel leak at 23, the gaseous fuel shutoff valve 27
Is opened to supply only gaseous fuel. Therefore, even if there is an abnormality in the liquid fuel supply system 24, when the driver turns on the ignition switch 42 again, the engine 11 is restarted with gaseous fuel to start the vehicle. Evacuation can be made to a safe place. Moreover, after confirming that there is no fuel leakage in the gaseous fuel supply system 23, the gaseous fuel shutoff valve 27
Gas gas fuel does not leak.

Further, in the present embodiment (1), when it is determined that both the liquid fuel supply system 24 and the gaseous fuel supply system 23 have a fuel leak, both the fuel cutoff valves 27 are maintained even after the ignition switch 42 is turned off. , 40 are kept closed and the supply cutoff state of both gaseous fuel and liquid fuel is maintained, so that leakage of gaseous fuel and liquid fuel can be reliably prevented even after the ignition switch 42 is turned off. it can.

By the way, after a large impact is applied to the vehicle, even if fuel leakage of the fuel supply systems 23 and 24 is not detected, cracks or deformations occur in the fuel supply systems 23 and 24 due to the impact. When the fuel supply is resumed, if the supply fuel pressure is increased to the same level as usual, the fuel supply system 23,
There is a possibility that the crack of the fuel cell 24 may be enlarged or a new crack may be generated at a deformed portion of the fuel supply system 23, 24, and a fuel leak may occur during the evacuation traveling.

In this regard, in the present embodiment (1), when the gaseous fuel or the liquid fuel is supplied after the collision is detected, the supply fuel pressure is limited to the maximum allowable supply fuel pressure or less. The load on the fuel supply systems 23 and 24 can be reduced by keeping the vehicle within the range in which the vehicle can be evacuated, and the occurrence of abnormalities such as fuel leakage in the fuel supply systems 23 and 24 during the evacuation traveling can be prevented. it can.

Further, in the present embodiment (1), when the gaseous fuel or the liquid fuel is supplied after the collision is detected, it is considered that the maneuverability and running stability of the vehicle may be reduced by the collision. In addition, the throttle opening and the engine speed are limited to the maximum allowable values or less. Etc.) can be restricted, and safety during evacuation traveling can be improved.

Further, in the present embodiment (1), as the impact applied to the vehicle at the time of the collision increases, the damage to the vehicle and the fuel supply systems 23 and 24 increases, and the maneuverability of the vehicle increases.
Considering that the influence on the running stability becomes large and that the fuel supply systems 23 and 24 are apt to be cracked or deformed, the larger the detection signal level (magnitude of the impact) of the impact sensor 43 becomes, the larger the maximum allowable is. Since the supply fuel pressure, the maximum permissible engine speed, and the maximum permissible throttle opening are set to be small, each maximum permissible value is set according to the degree of damage to the vehicle or the fuel supply system 23, 24 caused by the impact. It can be set to an appropriate value.

However, the maximum allowable supply fuel pressure, the maximum allowable engine speed, and the maximum allowable throttle opening are
It goes without saying that fixed values set in advance may be used.

In this embodiment (1), the supply fuel pressure, the engine rotation speed, and the throttle opening are all limited, but only one or two of them are limited. May be. Alternatively, the supply fuel pressure, the engine rotation speed, and the throttle opening may not be limited to all three.

Incidentally, as in the embodiment (1), when the fuel supply cut off at the time of impact detection is restarted thereafter,
The technical idea of limiting at least one of the supply fuel pressure, throttle opening, and engine speed to a predetermined limit range is based on a system that shuts off only one of gaseous fuel and liquid fuel when an impact is detected. Can also be applied.

That is, when the impact sensor 43 detects an impact of a predetermined level or more, the state is switched to a state in which only the supply of fuel (for example, gaseous fuel), which is likely to cause fuel leakage, is cut off, and then this cut off state is released. Then, when supplying the fuel, at least one of the supplied fuel pressure, the throttle opening, and the engine speed may be limited to a predetermined limit range. Further, the limit range may be set according to the magnitude of the impact detected by the impact sensor 43. According to this configuration, the same effect as that of the above-described embodiment (1) can be obtained for a system that shuts off only one of the gaseous fuel and the liquid fuel when an impact is detected.

The technical idea of restricting at least one of the supplied fuel pressure, the throttle opening, and the engine speed to a predetermined limit range when resuming the supply of fuel cut off at the time of detecting the impact is as follows. The present invention can be applied to a system having only one supply system.

[Embodiment (2)] By the way, in a system that shuts off only one of the gaseous fuel and the liquid fuel when an impact is detected, after the impact is detected, the fuel that is not interrupted is supplied and the vehicle travels limp. It is possible. In such a system, at least one of the supplied fuel pressure, the throttle opening, and the engine speed may be limited to a predetermined limit range when supplying the fuel that is not interrupted after the impact is detected.

Hereinafter, an embodiment (2) of the present invention that embodies this will be described with reference to FIG. This embodiment (2)
Is the same as the system configuration of the embodiment (1).

In the fuel supply cutoff control program of FIG. 6 executed in the embodiment (2), first, at step 501,
It is determined whether or not the vehicle has collided based on whether or not the impact detected by the impact sensor 43 is equal to or greater than a predetermined value. If it is determined that the vehicle has collided, the routine proceeds to step 502, where the gas fuel shutoff valve 27 is closed and the gas fuel pipe 26 is shut off. As a result, if the gaseous fuel has been supplied to the engine 11 until then, the supply of the gaseous fuel is immediately stopped.

Thereafter, the flow advances to step 503, and FIG.
The maps (a) to (c) are searched and the maximum permissible engine speed, the maximum permissible throttle opening, and the maximum permissible supply fuel pressure when supplying liquid fuel are determined by the impact sensor 4.
3 is calculated according to the detection signal. Note that the maximum allowable supply fuel pressure, the maximum allowable engine speed, and the maximum allowable throttle opening may be fixed values set in advance.

Thereafter, the routine proceeds to step 504, where the liquid fuel cutoff valve 40 is opened to allow only the liquid fuel to be supplied.
As a result, the engine 11 can be driven by supplying liquid fuel to the engine 11. At this time, the engine speed, the throttle opening, and the supply fuel pressure of the liquid fuel are limited to the maximum allowable engine speed, the maximum allowable throttle opening, and the maximum allowable supply fuel pressure, respectively. Note that the system configuration may be such that the liquid fuel cutoff valve 40 is omitted, and the process of step 504 may be omitted.

In the embodiment (2) described above, when the impact sensor 43 detects a collision of the vehicle (impact of a predetermined value or more), the gas fuel shutoff valve 27 is closed and the liquid fuel shutoff valve 40 is opened. As a result, only the liquid fuel can be supplied, so that the liquid fuel having a relatively high degree of safety is supplied to the engine 11 and the vehicle is evacuated to a safe place while preventing leakage of the gaseous fuel, which is likely to cause fuel leakage. You can run. Further, since the supply fuel pressure of the liquid fuel is limited to the maximum allowable supply fuel pressure or less, the load applied to the liquid fuel supply system 24 can be reduced, and the fuel supply to the liquid fuel supply system 24 during the limp-home operation is reduced. Leakage can be prevented as much as possible.

Further, in this embodiment (2), the throttle opening and the engine speed are limited to the maximum allowable values or less, respectively. The running performance (maximum speed, etc.) at the time can be limited, and the safety during the evacuation running can be improved.

In this embodiment (2), the supply fuel pressure, the engine speed, and the throttle opening are all limited, but the supply fuel pressure, the engine speed,
Only one or two of the throttle openings may be limited.

If the gas fuel supply system 23 is configured to be robust against vehicle collision and the possibility of gas fuel leakage is small, the impact sensor 43 detects vehicle collision (impact of a predetermined value or more). Upon detection, the liquid fuel cutoff valve 40 is closed and the gaseous fuel cutoff valve 27 is opened so that only gaseous fuel can be supplied. At least one of the gaseous fuel supply fuel pressure, the engine rotation speed, and the throttle opening degree One may be limited.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment (1) of the present invention.

FIG. 2 is a flowchart showing a processing flow of a fuel supply cutoff control program according to the embodiment (1).

FIG. 3 is a flowchart showing a processing flow of a fuel leakage detection program of the liquid fuel supply system.

FIG. 4 is a flowchart showing a processing flow of a fuel leakage detection program of the gaseous fuel supply system.

5A is a diagram conceptually showing a calculation map of a maximum allowable engine rotation speed, FIG. 5B is a diagram conceptually showing a calculation map of a maximum allowable throttle opening, and FIG. Diagram showing conceptually the pressure calculation map

FIG. 6 is a flowchart showing a processing flow of a fuel supply cutoff control program according to the embodiment (2).

[Explanation of symbols]

11 ... engine (internal combustion engine), 23 ... gaseous fuel supply system,
24 ... liquid fuel supply system, 25 ... gas fuel tank, 26 ...
Gas fuel pipe, 27 ... Gas fuel shutoff valve (gas fuel shutoff means), 28 ... Fuel pressure regulator, 29 ... Gas fuel injection valve, 30 ... Liquid fuel tank, 31 ... Liquid fuel pipe, 32
... Fuel pump, 33 ... Fuel pressure regulator, 34 ... Liquid fuel injection valve, 35 ... Fuel pressure sensor, 37 ... ECU (fuel supply control means, liquid fuel supply system abnormality detection means, gas fuel supply system abnormality detection means), 39 ... Gas fuel pressure sensor, 4
0: liquid fuel shutoff valve (liquid fuel shutoff means), 41: liquid fuel pressure sensor, 42: ignition switch, 43
... impact sensor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/32 F02D 41/32 D 45/00 345 45/00 345L 362 362R F02M 21/02 F02M 21/02 V 301 301A 51/02 55/02 350C 55/02 350 350F 51/02 RF term (reference) 3G065 CA38 CA40 FA06 GA50 3G066 AB02 AB05 BA28 BA35 CA32U CB07U CC68U CD25 CE22 CE29 DA02 DB19 DC26 3G084 AA05 BA11 CA07 DA28 FA13 FA14 FA36 3G092 AA01 AA05 AB02 AB08 AB12 BB10 CB08 DE10Y DE11Y DF03 DF05 DF08 DG09 EA11 EA14 EA28 FA29 FB09 GA10 HF20Z 3G301 HA01 HA22 HA24 JB08 KA28 LC01 LC10 MA24 NA08 NB06 NB20 NE07 PF16Z

Claims (11)

[Claims] An internal combustion engine comprising: a gas fuel supply system for supplying gaseous fuel to an internal combustion engine; a liquid fuel supply system for supplying liquid fuel; and fuel supply control means for controlling the supply of these gaseous fuel and liquid fuel. An engine fuel supply control device, comprising: an impact sensor for detecting an impact applied to a vehicle; a gas fuel shutoff unit for shutting off the supply of the gaseous fuel; and a liquid fuel shutoff unit for shutting off the supply of the liquid fuel. The fuel supply control means switches both the gaseous fuel shutoff means and the liquid fuel shutoff means to a state in which the supply of the gaseous fuel and the liquid fuel is interrupted when the impact sensor detects an impact equal to or greater than a predetermined value. A fuel supply control device for an internal combustion engine. 2. The apparatus according to claim 1, further comprising a liquid fuel supply system abnormality detecting unit for detecting whether or not the liquid fuel supply system is abnormal, wherein the fuel supply control unit turns off an ignition switch while the gaseous fuel and the liquid fuel are shut off. 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein when there is no abnormality in the liquid fuel supply system, only the liquid fuel cutoff means is switched from a cutoff state to a supplyable state. 3. A gas fuel supply system abnormality detecting means for detecting the presence or absence of an abnormality in the gas fuel supply system, wherein the fuel supply control means turns off an ignition switch while the gas fuel and the liquid fuel are shut off. When there is an abnormality in the liquid fuel supply system, when there is no abnormality in the gaseous fuel supply system, only the gaseous fuel shutoff means is switched from a cutoff state to a supplyable state. Or the fuel supply control device for an internal combustion engine according to 2. 4. The gas supply shut-off means and the liquid fuel cut-off means even after an ignition switch is turned off, when both the gaseous fuel supply system and the liquid fuel supply system are abnormal. The fuel supply control device for an internal combustion engine according to any one of claims 1 to 3, wherein both of them are kept in a shut-off state. 5. The fuel supply control means switches the gaseous fuel shutoff means or the liquid fuel shutoff means from a shutoff state to a supplyable state to supply the gaseous fuel or the liquid fuel. The fuel supply control device for an internal combustion engine according to any one of claims 1 to 4, wherein is limited to a predetermined limit range. 6. The throttle opening when the gaseous fuel or the liquid fuel is supplied by switching the gaseous fuel shutoff means or the liquid fuel shutoff means from a cutoff state to a supplyable state and supplying the gaseous fuel or the liquid fuel. The fuel supply control device for an internal combustion engine according to any one of claims 1 to 5, wherein is limited to a predetermined limit range. 7. The fuel supply control means switches the gaseous fuel cutoff means or the liquid fuel cutoff means from a cutoff state to a supplyable state and supplies the gaseous fuel or the liquid fuel. The fuel supply control device for an internal combustion engine according to any one of claims 1 to 6, wherein is limited to a predetermined limit range. 8. The internal combustion engine according to claim 5, wherein the fuel supply control unit sets the predetermined limit range according to the magnitude of the impact detected by the impact sensor. Engine fuel supply control device. 9. An internal combustion engine comprising: a gas fuel supply system for supplying gaseous fuel to an internal combustion engine; a liquid fuel supply system for supplying liquid fuel; and fuel supply control means for controlling the supply of these gaseous fuel and liquid fuel. An engine fuel supply control device, comprising: an impact sensor that detects an impact applied to a vehicle; and a fuel shutoff unit that shuts off the gaseous fuel or the liquid fuel. When an impact is detected, the fuel shut-off means is switched to a state in which the supply of the gaseous fuel or the liquid fuel is interrupted, and thereafter, when the shut-off state is released and the fuel is supplied, the supplied fuel pressure, the throttle opening, A fuel supply control device for an internal combustion engine, wherein at least one of the engine rotation speeds is limited to a predetermined limit range. 10. An internal combustion engine comprising: a gas fuel supply system for supplying gaseous fuel to an internal combustion engine; a liquid fuel supply system for supplying liquid fuel; and fuel supply control means for controlling the supply of these gaseous fuel and liquid fuel. An engine fuel supply control device, comprising: an impact sensor that detects an impact applied to a vehicle; and a fuel shutoff unit that shuts off the gaseous fuel or the liquid fuel. When an impact is detected, the fuel shutoff means is switched to a state in which the supply of the gaseous fuel or the liquid fuel is interrupted, and thereafter, when the fuel that is not interrupted is supplied, the supplied fuel pressure, throttle opening, engine rotation A fuel supply control device for an internal combustion engine, wherein at least one of the speeds is limited to a predetermined limit range. 11. The fuel for an internal combustion engine according to claim 9, wherein the fuel supply control unit sets the predetermined limit range according to the magnitude of an impact detected by the impact sensor. Supply control device.