JP4358778B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply device for an internal combustion engine that supplies fuel in a fuel tank to a fuel injection device of the internal combustion engine via a fuel supply passage by a fuel pump.

  Conventionally, as this type of fuel supply apparatus, for example, there is an apparatus described in Patent Document 1 below. In this apparatus, the fuel in the fuel tank is supplied to a fuel supply portion (fuel injection device) of the internal combustion engine through a fuel supply passage (fuel supply passage) by a fuel pump. Here, in the middle of the fuel supply passage, an upstream fuel cutoff valve is provided near the fuel tank, and a downstream fuel cutoff valve is provided near the fuel supply site. When the internal combustion engine is stopped, the fuel supply passage is held at a high pressure by closing the two fuel cutoff valves.

Here, for example, in a fuel supply device that uses high-pressure gas fuel as fuel, a fuel cutoff valve constituted by an electromagnetic valve is opened to supply fuel to the fuel supply passage when the internal combustion engine is started. The In order to open the fuel shut-off valve, a current that can be opened against the pressure difference between the upstream pressure and the downstream pressure of the fuel shut-off valve, that is, the pressure difference between the front and rear of the fuel shut-off valve is supplied to the fuel shut-off valve. It is necessary to supply. On the other hand, the current required to keep the fuel shut-off valve open may be smaller than the current required to open the fuel shut-off valve. Here, the pressure difference between the front and rear of the fuel cutoff valve is generated by the pressure of the gas fuel filled in the fuel tank and the pressure drop downstream of the fuel cutoff valve when the internal combustion engine is stopped.
Japanese Patent Laying-Open No. 2003-83172 (page 11-12, FIGS. 1 and 2)

  However, in the fuel supply device described in Patent Document 1, each fuel cutoff valve cannot be opened due to its structure when the pressure difference between the front and rear becomes a predetermined value or more. Here, when a part in the middle of the fuel supply passage is replaced at the time of maintenance, the fuel supply passage on the side where the part has been replaced with each fuel cutoff valve as a boundary is at atmospheric pressure, and the opposite side is in a residual fuel state. That is, a difference in pressure between the front and rear is generated in each fuel cutoff valve. In this state, if the starter is cranked or the fuel pump is driven to start the internal combustion engine, the fuel on the upstream side of each fuel cutoff valve is pressurized, and each fuel cutoff valve There is a risk that the fuel cutoff valve cannot be opened because the pressure difference between the front and rear exceeds a predetermined value. In addition, when each fuel cutoff valve is configured by a solenoid valve, if the fuel pump is driven when the internal combustion engine is started, the current value supplied to each fuel cutoff valve decreases and becomes insufficient. There is a risk that the driving force that can counter the pressure difference between the front and rear of the valve cannot be secured.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel supply for an internal combustion engine that can reliably open the fuel cutoff valve regardless of the pressure difference between the front and rear of the fuel cutoff valve after maintenance. To provide an apparatus.

  In order to achieve the above object, according to a first aspect of the present invention, fuel in a fuel tank is supplied to a fuel injection device of an internal combustion engine via a fuel supply passage by a fuel pump, and the fuel supply passage is provided when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that shuts off fuel in a fuel supply passage by closing a fuel cutoff valve provided in the engine, and when the pressure difference across the fuel cutoff valve exceeds a predetermined value, The purpose is to prohibit driving of the fuel pump until the fuel shut-off valve is opened.

  According to the configuration of the above invention, for example, when maintenance of the fuel supply passage and other parts is performed in a state where the fuel cutoff valve is closed when the internal combustion engine is stopped, the pressure difference between the front and rear of the fuel cutoff valve is reduced. When the value exceeds the predetermined value, the drive of the fuel pump is prohibited until the fuel shut-off valve is subsequently opened when starting the internal combustion engine. Therefore, before the fuel shut-off valve is opened, the fuel pump is not driven and the inlet side of the fuel shut-off valve is not pressurized, and the pressure difference between the front and rear of the fuel shut-off valve increases to a state where it is difficult to open the valve. Absent.

  In order to achieve the above object, the invention described in claim 2 is to supply the fuel in the fuel tank to the fuel injection device of the internal combustion engine through the fuel supply passage by the electric fuel pump, and to stop the fuel when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that shuts off fuel in the fuel supply passage by closing an electric fuel cutoff valve provided in the supply passage, and the internal combustion engine includes an electric device for assisting the start thereof When the pressure difference between the front and rear of the fuel shut-off valve exceeds a predetermined value, an operating current is supplied from the power source to the fuel shut-off valve to open the fuel shut-off valve when the internal combustion engine is started, and the fuel shut-off valve opens. The purpose is to prohibit the supply of operating current from the power source to at least one of the fuel pump and the electric device.

  According to the configuration of the above invention, for example, when maintenance of the fuel supply passage and other parts is performed in a state where the fuel cutoff valve is closed when the internal combustion engine is stopped, the pressure difference between the front and rear of the fuel cutoff valve is reduced. When the value exceeds the predetermined value, an operating current is supplied from the power source to the fuel cutoff valve in order to open the fuel cutoff valve when the internal combustion engine is subsequently started. At the same time, supply of an operating current from the power source to at least one of the fuel pump and the electric device is prohibited until the fuel cutoff valve is opened. Therefore, the supply of operating current to at least one of the fuel pump and the electric device does not cause a voltage drop before the fuel shut-off valve opens, and the fuel shut-off valve is opposed to the pressure difference between the front and rear. It is possible to secure an operating current sufficient to open the valve from the power source.

  In order to achieve the above object, according to a third aspect of the present invention, fuel in a fuel tank is supplied to a fuel injection device of an internal combustion engine via a fuel supply passage by a fuel pump, and the fuel supply passage is provided when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that shuts off the fuel in the fuel supply passage by closing the fuel cutoff valve provided in the fuel supply passage, and for determining whether the pressure difference across the fuel cutoff valve is greater than or equal to a predetermined value And a start operation means for operating the start of the internal combustion engine, and when the start operation means is operated, the fuel cutoff valve is opened when the determination means determines that the pressure difference between the front and rear is greater than a predetermined value. And a control means for starting the fuel pump after opening the valve.

  According to the configuration of the above invention, for example, when maintenance of the fuel supply passage and other parts is performed in a state where the fuel cutoff valve is closed when the internal combustion engine is stopped, the pressure difference between the front and rear of the fuel cutoff valve is reduced. When it is determined by the determination means that the value is equal to or greater than the predetermined value and the start operation means is operated to operate the start of the internal combustion engine, the control means opens the fuel cutoff valve, and after the opening, the fuel pump Will be started. Therefore, before the fuel shut-off valve is opened, the fuel pump is not driven and the fuel shut-off valve inlet side is not pressurized, and the pressure difference across the fuel shut-off valve does not increase.

  In order to achieve the above object, according to a fourth aspect of the present invention, fuel in a fuel tank is supplied to a fuel injection device of an internal combustion engine via a fuel supply passage by a fuel pump, and the fuel supply passage is provided when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that shuts off the fuel in the fuel supply passage by closing the fuel cutoff valve provided in the fuel supply passage, and for determining whether the pressure difference across the fuel cutoff valve is greater than or equal to a predetermined value Means, a first operating means operated to open the fuel shut-off valve, a second operating means operated to start the fuel pump, and a judging means that the front-rear pressure difference is greater than or equal to a predetermined value When the first operating means is determined and the first operating means is operated, standby notification means that operates to wait for a predetermined time for the operation of the second operating means is provided.

  According to the configuration of the above invention, for example, when maintenance of the fuel supply passage and other parts is performed in a state where the fuel cutoff valve is closed when the internal combustion engine is stopped, the pressure difference between the front and rear of the fuel cutoff valve is reduced. When the first operation means is operated to open the fuel cutoff valve when the determination means determines that the value is equal to or greater than the predetermined value, the standby notification means is used to wait for a predetermined time for the operation of the second operation means. Works. Accordingly, the fuel cutoff valve is first opened by the operation of the first operating means, and the fuel pressure on the upstream side and the downstream side of the fuel cutoff valve becomes substantially uniform, and then the fuel pump is operated by the operation of the second operating means. Therefore, before the fuel shut-off valve is opened, the fuel pump is not driven and the fuel shut-off valve inlet side is not pressurized, and the pressure difference between the front and rear of the fuel shut-off valve does not increase.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, the fuel pump and the fuel cutoff valve are operated by receiving power supply from a power source. The determination means is an electronic control device that operates by receiving power supply from the power source, and the electronic control device determines that the pressure difference between the front and rear is greater than or equal to a predetermined value when the power supply from the power source is cut off. The purpose is to have

  According to the configuration of the invention described above, in addition to the operation of the invention according to claim 3 or 4, for example, during the above-described maintenance, the electronic control unit can be configured to operate the fuel cutoff valve when the power supply from the power source is shut off. It is determined that the front-rear pressure difference is greater than or equal to a predetermined value. Therefore, it is not necessary to actually measure the pressure difference between the front and rear, and a device for actual measurement becomes unnecessary.

  According to the first aspect of the present invention, it is possible to reliably open the fuel cutoff valve by suppressing an increase in the pressure difference across the fuel cutoff valve after maintenance.

  According to the second aspect of the present invention, it is possible to reliably open the electric fuel cutoff valve by suppressing the power supply voltage from decreasing regardless of the pressure difference across the fuel cutoff valve after maintenance.

  According to the third aspect of the present invention, it is possible to reliably open the fuel cutoff valve by suppressing an increase in the pressure difference across the fuel cutoff valve after maintenance.

  According to the invention described in claim 4, it is possible to reliably open the fuel cutoff valve by suppressing an increase in the pressure difference between the front and rear of the fuel cutoff valve after maintenance.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 3 or 4, it is not necessary to actually measure the front-rear pressure difference, and the configuration of the fuel supply device can be simplified.

[First Embodiment]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a fuel supply device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In this embodiment, the fuel supply device of the present invention will be described as being embodied in an LPG engine that uses liquefied petroleum gas (LPG) as fuel.

  FIG. 1 is a schematic configuration diagram showing a fuel supply device for an internal combustion engine in this embodiment. An LPG engine system mounted on a vehicle includes an LPG engine 1 as an internal combustion engine and a fuel supply device 2 that injects and supplies LPG as fuel to the engine 1. The fuel supply device 2 includes a fuel tank 3 that stores LPG in a liquid phase state. The electric fuel pump 4 built in the fuel tank 3 sucks the liquid phase LPG stored in the tank 3 and discharges it to the fuel supply passage 5 at a high pressure. In this embodiment, the fuel pump 4 is of a type that sucks fuel by rotating an impeller by a motor and discharges the fuel to the fuel supply passage 5 at a high pressure. On the outlet side of the fuel pump 4, a relief valve 4a and a check valve 4b are provided. In this embodiment, the fuel tank 3 includes a main tank 3b and a sub tank 3c that are partitioned by a partition wall 3a. The fuel pump 4 is disposed and provided in the sub tank 3c.

  In this embodiment, the LPG engine 1 is of a four-cylinder reciprocating type, and a fuel injection valve (injector) 6 for high-pressure fuel that supplies LPG in a liquid phase is provided for each cylinder. . Each injector 6 is provided in a delivery pipe 7. A fuel supply passage 5 is connected to the delivery pipe 7. These injector 6 and delivery pipe 7 constitute the fuel injection device of the present invention.

  Here, the liquid phase LPG discharged from the fuel pump 4 is pressure-fed and supplied to each injector 6 through the fuel supply passage 5 and the delivery pipe 7. The supplied LPG in the liquid phase state is injected into each intake port of the LPG engine 1 in a liquid phase state by the operation of each injector 6. Liquid phase LPG injected from each injector 6 forms a combustible air-fuel mixture with air taken in through an intake passage (not shown) and is sucked into each cylinder. A fuel return passage 8 is connected to the delivery pipe 7. The liquid phase LPG remaining in the delivery pipe 7 is returned to the fuel tank 3 through the fuel return passage 8 as return fuel.

  In this embodiment, the fuel return passage 8 has a tip portion disposed in the sub tank 3c so that the return fuel is returned to the sub tank 3c. A pressure regulator 9 for keeping the fuel pressure constant is provided at the tip of the fuel return passage 8.

  Here, in the middle of the fuel supply passage 5, an electric tank side fuel cutoff valve 11 is provided in the vicinity of the fuel tank 3, and an electric delivery side fuel cutoff valve 12 is provided in the vicinity of the delivery pipe 7. Provided. Each of these fuel cutoff valves 11 and 12 is composed of an electromagnetic valve. A fuel filter 13 is provided on the upstream side of the tank side fuel cutoff valve 11. When the LPG engine 1 is stopped, the fuel supply passage 5 is held at a high pressure by closing the two fuel cutoff valves 11 and 12.

  In FIG. 2, each fuel cutoff valve 11 and 12 is shown with sectional drawing. Each fuel cutoff valve 11, 12 includes a valve body 31, a fuel passage 32 provided inside the valve body 31, a valve seat 33 provided corresponding to an outlet 32 a of the fuel passage 32, and a valve seat A valve body 34 provided so as to be capable of reciprocating toward the valve 33, a spring 35 for biasing the valve body 34 in a direction in which the valve body 34 is pressed against the valve seat 33 (a valve closing direction), and a coil 36 for moving the valve body 34. Is provided. FIG. 2 shows a closed state in which the valve body 34 is pressed against the valve seat 33 by the spring 35. The fuel pumped by the fuel pump 4 flows in the same direction as the valve closing direction of the valve element 34 as indicated by an arrow. The fuel shut-off valves 11 and 12 excite the coil 36 by energization to move the valve body 34 in the direction opposite to the direction in which the fuel flows against the urging force of the spring 35 and the fuel pressure. 34 is opened. Therefore, as in the conventional example, each of the fuel cutoff valves 11 and 12 has a difference between the pressure on the inlet 32b side and the pressure on the outlet 32a side, that is, the front-rear pressure difference becomes a predetermined value or more. Then, the valve cannot be opened due to the structure.

  A standby lamp 14 is provided in the driver's seat of the vehicle. The standby lamp 14 is lit when the LPG engine 1 is started under a predetermined condition.

  In this embodiment, an electronic control unit (ECU) 20 that controls the fuel pump 4, each injector 6, each fuel cutoff valve 11, 12, standby lamp 14, and the like is provided. The ECU 20 corresponds to determination means and control means of the present invention. The standby lamp 14 and the ECU 20 constitute standby notification means of the present invention. The ECU 20 is connected to the fuel pump 4, the injectors 6, the fuel cutoff valves 11 and 12, and the standby lamp 14. A power source (battery) 15 is connected to the ECU 20 via a main relay 16. An ignition switch (IG / SW) 17 is connected between the battery 15 and the main relay 16. A starter 18 as an electric device that operates to assist the start of the LPG engine 1 is connected to the ignition switch 17 and the battery 15 via a starter relay 19. The starter 18 is also connected to the ECU 20.

  The ignition switch 17 can be switched between a first position 17 a for supplying power to the ECU 20 and a second position 17 b for supplying power to the ECU 20 and starting the starter 18. The ignition switch 17 corresponds to the first operating means and the second operating means in the present invention. That is, in this embodiment, the fuel pump 4 and the fuel cutoff valves 11 and 12 are operated by receiving power supply from the battery 15 via the ECU 20. The ECU 20 is also operated by receiving power supply from the battery 15.

  The ECU 20 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The ECU 20 constitutes a logical operation circuit formed by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like through a bus. The ROM stores a predetermined control program related to various controls in advance. The RAM temporarily stores the calculation result of the CPU. Each backup RAM stores data stored in advance. The CPU is powered by the battery 15 and executes various controls according to a predetermined control program.

  Here, also in each of the fuel cutoff valves 11 and 12 of this embodiment, as described above, there is a possibility that the valve cannot be opened due to the structure when the pressure difference between the front and rear becomes a predetermined value or more. Assume that maintenance of the fuel supply passage 5 and other parts is performed after the LPG engine 1 is stopped. At this time, each fuel cutoff valve 11, 12 is in a closed state. For example, when the delivery-side fuel cutoff valve 12 is replaced during maintenance, the fuel is temporarily emptied in the fuel supply passage 5 from the tank-side fuel cutoff valve 11 to the delivery pipe 7. For this reason, the inlet side and the outlet side of the delivery side fuel cutoff valve 12 are almost at atmospheric pressure (“0.1 MPa”: absolute pressure), and the pressure difference across the cutoff valve 12 is almost eliminated. On the other hand, the outlet side of the tank-side fuel cutoff valve 11 is almost atmospheric pressure (0.1 MPa: absolute pressure), and the inlet side of the cutoff valve 11 is the holding pressure (1 MPa) of the relief valve 4 a and the fuel tank 3. Is a relatively high pressure (2.6 MPa) due to the sum of the fuel pressure (1.6 MPa). That is, the tank-side fuel cutoff valve 11 is in a state where a pressure difference of “2.5 MPa” is produced at the maximum. When the fuel pump 4 is driven to start the LPG engine 1 in this state, the inlet side of the tank side fuel cutoff valve 11 is pressurized, and the pressure difference across the tank side fuel cutoff valve 11 further increases. growing. For this reason, if the pressure difference across the tank-side fuel cutoff valve 11 exceeds a predetermined value, the fuel cutoff valve 11 may not be able to open even if an operating current is supplied. At this time, since there is almost no pressure difference between the front and rear of the delivery-side fuel cutoff valve 12, if the operating current is supplied, the cutoff valve 12 is opened. However, since the upstream tank-side fuel cutoff valve 11 does not open, fuel does not flow through the fuel supply passage 5 and fuel cannot be supplied to the delivery pipe 7 and each injector 6.

  On the other hand, for example, when the injector 6 is replaced during maintenance, the fuel in the delivery pipe 7 on the downstream side of the delivery-side fuel cutoff valve 12 is temporarily emptied. For this reason, the outlet side of the delivery side fuel shut-off valve 12 is almost atmospheric pressure (0.1 MPa: absolute pressure), and the inlet side of the shut-off valve 12 is the holding pressure (0.1 MPa) of the tank side fuel shut-off valve 11. And a relatively high pressure (2.7 MPa) that is the sum of the holding pressure (1 MPa) of the relief valve 4 a and the fuel pressure (1.6 MPa) in the fuel tank 3. That is, the delivery side fuel cutoff valve 12 is in a state in which a maximum pressure difference of “2.6 MPa” occurs. On the other hand, the inlet side of the tank side fuel cutoff valve 11 has a relatively high pressure (2.MPa) which is the sum of the holding pressure (1 MPa) of the relief valve 4a and the fuel pressure (1.6 MPa) in the fuel tank 3. 6 MPa), and the outlet side of the shut-off valve 11 has a relatively high pressure (2.7 MPa) as described above, and the pressure difference across the shut-off valve 11 is almost eliminated. In the above state, when the fuel pump 4 is driven to start the LPG engine 1, the inlet side of the tank side fuel cutoff valve 11 is pressurized, but there is almost no pressure difference across the tank side fuel cutoff valve 11. Therefore, the shut-off valve 11 is opened. As a result, the inlet side of the delivery side fuel cutoff valve 12 is pressurized, and the pressure difference across the cutoff valve 12 is further increased. For this reason, if the pressure difference between the front and rear of the delivery-side fuel cutoff valve 12 exceeds a predetermined value, the fuel cutoff valve 12 may not be opened even if an operating current is supplied. For this reason, fuel does not flow through the fuel supply passage 5, and fuel cannot be supplied to the delivery pipe 7 and each injector 6.

  FIG. 3 is a graph showing the operating characteristics of the fuel cutoff valves 11 and 12 (relationship of required operating current with respect to the front-rear pressure difference). In this graph, the horizontal axis indicates the “front-rear pressure difference” of the fuel cutoff valves 11 and 12, and the vertical axis indicates the “operating current” for opening the fuel cutoff valves 11 and 12. As can be seen from this graph, when the front-rear pressure difference between the fuel shut-off valves 11 and 12 is “2.6 MPa”, the fuel shut-off valves 11 and 12 are opened against the front-rear pressure difference. An operating current of “about 3.5 A” is required. Conventionally, when the fuel pump and starter are driven together with the fuel shut-off valve when starting the engine, the operating current supplied to the fuel shut-off valve is reduced, so that a driving force that can counter the pressure difference between the front and rear of the fuel shut-off valve is ensured. I couldn't. In other words, since the operating current flows through the fuel pump and the starter when the engine is started, the operating current actually flows through the fuel shut-off valve only at about “2.6 A” and cannot counter the pressure difference of “2.0 MPa”. . It was necessary to secure an operating current of “3.5 A” or more for the maximum pressure difference of “2.6 MPa”.

  Therefore, in this embodiment, after maintaining the fuel supply passage 5 and other parts and before starting the LPG engine 1, the pressure difference between the front and rear of the fuel shut-off valves 11, 12 is eliminated to equalize the pressure. In order to reliably open the shutoff valves 11 and 12, the following pressure equalization control is performed.

  4 and 5 are flowcharts showing the content of the pressure equalization control executed by the ECU 20.

  First, as shown in FIG. 4, when the fuel supply passage 5 and other parts are maintained, when the battery terminal is removed for maintenance in step 100, that is, the wiring terminal that connects the ECU 20 to the battery 15 is the battery. When removed from 15, the ECU 20 clears the backup RAM value in step 110. That is, various data stored in the backup RAM of the ECU 20 are deleted. Thereafter, in step 120, maintenance is performed by replacing the fuel supply passage 5 and other components.

  Since the above maintenance is performed in a state where the operation of the LPG engine 1 is stopped, the fuel cutoff valves 11 and 12 are closed in advance during the maintenance.

  After that, as shown in FIG. 5, when the maintenance is completed and the LPG engine 1 is started, when the ignition switch (IG / SW) 17 is operated to the second position 17b and turned on in step 200, the ECU 20 Shifts the processing to step 210.

  In step 210, the ECU 20 determines whether or not the backup RAM value has been cleared. Here, when the backup RAM value is not cleared, the ECU 20 proceeds to step 270 assuming that maintenance is not performed.

  In step 270, the ECU 20 performs a normal operation. That is, in order to start the LPG engine 1, an operating current is simultaneously supplied to the fuel pump 4 and each of the fuel cutoff valves 11, 12, and the starter 18 is allowed to be driven. At this time, since the starter 18 is in a state where power is supplied from the battery 15 via the starter relay 19, the ECU 20 allows the starter 18 to be driven as it is.

  On the other hand, if the backup RAM value is cleared in step 210, it is assumed that maintenance has been performed, and in step 220, the ECU 20 turns on the standby lamp 14. Thereby, the person who operates the ignition switch 17 can recognize that the fuel pump 4 and the starter 18 are in a standby state where they are not driven.

  Next, in step 230, the ECU 20 opens the fuel cutoff valves 11, 12. For this purpose, the ECU 20 supplies an operating current to each of the fuel cutoff valves 11 and 12.

  Subsequently, in step 240, the ECU 20 prohibits driving of the fuel pump 4 and the starter 18. Therefore, the ECU 20 prohibits the supply of the operating current to the fuel pump 4. Further, since the starter 18 is in a state where power is supplied from the battery 15 via the starter relay 19, the ECU 20 prohibits driving of the starter 18 by sending an operation inhibition signal to the starter 18. The starter 18 receives the operation inhibition signal and cuts off the power supply from the battery 15.

  Thereafter, in step 250, the ECU 20 determines whether or not a predetermined time (several seconds) has elapsed since the ignition switch (IG / SW) 17 was turned on. If the predetermined time has not elapsed, the ECU 20 returns to the process of step 220.

  On the other hand, if the predetermined time has elapsed in step 250, the ECU 20 turns off the standby lamp 14 in step 260, and performs normal operation in step 270. In other words, the operating current is supplied to the fuel pump 4 and each of the fuel cutoff valves 11 and 12, and the supply of the operation prohibiting signal to the starter 18 is stopped to allow the starter 18 to be driven.

  That is, according to the above control, after maintenance, the ECU 20 determines that the pressure difference between the fuel cutoff valves 11, 12 is greater than or equal to a predetermined value, and the ignition switch 17 is turned on at the second position 17b. At this time, the fuel cutoff valves 11 and 12 are opened, and the fuel pump 4 is started after the valves are opened.

  According to the above control, when the front-rear pressure difference between the fuel shut-off valves 11 and 12 exceeds a predetermined value (for example, “2.0 MPa”) after maintenance, the fuel shut-off valves 11 and 12 are opened when the LPG engine 1 is started. The driving of the fuel pump 4 is prohibited until the valve is operated. This control is performed by opening the fuel shut-off valves 11 and 12 and simultaneously driving the fuel pump 4 to pressurize the inlet sides of the fuel shut-off valves 11 and 12 before opening the valves so that the pressure difference between the front and rear This is to prevent the increase.

  Further, according to the above control, when the pressure difference between the front and rear of the fuel cutoff valves 11 and 12 is greater than or equal to a predetermined value (for example, “2.0 MPa”), the fuel cutoff valves 11 and 12 are opened when the LPG engine 1 is started. In order to make the valve operate, an operating current is supplied from the battery 15 to the fuel cutoff valves 11 and 12 via the ECU 20, and the operation from the battery 15 to the fuel pump 4 and the starter 18 is performed until the fuel cutoff valves 11 and 12 are opened. Current supply and power feeding are prohibited. This control is performed when the fuel cutoff valves 11 and 12 are opened, by simultaneously driving the fuel pump 4 and the starter 18, the voltage of the battery 15 is lowered and supplied to the fuel cutoff valves 11 and 12. This is to prevent a decrease in operating current.

  As described above, according to the fuel supply device 2 of this embodiment, the fuel supply passage 5 and other parts can be replaced while the fuel cutoff valves 11 and 12 are closed when the LPG engine 1 is stopped. When maintenance is performed, the pressure difference between the front and rear of each fuel cutoff valve 11, 12 may become a predetermined value (for example, 2.0 MPa) or more. In such a case, when the LPG engine 1 is subsequently started, the driving of the fuel pump 4 is prohibited until the fuel cutoff valves 11 and 12 are opened. More specifically, the ECU 20 determines that the back-and-forth pressure difference between the fuel cutoff valves 11 and 12 is greater than or equal to a predetermined value by determining that the backup RAM value of the ECU 20 has been cleared, and the ignition switch 17 is turned on. Sometimes, the fuel cutoff valves 11 and 12 are opened, and the fuel pump 4 and the starter 18 are started after the valves are opened. Therefore, according to this control, the inlet side of each fuel cutoff valve 11, 12 is not pressurized by the fuel pump 4 before each fuel cutoff valve 11, 12 is opened. The pressure difference of 12 before and after does not increase to the state where it is difficult to open the valve. For this reason, it is possible to reliably open the fuel cutoff valves 11 and 12 while suppressing an increase in the front-rear pressure difference after maintenance.

  Further, according to the fuel supply device 2 of this embodiment, when the pressure difference between the front and rear of each of the fuel cutoff valves 11, 12 exceeds a predetermined value (for example, “2.0 MPa”) after maintenance, the LPG engine 1 is started thereafter. At this time, an operating current is supplied from the battery 15 to the fuel cutoff valves 11 and 12 in order to open the fuel cutoff valves 11 and 12. At the same time, supply of operating current from the battery 15 to the fuel pump 4 and the starter 18 is prohibited until the fuel cutoff valves 11 and 12 are opened. Accordingly, since the supply of operating current to the fuel pump 4 and the starter 18 is prohibited until the fuel cutoff valves 11 and 12 are opened, the voltage of the battery 15 does not decrease, and the fuel cutoff valves 11 and 12 are not reduced. The battery 15 can secure an operating current sufficient to open the valve 12 against the pressure difference between the front and rear. In this sense as well, even if there is a slight difference in pressure before and after the maintenance, it is possible to reliably open the fuel cutoff valves 11 and 12 while suppressing the voltage drop of the battery 15.

  In this embodiment, during the above-described maintenance, the ECU 20 determines that the pressure difference between the front and rear fuel cutoff valves 11 and 12 is greater than or equal to a predetermined value when the power supply from the battery 15 is cut off by removing the battery terminal. Judging that it is. Therefore, it is not necessary to actually measure the pressure difference between the front and rear of each fuel shut-off valve 11, 12, and a device for actual measurement becomes unnecessary. In this sense, the configuration of the fuel supply device can be simplified.

[Second Embodiment]
Next, a second embodiment of the internal combustion engine fuel supply apparatus according to the present invention will be described in detail with reference to the drawings.

  In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different points will be mainly described.

  In this embodiment, in the configuration of FIG. 1, a signal line for sending an operation inhibition signal from the ECU 20 to the starter 18 is omitted. For this reason, in this embodiment, when the ignition switch 17 is operated to the second position 17b, the starter relay 19 is turned on and the starter 18 is always driven. In this embodiment, the configuration of the pressure equalization control is different from that of the first embodiment. FIG. 6 is a flowchart showing the control program. In this embodiment as well, the ECU 20 executes the process shown in FIG. 4 described above when the fuel supply passage 5 and other parts are maintained.

  Then, as shown in FIG. 6, when the maintenance is completed and the LPG engine 1 is started, in step 300, when the ignition switch (IG / SW) 17 is operated to the first position 17a and turned on, the ECU 20 Shifts the processing to step 310. Here, when the ignition switch 17 is operated to the first position 7a, the main relay 16 is turned on and power is supplied from the battery 15 to the ECU 20.

  In step 310, the ECU 20 determines whether or not the backup RAM value has been cleared. Here, when the backup RAM value is not cleared, the ECU 20 proceeds to step 370 assuming that maintenance is not performed.

  On the other hand, if the backup RAM value is cleared in step 310, it is assumed that maintenance has been performed, and in step 320, the ECU 20 turns on the standby lamp 14. In this embodiment, while the standby lamp 14 is lit, the operator is determined to hold the ignition switch 17 at the first position 17a without operating the ignition switch 17 to the second position 17b.

  Next, in step 330, the ECU 20 opens the fuel cutoff valves 11, 12. For this purpose, the ECU 20 supplies an operating current to each of the fuel cutoff valves 11 and 12.

  Next, in step 340, the ECU 20 prohibits driving of the fuel pump 4. Therefore, the ECU 20 prohibits the supply of the operating current to the fuel pump 4.

  In the above operation state, the starter 18 is not supplied with power from the battery 15 via the starter relay 19, so that the drive of the starter 18 is also stopped.

  Thereafter, in step 350, the ECU 20 determines whether or not a predetermined time (several seconds) has elapsed since the ignition switch (IG / SW) 17 was turned on to the first position 17a. If the predetermined time has not elapsed, the ECU 20 returns to the process of step 320. On the other hand, if the predetermined time has elapsed, in step 360, the ECU 20 turns off the standby lamp 14.

  When the standby lamp 14 is turned off and the operator operates the ignition switch (IG / SW) 17 to the second position in step 370, power is supplied from the battery 15 to the starter 18 via the starter relay 19, The starter 18 is driven.

  In step 380, the ECU 20 performs a normal operation in response to the operation of the ignition switch (IG / SW) 17 to the second position. That is, the ECU 20 causes an operating current to flow simultaneously with the fuel pump 4 and the fuel cutoff valves 11 and 12.

  On the other hand, even when the backup RAM value is cleared in step 310, the processing in steps 370 and 380 as described above is performed.

  That is, in the above control, after maintenance, the ECU 20 determines that the pressure difference between the front and rear of each fuel cutoff valve 11, 12 is greater than a predetermined value, and when the ignition switch 17 is operated to the first position 17a, The fuel shut-off valves 11 and 12 are opened, and the standby lamp 14 is lit to wait for a predetermined time for the operation of the switch 17 to the second position 17b. This control is performed in order to prevent the pressure difference between the front and rear from increasing due to the fuel pump 4 pressurizing the inlet side of each of the fuel cutoff valves 11 and 12 before the fuel cutoff valves 11 and 12 are opened. It is.

  Further, in the above control, when the pressure difference between the front and rear of each fuel cutoff valve 11, 12 exceeds a predetermined value (for example, “2.0 MPa”), the fuel cutoff valves 11, 12 are opened when the LPG engine 1 is started. Therefore, an operating current is supplied from the battery 15 to the fuel cutoff valves 11 and 12 via the ECU 20, and the operating current from the battery 15 to the fuel pump 4 and the starter 18 until the fuel cutoff valves 11 and 12 are opened. Supply and power supply are prohibited. This control is performed when the fuel shut-off valves 11 and 12 are opened, by simultaneously driving the fuel pump 4 and the starter 18, the voltage of the battery 15 is lowered and supplied to the fuel shut-off valves 11 and 12. This is to prevent a decrease in operating current.

  Therefore, also in this embodiment, before the fuel shut-off valves 11 and 12 are opened, the inlet sides of the fuel shut-off valves 11 and 12 are not pressurized by the drive of the fuel pump 4, and the fuel shut-off valves 11 and 12 are not pressurized. , 12 does not increase to a state where it is difficult to open the valve. For this reason, it is possible to reliably open the fuel cutoff valves 11 and 12 while suppressing an increase in the pressure difference between the front and rear after maintenance.

  Also in this embodiment, the supply of the operating current to the fuel pump 4 and the starter 18 is prohibited until the fuel shut-off valves 11 and 12 are opened. The battery 15 can secure an operating current sufficient to open the fuel cutoff valves 11 and 12 against the pressure difference between them. In this sense as well, even if there is a slight difference in pressure before and after the maintenance, it is possible to reliably open the fuel cutoff valves 11 and 12 while suppressing the voltage drop of the battery 15. Other functions and effects in this embodiment are basically the same as those in the first embodiment.

  The present invention is not limited to the embodiments described above, and can be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention.

  (1) In the first embodiment, when the ignition switch 17 is operated to the second position 17b, in order to prohibit the operation of the starter 18, as shown in FIG. Signal ". On the other hand, as a modification of the configuration of FIG. 7, as shown in FIG. 8, a starter operation prohibiting relay 21 is provided between the ignition switch 17, the starter relay 19 and the ECU 20, and the ECU 20 is connected to the relay 21. The starter relay 19 may be turned off and the operation of the starter 18 may be prohibited by giving a “starter drive prohibition” signal.

  (2) In the above-described embodiments, the configuration in which the two fuel cutoff valves 11 and 12 are provided in the fuel supply passage 5 has been described. However, one fuel cutoff valve may be provided in the fuel supply passage. Also in this case, the same effect can be obtained by performing pressure equalization control similar to that in each of the embodiments.

The schematic block diagram which shows the fuel supply apparatus of an internal combustion engine. Sectional drawing which shows a fuel cutoff valve. The graph which shows the operating characteristic of each fuel cutoff valve. The flowchart which shows the content of pressure equalization control. The flowchart which shows the content of pressure equalization control. The flowchart which shows the content of pressure equalization control. The electric circuit diagram which shows a starter operation prohibition structure. The electric circuit diagram which shows a starter operation prohibition structure.

Explanation of symbols

1 LPG engine (internal combustion engine)
2 Fuel supply device 3 Fuel tank 4 Fuel pump 5 Fuel supply passage 6 Injector (fuel injection device)
7 Delivery pipe (fuel injection equipment)
11 Tank side fuel cutoff valve 12 Delivery side fuel cutoff valve 14 Standby lamp (standby notification means)
15 Battery (Power)
17 Ignition switch (starting operation means, first operation means, second operation means)
18 Starter (Electric device)
20 ECU (determination means, control means, standby notification means)

Claims (5)

The fuel in the fuel tank is supplied to a fuel injection device of the internal combustion engine through a fuel supply passage by a fuel pump, and the fuel supply is performed by closing a fuel cutoff valve provided in the fuel supply passage when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that cuts off fuel in a passage,
A fuel supply apparatus for an internal combustion engine, wherein when the pressure difference between the front and rear of the fuel cutoff valve is equal to or greater than a predetermined value, the fuel pump is prohibited from driving until the fuel cutoff valve is opened when the internal combustion engine is started. . The fuel in the fuel tank is supplied by an electric fuel pump to the fuel injection device of the internal combustion engine through the fuel supply passage, and the electric fuel cutoff valve provided in the fuel supply passage is closed when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that shuts off fuel in the fuel supply passage,
The internal combustion engine includes an electric device for assisting the start thereof,
When the pressure difference between the front and rear of the fuel cutoff valve is equal to or greater than a predetermined value, an operating current is supplied from the power source to the fuel cutoff valve to open the fuel cutoff valve when starting the internal combustion engine, and the fuel cutoff valve A fuel supply device for an internal combustion engine, wherein supply of an operating current from the power source to at least one of the fuel pump and the electric device is prohibited until the valve is opened. The fuel in the fuel tank is supplied to a fuel injection device of the internal combustion engine through a fuel supply passage by a fuel pump, and the fuel supply is performed by closing a fuel cutoff valve provided in the fuel supply passage when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that cuts off fuel in a passage,
Determination means for determining that the pressure difference across the fuel shut-off valve is greater than or equal to a predetermined value;
Start operation means for operating start of the internal combustion engine;
Control for opening the fuel shut-off valve and starting the fuel pump after opening when the determination means determines that the pressure difference between the front and rear is greater than or equal to a predetermined value and the start operation means is operated And a fuel supply device for an internal combustion engine. The fuel in the fuel tank is supplied to a fuel injection device of the internal combustion engine through a fuel supply passage by a fuel pump, and the fuel supply is performed by closing a fuel cutoff valve provided in the fuel supply passage when the internal combustion engine is stopped. A fuel supply device for an internal combustion engine that cuts off fuel in a passage,
Determination means for determining that the pressure difference across the fuel shut-off valve is greater than or equal to a predetermined value;
First operating means operated to open the fuel shut-off valve;
Second operating means operated to start the fuel pump;
When the determination means determines that the front-rear pressure difference is greater than or equal to a predetermined value, and the first operation means is operated, a standby notification that operates to wait for a predetermined time of operation of the second operation means And a fuel supply device for an internal combustion engine. The fuel pump and the fuel shut-off valve operate by receiving power supply from a power source;
The determination means is an electronic control device that operates by receiving power supply from the power source;
5. The electronic control device according to claim 3, further comprising: determining that the front-rear pressure difference is equal to or greater than the predetermined value when power supply from the power source is interrupted. 6. A fuel supply device for an internal combustion engine.

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