JP4707156B2 - Liquefied gas fuel supply device for internal combustion engine - Google Patents

Description

The present invention relates to a liquefied gas fuel supply equipment for an internal combustion engine, in particular, relates to a liquefied gas fuel supply equipment for an internal combustion engine employing a common rail system.

  In recent years, attention has been focused on using DME (dimethyl ether) with clean exhaust gas as an alternative fuel instead of diesel oil as a countermeasure against air pollution by diesel engines. This DME fuel is a liquefied gas fuel, unlike conventional diesel fuel. That is, the boiling point is lower than that of light oil, and light oil is liquid at normal temperature under atmospheric pressure, whereas DME has a property of becoming a gas at normal temperature.

  Therefore, in a diesel engine using DME fuel, if DME fuel remains in the injection system after the engine is stopped, the DME fuel leaks into the engine cylinder from the injector nozzle hole and vaporizes, and fills the cylinder. As a result, when the engine is started next, abnormal combustion such as knocking occurs, and the engine cannot be started normally, and there is a risk of generating large vibrations and noise. Therefore, in a diesel engine using DME fuel, a purge process for removing DME fuel remaining in the injection system after the engine is stopped is performed.

  Here, when all the fuel in the common rail is recovered to the purge tank every time the engine is stopped, the work of the compressor that reliquefies the vaporized fuel by reducing the pressure by the purge tank increases. For this reason, the energy loss of the entire system may increase.

Therefore, a fuel supply device for a DME engine has been proposed in which the work amount of the compressor for re-liquefying the fuel collected in the purge tank can be suppressed to the necessary minimum, and the energy loss of the entire system can be greatly reduced. Yes. More specifically, as shown in FIG. 9, the fuel introduced from the fuel tank 201 is boosted by the high-pressure pump 204 and accumulated in the common rail 205, and the fuel is introduced from the common rail 205 to the injector 207 to the combustion chamber. 208, an injection line 206 for injecting the fuel into 208, a purge line 211 for extracting fuel from the common rail 205 to the purge tank 210 via the purge control valve 209, and fuel in the purge tank 210 is re-liquefied by the compressor 212 and returned to the fuel tank 201. In a fuel supply device for a DME engine provided with a communication line 213, a bypass line 214 that draws fuel from a downstream side of the purge control valve 209 of the purge line 211 and leads it directly to the fuel tank 201, and is provided in the middle of the bypass line 214 Fuel tank being A check valve 215 that prevents the flow of fuel from the 201 side to the purge line 211 side, and a fuel flow toward the purge tank 210 that is provided on the downstream side of the connection point of the bypass line 214 in the purge line 211 appropriately. The normally closed on / off valve 216 that shuts off, and when the engine is stopped, the valve opening command is output toward the purge control valve 209, and the valve is opened toward the on / off valve 216 when the pressure between the purge line 211 and the fuel tank 201 is substantially equalized. A fuel supply device for a DME engine is disclosed (see Patent Document 1), which includes a control device 217 that outputs a command.
JP 2003-56409 A (Claims, FIG. 1)

  However, in the fuel supply device for the DME engine described in Patent Document 1, if the DME fuel in the common rail is in a high pressure state, the check valve can be opened and the DME fuel can be recovered in the fuel tank. When the DME fuel inside is recovered and the pressure in the common rail decreases, the check valve is closed. In this state, the pressure in the common rail is at least equal to or lower than the vapor pressure, and a relatively large amount of DME fuel may still remain in the common rail. Since the remaining DME fuel is collected into the purge tank, the purge tank is required to have a relatively large capacity, and there is a possibility that the time required for the vaporization purge becomes long.

Therefore, the inventors of the present invention have made diligent efforts to connect the gas-phase introduction passage leading from the gas-phase portion of the fuel tank to the common rail and connect the common rail and the high-pressure pump by a purge passage. The present invention has been completed by finding that such problems can be solved.
That is, the present invention can perform vaporization purge after recovering most of the liquefied gas fuel in the high-pressure pump, common rail, and fuel injection section, thereby reducing the burden on the purge tank and utilizing a small purge tank. Another object of the present invention is to provide a liquefied gas fuel supply device for an internal combustion engine that can shorten the time required to recover the liquefied gas fuel.

According to the present invention, the liquefied gas fuel in the fuel tank is sent to the high pressure pump by the feed pump, and the liquefied gas fuel is pressurized by the high pressure pump to the common rail to which the fuel injection portion of the internal combustion engine is connected. A liquefied gas fuel supply device for supplying liquefied gas fuel from the section to the internal combustion engine, wherein the feed pump and the high pressure pump are connected by a fuel supply passage, and the fuel supply passage is provided with a first opening / closing means, The gas phase portion of the fuel tank and the common rail are connected by a gas phase introduction passage, the gas phase introduction passage is provided with a second opening / closing means, and a fuel supply passage on the high-pressure pump side with respect to the first opening / closing means. The purge is connected to the common rail by a purge passage, and the purge passage is provided with a third opening / closing means, and the gaseous component of the liquefied gas fuel is introduced from the gas phase introduction passage. However, the liquid purge means for recovering the liquefied gas fuel in the high pressure pump, the common rail and the fuel injection section into the fuel tank, and the liquefied gas fuel remaining in the high pressure pump, the common rail and the fuel injection section after the operation of the liquid purge means Vaporization purge means for vaporizing and collecting , and further, the third opening / closing means is opened when the liquid purge means and the vaporization purge means are operated, and before the internal combustion engine is started. A liquefied gas fuel supply device for an internal combustion engine, which is also opened when the liquefied gas fuel is filled, is provided, and the above-described problems can be solved.

  In constructing the liquefied gas fuel supply device for an internal combustion engine of the present invention, the liquid purge means includes a high pressure pump, a common rail, and a suction means for sucking the liquefied gas fuel in the fuel injection section, and the liquefied gas is sucked by the suction means. It is preferable that the liquefied gas fuel is collected in the fuel tank while sucking the fuel and replacing the gaseous component introduced from the gas phase introduction passage.

  The liquefied gas fuel supply device for an internal combustion engine according to the present invention includes a fuel circulation passage branched from the middle of the fuel supply passage and connected to the fuel tank, and the fuel circulation passage has an aspirator as a suction means. The high pressure pump and the aspirator are connected by a liquid purge passage, and the liquefied gas fuel sent by the feed pump is circulated as it is to the fuel tank via the aspirator, so that the high pressure pump, the common rail, and It is preferable that the liquefied gas fuel in the fuel injection section is sucked and collected in the fuel tank.

  In configuring the liquefied gas fuel supply apparatus for an internal combustion engine of the present invention, the vaporization purge means includes a low pressure tank, and after the operation of the liquid purge means, the high pressure pump and the low pressure tank are communicated via the vaporization purge passage. Thus, it is preferable that the remaining liquefied gas fuel is recovered.

  In constructing the liquefied gas fuel supply apparatus for an internal combustion engine of the present invention, the second opening / closing means is opened when the liquid purge means is operated, and is closed when the vaporization purge means is operated. Is preferred.

  Further, in configuring the liquefied gas fuel supply device for an internal combustion engine of the present invention, the flow of the liquefied gas fuel to the second opening / closing means side is stopped between the second opening / closing means of the gas phase introduction passage and the common rail. A check valve is preferably provided.

According to the liquefied gas fuel supply equipment for an internal combustion engine of the present invention comprises a first switching means to the fuel supply passage that connects the fuel tank and the high-pressure pump, the fuel supply of the high-pressure pump side than the first opening and closing means By connecting the passage and the common rail with a purge passage, and further connecting the gas phase portion of the fuel tank and the common rail with a gas phase introduction passage, most of the high pressure pump, common rail and fuel injection section are at the time of liquid purging. Liquefied gas fuel can be returned into the fuel tank. Therefore, since the vaporization purge is performed in a state where the liquefied gas fuel remaining in the high pressure pump, the common rail, and the fuel injection portion is reduced as much as possible, the burden on the purge tank (low pressure tank) for collecting the vaporized fuel can be suppressed. . As a result, the capacity of the purge tank can be reduced, the time required for the vaporization purge can be shortened, and the liquefied gas fuel can be quickly recovered after the operation of the internal combustion engine is completed.

  The purge passage disposed between the fuel supply passage on the high-pressure pump side of the first opening / closing means and the common rail can be used as a fuel supply passage for filling the common rail with liquefied gas fuel when the engine is started. . Therefore, since the liquefied gas fuel can be filled into the common rail simultaneously with the high-pressure pump, the engine can be started quickly.

It is a figure which shows the structural example of the liquefied gas fuel supply apparatus of the diesel engine concerning 1st Embodiment. It is a figure for demonstrating an example of a structure of a high pressure pump. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of an engine stop. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of fuel filling. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of engine operation. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of a liquid purge. It is a figure which shows the state of the liquefied gas fuel supply apparatus at the time of vaporization purge. It is a flow which shows the forced stop method of the internal combustion engine concerning 2nd Embodiment. It is a figure which shows the structure of the conventional liquefied gas fuel supply apparatus.

Hereinafter, with reference to the drawings, it will be specifically described embodiments regarding the liquefied gas fuel supply equipment for an internal combustion engine of the present invention. However, this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In addition, what attached | subjected the same code | symbol in each figure has shown the same member, and description is abbreviate | omitted suitably.

[First Embodiment]
The first embodiment of the present invention is a liquefied gas fuel supply device for an internal combustion engine and a liquefied gas fuel recovery method using the same.
A typical example of the liquefied gas fuel is dimethyl ether (DME), but the present invention can be applied to any liquefied gas fuel that can be used as a fuel for an internal combustion engine. is there.

1. Liquefied Gas Fuel Supply Device (1) Overall Configuration FIG. 1 shows a schematic configuration of a liquefied gas fuel supply device for a diesel engine according to this embodiment.
A liquefied gas fuel supply apparatus 100 for a diesel engine shown in FIG. 1 includes a fuel tank 1, an in-tank feed pump 2, a high-pressure pump 5, a common rail 10, an injector 13, a purge tank 9, and the like as main components. As prepared. Each component is connected by a fuel passage and a purge passage.

The fuel tank 1 stores liquefied gas fuel. The liquefied gas fuel is, for example, DME fuel, and the fuel tank 1 is not particularly limited as long as it can store the liquefied gas fuel.
An in-tank feed pump 2 is disposed in the fuel tank 1, and the in-tank feed pump 2 supplies the fuel in the fuel tank 1 to the high-pressure pump 5 through the fuel supply passage 18. It has become. For example, an electric pump is used as the in-tank feed pump 2, and a liquefied gas fuel having a predetermined flow rate is pumped by supplying a pulse voltage. In addition, a pre-filter 3 is interposed at the fuel suction port of the in-tank feed pump 2, and when foreign matter is mixed in the liquefied gas fuel in the fuel tank 1, the foreign matter is caught so as not to be sucked. It is supposed to be collected.

  The fuel supply passage 18 connecting the fuel tank 1 and the high-pressure pump 5 is provided with the filter 4 and the first opening / closing means 19. Floating matter in the liquefied gas fuel is collected by the filter 4 provided in the fuel supply passage 18 and does not flow into the high-pressure pump 5. The first opening / closing means 19 is, for example, an electromagnetically controlled ON-OFF valve, and the fuel supply passage 18 is opened and closed.

  The high-pressure pump 5 is provided with a flow rate control valve 8 so that the flow rate of the fuel supplied through the fuel supply passage 18 is controlled according to the required common rail pressure and sent to the fuel pressurizing chamber. It has become. For example, an electromagnetic proportional flow control valve can be used as the flow control valve 8. Further, fuel return passages 30 a and 30 b communicating with the fuel tank 1 are connected upstream of the flow control valve 8. The fuel return passage 30b is provided with an overflow valve 14 arranged in parallel with the flow control valve 8, and is opened when the fuel flow rate sent to the flow control valve 8 is excessive, and excess fuel is supplied. It is returned to the fuel tank 1.

  A flow sensor 15 and a fuel cooler 16 are provided in the middle of the fuel return passage 30a. Among them, the fuel cooler 16 cools the liquefied gas fuel returned into the fuel tank 1 so that the temperature of the liquefied gas fuel is maintained at a predetermined temperature or lower, and the pressure in the fuel tank 1 is always constant. By maintaining the pressure value below the vapor pressure, it can be held in a liquefied state. The flow sensor 15 is used for detecting the flow rate of the liquefied gas fuel passing through the fuel return passage 30a and measuring the engine start timing.

  The high pressure pump 5 pressurizes the liquefied gas fuel introduced into the fuel pressurizing chamber with a plunger (not shown), and supplies the liquefied gas fuel to the common rail 10 via a fuel discharge valve (not shown) and high pressure fuel passages 37a and 37b. It is designed to pump. The cam chamber (not shown) in which the cam for reciprocating the plunger in the high pressure pump 5 is a dedicated lubrication system separated from the lubrication system of the diesel engine.

  FIG. 2 shows an example of the configuration of the high-pressure pump 5. The high-pressure pump 5 includes a pump housing 111, a plunger barrel 112 mounted in a cylindrical space 111b of the pump housing 111, a plunger 113 slidably held in an internal space 112a of the plunger barrel 112, and plunger barrels 112 at both ends. And a spring 115 that is locked to the spring seat 119 and biases the plunger 113 downward, and is interposed between the plunger 113 and the cam 121, and pushes up the plunger 113 while centering as the cam 121 rotates. The tappet structure 118 is provided. An IO valve 120 is disposed in the upper opening of the internal space 112 a of the plunger barrel 112.

  In the high-pressure pump 5, a part of the inner space 112 a of the plunger barrel 112 is closed by the inner peripheral surface of the plunger barrel 112, the plunger 113 and the IO valve 120, and is configured as a fuel pressurizing chamber 114. The liquefied gas fuel that has flowed into the fuel pressurizing chamber 114 via the inlet valve 120a is pressurized by the plunger 113 that is pushed up by the rotational movement of the cam 121 in the fuel pressurizing chamber 114, and the outlet valve 120b. Is pushed open, so that the high-pressure liquefied gas fuel is pumped to a common rail (not shown) on the downstream side.

  In the high pressure pump 5, in order to prevent seizure due to the reciprocating motion of the plunger 113, the fuel pressurizing chamber 114 is interposed between the inner peripheral surface of the inner space 112 a of the plunger barrel 112 and the outer peripheral surface of the plunger 113. Part of the liquefied gas fuel that has flowed in leaks and functions as a lubricating oil. The basic configuration of the high-pressure pump 5 so far is basically the same as that of a high-pressure pump used in a conventional diesel engine fuel supply device using light oil as fuel.

On the other hand, in the high-pressure pump 5 used in this embodiment, two O-ring grooves 141a and 141b are provided on the outer peripheral surface of the plunger barrel 112 facing the cylindrical space 111b of the pump housing 111, and O-rings 143a and 143b are arranged, respectively. Has been. Further, a leak recovery chamber 145 is provided between the two O-ring grooves 143a and 143b. Therefore, the leak recovery chamber 145 is separated from the liquefied gas fuel passage 147 flowing into the fuel pressurizing chamber 114 via the upper inlet valve 120a and the lower spring chamber 161.
The plunger barrel 112 is provided with a leak recovery passage 149 so as to communicate between the leak recovery chamber 145 and the inner peripheral surface facing the outer peripheral surface of the plunger 113. One end of the leak recovery passage 149 on the inner peripheral surface side faces a position below the bottom dead center of the plunger 113.

The high pressure pump 5 is provided with a pressure adjusting means 151 for adjusting the pressure in the leak recovery chamber 145, and the pressure in the leak recovery chamber 145 is set to be slightly lower than the pressure in the cam chamber 111a. Has been. For example, a relief valve can be used as the pressure adjusting means 151. Since the pressure in the cam chamber 111a is normally equal to the atmospheric pressure, the opening pressure of the relief valve is set to be slightly lower than the atmospheric pressure. The
Accordingly, the lubricating oil in the cam chamber 111a is not sucked up via the spring chamber 161, but the liquefied gas fuel leaked to the outer peripheral surface of the plunger 113 does not leak into the cam chamber 111a, and the leak recovery passage 149 is And is collected in the leak collection chamber 145. Therefore, the liquefied gas fuel does not leak to the cam chamber 111a side and is not mixed with the lubricating oil in the cam chamber 111a even though the viscosity is relatively lower than that of light oil. Has been.

  The liquefied gas fuel recovered in the leak recovery chamber 145 is reduced in pressure and vaporized by the reliquefaction compressor 6 and then compressed and reliquefied and recovered in a fuel tank (not shown). By evaporating and recovering the liquefied gas fuel in the leak recovery chamber 145, there is no possibility that the lubricating oil is returned to the fuel tank even when the lubricating oil in the cam chamber 111a is mistakenly mixed. Lubricating oil is not mixed with liquefied gas fuel so that it is not supplied to the internal combustion engine. The reliquefaction compressor 6 is driven using a cam that drives the high-pressure pump 5.

  Further, the common rail 10 shown in FIG. 1 accumulates high-pressure fuel pumped from the high-pressure pump 5 and supplies it to the plurality of injectors 13 through the high-pressure fuel passage 39 at an equal pressure. A rail pressure sensor 11 and a pressure control valve 12 are attached to the common rail 10. The pressure control valve 12 is, for example, an electromagnetic proportional control valve, and a value detected by the rail pressure sensor 11 is sent to a control means (ECU) (not shown), and a pressure adjustment valve (not shown) is based on this value. )) Is controlled. A part of the fuel pumped from the high-pressure pump 5 is discharged into the fuel return passage 30c, whereby the pressure in the common rail 10 is adjusted to a desired value.

  In addition, an injector 13 as a fuel injection portion connected to the common rail 10 performs injection control of high-pressure fuel supplied from the common rail 10 so that fuel is supplied into the cylinders of the internal combustion engine. The form of the injector 13 is not particularly limited. For example, a known electromagnetically controlled fuel injection valve can be used. The discharged fuel used for back pressure control of the injector 13 is caused to flow through the check valve 31 to the fuel return passage 30e and returned to the fuel tank 1.

(2) Liquid Purging Means The liquefied gas fuel supply device for a diesel engine of this embodiment is provided with liquid purging means. This liquid purging means includes a gas phase introduction passage 20, a first purge passage 24, a second purge passage (liquid purge passage) 22 branched from the fuel return passage 30b, a fuel circulation passage 28, And an aspirator 17.
Among these, the gas phase introduction passage 20 is disposed between the gas phase portion of the fuel tank 1 and the common rail 10, and the second opening / closing means 21 is disposed in the middle. Further, a check valve 41 is disposed between the common rail 10 and the second opening / closing means 21 in the gas phase introduction passage 20, and the second opening / closing is performed even when high pressure fuel is accumulated in the common rail 10. The flow of the liquefied gas fuel to the means 21 side is stopped. Therefore, the second opening / closing means 21 can be made small and low withstand voltage type.

  The first purge passage 24 is disposed between the fuel supply passage 18 on the high-pressure pump 5 side of the first opening / closing means 19 and the common rail 10, and the third opening / closing means 25 is disposed in the middle. Yes. The fuel circulation passage 28 is configured as a circulation passage branched from the fuel supply passage 18 and returned to the fuel tank 1, and the fifth opening / closing means 29 and the aspirator 17 are disposed on the way. Further, the second purge passage 22 is configured to be disposed between the high-pressure pump 5 and the aspirator 17, and a fourth opening / closing means 23 is disposed in the middle.

The aspirator 17 is used as a suction means for recovering the liquefied gas fuel inside the common rail 10, the injector 13, and the high-pressure pump 5 to the fuel tank 1. As shown in FIG. 1, the aspirator 17 has an inlet 7a, an outlet 7b, and a suction port 7c. The inlet 7a and the outlet 7b communicate with each other in a straight line, and the suction port 7c is connected to the inlet 7a and the outlet. The second purge passage 22 is branched from the communication passage between the second purge passage 22 and the communication passage 7b in a substantially vertical direction.
The opening / closing means arranged in each passage can use, for example, an electromagnetically controlled ON-OFF valve.

  In the liquid purging means shown in this example, the second opening / closing means 21 disposed in the gas phase introduction passage 20, the third opening / closing means 25 disposed in the first purge passage 24, and the second purging means. In a state where the fourth opening / closing means 23 disposed in the passage 22 is opened, the injector 13, the common rail 10, and the high-pressure pump 5 communicate with the second purge passage 22. Further, when the in-tank feed pump 2 is driven while the first opening / closing means 19 disposed in the fuel supply passage 18 is closed while the fifth opening / closing means 29 is opened, the pressure-fed fuel is supplied to the fuel circulation passage 28. After flowing through the aspirator 17, the fuel tank 1 is returned to the fuel tank 1. At this time, the liquefied gas fuel in the second purge passage 22 is sucked by the suction differential pressure generated when the fuel passes through the aspirator 17. Then, the liquefied gas fuel inside the injector 13, the common rail 10, and the high-pressure pump 5 is recovered in the fuel tank 1 while being replaced by the gas phase portion introduced from the common rail 10 side through the gas phase introduction passage 20. It becomes like this.

  In the example of the present embodiment, the aspirator 17 is used as a means for sucking the liquefied gas fuel, but other suction means may be used. When using suction means other than an aspirator, for example, the fuel circulation passage may be omitted.

(3) Vaporization purge means The liquefied gas fuel supply device of the diesel engine of this embodiment is provided with a vaporization purge means. This vapor purge means includes a first purge passage 24, a third purge passage (vapor purge passage) 26 branched from the second purge passage 22, a purge tank (low pressure tank) 9, It has.
The third purge passage 26 is configured to be disposed between the high-pressure pump 5 and the purge tank 9, and is provided with sixth opening / closing means 27 on the way. For the sixth opening / closing means 27, for example, an electromagnetic control type ON-OFF valve can be used.

  The purge tank 9 vaporizes and recovers the liquefied gas fuel remaining in the common rail 10 and the high-pressure pump 5 and the injector 13 communicating with the third purge passage 26. A known tank can be used as the purge tank 9, but in the liquefied gas fuel supply apparatus of the present invention, the vapor purge is performed after most of the fuel is recovered by the liquid purge means. Even a small purge tank can be used.

In the vaporization purge means shown in this example, the first opening / closing means 19 disposed in the fuel supply passage 18, the second opening / closing means 21 disposed in the vapor phase introduction passage 20, and the second purge passage 22 are provided. The fourth opening / closing means 23 arranged is closed, while the third opening / closing means 25 arranged in the first purge passage 24 and the sixth opening / closing means 27 arranged in the third purge passage 26 are opened. In this state, the injector 13, the common rail 10, and the high pressure pump 5 communicate with the third purge passage 26. As a result, the pressure-reduced purge tank 9 is communicated, and the liquefied gas fuel remaining in the injector 13, common rail 10, and high-pressure pump 5 is vaporized and collected in the purge tank 9. .
The fuel recovered by the vaporization purge is sent to the reliquefaction compressor 6 through the check valve 33 in the next operation state of the engine, reliquefied, and then returned to the fuel tank 1.

2. Operation of Liquefied Gas Fuel Supply Device Next, the operation of the liquefied gas fuel supply device 100 of the diesel engine of the present embodiment described so far will be described with reference to FIGS.

  First, FIG. 3 shows a state when the engine is stopped. When the engine is stopped, the first to sixth opening / closing means 19, 21, 23, 25, 27, 29 are all closed. In this state, basically, the liquefied gas fuel does not exist in the injector 13, the common rail 10, and the high-pressure pump 5.

  Next, the state at the time of fuel filling before engine starting is shown in FIG. At the time of fuel filling, the second opening / closing means 21 provided in the gas phase introduction passage 20 provided between the fuel tank 1 and the common rail 10, the high pressure pump 5 and the aspirator 17 are provided. A fourth opening / closing means 23 provided in the second purge passage 22; a sixth opening / closing means 27 provided in the third purge passage 26 branched from the second purge passage 22; and a fuel circulation passage. The fifth opening / closing means 29 provided in 28 is closed. On the other hand, a first opening / closing means 19 provided in a fuel supply passage 18 disposed between the fuel tank 1 and the high-pressure pump 5, and a fuel supply passage 18 closer to the high-pressure pump 5 than the first opening / closing means 19. And the third opening / closing means 25 provided in the first purge passage 24 disposed between the common rail 10 and the common rail 10 are opened.

  When the in-tank feed pump 2 is driven in this state, the liquefied gas fuel in the fuel tank 1 is sent to the high-pressure pump 5 side through the prefilter 3 and the filter 4. The fuel supply passage 18 branches in the middle, and the liquefied gas fuel flows into the high-pressure pump 5 side and also flows into the common rail 10 side through the first purge passage 24. The liquefied gas fuel flowing into the common rail 10 side also flows into the injector 13 connected to the common rail 10 via the high-pressure fuel passage 39. When all of the injector 13, the common rail 10, and the high-pressure pump 5 are filled with the liquefied gas fuel, the internal pressure gradually increases, and the overflow valve 14 is opened when a predetermined pressure value is exceeded. It is sent to the fuel return passage 30 a via the valve 35 and returned to the fuel tank 1.

  Thereafter, when the detected value of the flow sensor 15 provided in the fuel return passage 30a exceeds a predetermined threshold value, it is determined that the liquefied gas fuel is reliably filled in the injector 13, the common rail 10, and the high-pressure pump 5. The engine is started.

  Next, the state at the time of engine operation is shown in FIG. During the engine operation, the first opening / closing means 19 is continuously opened, and the second opening / closing means 21 and the fourth to sixth opening / closing means 23, 27, 29 are continuously closed. On the other hand, the third opening / closing means 25 that was opened at the time of fuel filling is closed. The in-tank feed pump 2 is also continuously driven.

In this state, the liquefied gas fuel in the fuel tank 1 flows into the fuel pressurizing chamber of the high-pressure pump 5 after the flow rate is controlled by the flow control valve 8 and is pressurized by the plunger, and the fuel discharge valve and the high pressure It is pumped to the common rail 10 through the fuel passages 37a and 37b. The fuel pumped to the common rail 10 is supplied at a uniform pressure to the plurality of injectors 13 connected to the common rail 10 via the high-pressure fuel passage 39, and is supplied into the cylinder of the engine by the injection control of the injector 13. The At this time, since the check valve 41 is provided between the common rail 10 and the second opening / closing means 21, high-pressure fuel does not flow to the second opening / closing means 21 side of the gas phase introduction passage 20. It has become.
In addition, fuel that overflows from the high-pressure pump 5, fuel that is discharged from the pressure control valve 12 of the common rail 10, and fuel that is used for back pressure control of the injector 13 and is discharged through the check valve 31 is returned to the fuel. It is returned to the fuel tank via the passages 30a, 30b, 30c, 30e.

  Further, when the engine is started and the pump starts to be driven, the reliquefaction compressor 6 is also operated. Therefore, the vaporized fuel gas recovered in the purge tank 9 is recirculated through the check valve 33. 6 is re-liquefied and returned to the fuel tank 1.

  Next, FIG. 6 shows a state where the engine is stopped and the liquid purge is performed. At the time of the liquid purge, the sixth opening / closing means 27 that was closed when the engine was operating is continuously closed. On the other hand, the first opening / closing means 19 opened during engine operation is closed, and the second to fifth opening / closing means 21, 23, 25, 29 closed during engine operation are opened. Further, the in-tank feed pump 2 is continuously driven.

When the liquefied gas fuel is pumped by the in-tank feed pump 2 in this state, the liquefied gas fuel flows through the fuel circulation passage 28 and flows into the aspirator 17. When the liquefied gas fuel passes through the aspirator 17, the liquefied gas fuel in the second purge passage 22 is sucked by the generated suction differential pressure. The second purge passage 22 communicates with the high-pressure pump 5, the common rail 10, and the injector 13, and the second opening / closing means 21 disposed in the gas phase introduction passage 20 connected to the common rail 10 is opened. Therefore, the liquefied gas fuel in the high-pressure pump 5, the common rail 10, and the injector 13 is recovered in the fuel tank 1 while being replaced by the gas phase.
At the end of the liquid purge, most of the liquefied gas fuel in the high-pressure pump 5, the common rail 10, and the injector 13 is recovered.

  Next, FIG. 7 shows a state where the vapor purge is performed. During the vaporization purge, the first opening / closing means 19 that was closed during the liquid purge is continuously closed, and the third opening / closing means 25 that was open during the liquid purge is continuously opened. On the other hand, the second opening / closing means 21 and the fourth and fifth opening / closing means 23 and 29 opened during the liquid purge are closed, and the sixth opening / closing means 27 closed during the liquid purge is opened. Further, the driving of the in-tank feed pump 2 is stopped.

In this state, the high-pressure pump 5, the common rail 10, and the injector 13 are in communication with the purge tank 9 that has been depressurized, so that a small amount of liquefied gas fuel remaining inside is vaporized, and the third purge It is collected in the purge tank 9 through the passage 26.
In the example of the present embodiment, most of the liquefied gas fuel is recovered at the time of the above-described liquid purge, so that the burden on the purge tank 9 during the vaporization purge is minimized. Therefore, even when a small purge tank 9 is used, the time required for vaporization purge is reduced.

  At the end of the vaporization purge, almost all of the liquefied gas fuel is purged from the inside of the high-pressure pump 5, the common rail 10, and the injector 13. Therefore, the liquefied gas fuel remaining in the system other than the fuel tank 1 and the purge tank 9 before the next engine start is prevented from leaking, and abnormal combustion and fuel use efficiency at the next engine start are prevented. Is prevented.

[Second Embodiment]
The second embodiment according to the present invention is a method for forcibly stopping an internal combustion engine, which is performed using the liquefied gas fuel supply device for an internal combustion engine described in the first embodiment.
If an engine malfunctions when multiple vehicles are traveling at high speed, such as on an expressway, stopping the engine immediately can lead to major accidents such as rear-end collisions. The vehicle is moved to a safe place while braking and the engine is stopped. At this time, if the engine cannot be stopped due to an abnormality in the engine or its control system, some forced stop means may be required. The present embodiment is a method for forcibly stopping an internal combustion engine performed in such a case.

FIG. 8 shows the flow of the internal combustion engine forced stop method of the present embodiment.
First, in step S1, an abnormality of the engine is detected by the driver. In this step S1, not only when the driver himself feels an abnormality in the engine, there are cases where the driver is informed by a warning light or a warning sound indicating the abnormality of the engine provided in the vehicle. When an abnormality of the engine is detected, in step S2, the driver retreats the vehicle to a safe place while braking by braking.

Next, in step S3, the ignition switch is turned off, and in step S4, it is determined whether or not the engine has stopped. When the engine is stopped, the stop operation is terminated. On the other hand, when the engine is not stopped, the process proceeds to step S5, and the forced stop operation of the engine is executed. Specifically, from the normal operation state shown in FIG. 5 of the first embodiment, as shown in FIG. 7, the first opening / closing provided in the fuel supply passage 18 leading from the fuel tank 2 to the high pressure pump 5 is performed. While closing the second opening / closing means 21 provided in the gas phase introduction passage 20 connected between the means 19 and the gas phase portion of the fuel tank 2 and the common rail 10, the high-pressure pump 5 is higher than the first opening / closing means 19. The third opening / closing means 25 provided in the second purge passage 22 connected between the fuel supply passage 18 on the side and the common rail 10 and the sixth opening / closing means provided in the third purge passage 26 27 is opened and vaporization purge is performed.
As a result, after a while, the liquefied gas fuel is recovered from the high-pressure pump 5, the common rail 10, and the fuel injection unit 13, so that the liquefied gas fuel is not supplied to the internal combustion engine and the internal combustion engine is forcibly stopped ( Step S6), the forced engine stop operation ends.

  The timing at which the vaporization purge is performed in step S5 largely depends on the driver's judgment of the situation, and it is preferable to perform manual switch control. You may comprise so that it may be performed automatically.

Claims (6)

The liquefied gas fuel in the fuel tank is sent to a high pressure pump by a feed pump, the liquefied gas fuel is pressurized by the high pressure pump and pumped to a common rail to which a fuel injection section of an internal combustion engine is connected, and the internal combustion engine is fed from the fuel injection section to the internal combustion engine. In the liquefied gas fuel supply device for supplying the liquefied gas fuel to the engine,
The feed pump and the high-pressure pump are connected by a fuel supply passage, and the fuel supply passage is provided with a first opening / closing means,
The gas phase portion of the fuel tank and the common rail are connected by a gas phase introduction passage, and the gas phase introduction passage is provided with a second opening / closing means,
The fuel supply passage on the high-pressure pump side than the first opening / closing means and the common rail are connected by a purge passage, and the purge passage is provided with a third opening / closing means, and
Liquid purge means for recovering the liquefied gas fuel in the high pressure pump, the common rail and the fuel injection part into the fuel tank while introducing the gaseous component of the liquefied gas fuel from the gas phase introduction passage;
Vaporization purge means for vaporizing and recovering the liquefied gas fuel remaining in the high pressure pump, the common rail and the fuel injection section after the operation of the liquid purge means;
With
Further, the third opening / closing means is opened when the liquid purge means and the vaporization purge means are operated, and is also opened when the liquefied gas fuel is charged before starting the internal combustion engine. Engine liquefied gas fuel supply device.   The liquid purge means includes suction means for sucking the liquefied gas fuel in the high-pressure pump, the common rail, and the fuel injection section, and sucks the liquefied gas fuel by the suction means, and from the gas phase introduction passage. 2. The liquefied gas fuel supply for an internal combustion engine according to claim 1, wherein the liquefied gas fuel is recovered in the fuel tank while being replaced with a gaseous component to be introduced. 3. apparatus. A fuel circulation passage branched from the middle of the fuel supply passage and connected to the fuel tank, and an aspirator as the suction means is disposed in the fuel circulation passage;
The high-pressure pump and the aspirator are connected by a liquid purge passage,
The liquefied gas fuel sent by the feed pump is recirculated as it is to the fuel tank via the aspirator, so that the liquefied gas fuel in the high pressure pump, the common rail, and the fuel injection section is sucked and the fuel is supplied. The liquefied gas fuel supply device for an internal combustion engine according to claim 2, wherein the liquefied gas fuel supply device is configured to be recovered in a tank.   The vaporizing purge means includes a low-pressure tank, and after the operation of the liquid purging means, the residual liquefied gas fuel is recovered by connecting the high-pressure pump and the low-pressure tank through a vaporizing purge passage. The liquefied gas fuel supply device for an internal combustion engine according to any one of claims 1 to 3, wherein the liquefied gas fuel supply device is configured as described above. Said second switching means, said liquid while is opened when operating the purge means, first to fourth terms of the claims, characterized in that is closed when operating the vaporization purge means The liquefied gas fuel supply apparatus of the internal combustion engine according to any one of the above. A check valve for stopping the flow of the liquefied gas fuel toward the second opening / closing means is provided between the second opening / closing means and the common rail in the gas phase introduction passage. The liquefied gas fuel supply device for an internal combustion engine according to any one of claims 1 to 5 .

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