JP6217325B2 - Fuel injection system, internal combustion engine, and fuel injection method for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection system, an internal combustion engine, and a fuel injection method for an internal combustion engine, and more specifically, a fuel injection system that injects liquefied gas fuel such as dimethyl ether (hereinafter referred to as DME), an internal combustion engine, and an internal combustion engine. The present invention relates to a fuel injection method.

  An apparatus using DME as a clean fuel that does not generate sulfur oxide or particulate matter in place of light oil has been proposed (for example, see Patent Document 1). Like this device, an engine using DME is provided with a return flow path for returning DME vaporized in the injector to the storage tank.

  The injector used in the above apparatus is of the pressure balance type. This pressure balance type injector uses a solenoid to drive an on-off valve that opens and closes the orifice of the pressure control chamber, and releases the pressure in the pressure control chamber to the pressure release chamber, thereby driving the needle valve to open the injection port. ing. Therefore, the DME that has flowed into the pressure release chamber from the pressure control chamber is vaporized and returned to the gas phase of the storage tank via the return channel.

  However, when this DME is vaporized, there is a problem that an additive component derived from engine oil is deposited and adheres around the on-off valve. In an engine using DME, since DME has low viscosity, the pump cam and bearing of the supply pump are lubricated with engine oil. At this time, the engine oil may flow into the DME side from the seal portion that separates the DME and the engine oil by the plunger of the supply pump, and there is a possibility that the DME with the engine oil mixed in the common rail or the injector will spread.

  When the DME mixed with the engine oil is vaporized, the additive component deposited around the on-off valve adheres. When the engine is in a warm-up state, the deposited additive component has a high injector temperature and low viscosity, and therefore does not affect the operation of the on-off valve. However, in the cold state after the engine is stopped, the viscosity of the deposited additive component becomes high, so the on-off valve sticks and the pressure in the pressure control chamber cannot be released to the pressure release chamber, Injector may malfunction.

JP 2003-262167 A

  The present invention has been made in view of the above-mentioned problems, and its problem is to avoid the influence of deposits adhering to the fuel injection device that occurs when liquefied gas fuel is used, and at the time of starting the internal combustion engine. To provide a fuel injection system, an internal combustion engine, and a fuel injection method for an internal combustion engine that can start an internal combustion engine by reliably operating a combustion injection device.

Fuel injection system of the present invention to solve the aforementioned problem, with comprises a reservoir tank for storing a liquefied gas fuel, the injection pump for pressurizing the liquefied gas fuel, a fuel injection device for injecting liquefied gas fuel, A supply flow path for supplying liquid liquefied gas fuel from the storage tank to the fuel injection device via the injection pump, and returning liquefied gas fuel vaporized by the fuel injection device from the fuel injection device to the storage tank And a return flow path that branches from the supply flow path upstream of the injection pump and bypasses the injection pump to transfer liquid liquefied gas fuel to the fuel injection device; An electrically driven pumping pump that is arranged upstream of the supply channel and the branch of the transfer channel and pumps liquid liquefied gas fuel; and the supply channel and A flow path switching valve provided at a branch point of the feed flow path, and a control device that controls opening and closing of the flow path switching valve and driving of the pressure feed pump. , By switching the flow path to the flow path switching valve, liquid liquefied gas fuel is sent from the pressure pump through the transfer flow path to the fuel injection device until a predetermined circulation time elapses. After circulating through the return tank from the fuel injection device to the storage tank and the circulation time has elapsed, liquid liquefied gas fuel is routed from the pressure pump to the injection pump of the supply channel. It is configured to perform control to be sent to the fuel injection device .

  The injection pump here is a fuel injection pump such as a row injection pump, a distribution injection pump, an independent injection pump, and a unit injector injection pump, or a supply pump used in a pressure accumulation type using a common rail or the like. And so on.

  According to this configuration, the liquid liquefied gas fuel is circulated by transferring the liquid liquefied gas fuel to the fuel injection device without passing through the injection pump by the circulation channel. As a result, the deposit that adheres in the fuel injection device and hinders the injection operation of the fuel injection device is dissolved in the liquid liquefied gas fuel or washed away to clean the inside of the fuel injection device. It can be avoided.

  For example, when DME (dimethyl ether) is used as the liquefied gas fuel, according to the above configuration, the lubricating oil for lubricating the injection pump is obtained by circulating the liquid DME via the fuel injection device. Even when DME is vaporized and deposited in the fuel injection device, the deposited additive component derived from the lubricating oil is dissolved in DME. It is possible to avoid the poor injection operation. That is, even if there is a deposit adhered for a long period of time, the deposit can be dissolved or washed away with liquid DME to reliably avoid malfunction of the fuel injection device and start the internal combustion engine.

  Further, the fuel injection system includes an electrically driven pump for pumping liquid liquefied gas fuel, and drives the pump before injecting the liquefied gas fuel from the fuel injection device at the time of starting the internal combustion engine. If the liquid liquefied gas fuel is circulated through the circulation flow path, the liquid liquefied gas fuel can be pumped and circulated by an electrically driven pressure feed pump before the internal combustion engine is started. . As a result, the adhering matter adhering to the low-temperature and high-viscosity fuel injection device before starting the internal combustion engine can be dissolved or swept away with the liquid liquefied gas fuel before starting the internal combustion engine.

  In addition, in the fuel injection system described above, a transfer flow path that branches from the supply flow path upstream of the injection pump and transfers liquid liquefied gas fuel to the fuel injection device is provided in the circulation flow path. A fuel injection device provided with an on-off valve for opening and closing an orifice of a pressure control chamber of the fuel injection device, and configured to communicate the transfer flow channel with a pressure release chamber communicating with the return flow channel; The liquid liquefied gas fuel can be poured into the pressure release chamber, and the adhering matter adhering to the on-off valve of the pressure balance type fuel injection device can be dissolved or swept away. It is possible to avoid being unable to open.

  Furthermore, in the fuel injection system, the circulation flow path branches from the supply flow path and the supply flow path upstream of the injection pump to transfer liquid liquefied gas fuel to the fuel injection device. It is formed from a transfer flow path and the return flow path, and is provided at the branch point between the supply flow path and the transfer flow path. A flow path switching valve for switching the flow of the liquid liquefied gas fuel from the supply flow path to the transfer flow path, and leaving the flow of the liquid liquefied gas fuel in the closed state in the supply flow path; It is desirable to include a control device that controls opening and closing of the valve and driving of the pressure pump.

According to this configuration, the flow of the liquid liquefied gas fuel pumped by the pumping pump is switched from the supply channel to the transfer channel by the channel switching valve, and the storage tank is connected from the return channel via the fuel injection device. Can be circulated. As a result, the deposits deposited in the fuel injection device can be washed with liquid liquefied gas fuel with the easy control of driving the pressure pump and opening the flow path switching valve to avoid the influence of the deposits. can do.

  And the internal combustion engine for solving said subject is provided and provided with the fuel injection system as described above. According to this configuration, the internal combustion engine can be started by reliably operating the combustion injection device when starting the internal combustion engine while avoiding the influence due to the deposits in the fuel injection device that occurs when liquefied gas fuel is used. Can do.

In the internal combustion engine fuel injection method of the present invention for solving the above-described problems, liquid liquefied gas fuel is sent from a storage tank to an injection pump via a supply channel, and pressurized by the injection pump. In the fuel injection method of the internal combustion engine, the liquid liquefied gas fuel is injected by the fuel injection device and the vaporized liquefied gas fuel is returned from the fuel injection device to the storage tank via a return flow path . At the time of start-up, the pressure pump is driven to pump liquid liquefied gas fuel, and a preset circulation time is counted. Until the circulation time elapses, the upstream side of the supply flow path and the injection pump is counted. A flow path switching valve that branches from the supply flow path and bypasses the injection pump and that is disposed at a branch of a transfer flow path that transfers liquid liquefied gas fuel to the fuel injection device is a liquid liquefied gas The fuel is sent from the pressure feed pump to the fuel injection device via the transfer flow path, and the liquefied gas fuel of the sent liquid is circulated from the fuel injection device to the storage tank via the return flow path, After the circulation time has elapsed, the flow path switching valve sends the liquid liquefied gas fuel to the fuel injection device via the pressure feed pump, the supply flow path, and the injection pump, and sent the liquid liquefied gas. A fuel is injected from the fuel injection device .

  According to this method, since the liquid liquefied gas fuel is circulated through the fuel injection device before the fuel is injected from the fuel injection device at the start of the internal combustion engine, the deposits in the fuel injection device are removed. Since the liquid liquefied gas fuel is dissolved or washed away and washed, the malfunction of the fuel injector caused by the deposits in the fuel injector generated when using the liquefied gas fuel is avoided, and the internal combustion engine Can be reliably started.

  According to the fuel injection system, the internal combustion engine, and the fuel injection method for the internal combustion engine of the present invention, the liquid liquefied gas fuel is circulated through the circulation flow path, and the liquid liquefied gas is supplied to the fuel injection device without passing through the injection pump. Since the fuel is transferred, the inside of the fuel injection device can be cleaned by dissolving or pushing away deposits that adhere to the fuel injection device and hinder the injection operation of the fuel injection device with liquid liquefied gas fuel. .

  Thereby, the malfunction of the fuel injection device due to deposits can be avoided, and fuel can be reliably injected from the fuel injection device.

It is the figure which showed the structure of the fuel-injection system of embodiment which concerns on this invention, and an internal combustion engine provided with the same. It is a figure which shows the injection pump shown in FIG. 1, (a) is a general view which shows an injection pump, (b) is an enlarged view which shows the seal | sticker part of an injection pump. It is sectional drawing which showed the cross section of the fuel-injection apparatus shown in FIG. 1, (a) shows the state in which liquefied gas fuel was supplied, (b) shows the state in which liquefied gas fuel is injected. FIG. 2 is a cross-sectional view showing a cross section of the fuel injection device shown in FIG. 1, wherein (a) shows a state when the internal combustion engine is stopped, and (b) shows a state before liquefied gas fuel is injected when the internal combustion engine is started. Indicates. It is a flowchart which shows the fuel-injection method of the internal combustion engine of embodiment which concerns on this invention.

  Hereinafter, a fuel injection system, an internal combustion engine, and a fuel injection method for an internal combustion engine according to embodiments of the present invention will be described with reference to the drawings.

First, regarding the configuration of the fuel injection system and the internal combustion engine of the embodiment according to the present invention, FIG.
This will be described with reference to FIG. As shown in FIG. 1, an engine (internal combustion engine) 1 includes a fuel injection system 3 that injects DME (dimethyl ether; liquefied gas fuel) into a combustion chamber (not shown) provided in an engine body 2.

  This fuel injection system 3 pressurizes and pressurizes DME in a storage tank 4 with a feed pump (pressure pump) 5, and supplies a supply pump (injection pump) 7 in a liquid state via a supply line (supply channel) 6. To the injector (fuel injection device) 9 through the common rail 8 from the supply pump 7.

  Further, the fuel injection system 3 is configured to return surplus vaporized DME from the supply pump 7, the common rail 8, and the injector 9 to the storage tank 4 via a return line (return flow path) 10. Since the DME returning to the storage tank 4 is vaporized, the return line 10 is connected to communicate with the gas phase of the storage tank 4.

  In addition, this fuel injection system 3 includes valves 12a to 12d, check valves (check valves) 13a to 13e, and solenoid valves in the supply line 6, the return line 10, and the filling line 11 to the storage tank 4, respectively. 14a to 14c, and opens and closes the valves 12a to 12d and the electromagnetic valves 14a to 14c to fill the storage tank 4 with DME, supply the DME to the injector 9, and return the DME to the storage tank 4. Configured to do.

  The fuel injection system 3 further includes a pressure sensor 15 that detects the pressure of the DME in the supply pump 7, a temperature sensor 16 that detects the temperature of the DME, and a pressure sensor 17 that detects the pressure in the common rail 8. Sensors 15 to 17 are connected to an ECU (control device) 18.

  The feed pump 5 is a pump that pressurizes DME to about 3 MPa and pumps the DME from the storage tank 4 to the supply pump 7 in a liquid state, and the drive is controlled by the ECU 18. This feed pump 5 uses an electrically driven pump so that it can be driven before the engine 1 is started.

  As shown in FIG. 2A, the supply pump 7 causes the DME transferred from the supply line 6 to the pump gallery 20 to flow into the plunger cylinder 22 through opening and closing of the solenoid valve 21. The plunger 25 joined to the lifter 24 slid by the pump cam 23 moves up and down in the plunger cylinder 22 and is discharged from an outlet side flow path 27 provided with a check valve 26 at the outlet. The Further, the pump gallery 20 is provided with a leak recovery path 28 for returning DME leaked from the plunger cylinder 22.

  At this time, the ECU 18 controls the opening and closing timing of the valve 21 a of the solenoid valve 21, thereby adjusting the discharge amount of DME discharged from the plunger cylinder 22 to the outlet side flow path 27.

  As shown in FIG. 2B, the supply pump 7 seals the plunger 25 with a rod seal (seal member) 29 so that the DME in the plunger cylinder 22 and the engine oil that lubricates the pump cam 23 and the like are connected. Separated so as not to mix.

  The rod seal 29 includes a seal body 31 that is pressed against the plunger 25 by a spring 30, and is configured to form an intermediate chamber 32 between the two seal bodies 31 and the plunger 25. The seal body 31 is fixed by rod seal restraining.

  The injector 9 is a pressure balance type injector. In the injector 9, as shown in FIG. 3A, when high pressure DME is supplied from the common rail 8 into the injector body 40, the high pressure DME is introduced into the pressure control chamber 41. Then, the pressure in the pressure control chamber 41 is increased, and the needle valve 42 is urged downward by the needle spring 48 and the injection nozzle 43 is closed.

  Further, as shown in FIG. 3B, an armature (open / close valve) 45 urged in a closing direction by a spring (not shown) provided in the pressure release chamber 44 is moved upward by a solenoid 46, thereby causing a pressure control chamber. When the orifice 47 above 41 is opened, DME in the pressure control chamber 41 flows into the pressure release chamber 44 and the pressure in the pressure control chamber 41 decreases. At this time, the needle valve 42 is moved upward, the injection nozzle 43 is opened, and DME is injected.

  In this fuel injection system 3, there is a phenomenon in which engine oil enters the DME side from the rod seal 29 shown in FIG. 2B, and DME mixed with engine oil reaches the common rail 8 and the injector 9.

  Since the injector 9 is a pressure balance type as described above, DME flows into the pressure release chamber 44 when the armature 45 is moved by the solenoid 46. When the DME in the pressure release chamber 44 returns to the storage tank 4, the DME is vaporized. At this time, as shown in FIG. 4A, the engine oil-derived additive component (attachment) D precipitates and adheres around the armature 45.

  When the engine 1 is in a warm-air state, the temperature of the injector 9 is high and the viscosity of the deposited additive component D is low, so that there is no hindrance to the operation of the armature 45. On the other hand, when the engine 1 is in a cold state after being stopped, the temperature of the injector 9 is low and the viscosity of the additive component D is high, so that the armature 45 may be fixed by the adhering additive component D.

  Therefore, as shown in FIG. 1, the fuel injection system 3 according to the embodiment of the present invention sends liquid DME from the storage tank 4 to the injector 9 without passing through the supply pump 7, and returns from the injector 9 to the return line 10. Is provided with a circulation line 19 for circulating liquid DME to the storage tank 4 via the.

  Further, at the branch point between the supply line 6 and the transfer line 50, the flow of liquid DME is switched from the supply line 6 to the transfer line 50 in the open state, and the flow of liquid DME remains in the supply line 6 in the closed state. A flow path switching valve 51 is provided, and the opening and closing of the flow path switching valve 51 is controlled by the ECU 18.

  The circulation line 19 is formed from a supply line 6, a transfer line 50 that branches from the supply line 6 upstream of the supply pump 7, and transfers liquid DME to the injector 9, and a return line 10. Therefore, the circulation line 19 can transfer liquid DME to the injector 9 even when the supply pump 7 is not driven before the engine 1 is started.

  As shown in FIG. 1, the transfer line 50 branches from the supply line 6 between the storage tank 4 and the supply pump 7, more specifically between the feed pump 5 and the supply pump 7. As shown in (b) and (b), the pipe is provided so as to communicate with the return line 10 via the injector 9.

More specifically, the transfer line 50 is provided with an armature 45 that opens and closes an orifice 47 of the pressure control chamber 41 of the injector 9, and a pressure release chamber 44 that communicates with the return line 10.
It is configured to communicate with.

  As shown in FIG. 1, the flow path switching valve 51 is a valve for switching the flow of liquid DME transferred from the storage tank 4 to the supply pump 7 from the supply line 6 to the transfer line 50. The flow path switching valve 51 enables the liquid DME pressurized by the feed pump 5 from the storage tank 4 to be transferred to the supply pump 7 in the closed state, and pressurizes from the storage tank 4 by the feed pump 5 in the open state. This is a three-way switching valve configured to branch the liquid DME flow from the supply line 6 to the transfer line 50 and transfer it to the injector 9.

  The flow path switching valve 51 is controlled to be opened and closed by the ECU 18, and is controlled to be opened before injecting DME from the injector 9 when the engine 1 is started. It is configured to circulate DME.

  The ECU 18 is a microcontroller that electrically controls the engine 1 and the fuel injection system 3 based on the operation status of the engine 1 and the detection values of the sensors. In this embodiment, in addition to the control of the pump pressure of the supply pump 7 and the temperature of the DME, the control of the common rail pressure of the common rail 8, and the control of the injection amount of the injector 9, the drive control of the feed pump 5 and the flow path switching valve. 51 is controlled to open and close.

  Next, a fuel injection method for an internal combustion engine according to an embodiment of the present invention will be described with reference to the flowcharts of FIGS. In addition, about the fuel injection method demonstrated below, although only the process performed at the time of the start of the engine 1 is demonstrated, after the engine 1 starts, the injection amount based on the driving | running state is controlled from the injector 9, etc. Do.

  As shown in FIG. 5, first, the driver performs step S100 for turning on an ignition key (not shown). At this time, the engine 1 is in a cold state after being stopped, and the additive component D deposited on the armature 45 in the pressure release chamber 44 of the injector 9 is adhered as shown in FIG. When the engine 1 is in a cold state and the temperature of the injector 9 is low, the additive component D has a high viscosity.

  As shown in FIG. 5, when the ignition key is turned on in step S100, the ECU 18 performs step S110 for driving the feed pump 5. In this step S110, liquid DME is pumped from the storage tank 4 toward the supply pump 7.

  Next, the ECU 18 performs step S120 for opening the flow path switching valve 51. In step S120, the flow of the liquid DME is switched from the supply line 6 to the transfer line 50, and the liquid DME is transferred to the injector 9. As a result, as shown in FIG. 4B, the DME of the liquid transferred from the transfer line 50 is caused to flow into the pressure release chamber 44 of the injector 9 to dissolve the additive component D adhering to the armature 45. Or flush away. Then, this liquid DME is circulated to the storage tank 4 via the return line 10.

  As described above, by opening the flow path switching valve 51 in step S120, the armature 45 to which the additive component D in the injector 9 adheres is provided, specifically, the liquid DME is passed through the injector 9. And the inside of the pressure release chamber 44 of the injector 9 can be cleaned by circulating to the storage tank 4 via the pressure release chamber 44 communicated with the return line 10.

As shown in FIG. 5, next, a circulation time t1 predetermined as step S130 elapses. The circulation time t1 is set to a time during which the liquid DME flowing into the pressure release chamber 44 of the injector 9 can dissolve or push away the additive component D. In this embodiment, the circulation time t1 is set to 5 seconds, and the liquid DME is transferred to the pressure release chamber 44 within 5 seconds after the ignition key is turned on.

  When the circulation time t1 has elapsed in step S130, the ECU 18 next performs step S140 for closing the flow path switching valve 51. By this step S140, the liquid DME pressurized by the feed pump 5 is transferred to the supply pump 7 via the supply line 6. Then, the DME pressurized by the supply pump 7 is supplied to the injector 9 through the common rail 8.

  Next, the ECU 18 controls the solenoid 46 of the injector 9 to perform step S150 in which DME starts injection from the injector 9. In step S150, the ECU 18 controls the solenoid 46 to drive the armature 45. Next, DME in the pressure control chamber 41 flows into the pressure release chamber 44 from the orifice 47 opened by driving the armature 45. Next, when the pressure in the pressure control chamber 41 is lowered, the needle valve 42 is driven upward. Then, DME is injected from the opened injection nozzle 43 and the engine 1 is started.

  According to the fuel injection system 3 of the present invention, the engine 1 including the same, and the fuel injection method of the engine 1, the liquid DME liquefied gas fuel is transferred to the injector 9 through the circulation line 19 without passing through the supply pump 7. Circulate. As a result, the additive component D adhering to the injector 9 and hindering the injection operation of the injector 9 is dissolved in the liquid DME or washed away to wash the injector 9, thereby avoiding the influence of the additive component D. be able to.

  More specifically, first, before the DME is injected from the injector 9 at the start of the engine 1, the feed pump 5 can be electrically driven to circulate the liquid DME, so that the temperature of the engine 1 is low. Therefore, before starting the engine 1 where the viscosity of the additive component D adhering to the injector 9 becomes high, the additive component D can be dissolved or swept away with liquid DME.

  Secondly, the transfer line 50 of the circulation line 19 is provided with an armature 45 that opens and closes the orifice 47 of the pressure control chamber 41 of the injector 9, and communicates with the pressure release chamber 44 that communicates with the return line 10. The additive component D that precipitates when the DME that has flowed into the pressure release chamber 44 in order to operate the valve 42 is vaporized is directly dissolved or washed away by the liquid DME to clean the inside of the pressure release chamber 44. Can do.

  Third, before the engine 1 is started, the electrically driven feed pump 5 is driven to supply liquid DME from the storage tank 4 and the flow path switching valve 51 is opened. Can be transferred into the injector 9 and circulated.

  Thereby, even if the additive component D adheres over a long period of time, the additive component D is dissolved in the liquid DME or washed away to wash the inside of the injector 9, so that the influence of the additive component D is affected. It can be avoided. Therefore, DME can be reliably injected from the injector 9, and the engine 1 can be started normally.

  In the above embodiment, an in-line four-cylinder diesel engine has been described as an example. However, the present invention is not limited to this, and can be applied to an engine using liquefied gas fuel such as DME. The number of cylinders and arrangement are not limited. Moreover, although said engine 1 was demonstrated as what is mounted in a vehicle, this invention is not limited to this.

  In the above embodiment, the engine 1 using DME as the liquefied gas fuel has been described as an example. However, the present invention is not limited to DME, and LPG (liquefied petroleum gas), LNG (liquefied natural gas), and the like. It can also be applied to an engine using.

  In addition, in the above-described embodiment, the common rail fuel injection system 3 using the common rail 8 has been described as an example. However, the present invention is not limited to this, and for example, a row injection pump, a distribution injection pump, and the like. The present invention can also be applied to a fuel injection system using a stand-alone injection pump, a unit injector type injection pump, or the like.

  Furthermore, the configurations of the fuel injection system 3, the supply pump 7, and the injector 9 of the above embodiment are merely examples, and the present invention is not limited to this. For example, the fuel injection system 3 may be provided with a plurality of storage tanks, and the injector 9 may be other than the pressure balance system. In addition, since a pressure balance type was used as the injector 9, liquid DME was introduced into the pressure release chamber 44 of the injector 9, but the deposits such as additive component D were dissolved in liquid DME, or What is necessary is just to comprise so that it may flush away, and it is not limited to said structure.

  In addition, the fuel injection method of the above embodiment has been described as being performed before the engine 1 is started. However, in the case of starting from a temporary stop of the engine 1 such as an idling stop, When it is determined from the temperature, the temperature of the injector 9 or the like that the viscosity of the deposit such as the additive component D is not high, the liquid DME may be configured not to circulate.

  The fuel injection system according to the present invention avoids the influence of deposits adhering to the fuel injection device that occurs when liquefied gas fuel is used, and operates the combustion injection device reliably when the internal combustion engine is started. Can be started, so that it can be used for vehicles such as trucks equipped with diesel engines using DME as liquefied gas fuel.

1 engine (internal combustion engine)
3 Fuel injection system 4 Storage tank 5 Feed pump (pressure feed pump)
6 Supply line (supply flow path)
7 Supply pump (injection pump)
8 Common rail 9 Injector (fuel injection device)
10 Return line (return channel)
18 ECU (control device)
19 Circulation line (circulation flow path)
40 Injector body 41 Pressure control chamber 42 Needle valve 43 Injection nozzle (injection port)
44 Pressure release chamber 45 Armature (open / close valve)
46 Solenoid 47 Orifice 50 Transfer line (transfer channel)
51 Channel switching valve

Claims (5)

A storage tank for storing the liquefied gas fuel, an injection pump for pressurizing the liquefied gas fuel, and a fuel injection device for injecting the liquefied gas fuel, and a liquid liquefied gas fuel from the storage tank via the injection pump In a fuel injection system comprising: a supply flow path for supplying to the fuel injection device; and a return flow path for returning the liquefied gas fuel vaporized by the fuel injection device from the fuel injection device to the storage tank.
A transfer flow path that branches from the supply flow path upstream of the injection pump and bypasses the injection pump to transfer liquid liquefied gas fuel to the fuel injection device; and the supply flow path and the transfer flow path An electrically driven pressure pump disposed upstream of the branch to pump liquid liquefied gas fuel, a flow path switching valve provided at a branch point of the supply flow path and the transfer flow path, and the flow path switching A control device for controlling opening and closing of the valve and driving of the pressure pump,
When starting the internal combustion engine, the control device causes the flow path switching valve to switch the flow path, and the liquid liquefied gas fuel is transferred from the pressure pump to the transfer flow path until a predetermined circulation time elapses. Via the return flow path from the fuel injection device to circulate to the storage tank, after the circulation time has elapsed, liquid liquefied gas fuel from the pressure pump A fuel injection system configured to perform control to be sent to the fuel injection device via the injection pump of a supply channel . 2. The circulation time is set to a time during which an additive component existing inside the fuel injection device can be dissolved or pushed away from the inside of the fuel injection device to the return flow path. The fuel injection system described. It said transfer passage, claim 1, characterized in that it has a configuration which communicates with the pressure relief chamber closing valve for opening and closing the orifice of the pressure control chamber of the fuel injection device is communicated with the return flow path is provided, or The fuel injection system according to 2. An internal combustion engine comprising the fuel supply system according to any one of claims 1 to 3 . Liquid liquefied gas fuel is sent from the storage tank to the injection pump via the supply channel, and the liquid liquefied gas fuel pressurized by the injection pump is injected by the fuel injection device, and the vaporized liquefied gas fuel is In the fuel injection method of the internal combustion engine for returning from the fuel injection device to the storage tank via a return flow path,
At the start of the internal combustion engine, the pressure pump is driven to pump liquid liquefied gas fuel, and the preset circulation time is counted,
Until the circulation time elapses, a transfer branching from the supply flow channel and the supply flow channel upstream of the injection pump and bypassing the injection pump to transfer liquid liquefied gas fuel to the fuel injection device A flow path switching valve arranged at a branch of the flow path sends liquid liquefied gas fuel from the pressure feed pump to the fuel injection device via the transfer flow path, and the sent liquid liquefied gas fuel is injected into the fuel. Circulate from the device to the storage tank via the return channel,
After the circulation time has elapsed, the flow path switching valve sends liquid liquefied gas fuel to the fuel injection device via the pressure feed pump, the supply flow path, and the injection pump, and liquefies the sent liquid. A fuel injection method for an internal combustion engine , wherein gas fuel is injected from the fuel injection device .

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