JP2014077382A - Lubrication system of internal combustion engine, internal combustion engine, and lubrication method of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubrication system of an internal combustion engine which lubricates a high pressure pump for pumping a liquefied gas fuel with a lubrication oil from which an insoluble component that does not dissolve in the liquefied gas fuel is removed, and to provide an internal combustion engine including the lubrication system and a lubrication method of the internal combustion engine.SOLUTION: A lubrication system of an internal combustion engine includes an insoluble component removal oil supply device 40 which mixes an engine oil with dimethyl ether in a liquid phase, removes an insoluble component of the engine oil which does not dissolve in dimethyl ether in the liquid phase, and lubricates a supply pump 6 with the engine oil from which the insoluble component is removed.

Description

  The present invention relates to a lubrication system for an internal combustion engine that lubricates an internal combustion engine using a liquefied gas fuel such as dimethyl ether (hereinafter referred to as DME) with a lubricating oil, an internal combustion engine including the lubrication system, and a lubrication method for the internal combustion engine.

  At present, the use of a liquefied gas fuel such as dimethyl ether (DME) is attracting attention as an alternative fuel for light oil used in diesel engines. In the diesel engine using DME as a fuel, there is a problem that the viscosity of DME itself is low and DME leaks from a gap of a plunger such as a supply pump (high pressure pump).

  If the leak DME leaking into the cam chamber of this supply pump gets mixed into the lubricating oil in the cam chamber, the viscosity of the lubricating oil decreases due to the DME fuel being dissolved in the lubricating oil, which causes a malfunction in the supply pump. May occur. In addition, in the case of a fuel injection device using DME, since the entire device has a sealed structure, if the DME leaks into the cam chamber, the internal pressure of the supply pump increases due to vaporization of the DME and exceeds the pressure resistance of the seal portion. As a result, DME and lubricating oil may leak out.

  Alternatively, the leaked DME leaking into the cam chamber of the supply pump is mixed with the lubricating oil, enters the oil pan, stays in the crankcase, is sucked into the intake air by a blow-by recirculation device, etc., and the intake DME concentration is high This may cause abnormal combustion.

  In view of the above problems, a gas-liquid separation unit for separating and recovering the liquefied gas fuel mixed in the lubricating oil in the cam chamber is provided, and the liquefied gas fuel mixed in the lubricating oil is efficiently separated. There is an apparatus to collect (see, for example, Patent Document 1).

  In this apparatus, DME mixed in the lubricating oil is separated by gas-liquid separation and recovered, but the structure of recovering DME mixed in the cam chamber of the supply pump is complicated. Therefore, a seal material such as a rod seal is used for the plunger portion of the supply pump to prevent DME leakage and prevent DME from being mixed into the lubricating oil in the cam chamber of the supply pump.

  For example, when a sealing material such as a rod seal is used, in many cases, a sealing material such as a lip structure is used to seal the DME, and this lip structure appropriately performs the material, angle, and initial spring tension of the lip. Thus, DME can be sealed.

  Here, a conventional lubrication system for an internal combustion engine and a seal structure for a supply pump will be described with reference to FIGS. As shown in FIG. 3, this conventional lubrication system 1 </ b> X supplies engine oil to each device of a fuel injection device 3 provided in an engine 2 </ b> X and a DME supply system 5 including a fuel tank 4. The fuel injection device 3 includes a supply pump (high pressure pump) 6, a common rail 7, and an injector (fuel injection valve) 8.

  In order to use DME as fuel, the DME supply system 5 pressurizes the fuel pump 4 from the fuel tank 4 to the supply pump 6 to the extent that it is not vaporized by the feed pump 9, and supplies it in the liquid phase via the supply channel 10. Gas phase DME is returned from the fuel injection device 3 to the fuel tank 4 via the return flow path 11.

  The lubrication system 1X includes an oil pan 12, a strainer 13, an oil pump 14, a first lubricant supply channel 15, a second lubricant supply channel 16, a first lubricant return channel 17, and a second lubricant return flow. A passage 18 is provided, and the oil pump 14 is driven to remove impurities from the oil pan 12 by the strainer 13, and then the engine oil is supplied to various parts of the engine 2X and the supply pump 6.

  As shown in FIG. 4, the supply pump 6 includes a cylinder 22 having a suction port 20 and a discharge port 21, an electromagnetic valve 23 provided in the suction port 20, a check valve 24 provided in the discharge port 21, A plunger 25 provided in the cylinder 22 so as to be capable of reciprocating; a lip structure for sealing between the cylinder 22 and the plunger 25; a sealing device 26 provided in the cylinder 22; And a connected pump gallery 27.

  The electromagnetic valve 23 includes a valve body 28 for opening and closing the suction port 20 and a solenoid 29 for driving the valve body 28. Further, a leak recovery path 30 for returning high-pressure DME leaked between the plunger 25 and the cylinder 22 to the pump gallery 27 is connected to the side surface of the cylinder 22.

  A cylinder chamber 31 is formed in the cylinder 22 above the plunger 25. The plunger 25 is connected to an engine drive unit 32. The engine drive unit 32 includes a cam 33 that rotates with the power of the engine, and a cam follower 34 that is provided on the plunger 25 and abuts against the cam 33 and moves up and down in accordance with the rotation of the cam 33. The cam follower 34 includes a tappet 35 provided at the lower end of the plunger 25, and a roller 36 provided on the tappet 35 and in contact with the cam 33 and rotating in accordance with the rotation of the cam 33. The engine drive unit 32 is housed in a cam chamber 37 formed in the engine and is lubricated with engine oil.

  The sealing device 26 can prevent the liquid phase DME supplied from the fuel tank 4 from flowing into the drive unit 32 of the supply pump 6. However, on the other hand, there is a problem that engine oil is sucked into the DME in the cylinder chamber 31 from the lip portion of the sealing device 26 and the engine oil is mixed into the DME.

  Engine oil usually contains various additives (antioxidants, antiwear agents, cleaning dispersants, viscosity index improvers, antifoaming agents, and pour point depressants), among which inorganic metal elements, etc. Exists.

  Due to the solvent characteristics of DME, the base oil component of the engine oil flows away without adhering to the metal surface in the passage of the fuel injection device 3 of DME. However, a high molecular weight polymer such as a viscosity index improver is used on the metal surface or DME. In the fuel injection device 3, the engine oil that adheres to the location where the fuel passage stays, flows into the fuel injection device 3 after growing, and enters the injector 8 is finally injected into the combustion chamber together with DME and burned. Resulting in. Components used in antioxidants such as Zn-DTP contain metal components such as P, Ca, Zn, etc., and flow into the exhaust system together with the exhaust gas, leading to deterioration of the aftertreatment device (oxidation catalyst, etc.). become.

JP 2010-071219 A

The present invention has been made in view of the above problems, and an object of the present invention is to provide an internal combustion engine capable of lubricating a high-pressure pump that pumps liquefied gas fuel with a lubricating oil from which insoluble components that do not dissolve in the liquefied gas fuel are removed. An engine lubrication system, an internal combustion engine, and a method for lubricating an internal combustion engine are provided.

  An internal combustion engine lubrication system of the present invention for solving the above-mentioned object is an internal combustion engine lubrication system in which an internal combustion engine using liquefied gas fuel as a fuel is lubricated with lubricating oil. Mixing and removing insoluble components of the lubricating oil that does not dissolve in the liquid-phase liquefied gas fuel, and supplying a high-pressure pump that pumps at least the liquefied gas fuel with the lubricating oil from which the insoluble components have been removed. It is configured with a device.

  According to this configuration, insoluble components that do not dissolve in the liquefied gas fuel can be removed from the lubricating oil by the solvent characteristics (also referred to as solvent characteristics) of the liquefied gas fuel. By lubricating at least the high-pressure pump with the lubricating oil from which the insoluble components have been removed, even if the lubricating oil is mixed into the liquefied gas fuel, it will not affect the aftertreatment device such as the catalyst or the exhaust system. Therefore, durability can be improved.

  The dissolved component herein refers to a so-called base oil, for example, vegetable oil, animal oil, mineral oil, synthetic oil (PAO (polyalphaolefin), highly hydrocracked oil VHVI (Very High Viscosity Index), ester. Etc.), and their hybrid oils. The insoluble component refers to an additive, for example, an antioxidant, an antiwear agent, a cleaning dispersant, a viscosity index improver, an antifoaming agent, and a pour point depressant.

  In the internal combustion engine lubrication system, the insoluble component-removed oil supply device includes a lubricating component by mixing lubricating oil with a pressurized liquid-phase liquefied gas fuel supplied to the high-pressure pump. Separating the dissolved component of the lubricating oil dissolved in the liquefied gas fuel in the liquid phase and the insoluble component, and separating and separating the liquid liquefied gas fuel mixed with the lubricating gas into the gas and liquid, and removing the insoluble component When the insoluble component removing device is provided, the high-pressure pump can be lubricated with the dissolved component including the lubricating component from which the insoluble component has been removed and the mixed liquid-phase liquefied gas fuel has been vaporized.

  Specifically, first, the lubricating oil and the liquid liquefied gas fuel are mixed in the mixing / separating container. Next, the dissolved component and the insoluble component of the lubricating oil are separated, and the liquid liquefied gas fuel in which the dissolved component is dissolved is vaporized and gas-liquid separated. And it lubricates with what removed the insoluble component with the insoluble component remover.

  By performing gas-liquid separation in the mixing / separating container, it is possible to prevent the liquefied gas fuel from being mixed with the fluid to be lubricated, or even if the liquefied gas fuel is mixed, the amount can be suppressed to a small amount. Thereby, it can suppress that excess liquefied gas fuel leaks to the high pressure pump of lubrication destination. Preferably, when the liquefied gas fuel and the lubricating oil are gas-liquid separated in the mixing / separating vessel, all the liquefied gas fuel is vaporized and then the lubricating oil which is only dissolved components is supplied to the high pressure pump. desirable.

In addition, in the internal combustion engine lubrication system, a part of the pressurized liquid-phase liquefied gas fuel supplied from a fuel tank to the high-pressure pump is supplied to the insoluble component removal oil supply device. And a liquefied gas fuel introduction flow path to be introduced into the insoluble component removal oil supply device, and a gas phase liquefied gas fuel generated when the insoluble component is removed from the insoluble component removal oil supply device is returned to the fuel tank. A gas-phase return flow path and an insoluble component return flow path for returning the insoluble component from the insoluble component removal oil supply apparatus to a storage tank in which lubricating oil is stored, and the insoluble component removal oil supply apparatus It is preferable to arrange in a lubricating oil supply flow path for supplying lubricating oil from a storage tank to a lubricated portion in the high-pressure pump.

  By providing the flow rate regulator in the liquefied gas fuel introduction flow path, it is possible to prevent a large amount of the liquefied gas fuel that is pressurized and supplied in the liquid phase from being introduced into the insoluble component removal oil supply apparatus. Moreover, the insoluble component removed by the insoluble component removing oil supply device is a material that was originally dissolved in the lubricating oil and is returned to the storage tank because it is fat-soluble.

  In addition, an internal combustion engine for solving the above problem includes the above-described lubrication system of the internal combustion engine, and the lubrication system is configured to lubricate a high-pressure pump that pumps liquefied gas fuel to the common rail. According to this configuration, even when the liquefied gas fuel is sealed so as not to leak to the drive unit of the high pressure pump or the like, even if the lubricating oil is mixed into the liquefied gas fuel from the sealed portion, the liquefied gas fuel from the lubricating oil is previously stored. Since insoluble components (such as metal components) that do not dissolve in water are removed, it is possible to prevent insoluble components from being mixed into the exhaust gas.

  Further, an internal combustion engine lubrication method for solving the above-mentioned problem is an internal combustion engine lubrication method in which an internal combustion engine using liquefied gas fuel as a fuel is lubricated with lubricating oil. The lubricating oil is mixed with a liquid liquefied gas fuel. A high-pressure pump that removes insoluble components that do not dissolve in the liquefied gas fuel in the liquid phase of the lubricating oil, and at least a high-pressure pump that pumps the liquefied gas fuel. Lubricating with a dissolved component that dissolves in the gas fuel.

  In addition, in the above-described lubricating method for an internal combustion engine, before supplying lubricating oil to the high-pressure pump, a pressurized liquid-phase liquefied gas fuel is supplied to the high-pressure pump in a mixing and separating container. It is preferable to mix and separate the dissolved component and the insoluble component, gas-liquid separate the liquid liquefied gas fuel mixed with the lubricating oil, and remove the insoluble component with an insoluble component remover.

  According to the present invention, the high-pressure pump that pumps the liquefied gas fuel can be lubricated with the lubricating oil from which insoluble components that are not dissolved in the liquefied gas fuel are removed. As a result, even if the lubricating oil is mixed into the liquefied gas fuel in the high-pressure pump, the insoluble components are removed, so there is no impact on the aftertreatment device such as the catalyst and the exhaust system, improving durability. can do.

1 is a schematic diagram showing a lubrication system for an internal combustion engine according to a first embodiment of the present invention. It is the schematic which shows the lubrication system of the internal combustion engine of 2nd Embodiment which concerns on this invention. It is the schematic which shows the lubrication system of the conventional internal combustion engine. It is the schematic which shows the conventional supply pump.

  Hereinafter, an internal combustion engine lubrication system, an internal combustion engine including the same, and a lubrication method for an internal combustion engine according to embodiments of the present invention will be described with reference to the drawings. In this embodiment, a vehicle using dimethyl ether (hereinafter referred to as DME) as liquefied gas fuel will be described. For example, liquefied petroleum gas (LPG), liquefied natural gas (LNG), and liquefied butane gas (LBG) are described. ), Or liquefied hydrogen fuel.

Further, the engine oil (lubricating oil) is not particularly limited, but may be vegetable oil, animal oil, mineral oil, synthetic oil (PAO (polyalphaolefin), highly hydrocracked oil VHVI (Very).
High Viscosity Index), esters, etc.) and base oils such as hybrid oils thereof with additives such as antioxidants, antiwear agents, detergent dispersants, viscosity index improvers, antifoaming agents, and pour point depressants. The added one will be used.

  First, an internal combustion engine lubrication system according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the lubrication system 1 mixes engine oil with liquid DME to remove the insoluble components of the engine oil that do not dissolve in the liquid DME, as shown in FIG. The supply pump 6 includes an insoluble component removal oil supply device 40 that lubricates the engine with engine oil from which insoluble components have been removed.

  The insoluble component removal oil supply device 40 includes an engine oil DME trap (mixing / separating container) 41 and a filter (insoluble component removal device) 42. The engine oil DME trap 41 is disposed in the middle of the second lubricating oil supply channel 16, and is connected to a DME introduction channel 44 provided with an orifice (flow rate regulator) 43 and a gas phase return channel 45. The filter 42 is disposed downstream of the engine oil DME trap 41 and is connected to the insoluble component return flow path 46.

  The engine oil DME trap 41 is a container that introduces engine oil from the second lubricant supply channel 16a and supplies the engine oil to the supply pump 6 through the second lubricant supply channel 16b. There is no limitation.

  The engine oil DME trap 41 mixes engine oil with the pressurized liquid phase DME introduced from the DME introduction flow path 44, and dissolves in the DME in the engine oil and does not dissolve in the DME. It is comprised so that it may isolate | separate into an insoluble component. Here, the dissolved component is a component including a lubricating component, for example, a base oil, and the insoluble component is an additive, for example, an antioxidant, an antiwear agent, a cleaning dispersant, a viscosity index improvement. Agents, antifoaming agents, and pour point depressants.

  In addition, the engine oil DME trap 41 is also configured to gas-liquid separate the DME mixed with the engine oil. Specifically, the engine oil DME trap 41 is connected to the gas phase return flow path 45 and communicates with the gas phase portion of the fuel tank 4 so that the pressure in the engine oil DME trap 41 is set to normal pressure. . As a result, the liquid phase DME is vaporized to become gas phase DME, and the remaining liquid becomes engine oil separated into a dissolved component and an insoluble component.

  In this embodiment, the engine oil and DME are mixed, the engine oil dissolved component and the insoluble component are separated, and the DME is vaporized in one container. For example, mixing and separation are performed. A container to be performed and a container to perform gas-liquid separation may be provided. In that case, the pressure in the container for mixing and separation should be high so as to hold the liquid phase DME, and the pressure in the container for gas-liquid separation should be low so that the DME is easily vaporized.

  The filter 42 is a device that removes insoluble components from the dissolved components provided on the downstream side of the engine oil DME trap 41, that is, in the second lubricating oil supply passage 16b. The filter 42 is connected to an insoluble component return flow path 46, returns the insoluble component removed from the dissolved component by the filter 42 to the oil pan 12, and supplies only the dissolved component from which the insoluble component has been removed to the supply pump 6. Yes. In this embodiment, the filter 42 is used as a device for removing insoluble components. However, the present invention is not limited to the filter 42 as long as the insoluble components can be removed from the dissolved components.

Next, the operation of the lubrication system 1 for the engine 2 will be described. First, the oil pump 14 is driven to transfer engine oil from the oil pan 12 to the engine oil DME trap 41. Then, the engine oil DME trap 41 introduces liquid DME that has been pressurized to be supplied from the fuel tank 4 to the supply pump 6 and mixes it with the engine oil.

  When DME is used as a fuel, it is necessary to transfer the DME from the fuel tank 4 to the supply pump 6 while maintaining a liquid phase by applying a pressure at which DME is not vaporized to the DME, preferably about 3 MPa. When the pressurized liquid phase DME is introduced into the engine oil DME trap 41 via the DME introduction flow path 44, the flow rate of the pressurized DME increases, and therefore, the orifice 43 is placed in the DME introduction flow path 44. It is desirable to adjust the flow rate of DME.

  At this time, the ratio between the amount of engine oil mixed in the engine oil DME trap 41 and the amount of DME may be set to about 1: 1 to 10: 1. In particular, if the ratio of DME is reduced, the supply pump 6 The amount of DME leaking excessively can be reduced.

  In this embodiment, the amount of DME is adjusted by introducing DME into the engine oil DME trap 41 through the orifice 43. However, instead of the orifice 43 or separately from the orifice 43, the DME is introduced into the DME introduction flow path 44. You may provide the valve which adjusts the flow volume of this.

  Next, the engine oil mixed with DME in the engine oil DME trap 41 is separated into a dissolved component that dissolves in DME and an insoluble component that does not dissolve in DME. Further, in the engine oil DME trap 41, DME is vaporized because the pressure is released or the pressure is released because it is introduced through the orifice 43.

  In the engine oil DME trap 41, the engine oil is separated into a dissolved component and an insoluble component in the DME, and the DME mixed with the engine oil is vaporized and separated into gas phase DME and engine oil. Both events occur. Due to the solvent effect of DME, the dissolved component is dissolved in DME, the insoluble component remains in the mixed fluid of engine oil and DME, and the insoluble component is trapped in the dissolved component by further vaporizing DME. It is.

  DME is vaporized at normal temperature and normal pressure. The engine oil DME trap 41 communicates with the gas phase portion of the fuel tank 4 through the gas phase return flow path 45, and the inside is at normal temperature and normal pressure, specifically about 20 ° C. and about 0.5 MPa. The liquid phase DME is easily vaporized.

  Then, the engine oil that has been pressurized into the gas phase DME, that is, the engine oil separated into the dissolved component and the insoluble component in the engine oil DME trap 41 pressurized by the vapor pressure characteristic of the DME, passes through the filter 42. The insoluble component is removed (trapped), and the dissolved component is supplied to the supply pump 6 via the second lubricating oil supply channel 16b to lubricate the drive unit 32 of the supply pump 6. On the other hand, the insoluble component removed by the filter 42 is returned to the oil pan 12 through the insoluble component return flow path 46.

When DME is mixed with the lubrication of the supply pump 6, the DME finally enters the oil pan 12, stays in a crankcase (not shown), is sucked into the intake air by the blow-by recirculation device, and the DME concentration in the intake air is increased. It may cause abnormal combustion. Therefore, it is preferable to vaporize most of the liquid phase DME mixed with the engine oil in the engine oil DME trap 41, and more preferably to vaporize all the liquid phase DME mixed with the engine oil. Is good. For example, the flow rate of DME introduced into the engine oil DME trap 41 is adjusted by the orifice 43 or a valve for adjusting the flow rate, and the liquid phase DME is not introduced until the liquid phase DME is completely vaporized. It may be configured.

  According to the above operation, by using the solvent characteristics of DME and the pressurized DME supply line, the additive which is an insoluble component in the engine oil to the supply pump 6 can be eliminated, and the DME Even if it is mixed in, it affects the after-treatment devices such as catalysts (oxidation catalyst, SCR catalyst, etc.) and exhaust system (deposit deposits on EGR cooler, deposit deposits on variable capacity turbo nozzle moving parts) And durability can be improved.

  The insoluble component removed by the filter 42 is originally dissolved in the engine oil and is returned to the oil pan 12 through the insoluble component return flow path 46 because it is fat-soluble. Requires a small amount of engine oil, and there is almost no influence of concentration of insoluble components (additives) in the oil pan 12.

  Next, a second embodiment according to the present invention will be described with reference to FIG. The lubrication system 50 of the engine 2 includes a supply pump 52 directly including an insoluble component removal oil supply device 51 instead of the supply pump 6 and the insoluble component removal oil supply device 40 of the first embodiment shown in FIG. Configured.

  The insoluble component removal oil supply device 51 includes an engine oil DME trap 53, and the engine oil DME trap 53 is joined to a DME introduction channel 54, a gas phase return channel 55, and an insoluble component return channel 56. . The engine oil DME trap 53 is provided with an orifice on the inlet side of the DME introduction flow path 54, and with a filter on the outlet side to the second lubricating oil supply flow path 16b and the insoluble component return flow path 56. It is the apparatus formed in.

  According to this configuration, by providing the insoluble component removal oil supply device 51 in the supply pump 52, it is possible to reduce the number of pipes and make the structure easy to install.

  Compared with the conventional engine 2X shown in FIG. 3, the engine 2 including the lubrication systems 1 and 50 includes the insoluble component removal oil supply device 40 and the lubrication systems 1 and 50, as shown in FIGS. 1 and 2. 51, so that DME does not leak into the drive unit 32 of the supply pumps 6 and 52. Even if engine oil is mixed into the DME from the sealing device 26 provided on the plunger 25 or the like, the insoluble component that does not dissolve in the DME from the engine oil. Since (metal component etc.) is removed, it can prevent that an insoluble component mixes with waste gas.

  In the internal combustion engine lubrication system according to the present invention, the high-pressure pump that pumps the liquefied gas fuel can be lubricated with the lubricating oil from which insoluble components that are not dissolved in the liquefied gas fuel are removed. Therefore, the engine that uses the liquefied gas fuel such as DME. It can be used for vehicles equipped with. It can also be used for gas turbines using liquefied gas fuel.

DESCRIPTION OF SYMBOLS 1, 50, 1X Lubrication system 2, 2X Engine 3 Fuel injection apparatus 4 Fuel tank 5 DME supply system 6, 52 Supply pump 7 Common rail 8 Injector 9 Feed pump 10 Supply flow path 11 Return flow path 12 Oil pan 13 Strainer 14 Oil pump 15 1st lubricating oil supply flow path 16 2nd lubricating oil supply flow path 17 1st lubricating oil return flow path 18 2nd lubricating oil return flow path 40, 51 Insoluble component removal oil supply apparatus 41, 53 Engine oil DME trap (mixing) Separation container)
42 Filter (insoluble component remover)
43 Orifice (flow rate regulator)
44, 54 DME introduction channel (liquefied gas fuel introduction channel)
45, 55 Gas phase return channel 46, 56 Insoluble component return channel

Claims (6)

In an internal combustion engine lubrication system that lubricates an internal combustion engine fueled with liquefied gas fuel with a lubricating oil,
Lubricating oil is mixed with liquid-phase liquefied gas fuel to remove insoluble components of lubricating oil that do not dissolve in liquid-phase liquefied gas fuel,
A lubricating system for an internal combustion engine, comprising: an insoluble component removal oil supply device that lubricates at least a high-pressure pump that pumps liquefied gas fuel with the lubricating oil from which insoluble components have been removed. In the insoluble component removal oil supply device,
Lubricating oil is mixed with pressurized liquid-phase liquefied gas fuel supplied to the high-pressure pump, and the lubricating oil is dissolved in the liquid-phase liquefied gas fuel and dissolved in the liquid-phase liquefied gas fuel and the insoluble component. Separating and separating the liquid-phase liquefied gas fuel mixed with the lubricating oil and gas-liquid separation; and
The internal combustion engine lubrication system according to claim 1, further comprising an insoluble component remover that removes the insoluble component. In the insoluble component removal oil supply device,
A liquefied gas fuel introduction flow path for introducing a part of the pressurized liquid phase liquefied gas fuel supplied from the fuel tank to the high pressure pump into the insoluble component removal oil supply device via a flow rate regulator;
A gas-phase return flow path for returning a gas-phase liquefied gas fuel generated when removing the insoluble component from the insoluble component-removing oil supply device to the fuel tank;
An insoluble component return flow path for returning the insoluble component from the insoluble component removal oil supply device to a storage tank in which lubricating oil is stored, and
3. The internal combustion engine according to claim 1, wherein the insoluble component removing oil supply device is disposed in a lubricating oil supply flow path for supplying lubricating oil from the storage tank to a lubricated portion in the high-pressure pump. Lubrication system.   An internal combustion engine comprising the internal combustion engine lubrication system according to any one of claims 1 to 3, wherein the lubrication system is configured to lubricate a high-pressure pump that pumps liquefied gas fuel to a common rail. organ. In a method for lubricating an internal combustion engine in which an internal combustion engine using liquefied gas fuel as a fuel is lubricated with lubricating oil,
Lubricating oil is mixed with liquid-phase liquefied gas fuel to remove insoluble components that do not dissolve in the liquid-phase liquefied gas fuel of lubricating oil,
A method for lubricating an internal combustion engine, characterized in that at least a high-pressure pump that pumps liquefied gas fuel is lubricated with a dissolved component that removes the insoluble component and dissolves in the liquid liquefied gas fuel including the lubricating component of the lubricating oil. Before supplying the lubricating oil to the high-pressure pump, the lubricating oil is mixed with the pressurized liquid-phase liquefied gas fuel supplied to the high-pressure pump in a mixing and separating container, and the dissolved component and the insoluble component are mixed. Gas-liquid separation of the liquid liquefied gas fuel mixed with the lubricating oil,
6. The method for lubricating an internal combustion engine according to claim 5, wherein the insoluble component is removed by an insoluble component remover.

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