JP2004144076A - Fuel supplying device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always surely supply fuel from a fuel tank in a stable state without increasing cost and power consumption of a fuel supplying device and increasing the device in scale, in the fuel supplying device for a diesel engine for making liquefied gas fuel having the property of becoming gas at normal temperature as fuel. <P>SOLUTION: A feed pump 51 is disposed just below an outlet of DME fuel in a state of a suction port of the feed pump 51 directly mounted on the outlet of DME fuel provided at a bottom part of the fuel tank 4. Since the suction port of the feed pump 51 is directly disposed at the outlet of the DME fuel of the fuel tank 4, a fuel pipe from the fuel tank 4 to the feed pump 51 becomes unnecessary, the outlet of the DME fuel of the fuel tank 4 and the suction port of the feed pump 51 are integrated, and a relative temperature difference is not generated between the outlet of the DME fuel of the fuel tank 4 and the suction port of the feed pump 51. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention particularly relates to a fuel supply device for supplying fuel to a diesel engine using a fuel alternative to light oil represented by DME (dimethyl ether).

As a countermeasure against air pollution caused by diesel engines, for example, one that uses DME (dimethyl ether), whose exhaust gas is clean, as a fuel instead of light oil has attracted attention. DME fuel is a liquefied gas fuel unlike light oil which is a conventional fuel. That is, while the boiling point temperature is lower than that of light oil and light oil is liquid at normal temperature under atmospheric pressure, DME has the property of becoming a gas at normal temperature. The change in density due to change is large. Therefore, in the fuel pipe from the fuel tank to the feed pump for sending the DME fuel in the fuel tank to the injection pump, the temperature of the DME fuel at the feed pump inlet side is higher than the temperature of the DME fuel at the fuel tank outlet side. When a relative temperature difference occurs, the relative vapor pressure difference of the DME fuel caused by the temperature difference makes it difficult for the DME fuel to flow from the fuel tank to the feed pump. Then, when the relative temperature difference is further increased, a phenomenon occurs in which DME fuel does not flow at all from the fuel tank to the feed pump.

As an example of a conventional technique for solving the problem peculiar to a fuel supply device for a liquefied gas fuel having a property of being a gas at normal temperature, such as a DME fuel, for example, a DME fuel in a fuel tank is transferred from a fuel tank to an injection pump. In a fuel pipe up to a feed pump for delivery, there is a fuel pipe in which a temperature control means such as a cooler is disposed near an inlet side of the feed pump (for example, see Patent Document 1). For example, the feed pump is provided with a temperature detecting means such as a temperature sensor. Based on the temperature detected by the temperature sensor, the temperature of the DME fuel at the inlet of the feed pump is smaller than the temperature of the DME fuel at the outlet of the fuel tank as described above. The temperature control means such as a cooler disposed near the inlet side of the feed pump is controlled so that there is no relative temperature difference between the feed pumps. As a result, a vapor pressure difference due to the temperature difference can be prevented, so that it becomes difficult for the DME fuel to flow from the fuel tank to the feed pump, or the DME fuel does not flow at all from the fuel tank to the feed pump. Can be prevented.

JP-A-2002-61542 (FIG. 1)

However, in the conventional technique disclosed in Patent Document 1, a fuel temperature detecting means and a fuel temperature adjusting means are provided, and the fuel temperature adjusting means is controlled based on the temperature detected by the temperature detecting means. Providing a control device or the like as a control means for performing such a method has a problem in that the cost of the fuel supply device for the diesel engine is greatly increased. In addition, this causes a problem that the power consumption of the fuel supply device of the diesel engine increases and the size of the fuel supply device of the diesel engine increases.

The present invention has been made in view of such a situation, and an object thereof is to provide a fuel supply device for a diesel engine using a liquefied gas fuel such as DME which has a property of being a gas at normal temperature as a fuel. It is an object of the present invention to reliably supply fuel from a fuel tank in a stable state without increasing the cost and power consumption and without increasing the size of the fuel supply device.

In order to achieve the above object, a first aspect of the present invention is to provide a feed pump that pressurizes fuel in a fuel tank having a property of being a gas at normal temperature to a predetermined pressure and feeds the fuel to a feed pipe; And an injection pump for pressurizing the fuel delivered via the injection pump and delivering the fuel to a fuel injection nozzle of the diesel engine by a predetermined amount at a predetermined timing, wherein the feed pump is And a fuel supply device for a diesel engine, which is disposed immediately adjacent to a fuel outlet of the fuel tank.

By arranging the feed pump for pressurizing the fuel in the fuel tank to a predetermined pressure and sending the fuel to the feed pipe in the vicinity of the fuel outlet of the fuel tank, the fuel pipe from the fuel tank to the feed pump is provided. Can be extremely short. Therefore, a relative temperature difference between the fuel tank outlet side and the feed pump inlet side is unlikely to occur, and the relative vapor pressure difference of the fuel having a property of becoming a gas at normal temperature caused by the temperature difference is fed from the fuel tank. It can be made extremely small so as not to affect the flow of fuel to the pump. Therefore, the relative temperature difference at which the fuel temperature at the feed pump inlet side is higher than the fuel temperature at the fuel tank outlet side makes it difficult for fuel to flow from the fuel tank to the feed pump, It is possible to prevent the fuel from flowing at all to the pump.

Thus, according to the fuel supply device for a diesel engine according to the first aspect of the present invention, the feed pump that pressurizes the fuel in the fuel tank to a predetermined pressure and feeds the fuel to the feed pipe is provided by the fuel pump of the fuel tank. By arranging it near the outlet, it is possible to prevent the fuel from flowing from the fuel tank to the feed pump or prevent the fuel from flowing from the fuel tank to the feed pump at all. In a fuel supply system for a diesel engine using a liquefied gas fuel having a property of becoming a gas in a fuel tank, the fuel supply system can be used without increasing the cost and power consumption of the fuel supply system and without increasing the size of the fuel supply system. The effect of this is that the fuel supply can always be performed in a stable state. It is. It is more preferable that the feed pump is disposed as close as possible to the fuel tank, so that the fuel can be reliably supplied from the fuel tank to the feed pump in a more stable state.

According to a second aspect of the present invention, there is provided a fuel supply system for a diesel engine according to the first aspect, wherein the suction port of the feed pump is disposed directly at a fuel outlet of the fuel tank. Device.

As described above, since the inlet of the feed pump is disposed directly at the fuel outlet of the fuel tank, a fuel pipe from the fuel tank to the feed pump is not required, and the fuel tank outlet and the feed pump inlet are connected to each other. Become one. Therefore, since there is no relative temperature difference between the fuel tank outlet side and the feed pump inlet side, there is no relative vapor pressure difference of the fuel having the property of becoming gas at normal temperature caused by the temperature difference. Therefore, the relative temperature difference at which the fuel temperature at the feed pump inlet side is higher than the fuel temperature at the fuel tank outlet side makes it difficult for fuel to flow from the fuel tank to the feed pump, It is possible to prevent the fuel from flowing to the pump at all.

Thus, according to the fuel supply device for a diesel engine according to the second aspect of the present invention, in addition to the operation and effect according to the invention described in the first aspect, the fuel in the fuel tank is maintained at a predetermined pressure. By arranging the suction port of the feed pump, which pressurizes and feeds the feed pipe, directly to the fuel outlet of the fuel tank, it is possible to reliably supply the fuel from the fuel tank to the feed pump in a more stable state. The operation and effect can be obtained.

A third aspect of the present invention is the diesel engine according to the first or second aspect, wherein the feed pump is disposed directly below a fuel outlet at the bottom of the fuel tank. It is an engine fuel supply device.

According to the fuel supply device for a diesel engine according to the third aspect of the present invention, in addition to the operation and effect according to the invention described in the first aspect or the second aspect, the feed pump is provided with a fuel at the bottom of the fuel tank. Since the fuel tank is disposed immediately below the outlet, the fuel can easily flow from the fuel tank to the feed pump, and the operation and effect of smoothly supplying the fuel from the fuel tank to the feed pump can be obtained.

According to a fourth aspect of the present invention, there is provided a feed pump which pressurizes fuel in a fuel tank having a property of being a gas at normal temperature to a predetermined pressure and feeds the fuel to a feed pipe, and the feed pump delivered via the feed pipe A fuel supply device for a diesel engine, comprising: an injection pump configured to pressurize fuel and deliver a predetermined amount to a fuel injection nozzle of the diesel engine at a predetermined timing, wherein the fuel pump includes a fuel delivery port of the fuel tank and the feed pump. A fuel supply device for a diesel engine, characterized in that a pipe connecting the intake port of the diesel engine is coated with a heat insulating material.

If the feed pump cannot be installed in the immediate vicinity of the fuel tank due to restrictions on the installation space of the fuel supply device, etc., the fuel pump and the feed pump must be installed at a location separated from each other. There is a risk that a large relative temperature difference will occur between the pump and the inlet side of the pump. Thus, by covering the pipe connecting the fuel delivery port of the fuel tank and the suction port of the feed pump with a heat insulating material, the temperature change of the fuel in the fuel pipe from the fuel tank to the feed pump is extremely small. can do. Therefore, a relative temperature difference between the fuel tank outlet side and the feed pump inlet side is unlikely to occur, and the relative vapor pressure difference of the fuel having a property of becoming a gas at normal temperature caused by the temperature difference is fed from the fuel tank. It can be made very small so as not to affect the flow of fuel to the pump. Therefore, the relative temperature difference at which the fuel temperature at the feed pump inlet side is higher than the fuel temperature at the fuel tank outlet side makes it difficult for fuel to flow from the fuel tank to the feed pump, It is possible to prevent the fuel from flowing to the pump at all.

Thus, according to the fuel supply device for a diesel engine according to the fourth aspect of the present invention, the pipe connecting the fuel supply port of the fuel tank and the intake port of the feed pump is covered with the heat insulating material to thereby provide the fuel. Since it is possible to prevent the fuel from flowing from the tank to the feed pump hardly, or to prevent the fuel from flowing from the fuel tank to the feed pump at all, a liquefied gas fuel having a property of being a gas at normal temperature can be used. In a fuel supply system for a diesel engine that uses fuel, the supply of fuel from the fuel tank is always ensured in a stable state without increasing the cost and power consumption of the fuel supply system and without increasing the size of the fuel supply system. The operation and effect can be obtained.

According to a fifth aspect of the present invention, there is provided a feed pump that pressurizes fuel in a fuel tank having a property of being a gas at normal temperature to a predetermined pressure and sends the fuel to a feed pipe, and the feed pump delivered via the feed pipe. An injection pump that pressurizes fuel and sends a predetermined amount to a fuel injection nozzle of a diesel engine at a predetermined timing; and the fuel that overflows from the fuel injection nozzle and the fuel that overflows from the injection pump. An overflow fuel pipe for returning to the overflow fuel pipe, and the pressure of the fuel in the oil reservoir of the injection pump and the fuel in the fuel injection nozzle is maintained at a predetermined pressure or higher, and the overflowed fuel pipe is provided. In the direction that fuel returns to the fuel tank. A fuel supply device for a diesel engine, comprising: an overflow valve that regulates a flow direction of the fuel; a bypass passage that bypasses the overflow valve; bypass passage opening / closing means that opens and closes the bypass passage; In a stopped state, the fuel in the fuel tank is sent out by the feed pump, and bypass control means for opening and controlling the bypass passage opening / closing means only while filling the feed pipe and the injection pump with the fuel. A fuel supply device for a diesel engine, comprising:

(4) In a diesel engine fuel supply device, the fuel tank and the injection pump are generally arranged at a certain distance from each other. Therefore, when the temperature of the injection pump becomes high due to heat from the diesel engine or the like, a large relative temperature difference occurs between the fuel tank side and the injection pump side. As a result, a pressure difference is caused between the fuel tank side and the injection pump side due to the temperature difference, and the pressure difference may cause a problem that the feed pump cannot supply the fuel from the fuel tank smoothly.

Therefore, in this way, a bypass passage that bypasses the overflow valve is provided, and while the diesel engine is stopped, the fuel in the fuel tank is sent out by the feed pump and the fuel is supplied to the feed pipe and the injection pump while the fuel is being filled. Only the bypass passage is communicated. In a non-injection state (a state in which the diesel engine is stopped), the overflow valve bypasses the overflow valve because it is not necessary to regulate the pressure in the oil reservoir of the injection pump and the fuel injection nozzle to a predetermined pressure or more. There is no problem at all. When the bypass passage is communicated, the overflow fuel pipe and the fuel tank are in direct communication with each other without passing through the overflow valve.Therefore, the oil reservoir of the injection pump, which has been regulated to a predetermined pressure or more by the overflow valve, and the fuel injection A pressure difference between the pressure in the nozzle and the pressure in the fuel tank hardly occurs. Therefore, even if a temperature difference occurs between the injection pump and the fuel tank, a relative pressure difference between the two hardly occurs. As a result, the fuel delivered from the feed pump can be smoothly and in a short time without being substantially affected by the pressure difference between the pressure in the oil reservoir of the injection pump, the pressure in the fuel injection nozzle, and the pressure in the fuel tank. The oil is filled into the oil reservoir and the fuel injection nozzle of the injection pump.

Thus, according to the fuel supply device for a diesel engine according to the fifth aspect of the present invention, by bypassing the overflow valve at the time of filling the fuel while the diesel engine is stopped, the oil reservoir of the injection pump, Since the pressure in the injection nozzle and the pressure in the fuel tank hardly differ from each other, the fuel is supplied to the fuel supply device of the diesel engine using a liquefied gas fuel having a property of being a gas at normal temperature. In the above, the supply of fuel from the fuel tank to the oil reservoir of the injection pump and the fuel injection nozzle was always stabilized without increasing the cost and power consumption of the fuel supply device and without increasing the size of the fuel supply device. The operation and effect of being able to perform the operation reliably in the state can be obtained.

According to a sixth aspect of the present invention, in the fuel supply device for a diesel engine according to the fifth aspect, the feed pump is disposed immediately near a fuel outlet of the fuel tank. is there.

According to the fuel supply device for a diesel engine according to the sixth aspect of the present invention, in addition to the effect of the invention described in the fifth aspect, the fuel in the fuel tank is pressurized to a predetermined pressure. By arranging the feed pump that feeds to the feed pipe close to the fuel outlet of the fuel tank, it becomes difficult for fuel to flow from the fuel tank to the feed pump, or no fuel flows from the fuel tank to the feed pump. It is possible to always supply the fuel from the fuel tank to the feed pump without increasing the cost and power consumption of the fuel supply device and without increasing the size of the fuel supply device. The operation and effect can be obtained that the operation can be reliably performed in a stable state.

According to a seventh aspect of the present invention, there is provided a fuel supply system for a diesel engine according to the sixth aspect, wherein an inlet of the feed pump is disposed directly at a fuel outlet of the fuel tank. Device.

According to the fuel supply device for a diesel engine according to the seventh aspect of the present invention, in addition to the effect of the invention described in the sixth aspect, the fuel in the fuel tank is pressurized to a predetermined pressure. By arranging the inlet of the feed pump for feeding the feed pipe directly to the fuel outlet of the fuel tank, it is possible to reliably supply the fuel from the fuel tank to the feed pump in a more stable state. The effect of being able to obtain is obtained.

An eighth aspect of the present invention is the diesel engine according to the sixth or seventh aspect, wherein the feed pump is disposed immediately below a fuel outlet at the bottom of the fuel tank. It is an engine fuel supply device.

According to the fuel supply device for a diesel engine described in the eighth aspect of the present invention, in addition to the operation and effect according to the invention described in the sixth or seventh aspect, the feed pump is provided with the fuel at the bottom of the fuel tank. Since the fuel tank is disposed immediately below the outlet, the fuel can easily flow from the fuel tank to the feed pump, and the operation and effect of smoothly supplying the fuel from the fuel tank to the feed pump can be obtained.

According to a ninth aspect of the present invention, in the above-described fifth aspect, a pipe connecting a fuel supply port of the fuel tank and a suction port of the feed pump is coated with a heat insulating material. This is a diesel engine fuel supply device.

According to the fuel supply device for a diesel engine according to the ninth aspect of the present invention, in addition to the effects of the invention described in the fifth aspect, the fuel supply port of the fuel tank and the intake port of the feed pump are provided. By coating the heat insulating material on the pipe connecting the fuel tank, it is possible to prevent the fuel from being difficult to flow from the fuel tank to the feed pump or preventing the fuel from flowing from the fuel tank to the feed pump at all. Therefore, it is possible to reliably supply fuel from the fuel tank to the feed pump in a stable state without increasing the cost and power consumption of the fuel supply device and without increasing the size of the fuel supply device. The effect of being able to obtain is obtained.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects described above, the diesel engine is a diesel engine using DME as fuel, and the DME fuel in the fuel tank is used as the diesel engine. A fuel supply device for a diesel engine, wherein the fuel supply device is configured to supply the fuel to the engine.

As mentioned above, attention has been paid to diesel engines that use clean DME (dimethyl ether) as fuel instead of diesel oil as a measure against air pollution by diesel engines. According to the fuel supply device for a diesel engine according to the tenth aspect of the present invention, in the fuel supply device for a diesel engine using DME having a clean exhaust gas as a fuel, the first to ninth aspects described above. The operation and effect according to the invention described in any of the aspects are obtained.

According to the present invention, in a fuel supply system for a diesel engine using a liquefied gas fuel such as DME which has a property of being a gas at normal temperature, without increasing the cost and power consumption of the fuel supply system, It is possible to reliably supply the fuel from the fuel tank in a stable state without increasing the size of the fuel cell.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a first embodiment of a DME fuel supply device as a "fuel supply device" according to the present invention.

Ｄ The DME fuel supply device 100 that supplies DME fuel to a diesel engine includes the injection pump 1. The injection pump 1 includes the same number of injection pump elements 2 as the number of cylinders of the diesel engine. The feed pump 51 pressurizes the DME fuel in the liquid phase 4 a stored in the fuel tank 4 to a predetermined pressure and sends it to the feed pipe 5. The DME fuel sent to the feed pipe 5 is filtered by the filter 5a and sent to the injection pump 1 via the three-way solenoid valve 71. The three-way solenoid valve 71 is ON when in the injection state (during operation of the diesel engine) and communicates in the illustrated direction.

The DME fuel pressurized from the fuel tank 4 to a predetermined pressure by the feed pump 51 and sent out from each injection pump element 2 of the injection pump 1 via the injection pipe 3, and a predetermined amount of diesel fuel at a predetermined timing. The pressure is fed to a fuel injection nozzle 9 provided in each cylinder of the engine. The overflow fuel pipe 81 is provided with an overflow valve 82 for maintaining the pressure of the DME fuel in the oil reservoir 11 at a predetermined pressure and defining the flow direction of the DME fuel only in a direction in which the overflowed DME fuel returns to the fuel tank 4. Are arranged. The DME fuel overflowing from the injection pump 1 is returned to the fuel tank 4 via an overflow fuel pipe 81, an overflow valve 82, an overflow return pipe 8, and a cooler 42. The DME fuel overflowing from each fuel injection nozzle 9 is returned to the fuel tank 4 via the nozzle return pipe 6, the overflow fuel pipe 81, the overflow return pipe 8, and the cooler 42.

Further, when the diesel engine is stopped, the DME fuel supply device 100 supplies the DME fuel remaining in the oil reservoir 11, the overflow fuel pipe 81, the injection pump element 2, the injection pipe 3, and the nozzle return pipe 6 in the injection pump 1. As means for collecting fuel into the fuel tank 4, an aspirator 7, a three-way solenoid valve 71, a two-way solenoid valve 72, and a DME fuel recovery control unit 10 are provided. The DME fuel recovery control unit 10 detects the operation / stop state of the diesel engine (the injection / non-injection state of the DME fuel supply device 100), and according to each state, the three-way solenoid valve 71, the two-way solenoid valve 72, and On / off control of the feed pump 51 and the like is executed, and when the diesel engine is stopped, the DME fuel remaining in the oil reservoir 11, the overflow fuel pipe 81, the injection pump element 2, the injection pipe 3, and the nozzle return pipe 6 is removed. Execute control to collect.

The aspirator 7 has an inlet 7a, an outlet 7b, and a suction port 7c. The inlet 7a and the outlet 7b are in straight communication with each other, and the suction port 7c is branched in a substantially vertical direction from a communication path between the inlet 7a and the outlet 7b. The outlet side of the communication path communicating when the three-way solenoid valve 71 is OFF is connected to the inlet 7a, and the outlet 7b is connected to the path to the fuel tank 4 via the cooler 42. Further, the suction port 7c is connected to a two-way solenoid valve 72 which is closed in an OFF state in an injection state (during operation of a diesel engine).

In the non-injection state (when the diesel engine is stopped), the DME fuel recovery control unit 10 turns off the three-way solenoid valve 71 to form a communication path from the feed pipe 5 to the inlet 7a of the aspirator 7, and By turning on the one-way solenoid valve 72, communication is made between the overflow fuel pipe 81 upstream of the overflow valve 82 and the suction port 7 c of the aspirator 7. Therefore, the DME fuel sent from the feed pump 51 is sent to the aspirator 7 without being sent to the injection pump 1, passes through the inlet 7 a to the outlet 7 b, and overflows from the overflow fuel pipe 81 downstream of the overflow valve 82 to the overflow return. The fuel returns to the fuel tank 4 via the pipe 8 and the cooler 42, and is again sent from the feed pump 51 to the aspirator 7. That is, the DME fuel liquid recirculates through the aspirator 7. The DME fuel remaining in the oil reservoir 11 in the injection pump 1 and the overflow fuel pipe 81 on the upstream side of the overflow valve 82 is sucked by the suction force generated by the flow of the DME fuel flowing from the inlet 7a to the outlet 7b. It is sucked from the port 7c, absorbed by the DME fuel flowing from the inlet 7a to the outlet 7b, and collected in the fuel tank 4. Further, since the DME fuel recovery control unit 10 turns on the two-way solenoid valve 72 in the non-injection state, the nozzle return pipe 6 and the overflow fuel pipe 81 on the upstream side of the overflow valve 82 communicate with each other. The remaining DME fuel is sucked from the suction port 7c via the overflow fuel pipe 81 on the upstream side of the overflow valve 82 and collected in the fuel tank 4.

The DME fuel supply device 100 further includes a gas pressure delivery pipe 73 connecting the outlet of the gas phase 4b in the fuel tank 4 and the inlet side of the oil reservoir 11 of the injection pump 1. The gas-phase pressure delivery pipe 73 has a throttle part 75 whose inner diameter is partially narrowed, and a gas-phase pressure delivery pipe opening / closing solenoid valve 74 for opening and closing communication with the gas-phase pressure delivery pipe 73. When the DME fuel in the oil reservoir 11, the overflow fuel pipe 81, and the nozzle return pipe 6 is sucked and collected in the fuel tank 4, the DME fuel collection control unit 10 simultaneously sets the gas pressure delivery pipe open / close electromagnetic valve 74 to When it is turned on, the gas-phase pressure delivery pipe 73 connecting the gas-phase 4b of the fuel tank 4 and the inlet side of the oil reservoir 11 is connected. The liquid DME fuel remaining in the oil reservoir 11, the overflow fuel pipe 81, and the nozzle return pipe 6 is pumped toward the suction port 7c of the aspirator 7 by the high pressure of the gas phase 4b. .

The cam chamber 12 in the injection pump 1 is a dedicated lubrication system separated from the lubrication system of the diesel engine. The oil separator 13 is a cam in which the DME fuel leaked into the cam chamber 12 in the injection pump 1 is mixed. The lubricating oil in the chamber 12 is separated into DME fuel and lubricating oil, and the lubricating oil is returned to the cam chamber 12. The DME fuel separated by the oil separator 13 is sent out to the compressor 16 via the check valve 14 for preventing the pressure in the cam chamber 12 from becoming lower than the atmospheric pressure. The fuel is returned to the fuel tank 4 via the valve 15 and the cooler 42. The check valve 15 is provided to prevent the DME fuel from flowing back from the fuel tank 4 to the cam chamber 12 when the diesel engine is stopped. The compressor 16 is a compressor that uses a cam in the cam chamber 12 as a driving force source.

In the DME fuel supply device 100 as the “fuel supply device” according to the present invention, the DME fuel outlet 41 of the fuel tank 4 is provided below the level of the DME fuel in the fuel tank 4. Further, a feed pump 51 is disposed immediately near the DME fuel outlet 41 of the fuel tank 4, and the DME fuel outlet 41 of the fuel tank 4 and the feed pump 51 are connected by an extremely short pipe. Therefore, a relative temperature difference between the DME fuel outlet 41 of the fuel tank 4 and the suction port of the feed pump 51 is unlikely to occur, and a relative vapor pressure difference of the DME fuel caused by the temperature difference is reduced from the fuel tank 4. It can be made extremely small so as not to affect the flow of the DME fuel to the feed pump 51. Therefore, the relative temperature difference between the DME fuel in the fuel tank 4 and the DME fuel at the suction port of the feed pump 51 makes it difficult for the DME fuel to flow from the fuel tank 4 to the feed pump 51, It is possible to prevent the DME fuel from not flowing at all from the feed pump 51.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the DME fuel supply device 100 as a “fuel supply device” according to the present invention, and shows the vicinity of the fuel tank 4 in an enlarged manner.

The DME fuel supply device 100 shown in the present embodiment is different from the DME fuel supply device 100 shown in the first embodiment in that the suction port of the feed pump 51 is connected to the DME fuel outlet provided at the bottom of the fuel tank 4. In this state, the feed pump 51 is disposed immediately below the DME fuel delivery port in a state of being directly attached. As described above, since the suction port of the feed pump 51 is disposed directly at the DME fuel outlet of the fuel tank 4, a fuel pipe from the fuel tank 4 to the feed pump 51 becomes unnecessary, and the fuel tank 4 The delivery port of the DME fuel and the suction port of the feed pump 51 are integrated. Therefore, since there is no relative temperature difference between the DME fuel outlet of the fuel tank 4 and the inlet of the feed pump 51, there is no relative vapor pressure difference of the DME fuel caused by the temperature difference. Therefore, the relative temperature difference between the DME fuel in the fuel tank 4 and the DME fuel at the suction port of the feed pump 51 makes it difficult for the DME fuel to flow from the fuel tank 4 to the feed pump 51, It is possible to prevent the DME fuel from not flowing at all from the feed pump 51. Further, since the feed pump 51 is disposed directly below the DME fuel outlet at the bottom of the fuel tank 4, the DME fuel can easily flow from the fuel tank 4 to the feed pump 51, and the feed pump 51 DME fuel can be supplied more smoothly.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the DME fuel supply device 100 as the “fuel supply device” according to the present invention, and shows an enlarged view of the vicinity of the fuel tank 4.

The DME fuel supply device 100 shown in this embodiment is different from the DME fuel supply device 100 shown in the first embodiment in that the feed pump 51 is installed at a position away from the fuel tank 4. The suction port and the DME fuel outlet 41 are connected by a long pipe. The pipe connecting the inlet of the feed pump 51 and the DME fuel outlet 41 is covered with a heat insulating material 5b as shown in the figure. The pipe connecting the DME fuel outlet 41 of the fuel tank 4 and the inlet of the feed pump 51 is covered with a heat insulating material 5b to connect the DME fuel outlet 41 of the fuel tank 4 to the inlet of the feed pump 51. The temperature change of the DME fuel in the pipe can be extremely reduced. Therefore, for example, the relative temperature between the DME fuel outlet 41 of the fuel tank 4 and the inlet of the feed pump 51 caused by the temperature of the feed pump 51 rising due to heat generated from the diesel engine or the injection pump 1. A temperature difference is unlikely to occur, and the relative vapor pressure difference of the DME fuel caused by the temperature difference can be made extremely small so as not to affect the flow of the DME fuel from the fuel tank 4 to the feed pump 51. Therefore, the relative temperature difference between the DME fuel in the fuel tank 4 and the DME fuel at the inlet of the feed pump 51 makes it difficult for the DME fuel to flow from the fuel tank 4 to the feed pump 51, It is possible to prevent the DME fuel from flowing to the feed pump 51 at all.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the DME fuel supply device 100 as the “fuel supply device” according to the present invention.

The DME fuel supply device 100 shown in this embodiment is a “bypass passage” that bypasses the overflow valve 82 by connecting both sides of the overflow valve 82 in addition to the DME fuel supply device 100 shown in the first embodiment. , A solenoid valve 84 as “bypass passage opening and closing means” for opening and closing the bypass pipe 83, and a bypass as “bypass control means” for controlling opening and closing of the bypass pipe 83 by controlling opening and closing of the solenoid valve 84 And a control unit 80. The other configuration is the same as that of the first embodiment, and the description is omitted.

The DME remaining in the oil reservoir 11 in the injection pump 1 and the overflow fuel pipe 81 upstream of the overflow valve 82 by the aspirator 7 from the stopped state of the diesel engine (the DME fuel supply device 100 is in the non-injection state). After the fuel is collected in the fuel tank 4, the DME fuel supply device 100 stops. In order to operate the diesel engine again from this state, before starting the pumping of the DME fuel from the injection pump 1 to the fuel injection nozzle 9, the oil reservoir 11 in the injection pump 1 and the fuel It is necessary to supply and charge the DME fuel to the injection nozzle 9. The bypass control unit 80 controls the solenoid valve 84 to be in an open state only during the charging of the DME fuel. When the solenoid valve 84 is opened, both sides of the overflow valve 82 are in communication with each other by the bypass pipe 83, the overflow valve 82 is bypassed, and the oil reservoir 11 and the fuel tank 4 overflow through the overflow pipe 81 and the bypass pipe 83. It is in a state of communicating directly without passing through the valve 82.

In a state where the diesel engine is stopped, it is not necessary to maintain the pressure of the oil reservoir 11 of the injection pump 1 and the pressure of the fuel injection nozzle 9 at a predetermined pressure or more by the overflow valve 82. However, no problem arises. The fuel path returning from the fuel tank 4 to the fuel tank 4 via the feed pump 51, the feed pipe 5, the oil reservoir 11, the overflow pipe 81, the bypass pipe 83, and the cooler 42 directly communicates without passing through the pressure regulating valve. Therefore, there is almost no pressure difference between the pressure of the fuel tank 4 and the pressure of the oil reservoir 11 and the fuel injection nozzle 9 of the injection pump 1, which has been regulated to a predetermined pressure or more by the overflow valve 82. State. Therefore, even if a temperature difference occurs between the injection pump 1 and the fuel tank 4, a relative pressure difference between the two will hardly occur. As a result, the DME fuel delivered from the feed pump 51 is smoothly affected by the pressure difference between the pressure in the oil reservoir 11 and the fuel injection nozzle 9 of the injection pump 1 and the pressure in the fuel tank 4, with little effect. The oil is filled into the oil reservoir 11 and the fuel injection nozzle 9 of the injection pump 1 in a short time.

In this way, the cost and power consumption of the DME fuel supply device 100 are increased when the DME fuel supply device 100 of a diesel engine using DME, which is a liquefied gas fuel having a property of becoming a gas at normal temperature, is charged. Without increasing the size of the DME fuel supply device 100 and without increasing the size of the DME fuel supply device 100, the supply of the DME fuel from the fuel tank 4 to the oil reservoir 11 of the injection pump 1 and the fuel injection nozzle 9 can be performed reliably and stably. Can be

Further, as still another embodiment, there is an embodiment in which the above-described second embodiment (FIG. 2) or third embodiment (FIG. 3) is added to the embodiment shown in the fourth embodiment. Supply of the DME fuel from the fuel tank 4 to the feed pump 51 can be reliably performed in a more stable state, and supply of the DME fuel from the fuel tank 4 can be reliably performed in a more stable state. .

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the invention described in the claims, and they are also included in the scope of the present invention. Needless to say.

The present invention can be implemented by a fuel supply device that supplies the fuel to a diesel engine, particularly in a diesel engine system using a fuel alternative to light oil represented by DME (dimethyl ether). It is possible to provide the effect of the present invention to a diesel engine system including a device (particularly, a DME fuel supply device).

1 is a schematic configuration diagram illustrating a first embodiment of a DME fuel supply device as a “fuel supply device” according to the present invention.

FIG. 5 is a schematic configuration diagram showing a second embodiment of a DME fuel supply device as a “fuel supply device” according to the present invention, and shows an enlarged view of the vicinity of a fuel tank.

FIG. 7 is a schematic configuration diagram illustrating a third embodiment of a DME fuel supply device as a “fuel supply device” according to the present invention, and shows an enlarged view of the vicinity of a fuel tank.

It is a schematic structure figure showing a 4th example of a DME fuel supply device as a “fuel supply device” according to the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Injection pump 2 Injection pump element 3 Injection pipe 4 Fuel tank 5 Feed pipe 5a Filter 5b Insulation material 6 Nozzle return pipe 7 Aspirator 8 Overflow return pipe 9 Fuel injection nozzle 41 DME fuel outlet 51 Feed pump 80 Bypass controller 81 Overflow fuel Pipe 82 Overflow valve 83 Bypass pipe 100 DME fuel supply device

Claims (10)

A feed pump that pressurizes fuel in a fuel tank having a property of being a gas at room temperature to a predetermined pressure and sends it to a feed pipe, and pressurizes the fuel sent through the feed pipe to a predetermined timing An injection pump for delivering a predetermined amount to a fuel injection nozzle of the diesel engine, and a fuel supply device for the diesel engine,
The fuel supply device for a diesel engine, wherein the feed pump is disposed immediately adjacent to a fuel outlet of the fuel tank. 2. The fuel supply device for a diesel engine according to claim 1, wherein an inlet of the feed pump is disposed directly at a fuel outlet of the fuel tank. 3. The fuel supply device for a diesel engine according to claim 1, wherein the feed pump is disposed immediately below a fuel outlet at a bottom of the fuel tank. 4. A fuel pump having a property of being a gas at room temperature pressurizes fuel in a fuel tank to a predetermined pressure and feeds the fuel to a feed pipe, and pressurizes the fuel sent through the feed pipe to a predetermined timing. An injection pump for delivering a predetermined amount to a fuel injection nozzle of the diesel engine, and a fuel supply device for the diesel engine,
A fuel supply device for a diesel engine, wherein a pipe connecting a fuel supply port of the fuel tank and a suction port of the feed pump is coated with a heat insulating material. A feed pump that pressurizes fuel in a fuel tank having a property of being a gas at room temperature to a predetermined pressure and sends it to a feed pipe, and pressurizes the fuel sent through the feed pipe to a predetermined timing An injection pump that sends a predetermined amount to a fuel injection nozzle of a diesel engine, an overflow fuel pipe for returning the fuel that has overflowed from the fuel injection nozzle, and the fuel that has overflowed from the injection pump to the fuel tank, Disposed in the overflow fuel pipe, while maintaining the pressure of the fuel in the oil reservoir of the injection pump and in the fuel injection nozzle at a predetermined pressure or higher, and in a direction in which the overflowed fuel returns to the fuel tank. Only the flow direction of the fuel A fuel supply device for a diesel engine equipped with an overflow valve which,
A bypass passage bypassing the overflow valve;
Bypass passage opening and closing means for opening and closing the bypass passage;
In a state where the diesel engine is stopped, the fuel in the fuel tank is sent out by the feed pump, and the bypass passage opening / closing unit is controlled to be opened only while the fuel is filled in the feed pipe and the injection pump. A fuel supply device for a diesel engine, comprising: 6. The fuel supply device for a diesel engine according to claim 5, wherein the feed pump is disposed immediately near a fuel outlet of the fuel tank. 7. The fuel supply device for a diesel engine according to claim 6, wherein an inlet of the feed pump is disposed directly at a fuel outlet of the fuel tank. 8. The fuel supply device for a diesel engine according to claim 6, wherein the feed pump is disposed immediately below a fuel outlet at the bottom of the fuel tank. 9. 6. The fuel supply device for a diesel engine according to claim 5, wherein a pipe connecting a fuel supply port of the fuel tank and a suction port of the feed pump is coated with a heat insulating material. The diesel engine according to any one of claims 1 to 9, wherein the diesel engine is a diesel engine using DME as fuel, and is configured to supply DME fuel in the fuel tank to the diesel engine. Diesel engine fuel supply system.

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