JP2003328875A - Dme fuel supply device of diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize an injection characteristic of DME fuel without correcting a temperature of an injection volume of the DME fuel by maintaining the temperature of the DME fuel in an oil reservoir chamber constant. <P>SOLUTION: A fuel cooler 53 evaporates the DME fuel flowing through a cooling medium supply pipe 5a with a fuel carburetor 55, and cools the DME fuel flowing through a feed pipe 5 using evaporation heats generated by evaporating the DME fuel. A supply fuel temperature control part 20 controls a cooling medium supply pipe opening/closing electromagnetic valve 54 to be opened, for supplying the DME fuel as cooling medium to the fuel cooler 53 to cool the DME fuel flowing through the feed pipe 5, when a temperature of the DME fuel in an oil reservoir chamber 11 detected by a temperature sensor 11a is higher than a predetermined temperature. When the temperature of the DME fuel in the oil reservoir chamber 11 detected by the temperature sensor 11a is not more than the predetermined temperature, the control part controls the cooling medium supply pipe opening/closing electromagnetic valve 54 to be closed, so as not to supply the DME fuel as cooling medium to the fuel cooler 53. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a diesel engine DME using DME (dimethyl ether) as a fuel.
The present invention relates to a fuel supply device.

[0002]

2. Description of the Related Art As a measure against air pollution by a diesel engine, attention has been paid to one using DME (dimethyl ether), whose exhaust gas is clean, as fuel instead of light oil. D
The ME fuel is a liquefied gas fuel, unlike the conventional fuel, light oil. That is, the boiling point temperature is lower than that of light oil, and light oil is a liquid at room temperature under atmospheric pressure.
ME has the property of becoming a gas at room temperature.

A DME fuel supply device for a diesel engine using DME as a fuel having such a property is generally operated from a fuel tank to an injection pump while being pressurized by a feed pump or the like so that the DME fuel is not vaporized. The high-pressure DME fuel is supplied from the injection pump through the injection pipe to the fuel injection nozzles of the diesel engine under pressure. And D overflowing from the fuel injection nozzle
The ME fuel is delivered to the nozzle return pipe, the DME fuel overflowing from the oil reservoir is delivered to the overflow fuel pipe, and the DME fuel delivered to the nozzle return pipe and the overflow fuel pipe passes through the overflow return pipe, After being cooled by a cooler, etc., it is returned to the fuel tank.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Since the DME fuel is much more affected by the temperature than the light oil fuel due to its peculiar property, the fuel injection characteristics of the DME fuel by the fuel injection nozzle will be greatly changed by a slight temperature rise. Therefore, due to the heat of the injection pump, the heat transferred from the diesel engine to the injection pipe, etc.
Since the temperature of the fuel rises, the temperature of the DME fuel that is pressure-fed to the fuel injection nozzle rises, which may change the injection characteristic of the DME fuel by the fuel injection nozzle, particularly the injection amount. Therefore, in order to make the injection amount of the DME fuel of the injection pump constant with respect to the temperature change of the DME fuel of the oil reservoir, the temperature of the injection amount of the DME fuel must be corrected by an electronic governor or the like. . Therefore, in the injection pump equipped with the mechanical governor, the injection amount of the DME fuel of the injection pump cannot be made constant with respect to the temperature change of the DME fuel in the oil reservoir, and the injection characteristic of the DME fuel can be stabilized. The problem arises that you can't.

The present invention has been made in view of such a situation, and its problem is to perform temperature correction of the injection amount of DME fuel by maintaining a constant temperature of DME fuel in the oil reservoir. Without stabilizing the injection characteristics of the DME fuel.

[0006]

In order to achieve the above object, the invention according to claim 1 of the present application provides DME fuel supplied from a fuel tank via a feed pipe by a predetermined amount at a predetermined timing. A DME fuel supply apparatus for a diesel engine, comprising an injection pump for delivering to an injection pipe communicating with a fuel injection nozzle of a diesel engine, wherein the DME flowing through the feed pipe by a cooling cycle using the DME fuel as a cooling medium. Based on the temperature in the injection pump detected by the temperature detecting means for detecting the temperature of the DME fuel in the injection pump and the temperature in the injection pump for cooling the fuel to the injection pipe. The DM sent out
E DME fuel for a diesel engine, comprising: a supply fuel temperature controller for controlling the supply fuel cooling device to control the temperature of the DME fuel flowing through the feed pipe so that the temperature of the E fuel becomes constant. It is a supply device.

As described above, based on the temperature inside the injection pump detected by the temperature detecting means, the supply fuel cooling device is controlled so that the temperature of the DME fuel delivered to the injection pipe becomes constant. By controlling the temperature of the flowing DME fuel, the temperature of the DME fuel in the oil sump can be controlled to a constant temperature.

Thus, according to the DME fuel supply device for a diesel engine according to the first aspect of the present invention, the temperature of the DME fuel in the oil sump chamber can be controlled to a constant temperature. It is possible to maintain the temperature of the DME fuel constant, and thereby, the operation effect that the injection characteristic of the DME fuel can be stabilized without performing the temperature correction of the injection amount of the DME fuel is obtained.

According to a second aspect of the present invention, in the first aspect, the supply fuel cooling device includes a fuel cooler using the DME fuel as a cooling medium, and the DME fuel serving as the cooling medium in the fuel tank. A cooling medium supply pipe for supplying the cooling medium supply pipe from the above to the fuel cooler, and a cooling medium supply pipe opening / closing solenoid valve capable of opening and closing the cooling medium supply pipe, and the D flowing through the cooling medium supply pipe in the fuel cooler.
The ME fuel is vaporized, and the DME fuel flowing to the feed pipe is cooled by utilizing the vaporization heat caused by the vaporization of the DME fuel, and the supply fuel temperature control unit is configured to supply the cooling medium supply pipe. It is a DME fuel supply device for a diesel engine, which is controlled by controlling opening / closing of an opening / closing solenoid valve.

As described above, since the DME fuel has a property of becoming a gas at room temperature, it constitutes a cooling cycle using the DME fuel as a cooling medium and utilizes the heat of vaporization due to the vaporization of the DME fuel. Can cool the DME fuel in the feed pipe. That is, since the DME fuel in the feed pipe is cooled by the fuel cooler that effectively utilizes the excellent characteristics of the DME fuel as a cooling medium, the supply fuel cooling device can be rationally configured.

As a result, according to the DME fuel supply device for a diesel engine according to the invention described in claim 2 of the present application, in addition to the effect of the invention described in claim 1 of the application, it is excellent as a cooling medium for the DME fuel. With the fuel cooler that effectively utilizes the above characteristics, the supply fuel cooling device can be rationally configured.
The effect that the cost of the ME fuel supply device can be reduced can be obtained.

According to a third aspect of the present invention, in the second aspect, the DME fuel mixed in the lubricating oil in the cam chamber of the injection pump, which is a dedicated lubricating system separated from the lubricating system of the diesel engine, is used. And a compressor for pressurizing the DME fuel separated by the oil separator and delivering the pressurized DME fuel to the fuel tank. The DME fuel vaporized by being supplied from the fuel tank to the fuel cooler is The DME fuel supply device for a diesel engine is characterized in that it is delivered to the compressor.

As described above, since the DME fuel has a property of becoming a gas at room temperature and has a low viscosity, the DME fuel is injected into the cam chamber from the plunger of the injection pump element in the injection pump element.
Fuel leaks out. Therefore, the injection pump cam chamber was made into a dedicated lubrication system separated from the diesel engine lubrication system, and D leaked into the cam chamber and mixed with the lubricating oil.
ME fuel is separated by an oil separator and sent to a fuel tank by a compressor. As a result, it is possible to eliminate the risk of ignition of the DME fuel leaking into the cam chamber. Then, the DME fuel that is supplied to the fuel cooler and vaporized is
By being configured to be sent to the compressor, it is separated from the lubricating oil by the oil separator and D
Since the ME fuel and the DME fuel supplied to the fuel cooler and vaporized to be pressurized by one compressor can be delivered to the fuel tank, the supplied fuel cooling device can be efficiently configured.

As a result, according to the DME fuel supply device for a diesel engine according to the third aspect of the present invention, in addition to the function and effect of the second aspect of the present invention, the supply fuel cooling device can be efficiently used. Since it can be configured, there is an effect that the cost of the DME fuel supply device of the diesel engine can be further reduced.

The invention according to claim 4 of the present application is defined by claims 1 to 3.
In any one of 3 above, the fuel temperature detecting means is
A DME fuel supply device for a diesel engine, wherein the temperature of the DME fuel in the oil reservoir is detected.

According to the DME fuel supply device for a diesel engine of the invention described in claim 4 of the present application, in addition to the action and effect of the invention described in any one of claims 1 to 3, the fuel temperature detection means is provided. The temperature of the DME fuel in the oil sump chamber is detected by the
Since the supply fuel cooling device is controlled based on the ME fuel,
The effect that the temperature of the DME fuel in the oil reservoir can be maintained constant with higher accuracy can be obtained.

The invention according to claim 5 of the present application includes claims 1 to
4. The DME fuel supply device for a diesel engine according to any one of 4 above, further comprising means for cooling the injection pipe.

As described above, since the means for cooling the injection pipe is provided, heat generated by the DME fuel supply device, heat from the diesel engine, etc. are transmitted to the injection pipe and the temperature of the injection pipe rises. Can be prevented.

As a result, according to the DME fuel supply device for a diesel engine of the invention described in claim 5 of the present application, in addition to the operation and effect of the invention described in any one of claims 1 to 4, the injection is performed. Since it is possible to prevent the temperature of the pipe from rising, it is possible to prevent the temperature of the DME fuel pumped to the fuel injection nozzle from rising, thereby injecting the DME fuel by the fuel injection nozzle. It is possible to obtain the effect of reducing the possibility that the characteristics become unstable. Further, since it is possible to prevent the temperature of the injection pipe from rising, when the injection pipe just after the diesel engine is stopped is filled with the DME fuel from the fuel tank, a part of the filled DME fuel is vaporized. It is possible to reduce the possibility that the DME fuel cannot be completely filled.

According to a sixth aspect of the present invention, in the fifth aspect, the injection pipe includes an injection fuel passage through which the DME fuel sent from the injection pump to the fuel injection nozzle flows, and an injection fuel passage. And a cooling medium passage through which a cooling medium for cooling the flowing DME fuel flows, and the cooling medium passage is configured so that the cooling medium flows along the outer peripheral surface of the fuel injection passage. It is a DME fuel supply device for a diesel engine characterized by the fact that

As described above, since the injection pipe has the double pipe structure having the injection fuel passage and the cooling medium passage through which the cooling medium for cooling the DME fuel flowing in the injection fuel passage flows, the cooling medium passage is formed. It is possible to prevent the temperature of the injection pipe from rising due to the flowing cooling medium.

Thus, in the DME fuel supply device for a diesel engine according to the invention of claim 6, the injection pipe cools the injection fuel passage and the cooling medium for cooling the DME fuel flowing in the injection fuel passage. By forming the double pipe structure having the medium passage, it is possible to obtain the action and effect of the invention according to claim 5 of the present application.

The invention according to claim 7 of the present application is the DME fuel supply device for a diesel engine according to claim 6, characterized in that the outer peripheral surface of the injection pipe is coated with a heat insulating material. is there.

According to the DME fuel supply device for a diesel engine according to the invention described in claim 7 of the present application, in addition to the effect of the invention described in claim 6 of the present application, the heat insulating property applied to the outer peripheral surface of the injection pipe is provided. With the coating having the above, the heat from the periphery of the injection pipe can be shut off, so that the effect that the temperature rise of the injection pipe can be prevented more reliably can be obtained.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the overflow fuel pipe for returning the DME fuel overflowing from the injection pump to the fuel tank, and the overflow fuel pipe overflowing from the fuel injection nozzle are provided. A nozzle return pipe for communicating DME fuel with the overflow fuel pipe, wherein the cooling medium passage is configured such that the DME fuel flows from the feed pipe to the nozzle return pipe as the cooling medium. It is a characteristic DME fuel supply device for diesel engines.

According to the DME fuel supply device for a diesel engine according to the present invention as defined in claim 8, in addition to the action and effect according to the invention as defined in claim 6 or 7, before entering the oil sump chamber from the feed pipe. By using the relatively low temperature DME fuel as a cooling medium, that is, by configuring a cooling medium circulation path for circulating the DME fuel from the feed pipe through the cooling medium passage and the nozzle return pipe to the fuel tank, D in the fuel tank
Since it is possible to efficiently cool the injection pipe by using the ME fuel as a cooling medium, it is possible to obtain a function and effect that the means for cooling the injection pipe can be configured at low cost.

The invention described in claim 9 of the present application is defined by claims 1 to 1.
8. The diesel engine according to any one of 8 above, wherein the DME fuel delivered from the injection pump is supplied to a common rail and delivered from the common rail to each fuel injection nozzle. Is a DME fuel supply device.

According to the DME fuel supply apparatus for a diesel engine according to the invention of claim 9 of the present application, the DME fuel supply apparatus for a common rail type diesel engine is described in any one of claims 1 to 8 of the application. The effect of the invention can be obtained.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, D of diesel engine
A schematic configuration of the ME fuel supply device will be described. Figure 1
FIG. 1 is a schematic configuration diagram showing a first embodiment of a DME fuel supply device according to the present invention.

A DME fuel supply system 100 for supplying DME fuel to a diesel engine includes an injection pump 1. The injection pump 1 has the same number of injection pump elements 2 as the number of cylinders of a diesel engine. The feed pump 51 pressurizes the DME fuel stored in the fuel tank 4 to a predetermined pressure and sends it to the feed pipe 5. The DME fuel delivery port 41 of the fuel tank 4 is provided below the liquid level of the DME fuel in the fuel tank 4, and the feed pump 51 serves as the DME fuel delivery port 4 of the fuel tank 4.
It is arranged in the vicinity of 1. The DME fuel delivered to the feed pipe 5 is filtered by the filter 51 and delivered to the injection pump 1 via the three-way solenoid valve 71.
The three-way solenoid valve 71 is ON in the injection state (during operation of the diesel engine) and communicates in the direction shown in the figure.

A cam chamber 12 in the injection pump 1
Is a dedicated lubricating system separated from the lubricating system of the diesel engine, and the oil separator 13 uses the DME to mix the lubricating oil in the cam chamber 12 in the injection pump 1 with the DME fuel leaking into the cam chamber 12. The fuel and the lubricating oil are separated and the lubricating oil is returned to the cam chamber 12. The DME fuel separated by the oil separator 13 is a check valve (check valve) that prevents the pressure in the cam chamber 12 from becoming below atmospheric pressure.
After being sent to the compressor 16 via 14 and pressurized by the compressor 16, a check valve (check valve) 1
5, and is returned to the fuel tank 4 via 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. Since the DME fuel supply device 100 according to the present invention does not require an electric compressor, the compressor 16 is used in the embodiment.
Is a compressor that uses a cam in the cam chamber 12 as a driving force source. This enables the DME fuel supply device 100 to be more power-saving.

The DME fuel pressurized from the fuel tank 4 to a predetermined pressure by the feed pump 51 and delivered,
From each injection pump element 2 of the injection pump 1 via the injection pipe 3, a predetermined amount is pressure-fed to the fuel injection nozzle 9 arranged in each cylinder of the diesel engine. The overflow fuel pipe 81 is provided with an overflow valve 82 which maintains the pressure of the DME fuel in the oil reservoir 11 at a predetermined pressure and regulates the flow direction of the DME fuel only in the direction in which the overflowed DME fuel returns to the fuel tank. It is arranged. The DME fuel overflowing from the injection pump 1 is returned to the fuel tank 4 via the overflow fuel pipe 81, the overflow valve 82, the overflow return pipe 8 and the 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, the DME fuel supply device 100 collects the DME fuel remaining in the oil reservoir chamber 11 in the injection pump 1, the overflow fuel pipe 81, and the nozzle return pipe 6 into the fuel tank 4 when the diesel engine is stopped. It is equipped with "residual fuel recovery means". The “residual fuel recovery means” includes an aspirator 7, a three-way electromagnetic valve 71, a two-way electromagnetic valve 72, and a DME fuel recovery control unit 10. The DME fuel recovery control unit 10 detects an operating / stopped state of the diesel engine (injection / non-injection state of the DME fuel supply device 100), and depending on each state, the three-way solenoid valve 71, the two-way solenoid valve 72, and The ON / OFF control of the feed pump 51 and the like is executed, and when the diesel engine is stopped, the DM remaining in the oil sump chamber 11, the overflow fuel pipe 81, and the nozzle return pipe 6
E Control for collecting fuel is executed.

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

The DME fuel recovery control unit 10 controls the three-way solenoid valve 7 in the non-injection state (when the diesel engine is stopped).
1 is turned off to form a communication passage from the feed pipe 5 to the inlet 7a of the aspirator 7, and the two-way solenoid valve 7
2 is turned on to connect the overflow fuel pipe 81 on the upstream side of the overflow valve 82 with the suction port 7c of the aspirator 7. Therefore, the DME fuel delivered from the feed pump 51 is delivered to the aspirator 7 without being delivered to the injection pump 1, passes through the inlet 7 a to the outlet 7 b, and the overflow valve 82.
The fuel is returned to the fuel tank 4 via the overflow fuel pipe 81, the overflow return pipe 8 and the cooler 42 on the downstream side of, and again fed from the feed pump 51 to the aspirator 7. That is, the DME fuel liquid is circulated through the aspirator 7. Then, the DME fuel remaining in the oil reservoir chamber 11 in the injection pump 1 and the overflow fuel pipe 81 upstream of the overflow valve 82 is vaporized by the suction force generated by the flow of the DME fuel flowing from the inlet 7a to the outlet 7b. The vaporized DME fuel is sucked from the suction port 7c, absorbed by the DME fuel flowing from the inlet 7a to the outlet 7b, and collected in the fuel tank 4.

Further, the DME fuel supply device 100 includes a gas-phase pressure delivery pipe for connecting the outlet of the gas phase 4b in the fuel tank 4 (gas-phase delivery outlet 43) and the inlet side of the oil reservoir 11 of the injection pump 1. It is equipped with 73. The vapor-phase pressure delivery pipe 73 has a throttle portion 75 whose inner diameter is partially narrowed, and a vapor-phase pressure delivery pipe opening / closing solenoid valve 74 that opens and closes the communication of the vapor-phase pressure delivery pipe 73. When the DME fuel in the oil sump chamber 11, the overflow fuel pipe 81, and the nozzle return pipe 6 is sucked and collected in the fuel tank 4 by the above-mentioned “residual fuel recovery means”, the DME fuel recovery control unit 10 simultaneously The gas phase pressure delivery pipe opening / closing solenoid valve 74 is turned on to bring the gas phase pressure delivery pipe 73, which connects the gas phase 4b of the fuel tank 4 and the inlet side of the oil sump chamber 11, into a communicating state. 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 due to the high pressure of the gas phase 4b. . Moreover, the pressure is further compressed to a higher pressure by the throttle portion 75 in which the inner diameter of the gas-phase pressure delivery pipe 73 is partially narrowed, and the gas can be delivered at a higher pressure.

As described above, since the suction force by the aspirator 7 is only a suction force for sucking the vaporized DME fuel, the DM in the liquid state is utilized by utilizing the pressure of the gas phase 4b.
By pumping E fuel to the suction port 7c of the aspirator 7, the oil sump chamber 11, the overflow fuel pipe 81,
Also, the time for collecting the DME fuel remaining in the nozzle return pipe 6 can be greatly shortened. Then, the DME fuel recovery control unit 10 closes only the gas-phase pressure delivery pipe opening / closing solenoid valve 74 after a lapse of a predetermined time, and disconnects the communication with the gas phase 4b in the high pressure state. Thereby,
Since the pressure in the oil reservoir chamber 11, the overflow fuel pipe 81, and the nozzle return pipe 6 can be set to a lower pressure state, vaporization of the liquid state DME fuel that cannot be pressure-fed due to the vapor phase pressure is promoted. The time required to recover the remaining DME fuel by the "residual fuel recovery means" can be further shortened.

The DME fuel supply device 100 is a "supply fuel cooling device", and a temperature sensor 11a is a "temperature detecting means" for detecting the temperature of the DME fuel in the oil reservoir 11.
And DME fuel as a cooling medium and DM as a cooling medium.
E Fuel cooler 53 having a fuel vaporizer 55 for vaporizing the fuel, and DME fuel from the fuel tank 4 to the fuel cooler 53.
To the cooling medium supply pipe 5a, and a cooling medium supply pipe opening / closing solenoid valve 5 capable of opening / closing the cooling medium supply pipe 5a
4 and a supply fuel temperature control unit 20. The supply fuel temperature control unit 20 determines the oil reservoir chamber 11 based on the temperature of the DME fuel in the oil reservoir chamber 11 detected by the temperature sensor 11a.
The cooling medium supply pipe opening / closing solenoid valve 54 is controlled to control the temperature of the DME fuel flowing to the feed pipe 5 so that the temperature of the DME fuel sent from the injection pipe 3 to the injection pipe 3 (injection fuel passage 31) becomes constant.

The fuel cooler 53 is the cooling medium supply pipe 5
The DME fuel flowing in a is vaporized by the fuel vaporizer 55,
The DME fuel flowing through the feed pipe 5 is cooled by utilizing the heat of vaporization resulting from the vaporization of the DME fuel. The supply fuel temperature control unit 20 includes the temperature sensor 11a.
When the temperature of the DME fuel in the oil sump chamber 11 detected by the above is higher than a predetermined temperature, the cooling medium supply pipe opening / closing solenoid valve 5
4 is controlled to open and the fuel cooler 53 receives D as a cooling medium.
When the ME fuel is supplied to cool the DME fuel flowing through the feed pipe 5 and the temperature of the DME fuel in the oil reservoir chamber 11 detected by the temperature sensor 11a is equal to or lower than a predetermined temperature, the cooling medium supply pipe opening / closing solenoid valve By controlling the closing of 54, the DME fuel as the cooling medium is not supplied to the fuel cooler 53.

By controlling the cooling of the DME fuel flowing through the feed pipe 5 in this manner, the oil sump chamber 1
Since the temperature of the DME fuel in 1 can be maintained constant, the injection characteristics of the fuel injection nozzle 9 can be stabilized without performing temperature correction of the injection amount of the DME fuel by the injection pump 1.

Further, as a second embodiment of the DME fuel supply device 100 according to the present invention, in addition to the first embodiment described above, the injection pipe 3 has a double pipe structure. FIG. 2 is a schematic configuration diagram showing a second embodiment of the DME fuel supply device 100 according to the present invention.

The DME fuel supply device 100 has a double pipe structure in which the injection pipe 3 has an injection fuel passage 31 and a cooling medium passage 32 as means for cooling the injection pipe 3. FIG. 5 is a cross-sectional view showing the structure of the injection pipe 3. The injection fuel passage 31 connects the delivery port of the injection pump element 2 and the fuel injection nozzle 9 to each other, and delivers the high-pressure DME fuel of the oil reservoir 11 that is pressure-fed from the injection pump element 2 to the fuel injection nozzle 9. The cooling medium passage 32 is formed on the outer peripheral surface of the injected fuel passage 31, communicates the feed pipe 5 in front of the inlet of the oil reservoir 11 and the nozzle return pipe 6, and is delivered to the feed pipe 5 by the feed pump 51. The DME fuel in the fuel tank 4 that flows flows as a cooling medium that cools the DME fuel that flows in the injection fuel passage 31.

That is, when the feed pump 51 is operating, the DME fuel flows into the cooling medium passage 32 from the feed pipe 5 via the pipe 34, and the pipe 3
DME fuel flows out to the nozzle return pipe 6 via 3, and the check valve 36, the overflow fuel pipe 81,
The DME fuel in the fuel tank 4 flows as a cooling medium in the circulation path returning to the fuel tank 4 via the overflow return pipe 8 and the cooler 42. The check valve 36 prevents the DME fuel in the fuel tank 4 from flowing back from the overflow fuel pipe 81 to the cooling medium passage 32.
Then, the injected fuel passage 31 is cooled by the DME fuel flowing through the cooling medium passage 32, whereby the temperature of the injected fuel passage 31 can be prevented from rising.

Further, the DME fuel remaining in the cooling medium passage 32 in the non-injection state is recovered by the above-mentioned "residual fuel recovery means". DME fuel recovery control unit 10
Turns on the two-way solenoid valve 35 in the non-injection state, and the nozzle return pipe 6 through the cooling medium passage recovery pipe 37.
And the overflow fuel pipe 81 upstream of the overflow valve 82. Therefore, D remaining in the nozzle return pipe 6 and the cooling medium passage 32
The ME fuel is sucked from the suction port 7c of the aspirator 7 via the cooling medium passage recovery pipe 37 and the overflow fuel pipe 81 on the upstream side of the overflow valve 82, and is recovered in the fuel tank 4.

In this way, the injection fuel passage 3 is formed by the DME fuel as the cooling medium flowing through the cooling medium passage 32.
1 can be cooled, so that the DME fuel supply device 1
It is possible to prevent the heat generated by 00, heat from the diesel engine, etc. from being transmitted to the injection pipe 3 and raising the temperature of the injection pipe. Therefore, the DME pressure-fed to the fuel injection nozzle 9
It is possible to prevent the temperature of the fuel from rising, thereby reducing the risk that the injection characteristics of the DME fuel by the fuel injection nozzle 9 become unstable. Then, the injection pipe 3 has a double pipe structure composed of the injection fuel passage 31 and the cooling medium passage 32, and the DME fuel in the fuel tank 4 is circulated to the cooling medium passage 32 as a cooling medium to cool the injection pipe 3. The means for doing so can be constructed at low cost.

Further, since it is possible to prevent the temperature of the injection pipe 3 from rising, when the injection fuel passage 31 of the injection pipe 3 is filled with DME fuel from the fuel tank 4 immediately after the diesel engine is stopped, Part of the filled DME fuel vaporizes and DME
It is possible to reduce the possibility that the fuel cannot be completely filled. Further, the outer peripheral surface of the injection pipe 3 is provided with a heat-insulating coating 3a, whereby heat from the surroundings to the injection pipe 3 can be shut off, so that the temperature rise of the injection pipe 3 can be further suppressed. It can be surely prevented.

Further, as a third embodiment of the DME fuel supply device 100 according to the present invention, in addition to the second embodiment described above, a low pressure tank 17 is provided between the oil separator 13 and the compressor 16. To be Figure 3
It is a schematic block diagram which showed 3rd Example of the DME fuel supply apparatus 100 which concerns on this invention.

Oil separator 13 and compressor 1
A low-pressure tank 17 having a closed structure having a smaller capacity than the fuel tank 4 is disposed between the fuel tank 4 and the fuel tank 6. The low-pressure tank 17 communicates with the overflow fuel pipe 81 upstream of the overflow valve 82 by the purge pipe 19. The purge pipe 19 is provided with a purge pipe opening / closing solenoid valve 18 capable of opening / closing the purge pipe 19. The purge pipe opening / closing solenoid valve 18 is controlled by the DME fuel recovery control unit 10 and is turned on to be in an open state when the diesel engine is stopped so that the low pressure tank 17 and the overflow fuel pipe 81 are in communication with each other and turned off when the diesel engine is operating. And then closed, low pressure tank 1
The communication between 7 and the overflow fuel pipe 81 is cut off. A check valve 14 is arranged between the low pressure tank 17 and the oil separator 13. The check valve 14 maintains the pressure on the oil separator 13 side at a constant pressure, and moves from the low pressure tank 17 to the oil separator 13 side by D
It prevents the ME fuel from flowing back.

The cam chamber 12 is provided by the oil separator 13.
DME fuel separated from the lubricating oil in the low pressure tank 1
It is sucked by the compressor 16 via 7. Therefore, the low-pressure tank 17 has its internal pressure lowered by being sucked by the compressor 16, and the check valve 14
By maintaining a constant pressure on the oil separator 13 side, the inside of the low-pressure tank 17 is in a constant low-pressure state. Further, since the low-pressure tank 17 has a closed structure, it is possible to maintain a constant low-pressure state even if the compressor 16 is stopped when the diesel engine is stopped.
Then, when the inside of the low pressure tank 17 is maintained at a constant low pressure state, the purge pipe opening / closing solenoid valve 18 is turned on when the diesel engine is stopped and the low pressure tank 17 and the overflow fuel pipe 81 are communicated with each other.
One of the DME fuel remaining in the overflow fuel pipe 81 due to the negative pressure in 7 (and also the DME fuel remaining in the nozzle return pipe 6 when the two-way solenoid valve 35 is ON and communicating). The part is sucked into the low-pressure tank 17 and collected. The DME fuel sucked into the low-pressure tank 17 is sucked into the compressor 16 and collected in the fuel tank 4 when the diesel engine is restarted and the compressor 16 operates.

Therefore, after the DME fuel remaining in the oil sump chamber 11, the overflow fuel pipe 81 and the nozzle return pipe 6 is recovered by the "residual fuel recovery means", the purge pipe opening / closing solenoid valve 18 is turned on. As a result, the DME fuel that has not been completely collected by the “residual fuel collecting means” and remains can be sucked into the low-pressure tank 17 and collected. Thereby, the recovery time of the DME fuel by the "residual fuel recovery means" can be shortened. In addition, by the "residual fuel recovery means", the oil reservoir 1
1, the same effect can be expected before collecting the DME fuel remaining in the overflow fuel pipe 81 and the nozzle return pipe 6.

Furthermore, as a fourth embodiment of the DME fuel supply apparatus 100 according to the present invention, there is a common rail type of the DME fuel supply apparatus 100 in the third embodiment. FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the DME fuel supply device 100 according to the present invention.

As described above, the DME fuel pressure-fed from the injection pump 1 is also supplied to the common rail type DME fuel supply device 100 in which the DME fuel is supplied through the common rail 91 to which the fuel injection nozzles 9 are connected. This is possible, and the effects of the present invention can be obtained.

The invention of the present application is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the invention of the present application. Needless to say.

[0054]

According to the present invention, by maintaining the temperature of the DME fuel in the oil reservoir constant, the injection characteristic of the DME fuel can be stabilized without correcting the temperature of the injection amount of the DME fuel. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a DME fuel supply device according to the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the DME fuel supply device according to the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the DME fuel supply device according to the present invention.

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

FIG. 5 is a cross-sectional view showing a configuration of an injection pipe 3.

[Explanation of symbols]

1 injection pump 2 Injection pump element 3 injection pipes 4 fuel tank 5 feed pipe 6 nozzle return pipe 7 Aspirator 8 overflow return pipe 9 Fuel injection nozzle 10 DME fuel recovery control unit 11 oil reservoir 12 cam room 13 Oil separator 16 compressor 17 Low pressure tank 18 Purge pipe open / close solenoid valve 19 Purge pipe 20 Supply fuel cooling control unit 31 Injection fuel passage 32 Coolant passage 37 Cooling medium passage recovery pipe 42 cooler 51 feed pump 52 Filter 53 Fuel cooler 54 Cooling medium supply pipe opening / closing solenoid valve 55 Fuel vaporizer 5a Cooling medium supply pipe 61 Compressor 73 Gas phase pressure delivery pipe 74 Gas phase pressure delivery pipe open / close solenoid valve 75 Throttle 81 Overflow Fuel Pipe 82 Overflow valve 100 DME fuel supply system 200 diesel engine

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) F02M 53/00 F02M 53/00 C (72) Inventor Shunka Noda 3-13, Yasumimachi, Higashimatsuyama, Saitama No.26 Incorporated company Bosch Automotive System Higashimatsuyama Factory (72) Inventor Yukihiro Hayasaka 3-13-13, Yasumi-cho, Higashimatsuyama City, Saitama Prefecture No.26 Incorporated Company Bosch Automotive System Higashimatsuyama Factory F-term (reference) 3G084 AA01 BA11 DA13 FA13

Claims (9)

[Claims] 1. An injection pump for delivering DME fuel supplied from a fuel tank via a feed pipe to a injection pipe communicating with a fuel injection nozzle of a diesel engine at a predetermined timing and in a predetermined amount. A DME fuel supply device for a diesel engine, comprising: a supply fuel cooling device that cools the DME fuel flowing through the feed pipe by a cooling cycle using the DME fuel as a cooling medium; and a temperature of the DME fuel in the injection pump. Based on the temperature detecting means for detecting and the temperature in the injection pump detected by the temperature detecting means, the supply fuel cooling device is controlled so that the temperature of the DME fuel delivered to the injection pipe becomes constant. And before flowing into the feed pipe Note D of a diesel engine characterized by comprising a supply fuel temperature control unit for controlling the temperature of the DME fuel.
ME fuel supply device. 2. A fuel cooler according to claim 1, wherein the supply fuel cooling device uses the DME fuel as a cooling medium.
A cooling medium supply pipe for supplying the DME fuel as the cooling medium from the fuel tank to the fuel cooler;
A cooling medium supply pipe opening / closing solenoid valve capable of opening / closing the cooling medium supply pipe, and vaporizing the DME fuel flowing through the cooling medium supply pipe by the fuel cooler to vaporize the DME fuel. Is configured to cool the DME fuel flowing to the feed pipe, and the supply fuel temperature control unit is controlled by opening / closing the cooling medium supply pipe opening / closing solenoid valve. DME fuel supply device for diesel engine. 3. The oil separator for separating the DME fuel mixed in the lubricating oil in the cam chamber of the injection pump, which is a dedicated lubricating system separated from the lubricating system of the diesel engine, according to claim 2. A compressor that pressurizes the DME fuel separated by an oil separator and sends it to the fuel tank, and the DME fuel that is vaporized by being supplied from the fuel tank to the fuel cooler is sent to the compressor. A DME fuel supply device for a diesel engine, which is characterized in that 4. The method according to claim 1, wherein
The DME fuel supply device for a diesel engine, wherein the fuel temperature detection means detects the temperature of the DME fuel in the oil reservoir. 5. The method according to any one of claims 1 to 4,
Comprising means for cooling the injection pipe,
A DME fuel supply device for a diesel engine, which is characterized in that 6. The injection pipe according to claim 5, wherein the injection pipe cools the injection fuel passage through which the DME fuel sent from the injection pump to the fuel injection nozzle flows, and the DME fuel flowing through the injection fuel passage. A cooling medium passage through which a medium flows, and a double pipe structure in which the cooling medium passage is configured so that the cooling medium flows along the outer peripheral surface of the fuel injection passage.
A DME fuel supply device for a diesel engine, which is characterized in that 7. The DME fuel supply device for a diesel engine according to claim 6, wherein the injection pipe is provided with a heat insulating coating on its outer peripheral surface. 8. The overflow fuel pipe according to claim 6 or 7, for returning the DME fuel overflowing from the injection pump to the fuel tank, and the DME fuel overflowing from the fuel injection nozzle to the overflow fuel pipe. And a nozzle return pipe communicating with each other, wherein the cooling medium passage is configured such that the DME fuel flows as the cooling medium from the feed pipe to the nozzle return pipe.
E fuel supply device. 9. The method according to claim 1, wherein
The DME delivered from the injection pump
A DME fuel supply device for a diesel engine, characterized in that fuel is supplied to a common rail and is delivered from the common rail to each fuel injection nozzle.