JP4140560B2 - Fuel fractionator for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel fractionator for an internal combustion engine.

  A fuel fractionation device is known in which fuel is separated into a liquid phase and a gas phase using the exhaust heat of the exhaust pipe, and the separated gas phase is added as a reducing agent to an NOx storage reduction catalyst ( Patent Document 1). Other prior art documents relating to the present invention include Patent Documents 2 and 3.

JP-A-6-272539 JP 2001-193525 A Japanese Patent No. 2850547

  In this type of apparatus, exhaust heat is used to separate the liquid phase and the gas phase, so that the properties of the fuel taken out as the gas phase change depending on the temperature of the exhaust pipe. In particular, when the temperature of the exhaust pipe is high, even unnecessary high boiling point components (heavy components) are fractionated as a gas phase, with the result that the properties of the reducing agent may deteriorate.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel fractionation device for an internal combustion engine capable of efficiently fractionating high-quality fuel while suppressing deterioration of the properties of fuel fractionated as a gas phase.

  The fuel fractionating device of the present invention is branched from a branching passage that reaches a branching point through a fractionation section in which fuel is fractionated into a gas phase and a liquid phase using exhaust heat of an internal combustion engine. A gas phase passage, a liquid phase passage branched from the branch point, condition changing means for changing at least one of the conditions affecting fuel distribution to each of the gas phase passage and the liquid phase passage, and At least one of an operation for promoting the distribution of fuel to the liquid phase passage when the temperature of the fractionation section is high and an operation for prompting the distribution of fuel to the gas phase passage when the temperature of the fractionation section is low. The above-described problem is solved by including a fuel distribution control unit that controls the condition changing unit so that the operation is performed.

  When the temperature of the fractionation section is high, the amount of fuel that is in the gas phase increases more than when the temperature is low. The fuel guided to the branch point is distributed to the gas phase passage and the liquid phase passage according to conditions that affect the fuel distribution to the gas phase passage and the liquid phase passage. Unless the conditions affecting this distribution are changed according to the temperature of the fractionation section, the higher the fractionation section temperature, the more high-boiling components (heavy components) that are unnecessary are introduced into the gas phase passage. It is burned. For this reason, the property of the fuel led to the gas phase passage is deteriorated. This problem becomes more conspicuous when the amount of fuel led to the fractionation passage is increased as the temperature of the fractionation section is higher in order to suppress overheating of the fractionation section. On the other hand, when the temperature of the fractionation section is low, the properties of the fuel are not deteriorated as in the case of a high fraction, but the absolute amount of fuel that becomes a gas phase in the fractionation section decreases, so The lower the temperature is, the less fuel is led to the gas phase passage and the lower the efficiency of recovering low-boiling components (light components).

  According to the present invention, when the temperature of the fractionation section is high, an operation for urging the fuel to be distributed to the liquid phase passage is executed, so that the fuel that has passed through the fractionation section is easily guided to the liquid phase passage. As a result, the fuel containing a large amount of high-boiling components (heavy components) can be prevented from being led to the gas phase passage, and deterioration of the properties of the fuel can be suppressed. On the other hand, when the temperature of the fractionation section is low, an operation for urging the fuel to be distributed to the gas phase passage is performed, so that the fuel that has passed through the fractionation section is easily guided to the gas phase passage, and much fuel is consumed. It can lead to the gas phase passage. For this reason, the efficiency of collection | recovery of a light part improves.

  In the fuel fractionating device of the present invention, as the condition changing means, a liquid phase tank for storing fuel introduced into the liquid phase passage, and a liquid for returning the fuel in the liquid phase tank to the fuel tank of the internal combustion engine. A phase return passage and liquid level adjusting means for adjusting the liquid level of the liquid phase tank by introducing the fuel in the liquid phase tank to the liquid phase return passage, and the fuel distribution control As an operation for urging fuel to be distributed to the liquid phase passage, the liquid surface level of the liquid phase tank is lower when the temperature of the fractionation section is higher than when the temperature is low. The adjusting means may be controlled (claim 2). According to this embodiment, when the temperature of the fractionation section is high, the space formed in the liquid phase tank becomes wider than when the temperature is low, and thus the fuel is easily guided to the liquid phase passage. The gas phase fuel guided to the liquid phase passage is cooled and liquefied in the liquid phase passage or the liquid phase tank. As the gas phase fuel is liquefied, the volume rapidly decreases. As a result, the inside of the liquid phase tank temporarily becomes a negative pressure, and the gas phase fuel is continuously drawn into the liquid phase tank to promote the distribution of the fuel to the liquid phase passage.

  As the liquid level control, the fuel distribution control means may control the liquid level adjustment means so that the liquid level of the liquid phase tank becomes lower as the temperature of the fractionation section becomes higher. 3). In this case, since it is possible to control the liquid level more accurately and finely, it is possible to efficiently recover the light fuel while considering the degree of deterioration of the properties of the fuel guided to the gas phase passage. .

  In the fuel fractionating apparatus of the present invention, as the condition changing means, a plurality of inlets are arranged in the liquid phase tank so that the heights of the inlets are different from each other, and each outlet is connected to the liquid phase return passage. The liquid level adjustment passage is further provided, and as the liquid level adjustment means, the fuel in the liquid phase tank is selectively passed through at least one of the plurality of liquid level adjustment passages. A passage switching valve that leads to the return passage for changing the liquid level of the liquid phase tank is provided, and the fuel distribution control means performs the fractionation section as an operation for urging distribution of the fuel to the liquid phase passage. When the temperature is high, the passage switching valve may be controlled so that the liquid level of the liquid phase tank is lower than when the temperature is low. In this case, the liquid level can be controlled with a simple configuration without providing a detecting means for detecting the liquid level and a control valve for controlling the opening degree according to the detection result. Cost can be reduced.

  In the fuel fractionating apparatus of the present invention, as the condition changing means, a gas phase tank for storing fuel introduced into the gas phase passage, a negative pressure generating means for generating a negative pressure in the gas phase tank, The fuel distribution control means may control the negative pressure generating means so as to generate a negative pressure in the gas phase tank as an operation for prompting the fuel to be distributed to the gas phase passage. (Claim 5). According to this embodiment, the pressure balance in the gas phase tank is temporarily lost, negative pressure is generated, and the fuel is drawn into the gas phase tank, so that the fuel is easily guided to the gas phase passage. Fuel distribution to the aisle is encouraged.

  As described above, according to the present invention, the operation for prompting the fuel to be distributed to the liquid phase passage when the temperature of the fractionation section is high and the distribution of the fuel to the gas phase passage when the temperature of the fractionation section is low. And at least one of the conditions affecting the distribution of fuel to each of the gas phase passage and the liquid phase passage is changed to execute at least one of the operations for prompting the fuel. It is possible to provide a fuel fractionating device for an internal combustion engine that can suppress the deterioration of properties and efficiently fractionate a high-quality fuel.

  FIG. 1 shows an embodiment in which the fuel fractionation device of the present invention is applied to a diesel engine 1 as an internal combustion engine. As shown in this figure, an intake passage 2 and an exhaust passage 3 are connected to the engine 1. The intake passage 2 is provided with a compressor 4a of a supercharger 4 that uses exhaust energy to increase the intake pressure, and a throttle valve 5 for adjusting the intake air amount. The exhaust passage 3 is provided downstream of the exhaust manifold 3a. The exhaust gas purification device 6 disposed downstream of the turbine 4b and the turbine 4b of the turbocharger 4 disposed in the turbine 4 is provided. The exhaust purification device 6 is a known device in which, for example, an NOx storage reduction catalyst or a NOx storage reduction catalyst material is carried on a filter base material for collecting particulates. The NOx occlusion is not limited as long as it can hold NOx.

  The engine 1 includes a fuel tank 7 that stores fuel (light oil), a feed passage 8 extending from the fuel tank 7, a supply pump unit 10 that pumps fuel from the fuel tank 7 to the common rail 9 through the feed passage 8, and a common rail 9. A plurality of (four in the figure) connected injectors 11 and return passages 12 for returning the fuel pumped from the fuel tank 7 to the fuel tank 7 are provided. Excess fuel such as fuel returned from the common rail 9 and the injector 11 is guided to the return passage 12.

  In the middle of the return passage 12, there is connected a fractionation passage 14 for guiding the fuel to a fractionation section 13 for fractionating the fuel into a gas phase and a liquid phase. A pressure adjusting valve 15 for adjusting the pressure balance is provided at a connection portion between the return passage 12 and the fractionation passage 14. A flow rate control valve 16 that controls the flow rate of the fuel guided to the fractionation unit 13 is provided in the fractionation passage 14 on the downstream side of the pressure adjustment valve 15. These valves 15 and 16 are both electromagnetic control valves whose opening degree can be adjusted.

  As shown in detail in FIG. 2, the fractionation passage 14 passes through the fractionation section 14 a and the horizontal portion 14 b, reaches the branch point 14 c, and branches into the liquid phase passage 17 and the gas phase passage 18. While the fractionation section 14a is inclined with respect to the horizontal direction, it passes through the exhaust passage 3 on the downstream side of the exhaust purification device 6 obliquely. Thereby, the fractionation section 14a is heated by the exhaust gas in the exhaust passage 3, and the fuel supplied from the return passage 12 to the fractionation section 13 is divided into the liquid phase fuel f1 and the gas phase fuel f2. The horizontal portion 14b and the branch point 14c are provided outside the exhaust passage 3, respectively. The fractionation passage 14 extends downward as a whole, and the liquid phase fuel f1 flows toward the branch point 14c by gravity.

  The liquid phase passage 17 extends vertically downward from the branch point 14c, and its downstream side is connected to a liquid phase tank 19 for temporarily storing the fuel guided to the liquid phase passage 17. A liquid-phase return passage 20 is connected to the bottom of the liquid-phase tank 19, and the fuel in the liquid-phase tank 19 is guided to the fuel tank 7 via the adjustment valve 21. The adjusting valve 21 is an electromagnetic control valve capable of adjusting the amount of fuel guided to the liquid phase return passage 20. By adjusting the opening degree of the adjusting valve 21, it can function as a liquid level adjusting means for changing the liquid level L of the liquid phase tank 19. When the liquid level L of the liquid phase tank 19 is lowered, the space S of the liquid phase tank 19 is widened, and the fuel fractionated as a gas phase in the fractionation section 14 a is easily guided to the liquid phase tank 19. . That is, the liquid level L of the liquid phase tank 19 is one of the conditions that affect the distribution of fuel to each of the liquid phase passage 17 and the gas phase passage 18. The tank 19, the liquid phase return passage 20, and the adjusting valve 21 function as condition changing means of the present invention.

  The gas phase passage 18 extends in the horizontal direction from the branch point 14c, and the downstream side thereof is connected to a gas phase tank 22 (FIG. 1) for storing the fuel guided to the gas phase passage 18. As shown in FIG. 1, the gas phase tank 22 is provided with an intake communication pipe 23 that communicates with the intake passage 2. A negative pressure adjusting valve 24 is provided in the intake communication pipe 23 on the gas-phase fuel tank 22 side. By opening the negative pressure adjusting valve 24, the intake communication pipe 23 can function as a negative pressure generating means. When a negative pressure is generated in the gas phase tank 22 and the pressure balance is lost, liquefaction of the fuel guided to the gas phase tank 22 in the gas phase state is promoted. For this reason, the gas-phase fuel guided to the branching point 14 c through the fractionation section 14 a is easily guided to the gas-phase tank 22. Therefore, the pressure in the gas phase tank 22 is one of the conditions that affect the fuel distribution to the liquid phase passage 17 and the gas phase passage 18. The intake communication pipe 23 and the negative pressure adjusting valve 24 that generate a negative pressure in the gas phase tank 22 function as the condition changing means of the present invention.

  The fuel stored in the gas phase tank 22 is added into the exhaust passage 3 upstream of the exhaust purification device 6 by the addition injector 25. The supply of fuel to the addition injector 25 is performed by a supply pump unit 10 provided in the middle of the addition feed passage 26. Excess fuel out of the fuel sent to the addition injector 25 is returned to the gas phase tank 22 through an addition return passage (not shown).

  As shown in FIGS. 1 and 2, the pressure adjustment valve 15, the flow rate control valve 16, the adjustment valve 21, and the negative pressure adjustment valve 24 described above are controlled by an engine control unit (ECU) 27. The ECU 27 is a computer for properly operating the engine 1 by controlling the fuel injection amount, the fuel injection timing, etc. In this embodiment, the ECU 27 functions as a control means for controlling the fuel fractionation device of the present invention. To do. FIG. 3 is a flowchart showing the procedure of a control routine executed by the ECU 27 to control the opening / closing operation of these valves 15, 16, 21, 24. This routine is repeatedly executed at a predetermined cycle.

  The ECU 27 first detects the temperature of the fractionation section 14a in step S1. As shown in FIGS. 1 and 2, the temperature detection of the fractionation section 14a can be realized by estimating from the input value of the exhaust temperature sensor 28 provided in the exhaust passage 3 upstream of the fractionation section 14a. Next, in step S2, the ECU 27 determines whether or not the temperature of the fractionation section 14a is equal to or higher than a first predetermined value. The first predetermined value is appropriately set as a lower limit value of the temperature at which the fuel having properties suitable for the purpose of use can be fractionated. In the present embodiment, since the fractionated fuel is used for fuel addition upstream of the exhaust purification device 6, the first predetermined value is set to, for example, 230 ° C. If the ECU 27 determines that the temperature of the fractionation section 14a is equal to or higher than the first predetermined value, the ECU 27 advances the process to step S3. On the other hand, if it is determined that the value is less than the first predetermined value, the subsequent processing is skipped and the current routine is terminated.

  In step S <b> 3, the respective opening amounts of the pressure adjustment valve 15 and the flow rate control valve 16 are controlled to supply an appropriate amount of fuel to the fractionation unit 13. In this case, in order to suppress overheating of the fractionation section 14a, it is preferable to increase the amount of fuel supplied to the fractionation section 13 as the temperature of the fractionation section 14a increases. The calculation of the appropriate amount can be realized, for example, by previously storing a map in which the temperature of the fractionation section 14a and the opening degree of the valves 15 and 16 are associated with the fuel supply amount in the ROM of the ECU 27 and referring to this. Next, in step S4, the ECU 27 controls the liquid level L of the liquid phase tank 19 according to the temperature of the fractionation section 14a. When the ECU 27 executes this step, the ECU 27 functions as the fuel distribution control means of the present invention. As an operation for urging fuel distribution to the liquid phase passage 17, the ECU 27 causes the liquid level L to be lower when the temperature of the fractionation section 14a is higher than when it is low, and the higher the temperature of the fractionation section 14a. The operation of the adjustment valve 21 is controlled so that the liquid level L is lowered. For such control of the adjusting valve 21, for example, a duty ratio for obtaining an appropriate liquid level L according to the temperature of the fractionation section 14a is set in advance, and the temperature and the liquid level L of the fractionation section 14a are set. This can be realized by duty-controlling the adjustment valve 21 at a duty ratio corresponding to the current value. As shown in FIGS. 1 and 2, the liquid level L can be detected from this input value by providing a liquid pressure level sensor 29 in the liquid phase tank 19.

  Next, the ECU 27 determines whether or not the temperature of the fractionation section 14a is equal to or lower than a second predetermined value in step S5. The second predetermined value may be appropriately set in a temperature range where it is necessary to generate the negative pressure in the gas phase tank 22 and prompt the introduction of fuel into the gas phase passage 18. If it is determined in step S5 that it is equal to or smaller than the second predetermined value, the ECU 27 advances the process to step S6. On the other hand, when it is determined that the second predetermined value is exceeded, step S6 is skipped and the current routine is terminated.

  In step S6, the ECU 27 opens the negative pressure adjusting valve 24, generates a negative pressure in the gas phase tank 22, and ends the current routine. Since it is only necessary to give an opportunity to break the pressure balance in the gas phase tank 22 by the intake communication pipe 23, the opening of the negative pressure adjusting valve 24 may be temporary. When the ECU 27 executes this step, the ECU 27 functions as the fuel distribution control means of the present invention.

  The present invention is not limited to the above embodiment, and may be implemented in various forms. The configuration for changing the liquid level L of the liquid phase tank 19 is not limited to the above-described embodiment, and an appropriate configuration may be adopted. For example, as shown in FIGS. 4A and 4B, the inlets 29a and 30a are arranged in the liquid phase tank 19 so that their heights are different from each other, and the outlets 29b and 30b are used for the liquid phase. The liquid level adjusting passages 29 and 30 connected to the return passage 20 and the fuel in the liquid phase tank 19 are guided to the liquid phase return passage 20 via one of these passages 29 and 30. A passage switching valve 31 capable of switching the passages 29 and 30 may be provided.

  In this case, as an operation for urging the fuel to be distributed to the liquid phase passage 17, the passage switching valve 31 is controlled so that the fuel in the liquid phase tank 19 passes through the liquid level adjustment passage 29 as shown in FIG. 4 is changed to a state of passing through the liquid level adjustment passage 30 as shown in FIG. 4B, and the liquid level L is lowered. Thereby, the fuel tank 19, the liquid level adjustment passages 29 and 30, and the passage switching valve 31 can function as the condition changing means of the present invention. According to this embodiment, when the liquid level L is controlled, it is sufficient for the ECU 27 to selectively switch the liquid level adjustment passages 29 and 30 by operating the passage switching valve 31 according to the temperature of the fractionation section 14a. Therefore, it is not necessary to detect the current liquid level L and duty control the passage switching valve 31 as in the above embodiment. For this reason, the liquid level sensor 29 of FIG. 1 becomes unnecessary, and the configuration can be simplified. The liquid level adjusting passages 29 and 30 are not limited to two, and may be three or more. In this case, the passage switching valve 31 may be added according to the increase of the adjustment passage.

  In the above-described embodiment, the embodiment for performing both the operation for prompting the distribution of the fuel to the liquid phase passage 17 and the operation for the prompting the distribution of the fuel to the gas phase passage 18 has been described. May only do. Moreover, the internal combustion engine to which the fuel fractionation device of the present invention is applied is not limited to a diesel engine, and may be a gasoline engine. The use of the fuel stored in the gas phase tank 22 is not limited and may be used for injection into the cylinder of the engine 1.

The figure which showed one Embodiment which applied the fuel fractionation apparatus of this invention to the diesel engine 1 as an internal combustion engine. The figure which showed the detail of the fractionation part and the tank for liquid phases. The flowchart which showed the procedure of the control routine performed in order to control the opening / closing operation | movement of various valves. The figure which showed the detail of the fractionation part and liquid phase tank which concern on other embodiment of this invention.

Explanation of symbols

1 Diesel engine (internal combustion engine)
14 fractionation passage 14a fractionation zone 14c branch point 17 liquid phase passage 18 gas phase passage 19 liquid phase tank 20 liquid phase return passage 21 adjustment valve (liquid level adjustment means)
22 Gas phase tank 23 Intake communication pipe (negative pressure generating means)
24 Negative pressure adjusting valve 29, 30 Liquid level adjusting passage 29a, 30a Inlet 29b, 30b Outlet 31 Passage switching valve (liquid level adjusting means)
L Liquid level

Claims (5)

  A fractionation passage that reaches a branch point through a fractionation section that fractionates fuel into a gas phase and a liquid phase using exhaust heat of an internal combustion engine, a gas phase passage that branches from the branch point, and the branch point When the temperature of the fractionation section is high, the liquid phase passage branched from the liquid phase passage, the condition changing means for changing at least one of the conditions affecting the distribution of fuel to the gas phase passage and the liquid phase passage, respectively. The condition is set so that at least one of an operation for prompting fuel distribution to the liquid phase passage and an operation for prompting fuel distribution to the gas phase passage when the temperature of the fractionation section is low is executed. And a fuel distribution control means for controlling the changing means. As the condition changing means, a liquid phase tank for storing fuel introduced into the liquid phase passage, a liquid phase return passage for returning the fuel in the liquid phase tank to the fuel tank of the internal combustion engine, and the liquid phase Liquid level adjustment means for guiding the fuel in the liquid phase tank to the liquid phase return passage and adjusting the liquid level of the liquid phase tank; and
The fuel distribution control means, as an operation for urging fuel distribution to the liquid phase passage, is such that the liquid level of the liquid phase tank is lower when the temperature of the fractionation section is high than when the temperature is low. 2. The fuel fractionating device for an internal combustion engine according to claim 1, wherein the liquid level adjusting means is controlled.   The internal combustion engine according to claim 2, wherein the fuel distribution control means controls the liquid level adjustment means so that the liquid level of the liquid phase tank becomes lower as the temperature of the fractionation section becomes higher. Fuel fractionator. As the condition changing means, the liquid phase tank further includes a plurality of liquid level adjusting passages arranged at different inlet heights, each outlet being connected to the liquid phase return passage. ,
As the liquid level adjusting means, the fuel in the liquid phase tank is led to the liquid phase return path by selectively passing at least one of the plurality of liquid level adjusting paths, and is used for the liquid phase. A passage switching valve is provided to change the liquid level of the tank.
The fuel distribution control means, as an operation for urging fuel distribution to the liquid phase passage, is such that the liquid level of the liquid phase tank is lower when the temperature of the fractionation section is high than when the temperature is low. 3. The fuel fractionating device for an internal combustion engine according to claim 2, wherein the passage switching valve is controlled. As the condition changing means, a gas phase tank for storing fuel introduced into the gas phase passage, a negative pressure generating means for generating a negative pressure in the gas phase tank, and a negative pressure generated by the negative pressure generating means. A negative pressure adjustment valve that switches between generation and stoppage is provided,
The fuel distribution control means controls the negative pressure adjusting valve so as to generate a negative pressure in the gas phase tank as an operation for prompting the fuel distribution to the gas phase passage. 2. A fuel fractionating device for an internal combustion engine according to 1.

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