JP6004987B2 - Fuel separation system for internal combustion engines - Google Patents

Description

  The present invention relates to a fuel separation system for an internal combustion engine. More specifically, the present invention relates to a fuel separation system for an internal combustion engine that separates a mixed fuel of alcohol and gasoline into a high-octane fuel having a high octane number and a low-octane fuel having a low octane number.

  As fuel for internal combustion engines (hereinafter referred to as “engines”), alcohol fuel that can be produced from many crops such as sugar cane, corn, and potatoes has attracted attention. Particularly in recent years, mixed fuels in which alcohol fuel is added to gasoline are in circulation and are expected to become more widespread in the future. There are various types of alcohol fuel such as ethanol and methanol, and ethanol is the most popular among these.

  Along with the widespread use of the above-mentioned mixed fuels, the fuel that is refueled from outside is separated into high gasoline concentration fuel (low octane fuel) and high alcohol concentration fuel (high octane fuel) while the vehicle is running. A separation system is known (see, for example, Patent Document 1). There are various differences in fuel properties such as octane number and calorific value between gasoline and alcohol.Therefore, instead of using the mixed fuel supplied from the outside as it is, it is separated again on the vehicle and put into the engine operating state. This is because it may be preferable to use gasoline and alcohol properly. For example, since alcohol has better knock resistance than gasoline, knocking is suppressed by supplying alcohol to the engine.

  Here, FIG. 4 is a system circuit diagram showing a configuration of a conventional fuel separation system 1A. As shown in FIG. 4, the fuel separation system 1A includes a main tank 10 that stores a mixed fuel, a heat exchanger 11 that heats the mixed fuel, and a separation that separates the mixed fuel into a high-octane fuel and a low-octane fuel. Separator 12 including membrane 122, condenser 13 for condensing gaseous high-octane fuel separated by separation membrane 122, and high-octane fuel buffer tank for temporarily storing liquid high-octane fuel under negative pressure 14 and a high-octane fuel tank 15 for storing high-octane fuel under atmospheric pressure.

The fuel separation system 1A described above operates as follows.
First, the mixed fuel in the main tank 10 is supplied to the heat exchanger 11 by the fuel pump 102 and heated. The heated mixed fuel is supplied to the separation membrane 122 in the separator 12, and the high octane component (alcohol) selectively permeates through the separation membrane 122, so that the gaseous high octane fuel and the liquid state low Separated into octane fuel.

  After the liquid low-octane fuel separated in the high-pressure chamber 123 is cooled by the radiator 16, the fuel pressure is removed by the fuel pressure regulator 165. Thereafter, the low-octane fuel is returned to the main tank 10 and mixed with the mixed fuel, and again subjected to separation. Since the high-octane component cannot be completely separated only by bringing the mixed fuel into contact with the separation membrane 122 once, it is brought into contact with the separation membrane 122 a plurality of times. After the separation is completed, the low-octane fuel stored in the main tank 10 is appropriately injected into the combustion chamber of the engine by the direct injection injector.

  On the other hand, the high octane fuel in the gaseous state separated in the low pressure chamber 124 is supplied to the condenser 13 and condensed. The condensed high-octane fuel is supplied to the high-octane fuel buffer tank 14 under a negative pressure and temporarily stored. The high-octane fuel in the high-octane fuel buffer tank 14 is transferred into the high-octane fuel tank 15 at a predetermined timing. The high-octane fuel that has been transferred and stored in the high-octane fuel tank 15 is appropriately injected into the intake port by the port injector. The evaporated fuel generated in the main tank 10 and the high-octane fuel tank 15 is adsorbed by the canister 18 and then purged to be used for engine combustion.

JP 2013-40569 A

  By the way, in order to transfer the high-octane fuel stored in the high-octane fuel buffer tank 14 under negative pressure into the high-octane fuel tank 15 under atmospheric pressure, the high-octane fuel is greatly added by the liquid feed pump 149. It is necessary to press. Therefore, the power consumption of the liquid feed pump 149 is large.

  Therefore, in the fuel separation system 1A, first, by opening the open valve 127, the negative pressure of the low pressure chamber 124, the condenser 13, the high octane fuel buffer tank 14 and the liquid feed pump 149 is released, and these internal pressures are increased. Atmospheric pressure. Thereafter, by pressurizing the high-octane fuel with the liquid feed pump 149, a large pressurization is unnecessary, and the power consumption of the liquid feed pump 149 is suppressed.

However, in the fuel separation system 1A, when the high-octane fuel is transferred, the fuel is released to the negative pressure in the low-pressure chamber 124 of the separator 12, so that the fuel separation speed is significantly reduced during the transfer.
Further, after the transfer of the high-octane fuel is completed, in order to recover the fuel separation speed, it is necessary to bring the low-pressure chamber 124 and the like into a negative pressure state again. However, it takes time to recover the negative pressure state, which increases the power consumption of the negative pressure pump.

  The present invention has been made in view of the above, and an object thereof is to provide a fuel separation system for an internal combustion engine that can reduce the time required for fuel separation and transfer of the separated high octane fuel while suppressing power consumption. There is to do.

  In order to achieve the above object, the present invention provides a mixed fuel of alcohol (for example, ethanol described later) and gasoline, a high-octane fuel having a higher octane number than the mixed fuel (for example, a higher ethanol concentration and a higher octane number than the mixed fuel described later). Fuel of an internal combustion engine (for example, engine 2 to be described later) that is separated into a high octane number fuel) and a low octane fuel having a lower octane number than that of the mixed fuel (for example, a low octane fuel having a lower ethanol concentration and a lower octane number than the mixed fuel described later) A separation system for storing the mixed fuel (for example, a main tank 10 described later), and a heater (for example, a heat exchanger 11 described below) for heating the mixed fuel supplied from the main tank; , A separator that separates the mixed fuel heated by the heater into a high-octane fuel and a low-octane fuel ( For example, a separator 12) which will be described later, a condenser (for example, a condenser 13 which will be described later) that condenses the gaseous high-octane fuel separated by the separator, and a high-octane fuel that has been condensed by the condenser. A high-octane fuel buffer tank (for example, a high-octane fuel buffer tank 14 to be described later) that temporarily stores under negative pressure, and a high-octane fuel buffer tank disposed below the high-octane fuel buffer tank and supplied from the high-octane fuel buffer tank A high-octane fuel tank (for example, a high-octane fuel tank 15 described later) that stores octane fuel under atmospheric pressure, and an intake side are connected to an upper space (for example, an upper space 146 described later) in the high-octane fuel buffer tank. And the exhaust side is connected to a reservoir (for example, a reservoir 155 described later) in the high octane fuel tank. A negative pressure pump (for example, a negative pressure pump 141 described later), and a first communication passage that communicates an intake side of the negative pressure pump and an upper space (for example, an upper space 154 described later) in the high-octane fuel tank. (For example, a control valve (for example, a pressure control valve 142, which will be described later) provided in the first communication path 144, which will be described later, and opens or shuts off the first communication path, and a storage unit in the high-octane fuel buffer tank ( For example, it is provided in a second communication passage (for example, a second communication passage 145 described later) that connects a storage portion 147 described later and an upper space (for example, an upper space 154 described later) in the high octane fuel tank, A first check valve (for example, a first check valve 143 described later) that blocks the flow of fuel from the high-octane fuel tank, a lower portion (for example, a lower portion 134 described later) in the condenser, and the high-octane fuel Ba Provided in a third communication path (for example, a third communication path 133 described later) that communicates with an upper space (for example, an upper space 146 described later) in the buffer tank, and prevents the flow of fuel from the high octane fuel buffer tank. A second check valve (for example, a second check valve 131 described later), and when the first communication path is opened by the control valve, the negative pressure in the high octane number fuel buffer tank is released. As a result, the second check valve is closed, and the first check valve is opened by the dead weight of the high octane fuel in the high octane fuel buffer tank so that the high octane fuel is A fuel separation system for an internal combustion engine, wherein the fuel separation system is transferred into the high octane fuel tank through a second communication path.

In the present invention, a high-octane fuel tank is disposed below the high-octane fuel buffer tank, and a pressure control valve for releasing the negative pressure in the high-octane fuel buffer tank is provided. In addition, a first check valve is provided for preventing the flow of fuel from the high octane fuel tank in the second communication path that communicates the reservoir in the high octane fuel buffer tank and the upper space in the high octane fuel tank, A second check valve is provided to prevent the flow of fuel from the high octane fuel buffer tank in a third communication path that communicates the lower part in the condenser and the upper space in the high octane fuel buffer tank.
According to the present invention, by opening the pressure control valve, the negative pressure in the high-octane fuel buffer tank can be released, and the internal pressure of the high-octane fuel buffer tank can be set to approximately atmospheric pressure. Then, the first check valve 143 is opened by the dead weight of the high octane fuel stored in the reservoir of the high octane fuel buffer tank, and the high octane fuel is transferred into the high octane fuel tank. Therefore, according to the present invention, a liquid feed pump is unnecessary, and power consumption can be suppressed.
Further, since the internal pressure of the high-octane fuel buffer tank becomes approximately atmospheric pressure, a differential pressure is generated between the high-octane fuel buffer tank and the internal pressure of the condenser, thereby closing the second check valve. And the negative pressure in the condenser is maintained. Thereby, even during the transfer of the high octane fuel, it is possible to suppress a decrease in the fuel separation speed and to continue the fuel separation.
Further, since the negative pressure is released only in the high octane fuel buffer tank, the original negative pressure state can be quickly recovered after the transfer of the high octane fuel is completed, and the power consumption of the negative pressure pump can be suppressed.
Therefore, according to the present invention, it is possible to shorten the time required to separate the fuel and transfer the separated high octane fuel while suppressing power consumption.

  Preferably, the condenser is disposed below the separator, and the high octane fuel buffer tank is disposed below the condenser.

By the way, in the fuel separation system, the high-octane fuel may be liquefied in the negative pressure region other than the condenser, and it is necessary to drain the liquefied high-octane fuel with a negative pressure pump. However, when there are a plurality of liquefaction sites, it is necessary to install a plurality of negative pressure pumps, which increases power consumption.
Therefore, according to the present invention, the condenser is disposed below the separator, and the high octane fuel buffer tank is disposed below the condenser. That is, according to the present invention, since the separator, the condenser, and the high-octane fuel buffer tank are arranged in order from the top to the bottom, the high-octane fuel is liquefied at the negative pressure portion other than the condenser. However, due to gravity, the liquefied high octane fuel can be introduced into the lower high octane fuel buffer tank. Therefore, a drain discharge pump is unnecessary, and power consumption can be further suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel separation system of the internal combustion engine which can shorten the time which the separation of a fuel and the transfer of the separated high octane fuel are reduced can be provided, suppressing power consumption.

It is a figure which shows the structure of the fuel separation system of the engine which concerns on one Embodiment of this invention. It is a system circuit diagram of the fuel separation system which concerns on the said embodiment. It is a flowchart which shows the procedure of the transfer control of the high octane fuel which concerns on the said embodiment. It is a system circuit diagram of the conventional fuel separation system.

An embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a fuel separation system 1 for an engine 2 according to an embodiment of the present invention. The fuel separation system 1 of the engine 2 is mounted on a vehicle (not shown), and a mixed fuel of ethanol and gasoline, a high octane fuel having a higher ethanol concentration than the mixed fuel and a higher octane number, and an ethanol concentration than the mixed fuel while the vehicle is running. Separated into low octane fuel with low octane number.

  As shown in FIG. 1, the fuel separation system 1 of the engine 2 according to the present embodiment includes a main tank 10, a heat exchanger 11, a separator 12, a condenser 13, a high octane fuel buffer tank 14, A high-octane fuel tank 15, a radiator 16, a canister 18, and an electronic control unit (hereinafter referred to as “ECU”) 5 are provided.

  The main tank 10 stores a mixed fuel of ethanol and gasoline supplied from a fuel filler port. In this embodiment, the most popular mixed fuel (E10) having an ethanol content of 10% is preferably used as the mixed fuel. The main tank 10 is connected to a first fuel passage 101 for supplying fuel to a heat exchanger 11 and a separator 12 described later.

A fuel pump 102 connected to the first fuel passage 101 is provided in the reservoir 10 a in the main tank 10. The rotational speed of the fuel pump 102 is controlled by the ECU 5, whereby the mixed fuel in the main tank 10 is supplied into the heat exchanger 11 through the first fuel passage 101.
A first temperature sensor 104 is provided in the first fuel passage 101 upstream of the heat exchanger 11. The first temperature sensor 104 detects the temperature of the fuel supplied into the heat exchanger 11 through the first fuel passage 101, and outputs a detection signal corresponding to the temperature to the ECU 5.

The heat exchanger 11 is provided in the middle of the first fuel passage 101 and heats the fuel supplied by the fuel pump 102 via the first fuel passage 101 by heat exchange with the cooling water (LLC) of the engine 2. . Thereby, the temperature of the fuel supplied to the separation membrane 122 of the separator 12 to be described later is raised, so that the separation efficiency by the separation membrane 122 is improved.
A cooling water passage 111 through which the cooling water of the engine 2 flows is connected to the heat exchanger 11, and the cooling water of the engine 2 circulates in the heat exchanger 11. The cooling water passage 111 is provided with a flow rate adjusting valve 112 that adjusts the flow rate of the cooling water flowing through the cooling water passage 111, and the flow rate adjusting valve 112 is controlled by the ECU 5. Further, a water temperature sensor 113 is provided on the engine 2 side of the cooling water passage 111. The water temperature sensor 113 detects the temperature of the cooling water flowing in the cooling water passage 111, and sends a detection signal corresponding to this to the ECU 5. Output.
The cooling water flowing through the cooling water passage 111 is appropriately cooled by a vehicle radiator (not shown). The heat exchanger 11 may further include an electric heater, or may be replaced with an electric heater.

The separator 12 separates the mixed fuel supplied by being heated by the heat exchanger 11 into a high octane fuel having a higher ethanol concentration and a higher octane number than the mixed fuel and a low octane fuel having a lower ethanol concentration and a lower octane number. To do.
A second temperature sensor 126 is provided in the first fuel passage 101 downstream of the heat exchanger 11 and upstream of the separator 12. The second temperature sensor 126 detects the temperature of the fuel heated by the heat exchanger 11 and supplied to the separator 12 and outputs a detection signal corresponding to the detected temperature to the ECU 5.

  The separator 12 is a separator using a pervaporation method (pervaporation method). The separator 12 is a separation membrane 122 that selectively permeates ethanol, which is a high-octane component in the mixed fuel, a high-pressure chamber 123 and a low-pressure chamber 124 that are partitioned by the separation membrane 122, and the pressure in the low-pressure chamber 124. And a pressure sensor 125 to detect.

  The high pressure chamber 123 is connected to the downstream side of the heat exchanger 11 of the first fuel passage 101, is pressurized by the fuel pump 102 provided in the first fuel passage 101, and is maintained at a pressure set by the fuel pressure regulator 165. . The low pressure chamber 124 is connected to the intake side of the negative pressure pump 141 via a condenser 13 and a high octane fuel buffer tank 14 which will be described later, and is thereby kept at a negative pressure. A pressure sensor 125 is provided in the low pressure chamber 124. The pressure sensor 125 detects the pressure in the low-pressure chamber 124 and outputs a detection signal corresponding to the pressure to the ECU 5.

When the fuel heated by the heat exchanger 11 is supplied into the high pressure chamber 123, the high octane component ethanol selectively permeates the separation membrane 122, and the high octane fuel is leached into the low pressure chamber 124 in a gaseous state. . On the other hand, low-octane fuel remains in the high-pressure chamber 123. As a result, the fuel is separated into a high-octane fuel and a low-octane fuel.
The separation efficiency of the separator 12 is adjusted by the temperature and flow rate of the supplied fuel and the pressure in the high pressure chamber 123 and the low pressure chamber 124.

The condenser 13 condenses the high-octane fuel in the gaseous state. The condenser 13 is disposed below the separator 12. The upstream side of the condenser 13 is connected to the low pressure chamber 124 of the separator 12, and the downstream side thereof is connected to the intake side of the negative pressure pump 141 via a high octane fuel buffer tank 14 described later. As a result, the inside of the condenser 13 is controlled to a negative pressure and is kept at a pressure lower than the vapor pressure of the high octane fuel, so that the gaseous high octane fuel is supplied from the low pressure chamber 124 into the condenser 13 and condensed. Is done.
The condenser 13 is an air-cooled condenser, and includes a plurality of plate-shaped fins 130 and a cooling fan 132. The number of rotations of the cooling fan 132 is controlled by the ECU 5. The condenser 13 may be a water-cooled type or a condenser using another refrigerant.

The high octane fuel buffer tank 14 temporarily stores high octane fuel under a negative pressure. The high octane number fuel buffer tank 14 is disposed below the condenser 13. The upper space 146 of the high-octane fuel buffer tank 14 is connected to the lower part 134 of the condenser 13 by the third communication path 133 and is connected to the intake side of the negative pressure pump 141 described later. As a result, the high octane fuel is supplied from the condenser 13 into the high octane fuel buffer tank 14.
A third check passage 133 that connects the upper space 146 of the high-octane fuel buffer tank 14 and the lower part 134 of the condenser 13 has a second check that prevents the flow of fuel from the high-octane fuel buffer tank 14 to the condenser 13. A valve 131 is provided.
A high octane fuel buffer tank remaining amount sensor 148 for detecting the remaining amount of high octane fuel is provided in the high octane fuel buffer tank 14.

  The high octane fuel tank 15 stores high octane fuel under atmospheric pressure. The high octane fuel tank 15 is disposed below the high octane fuel buffer tank 14. The upper space 154 of the high octane fuel tank 15 is communicated with the storage portion 147 of the high octane fuel buffer tank 14 by the second communication path 145. The second communication passage 145 is provided with a first check valve 143 that prevents the flow of fuel from the high octane fuel tank 15 to the high octane fuel buffer tank 14.

The reservoir 155 of the high octane fuel tank 15 is connected to the exhaust side of the negative pressure pump 141 whose intake side is connected to the upper space 146 of the high octane fuel buffer tank 14. The upper space 154 of the high octane fuel tank 15 is communicated with the intake side of the negative pressure pump 141 by the first communication path 144. The first communication path 144 is provided with a pressure control valve 142 that opens or closes the first communication path 144. The number of rotations of the negative pressure pump 141 and the opening / closing of the pressure control valve 142 are controlled by the ECU 5. The pressure control valve 142 is composed of, for example, an electromagnetic valve.
In the high octane fuel tank 15, a high octane fuel tank remaining amount sensor 156 for detecting the remaining amount of high octane fuel is provided.

When the pressure control valve 142 is opened, the upper space 146 of the high-octane fuel buffer tank 14 is blocked from the intake side of the negative pressure pump 141, while the upper space 154 of the high-octane fuel tank 15 under atmospheric pressure. Communicated with. As a result, the negative pressure in the high-octane fuel buffer tank 14 is released, and the internal pressure in the high-octane fuel buffer tank 14 becomes approximately atmospheric pressure. Then, the first check valve 143 is opened by the own weight of the high octane fuel stored in the storage unit 147 of the high octane fuel buffer tank 14, and the high octane fuel is transferred into the high octane fuel tank 15.
In addition, since the internal pressure of the high-octane fuel buffer tank 14 becomes approximately atmospheric pressure, a differential pressure is generated between the internal pressure of the condenser 13 and the second check valve 131 is thereby closed. The negative pressure in the 12 low-pressure chambers 124 and in the condenser 13 is maintained. Strictly speaking, although there is a negative pressure drop due to the progress of fuel separation, the negative pressure in the low-pressure chamber 124 and the condenser 13 of the separator 12 is maintained for a short time, and separation can be continued.

  The high-octane fuel stored in the high-octane fuel tank 15 is boosted to a predetermined pressure set by a fuel pressure regulator (not shown) by a fuel pump 151 provided in the lower part (storage part) of the high-octane fuel tank 15, It is pumped into the high octane fuel passage 152. The pumped high-octane fuel is appropriately injected into the intake port 30 of the engine 2 by the port injector 51. The injection timing and injection time of the port injector 51 are controlled by the ECU 5.

  Further, the upper space 154 of the high octane fuel tank 15 is connected to a canister 18 described later via a two-way valve 153. When the pressure in the canister 18 becomes higher than the pressure in the high octane fuel tank 15, the evaporated fuel in the canister 18 is supplied into the high octane fuel tank 15. On the other hand, when the pressure in the high octane fuel tank 15 becomes higher than the pressure in the canister 18, the evaporated fuel in the high octane fuel tank 15 is supplied into the canister 18.

The radiator 16 cools the low-octane fuel separated by the separator 12. The radiator 16 is provided in the middle of the second fuel passage 121 and is disposed on the downstream side of the separator 12. The radiator 16 includes a plurality of corrugated fins 160 and a cooling fan 161. The rotation speed of the cooling fan 161 is controlled by the ECU 5. The high-temperature low-octane fuel separated by the separation membrane 122 is cooled by the radiator 16.
A temperature sensor 162 is provided at the outlet of the radiator 16. The temperature sensor 162 detects the temperature of the fuel cooled by the radiator 16 and outputs a detection signal corresponding to the detected temperature to the ECU 5.

  The downstream side of the radiator 16 is connected to the main tank 10 by the second fuel passage 121. That is, the low-octane fuel separated by the separation membrane 122 is supplied into the main tank 10 and mixed with the mixed fuel before separation, and again used for separation. In this way, the fuel is circulated between the main tank 10 and the separation membrane 122 until the high octane component concentration in the fuel becomes equal to or lower than a predetermined threshold value at which it can be determined that the separation is completed.

A fuel pressure regulator 165 is provided in the second fuel passage 121. The fuel pressure regulator 165 removes the fuel pressure of the fuel flowing in the second fuel passage 121.
Further, in the second fuel passage 121 downstream of the fuel pressure regulator 165, a high octane component concentration sensor 166 such as an ethanol sensor is used as a high octane component concentration detector that can detect or estimate the high octane component concentration in the fuel. Is provided. The high octane number component concentration sensor 166 detects the high octane number component concentration in the fuel and outputs a detection signal corresponding to this to the ECU 5.

When the high octane component concentration in the fuel detected by the high octane component concentration sensor 166 is equal to or less than a predetermined threshold at which separation can be determined, the high octane component concentration in the main tank 10 is sufficiently small. Low octane fuel is stored.
The low-octane fuel in the main tank 10 is pressurized to a predetermined pressure by the fuel pump 103 provided in the reservoir 10 a of the main tank 10 and is pumped into the low-octane fuel passage 106. The pumped low-octane fuel is appropriately injected into the combustion chamber 20 of the engine 2 by the direct injection injector 52. The number of revolutions of the fuel pump 103 and the injection timing and injection time of the direct injection injector 52 are controlled by the ECU 5.

  The upper space 10b of the main tank 10 is connected via a canister 18 and a two-way valve 105 described later. When the pressure in the canister 18 becomes higher than the pressure in the main tank 10, the evaporated fuel in the canister 18 is supplied into the main tank 10. On the other hand, when the pressure in the main tank 10 becomes higher than the pressure in the canister 18, the evaporated fuel in the main tank 10 is supplied into the canister 18.

The canister 18 contains an adsorbent such as activated carbon, and adsorbs and holds high octane component ethanol and low octane component gasoline (hydrocarbon). The canister 18 is connected to the intake port 30 of the engine 2 via the canister control valve 181. The opening and closing of the canister control valve 181 is controlled by the ECU 5.
Since the intake port 30 is in a negative pressure state, when the canister control valve 181 is opened, the ethanol and gasoline (hydrocarbon) adsorbed and held by the canister 18 are evaporated again and evaporated as fuel. Thus, the air is supplied into the intake port 30. As a result, the evaporated fuel is supplied into the combustion chamber 20 of the engine 2 and burned.
Air components such as nitrogen other than the evaporated fuel are discharged from the canister 18 through the discharge passage 182 to the outside of the vehicle.

  The engine 2 is a multi-cylinder engine having a plurality of cylinders 23. FIG. 1 representatively shows one of them. The engine 2 is configured by combining a cylinder block 21 in which a cylinder 23 is formed and a cylinder head 22. A piston 24 is slidably provided in the cylinder 23. A combustion chamber 20 of the engine 2 is formed by the top surface of the piston 24 and the surface of the cylinder head 22 on the cylinder 23 side. The piston 24 is connected to a crankshaft (not shown) via a connecting rod. That is, a crankshaft (not shown) rotates according to the reciprocating motion of the piston 24 in the cylinder 23.

  The engine 2 is provided with an intake pipe 3 through which intake air flows and an exhaust pipe 4 through which exhaust flows. The cylinder head 22 is formed with an intake port 30 that connects the combustion chamber 20 and the intake pipe 3, and an exhaust port 40 that connects the combustion chamber 20 and the exhaust pipe 4. An intake opening facing the combustion chamber 20 in the intake port 30 is opened and closed by an intake valve 27. An exhaust opening facing the combustion chamber 20 in the exhaust port 40 is opened and closed by an exhaust valve 28.

  The cylinder head 22 is provided with an ignition plug 29 facing the combustion chamber 20, an intake camshaft (not shown) that drives the intake valve 27 to open and close, and an exhaust camshaft that drives the exhaust valve 28 to open and close. The spark plug 29 is connected to the ECU 5 via an igniter (not shown) and its driver, and the ignition timing is controlled by the ECU 5.

  The intake pipe 3 is provided with a compressor, an intercooler, and a throttle valve 31 (not shown) in order from the upstream side to the downstream side. The throttle valve 31 controls the flow rate (intake flow rate) of air supplied into the combustion chamber 20 of the engine 2. The throttle valve 31 is connected to the ECU 5 via a driver (not shown).

  The exhaust pipe 4 is provided with a turbocharger turbine (not shown) and an exhaust purification catalyst for purifying exhaust gas in order from the upstream side to the downstream side. The exhaust purification catalyst is, for example, a three-way catalyst, and purifies HC, CO, NOx, etc. in the exhaust.

  The ECU 5 is an electronic control unit that controls the engine 2 and the fuel separation system 1 and includes electronic circuits such as a CPU, a ROM, a RAM, and various interfaces. In addition, the ECU 5 is configured with a fuel separation control unit that performs fuel separation control of a mixed fuel, which will be described later, and this fuel separation control unit includes a transfer control unit that performs transfer of high-octane fuel. The ECU 5 is connected to the above-described various sensors, valves, pumps, fans, and the like in order to grasp the state of the engine 2 and the fuel separation system 1 and the state of the vehicle on which these are mounted.

Next, the operation of the fuel separation control in the fuel separation system 1 according to the present embodiment will be described with reference to FIG.
FIG. 2 is a system circuit diagram of the fuel separation system 1 according to the present embodiment. As shown in FIG. 2, first, the mixed fuel supplied into the main tank 10 is supplied to the heat exchanger 11 provided in the middle of the first fuel passage 101 by the fuel pump 102 (fuel pressure 300 to 400 kPa). The heat exchanger 11 is heated by heat exchange with the cooling water of the engine 2 circulating in the heat exchanger 11. The heated mixed fuel is supplied to the separation membrane 122 in the separator 12, and the high octane component (alcohol) selectively permeates the separation membrane 122. Thereby, the mixed fuel is separated into a high-octane fuel and a low-octane fuel.

  The high-octane fuel separated in the low-pressure chamber 124 is in a gas state, and is supplied from the low-pressure chamber 124 kept in the negative pressure state by the action of the negative pressure pump 141 into the condenser 13 that is also kept in the negative pressure state. Is done. The high-octane fuel in the gaseous state is condensed in the condenser 13 to be in a liquid state, and then supplied into the high-octane fuel buffer tank 14 maintained in a negative pressure state by the action of the negative pressure pump 141. Is temporarily stored.

The high-octane fuel in the high-octane fuel buffer tank 14 is transferred into the high-octane fuel tank 15 at a predetermined timing. The transfer of the high octane fuel is executed by the transfer control of the ECU 5, which will be described in detail later.
The high-octane fuel that has been transferred and stored in the high-octane fuel tank 15 is appropriately injected into the intake port 30 by the port injector 51. The evaporated fuel generated in the main tank 10 and the high octane fuel tank 15 is adsorbed by the canister 18 and then purged to be used for combustion of the engine 2.

  On the other hand, the liquid low-octane fuel separated in the high-pressure chamber 123 is cooled by the radiator 16, and then the fuel pressure is removed by the fuel pressure regulator 165. Thereafter, the low-octane fuel is returned to the main tank 10 and mixed with the mixed fuel, and again subjected to separation. Since the high-octane component cannot be completely separated only by bringing the mixed fuel into contact with the separation membrane 122 once, it is brought into contact with the separation membrane 122 a plurality of times. When the high octane component concentration detected by the high octane component concentration sensor 166 is equal to or lower than a predetermined threshold value, it is determined that the separation is completed, and the fuel separation control is terminated. The low octane fuel in the main tank 10 is appropriately injected into the combustion chamber 20 of the engine 2 by the direct injection injector 52.

Next, transfer control of the high octane fuel in the fuel separation system 1 according to the present embodiment will be described with reference to FIG.
FIG. 3 is a flowchart showing a procedure of transfer control of the high octane fuel according to the present embodiment. This transfer control is executed by the transfer control unit of the ECU 5 in response to the start of the fuel separation control described above.

  In step S1, first, the pressure control valve 142 is closed, and the process proceeds to step S2. As a result, the intake side of the negative pressure pump 141 and the upper space 154 of the high octane fuel tank 15 under atmospheric pressure are shut off, and the inside of the high octane fuel buffer tank 14 is maintained at a negative pressure. That is, the fuel is separated.

In step S2, it is determined whether or not the remaining amount of high octane fuel in the high octane fuel tank 15 is equal to or less than a specified amount. If this determination is YES, it is determined that the high-octane fuel can be transferred from the high-octane fuel buffer tank 14 to the high-octane fuel tank 15, and the process proceeds to step S3. If this determination is NO, it is determined that the transfer of the high octane fuel is impossible, and the process proceeds to step S7.
The prescribed amount is set in advance according to the capacity of the high octane fuel tank (the same applies to step S5).

In step S7, it is determined whether or not the remaining amount of high-octane fuel in the high-octane fuel buffer tank 14 is equal to or less than a specified amount. If this determination is YES, the process moves to step S9 to determine whether or not to continue the fuel separation, and returns to step S2. If this determination is NO, the process proceeds to step S8, where it is determined to stop fuel separation, and the process returns to step S2. Thereby, fuel separation control is stopped.
The prescribed amount is set in advance according to the capacity of the high octane fuel buffer tank.

In step S3, the pressure control valve 142 is opened to execute the transfer of the high octane fuel. As a result, the negative pressure in the high-octane fuel buffer tank 14 is released, and the internal pressure in the high-octane fuel buffer tank 14 becomes approximately atmospheric pressure. Then, the first check valve 143 is opened by the own weight of the high octane fuel stored in the storage unit 147 of the high octane fuel buffer tank 14, and the high octane fuel is transferred into the high octane fuel tank 15.
At this time, since the internal pressure of the high-octane fuel buffer tank 14 becomes almost atmospheric pressure, a differential pressure is generated between the internal pressure of the condenser 13 and the second check valve 131 is thereby closed. The negative pressure in the low pressure chamber 124 and the condenser 13 of the separator 12 is maintained.

  In step S4, it is determined whether or not the remaining amount of high octane fuel in the high octane fuel buffer tank 14 is zero. If this determination is YES, it is determined that the transfer of the high-octane fuel from the high-octane fuel buffer tank 14 to the high-octane fuel tank 15 has been completed, and the process proceeds to step S6 to close the pressure control valve 142. To end this process. By closing the pressure control valve 142, the inside of the high-octane fuel buffer tank 14 is again in a negative pressure state, the first check valve 143 is closed, and fuel is separated again.

  Further, when the determination in step S4 is NO, the process proceeds to step S5 to determine whether or not the remaining amount of the high octane fuel in the high octane fuel tank 15 is equal to or less than the specified amount. If this determination is YES, it is determined that the high-octane fuel can be transferred, and the process returns to step S4. If this determination is NO, it is determined that high-octane fuel cannot be transferred, the process proceeds to step S6, the pressure control valve 142 is closed, and this process is terminated.

According to this embodiment, the following effects are produced.
In the present embodiment, the high octane fuel tank 15 is disposed below the high octane fuel buffer tank 14, and the pressure control valve 142 for releasing the negative pressure in the high octane fuel buffer tank 14 is provided. In addition, a first reverse that hinders the flow of fuel from the high octane fuel tank 15 in the second communication path 145 that communicates the reservoir 147 in the high octane fuel buffer tank 14 and the upper space 154 in the high octane fuel tank 15. A stop valve 143 is provided, and the flow of fuel from the high octane fuel buffer tank 14 in the third communication passage 133 that connects the lower part 134 in the condenser 13 and the upper space 146 in the high octane fuel buffer tank 14 is prevented. A second check valve 131 was provided.
According to the present embodiment, by opening the pressure control valve 142, the negative pressure in the high-octane fuel buffer tank 14 can be released, and the internal pressure in the high-octane fuel buffer tank 14 can be set to approximately atmospheric pressure. Then, the first check valve 143 is opened by the own weight of the high octane fuel stored in the storage unit 147 of the high octane fuel buffer tank 14, and the high octane fuel is transferred into the high octane fuel tank 15. Therefore, according to this embodiment, a liquid feeding pump is unnecessary and power consumption can be suppressed.
In addition, since the internal pressure of the high-octane fuel buffer tank 14 becomes approximately atmospheric pressure, a differential pressure is generated between the internal pressure of the condenser 13 and the second check valve 131 is thereby closed. The negative pressure in the 12 low-pressure chambers 124 and in the condenser 13 is maintained. Thereby, even during the transfer of the high octane fuel, it is possible to suppress a decrease in the fuel separation speed and to continue the fuel separation.
Furthermore, since only the high-octane fuel buffer tank 14 releases the negative pressure, the original negative pressure state can be quickly recovered after the transfer of the high-octane fuel is completed, and the power consumption of the negative pressure pump 141 can be suppressed. .
Therefore, according to the fuel separation system 1 according to the present embodiment, it is possible to shorten the time required to separate the fuel and transfer the separated high octane fuel while suppressing power consumption.

By the way, in the fuel separation system, the high octane fuel may be liquefied in the negative pressure region other than the condenser 13, and the liquefied high octane fuel needs to be drained by the negative pressure pump 141. However, when the liquefaction part covers a plurality of places, it is necessary to install a plurality of negative pressure pumps 141, and power consumption increases.
Therefore, according to the present embodiment, the condenser 13 is disposed below the separator 12, and the high octane fuel buffer tank 14 is disposed below the condenser 13. That is, according to this embodiment, since the separator 12, the condenser 13, and the high octane fuel buffer tank 14 are arranged in order from the top to the bottom, the high octane fuel is liquefied at the negative pressure portion other than the condenser 13. Even in this case, the liquefied high octane fuel can be guided into the lower high octane fuel buffer tank 14 by gravity. Therefore, a drain discharge pump is unnecessary, and power consumption can be further suppressed.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
In the said embodiment, although the use of the mixed fuel of ethanol and gasoline was assumed, this invention is not limited to this. The alcohol component mixed with gasoline is not limited to ethanol, but may be methanol, butanol, or the like.

  In the above embodiment, the low octane fuel separated by the separator 12 is returned to the main tank 10, but the present invention is not limited to this. For example, a low octane fuel tank may be provided separately, and the low octane fuel may be stored in the low octane fuel tank.

  Further, a circulation circuit may be provided in addition to the low octane fuel tank, and a small amount of fuel may be circulated in the circulation circuit so as to be separated. In this case, separation of the fuel circulating in the circulation circuit is completed, and the pressure control valve 142 is opened at the same timing as the replacement of the fuel in the circulation circuit, that is, the fuel is discharged to the low octane fuel tank. It is preferable to transfer the high-octane fuel in the high-octane fuel buffer tank 14 to the high-octane fuel tank 15. Thereby, the time required for the separation of the fuel and the transfer of the separated high-octane fuel can be further shortened.

DESCRIPTION OF SYMBOLS 1 ... Fuel separation system 2 ... Engine (internal combustion engine)
5 ... ECU
10 ... Main tank 11 ... Heater (heat exchanger)
DESCRIPTION OF SYMBOLS 12 ... Separator 13 ... Condenser 14 ... High octane fuel buffer tank 15 ... High octane fuel tank 51 ... Port injector (high octane fuel supply means)
52. Direct injection injector (low octane fuel supply means)
131 ... Second check valve 133 ... Third communication path 134 ... Lower part 141 ... Negative pressure pump 142 ... Control valve (pressure control valve)
143 ... First check valve 144 ... First communication passage 145 ... Second communication passage 146, 154 ... Upper space 147, 155 ... Storage section

Claims (2)

A fuel separation system for an internal combustion engine that separates a mixed fuel of alcohol and gasoline into a high-octane fuel having a higher octane number than the mixed fuel and a low-octane fuel having a lower octane number than the mixed fuel,
A main tank for storing the mixed fuel;
A heater for heating the mixed fuel supplied from the main tank;
A separator for separating the mixed fuel heated by the heater into a high-octane fuel and a low-octane fuel;
A condenser for condensing the high octane fuel in the gaseous state separated by the separator;
A high octane fuel buffer tank for temporarily storing the high octane fuel condensed by the condenser under a negative pressure;
A high-octane fuel tank disposed below the high-octane fuel buffer tank and storing high-octane fuel supplied from the high-octane fuel buffer tank under atmospheric pressure;
A negative pressure pump having an intake side connected to an upper space in the high octane number fuel buffer tank and an exhaust side connected to a reservoir in the high octane number fuel tank;
A control valve that is provided in a first communication path that communicates an intake side of the negative pressure pump and an upper space in the high octane fuel tank, and that opens or closes the first communication path;
A first check valve that is provided in a second communication passage that communicates the storage in the high octane fuel tank and the upper space in the high octane fuel tank, and prevents the flow of fuel from the high octane fuel tank; ,
A second check valve provided in a third communication passage that communicates a lower portion in the condenser and an upper space in the high octane fuel buffer tank, and prevents a fuel flow from the high octane fuel buffer tank; Prepared,
When the first communication path is opened by the control valve, the negative pressure in the high-octane fuel buffer tank is released to close the second check valve, and the high-octane fuel buffer tank The high-octane fuel is transferred into the high-octane fuel tank through the second communication passage by opening the first check valve by the dead weight of the high-octane fuel in the tank. Fuel separation system for internal combustion engines. The condenser is disposed below the separator;
The fuel separation system for an internal combustion engine according to claim 1, wherein the high octane fuel buffer tank is disposed below the condenser.

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