JP6109644B2 - 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). The fuel separation system has various differences in fuel properties, such as octane number and calorific value, between gasoline and alcohol, so it is separated again on the vehicle rather than using the mixed fuel supplied from outside as it is, and the engine It is provided because it may be preferable to use gasoline and alcohol properly depending on the driving state. For example, since alcohol has better knocking resistance than gasoline, knocking is suppressed by supplying alcohol to the engine.

  Here, FIG. 4 is a diagram showing a configuration of a conventional fuel separation system. As shown in FIG. 4, a conventional fuel separation system 1A includes a main tank 10 that stores a mixed fuel, a separator 12 that separates the mixed fuel into a high-octane fuel and a low-octane fuel, and a high-octane fuel under a negative pressure. A high-octane fuel buffer tank 14 that temporarily stores, a high-octane fuel tank 15 that stores high-octane fuel under atmospheric pressure, and a low-octane fuel tank 17 that stores low-octane fuel are configured.

The fuel separation system 1A described above operates as follows.
First, the mixed fuel in the main tank 10 is pressurized and supplied to the heat exchanger 11 provided in the middle of the first fuel passage 101 by the fuel pump 103 up to the set pressure of the fuel pressure regulator 165. It is heated by heat exchange with the cooling water of the engine 2 that circulates. 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 and flows into the low pressure chamber 124 under a negative pressure in a vaporized state. Thus, the high-octane fuel and the low-octane fuel are separated. The separated high-octane fuel is condensed by the condenser 13 and supplied to the high-octane fuel buffer tank 14 under negative pressure, temporarily stored, and then appropriately supplied to the high-octane fuel tank 15 under atmospheric pressure. . The high octane fuel stored in the high octane fuel tank 15 is appropriately injected into the intake port 30 by the port injector 51.

  On the other hand, the separated low-octane fuel is cooled by the radiator 16 and then circulated in the main tank 10 to be separated again. This is because the high-octane component cannot be completely separated only by allowing the mixed fuel to permeate the separation membrane 122 once, and it is necessary to permeate the separation membrane 122 a plurality of times. After the mixed fuel is permeated through the separation membrane 122 a plurality of times and the separation is completed, the low octane number fuel in the main tank 10 is supplied and stored in the low octane number fuel tank 17. The low-octane fuel stored in the low-octane fuel tank 17 is appropriately injected into the combustion chamber 20 of the engine 2 by the direct injection injector 52.

  According to the fuel separation system 1A described above, for example, when fuel separation has not been completed immediately after refueling, the low octane fuel obtained in the previous separation and stored in the low octane fuel tank 17 is used as the engine 2. By using it for operation, consumption of the mixed fuel before separation can be avoided. As a result, the amount of the high-octane component that can be separated can be maximized.

JP 2013-40569 A

  By the way, in order to separate the mixed fuel in the main tank 10 into the high-octane fuel and the low-octane fuel, the mixed fuel is supplied to the heat exchanger 11 and heated, and the heated mixed fuel is separated by the separation membrane 122. In addition to condensing and cooling the high octane fuel, it is necessary to cool the low octane fuel to below the boiling point.

  However, if cooling water, exhaust, engine wall radiation, or the like is used as a heating source to heat the mixed fuel before separation, the fuel temperature in the main tank 10 is low when the engine 2 is warmed up or under low load operation. When the temperature is low, the heat exchange amount for heating the mixed fuel in the heating source is insufficient. And the mixed fuel before separation cannot be heated to the temperature necessary for separation, and the fuel separation performance is lowered.

  In addition, when a cooling means such as the radiator 16 using the outside air introduced by a fan, a blower or the like to cool the mixed fuel, the running wind, or the cooling medium heat-exchanged with these is used, the outside air temperature or the road surface temperature When the temperature is high, the amount of heat exchange for condensing and cooling the separated fuel is insufficient. In addition, a decrease in the condensation performance of the fuel after separation, deterioration of the fuel and fuel system parts, a large amount of fuel vapor generated due to fuel boiling, etc. are caused, which impedes fuel separation performance and safety.

  The present invention is for solving the above-mentioned problems, and its purpose is to reliably raise the temperature of the mixed fuel before separation to a temperature necessary for separation and to reliably cool the fuel after separation to a temperature that does not hinder it. An object of the present invention is to provide a fuel separation system for an internal combustion engine.

  The fuel separation system for an internal combustion engine of the present invention 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 (for example, described later). A fuel separation system (for example, a fuel separation system 1 described later) of the engine 2), a main tank (for example, a later-described main tank 10) for storing the mixed fuel, and a fuel passage (for example, A circulation passage (for example, a circulation passage 100 described later) for separating the mixed fuel supplied via the first fuel passage 101 described later into a high-octane fuel and a low-octane fuel; and a fuel flowing through the circulation passage; A heat exchanger (for example, a heat exchanger 11 described later) for exchanging heat with a cooling medium (for example, a cooling water described later) for cooling the internal combustion engine. A flow rate adjusting valve (for example, a flow rate adjusting valve 112 described later) for controlling the flow rate of the cooling medium flowing through the heat exchanger, and a cooling means (for example, a radiator 16 described later) for cooling the fuel flowing through the circulation passage. ) And temperature adjusting means (for example, ECU 5 described later) for adjusting the temperature of the fuel flowing through the circulation passage by controlling at least one of the flow rate adjusting valve or the cooling means. To do.

According to the present invention, the temperature adjusting means adjusts the temperature of the fuel flowing through the circulation passage by controlling at least one of the cooling means or the flow rate adjusting valve. That is, the fuel flowing through the circulation passage is heated by supplying it to a heat exchanger whose temperature can be adjusted by controlling the flow rate adjusting valve. And the heated fuel which distribute | circulates a circulation path is isolate | separated into a high octane number fuel and a low octane number fuel. Thereafter, the separated fuel flowing through the circulation passage is cooled by a cooling means that can control and adjust the temperature.
Here, if the amount of fuel flowing through the circulation passage is a part of the amount of fuel stored in the main tank, the heat mass of the fuel flowing through the circulation passage is small, and the temperature responsiveness of the fuel flowing through the circulation passage is small. Becomes better. For this reason, the temperature adjusting means can efficiently adjust the temperature of the fuel flowing through the circulation passage with good responsiveness.
Therefore, it is possible to reliably raise the temperature of the fuel before separation to a temperature necessary for separation, and it is possible to reliably cool the fuel after separation to a temperature that does not hinder.

  The temperature adjusting means preferably adjusts the temperature of the fuel flowing through the circulation passage based on the temperature of the fuel at a plurality of different locations in the circulation passage.

  A heat exchanger and cooling means are arranged in the circulation passage. For this reason, the temperature of the fuel flowing through the circulation passage rises on the downstream side of the heat exchanger, decreases on the downstream side of the cooling means, and is not constant in the circulation passage. According to the present invention, the temperature adjusting means adjusts the temperature of the fuel flowing through the circulation passage based on the temperature of the fuel at a plurality of different locations in the circulation passage. Therefore, the temperature adjusting means can accurately grasp the temperature of the fuel flowing through the circulation passage. For this reason, the temperature adjusting means can adjust the temperature of the fuel flowing through the circulation passage more efficiently and with good responsiveness.

  According to the present invention, it is possible to provide a fuel separation system for an internal combustion engine that reliably raises the temperature of a mixed fuel before separation to a temperature necessary for separation and reliably cools the fuel after separation to a temperature that does not hinder the separation. .

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 figure which shows the circuit of the fuel separation system of the engine which concerns on the said embodiment. It is a flowchart which shows the procedure of the fuel separation control which concerns on the said embodiment. It is a figure which shows the structure of the fuel separation system of the engine of a prior art.

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. FIG. 2 is a diagram illustrating a circuit of the fuel separation system 1 of the engine 2 according to the present embodiment.
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 low octane fuel tank 17, 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 the present embodiment, the most popular mixed fuel 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.
The upper space of the main tank 10 communicates with the upper space of the low octane fuel tank 17 described later. Thereby, the main tank 10 and the low octane fuel tank 17 are maintained at the same pressure. Even if an overflow occurs in the low octane fuel tank 17, the overflow can be stored in the main tank 10.

A first check valve 102 that prevents the flow of fuel from the heat exchanger 11 to the main tank 10 is provided on the main tank 10 side of the first fuel passage 101. A high-pressure fuel pump 103 is provided on the downstream side of the first check valve 102 in the first fuel passage 101. The rotational speed of the high-pressure fuel pump 103 is controlled by the ECU 5, whereby the mixed fuel in the main tank 10 is supplied into the heat exchanger 11 via 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 of the fuel 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 high-pressure fuel pump 103 via the first fuel passage 101 by heat exchange with the cooling water (LLC) of the engine 2. To do. Thereby, the temperature of the fuel supplied to the separation membrane 122 of the separator 12 to be described later is raised, and the separation efficiency by the separation membrane 122 is improved.
A cooling water passage 111 through which the cooling water for the engine 2 flows is connected to the heat exchanger 11, and the cooling water for the engine 2 flows through 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 a detection signal corresponding to the temperature of the cooling water. Is output to the ECU 5.
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 temperature of the fuel 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 in the first fuel passage 101 and is maintained at a high pressure by a high-pressure fuel pump 103 provided in the first fuel passage 101. 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 described later, and is maintained at a negative pressure by driving the negative pressure pump 141. 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. In this way, 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 condenses the high-octane fuel in the gaseous state. 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 negative pressure pump 141 is driven and 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 high octane fuel in the gaseous state is fed from the low pressure chamber 124 to the condenser. 13 is supplied and condensed.
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 upper space of the high octane fuel buffer tank 14 is connected to the lower part (reservoir) of the condenser 13 and to the intake side of a 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 by some fuel transportation means such as a fuel pump (not shown).

The high octane fuel tank 15 stores high octane fuel under atmospheric pressure. The upper space of the high octane fuel tank 15 is connected to the lower part (storage part) of the high octane fuel buffer tank 14.
The fuel passage connecting the high-octane fuel tank 15 and the lower part (storage part) of the high-octane fuel buffer tank 14 is provided with some fuel transportation means such as an open / close valve and a fuel pump (not shown). The (evaporated) fuel is transported to the high octane number fuel buffer tank 14.

  The lower part (reservoir) 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 space above the high octane fuel buffer tank 14.

  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.

  The upper space of the high octane fuel tank 15 is connected via a canister 18 and a two-way valve 153 described later. 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.

  The downstream side of the radiator 16 is connected to a low-octane fuel tank 17 and a second fuel passage 121 which will be described later. The second fuel passage 121 is provided with a second check valve 164 that blocks the flow of fuel from the low octane fuel tank 17 to the radiator 16. A fuel pressure regulator 165 is provided in the second fuel passage 121 on the upstream side of the second check valve 164. The fuel pressure regulator 165 is controlled by the ECU 5, thereby adjusting the fuel pressure of the fuel flowing in the second fuel passage 121.

Between the upstream side of the second check valve 164 of the second fuel passage 121 and the downstream side of the first check valve 102 of the first fuel passage 101, there is a bypass passage 162 that connects these fuel passages. Provided. More specifically, the bypass passage 162 includes a second fuel passage 121 between the second check valve 164 and the fuel pressure regulator 165, and a first fuel passage 101 between the first check valve 102 and the high pressure fuel pump 103. And
The bypass passage 162 is provided with a circulation control valve 163 that opens or closes the bypass passage 162. The opening / closing of the circulation control valve 163 is controlled by the ECU 5. The circulation control valve 163 is composed of, for example, an electromagnetic valve.
In addition, a high-octane component concentration sensor 166 such as an ethanol sensor is provided at the connection portion between the bypass passage 162 and the second fuel passage 121 as a high-octane component concentration detector that can detect or estimate the high-octane component concentration in the fuel. Provided. The high octane number component concentration sensor 166 detects the high octane number component concentration in the circulating fuel, and outputs a detection signal corresponding to the high octane number component concentration to the ECU 5.

When the circulation control valve 163 is opened, the bypass passage 162 is opened, whereby the first fuel passage 101, the second fuel passage 121, and the bypass passage 162 form the circulation passage 100 through which the low-octane fuel circulates. . As a result, the mixed fuel heated by the heat exchanger 11 and the low-octane fuel cooled by the radiator 16 circulate in the circulation passage 100 by driving the high-pressure fuel pump 103. Here, the amount of fuel circulating in the circulation passage 100 is smaller than the amount of fuel stored in the main tank 10 in a full tank.
Further, when the circulation control valve 163 is closed, the bypass passage 162 is blocked, and the circulation passage 100 is blocked. As a result, the low-octane fuel cooled by the radiator 16 is supplied into the low-octane fuel tank 17 described later via the second fuel passage 121. At the same time, the mixed fuel in the main tank 10 is supplied to the first fuel passage 101.

  The low-octane fuel stored in the low-octane fuel tank 17 is boosted to a predetermined pressure set by a fuel pressure regulator (not shown) by a fuel pump 171 provided at the lower part (storage part) of the low-octane fuel tank 17. It is pumped into the low octane fuel passage 172. The low-octane fuel thus pumped is pressurized by a high-pressure fuel pump (not shown) and then appropriately injected into the combustion chamber 20 of the engine 2 by the direct injection injector 52. The pressure of the fuel supplied to the direct injection injector and the injection timing and injection time of the direct injection injector 52 are controlled by the ECU 5.

  As described above, the upper space of the low octane fuel tank 17 communicates with the upper space of the main tank 10. The space above the low-octane fuel tank 17 is connected via a canister 18 and a two-way valve 173 described later. When the pressure in the canister 18 becomes higher than the pressure in the low-octane fuel tank 17 and the main tank 10, the evaporated fuel in the canister 18 is supplied into the low-octane fuel tank 17. On the other hand, when the pressure in the low octane fuel tank 17 and the main tank 10 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 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 during engine operation, when the canister control valve 181 is opened, ethanol and gasoline (hydrocarbon) adsorbed and held by the canister 18 are evaporated again. Evaporated fuel 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.
Note that 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 includes a fuel separation control unit that performs fuel separation control, which will be described later. The ECU 5 is connected to the various sensors described above 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. The ECU 5 is connected to the above-described various valves, pumps, fans, and the like in order to control the state of the engine 2 and the fuel separation system 1 and the state of the vehicle on which these are mounted.

  Next, fuel separation control of the fuel separation system 1 according to the present embodiment will be described. FIG. 3 is a flowchart showing a procedure of fuel separation control according to the present embodiment. This fuel separation control is repeatedly executed at a predetermined cycle after the ignition switch of the vehicle is turned on by the ECU 5.

  In step S1, the circulation control valve 163 is opened and the operation of the high-pressure fuel pump 103 is started. By opening the circulation control valve 163, the bypass passage 162 is opened to form the circulation passage 100, and a small amount of fuel is contained in comparison with the amount stored in the main tank 10 by the operation of the high-pressure fuel pump 103. It circulates in the circulation passage 100. In the process of circulating in the circulation passage 100, the fuel comes into contact with the separation membrane 122 a plurality of times, so that many of the high octane components are separated. Here, when the main tank 10 is refueled, the processing number n is set to zero.

  In step S2, it is determined whether or not the high octane component concentration in the fuel circulating through the circulation passage 100 detected by the high octane component concentration sensor 166 is equal to or higher than a predetermined threshold CL. If this determination is YES, it is determined that the current fuel separation has been completed, and the routine proceeds to step S3 where the fuel separation control end determination is made and the routine is ended. If this determination is NO, the process proceeds to step S4.

  In step S4, adjustment control is performed so that the temperature of the fuel circulating in the circulation passage 100 becomes a high temperature suitable for separation. The control of the fuel temperature is controlled by the ECU 5 by controlling the flow rate adjusting valve 112 that controls the flow rate of the cooling water to raise the temperature of the fuel by the heat exchanger 11 or by controlling the cooling fan 161 of the radiator 16 and by the radiator 16. Cool the fuel. The fuel temperature adjustment control method uses the detected temperature detected by the first temperature sensor 104 and the detected water temperature detected by the water temperature sensor 113 as initial values so that the detected temperature detected by the second temperature sensor 126 reaches the target temperature T1. In addition, the flow rate adjustment valve 112 and the cooling fan 161 are PID-controlled. For example, when the fuel circulating in the circulation passage 100 is initially replaced and the fuel temperature is lower than the target temperature T1, the ECU 5 fully opens the flow rate adjustment valve 112 and generates heat from the heat exchanger 11. While the amount is maximized, the cooling fan 161 is stopped to control the heat absorption amount of the radiator 16 to a minimum. When the fuel temperature is close to the target temperature T1, the ECU 5 finely adjusts the valve opening amount of the flow rate adjustment valve 112 and the rotation speed of the cooling fan 161 so that the fuel temperature converges to the target temperature T1. Control. As described above, the temperature of the fuel supplied from the main tank 10 as the detected temperature detected by the first temperature sensor 104 may be detected only at the time of replacement. The target temperature T1 is obtained by conducting an experiment in advance, and is set to a value that is not efficient for fuel separation because the temperature of the fuel circulating in the circulation passage 100 is too low and is not more than the upper limit. . Here, since the amount of fuel whose temperature is adjusted by circulating in the circulation passage 100 is small as compared with the amount stored in the main tank 10 in a full tank, it is likely to become a high temperature suitable for separation and has a temperature responsiveness. Good. When the process of step S4 ends, the process proceeds to step S5.

In step S5, it is determined whether or not the detected temperature detected by the second temperature sensor 126 (the temperature of the fuel circulating in the circulation passage 100) is equal to or higher than a predetermined temperature T2. The predetermined temperature T2 is obtained by conducting an experiment in advance, is a temperature lower than the target temperature T1, and is a temperature at which separation should be started in order to shorten the total separation time.
If this determination is NO, it is determined that the temperature of the fuel circulating in the circulation passage 100 is still not preferable for fuel separation, and the process returns to step S4. If this determination is YES, it is determined that the temperature of the fuel circulating in the circulation passage 100 is preferable for fuel separation, and the process proceeds to step S6.

  In step S6, the fuel separation control start determination is made at the time of the first processing of this routine and the processing after the n-th fuel separation control end determination of step S8, the number of processings n is set to n + 1, and negative. The operation of the pressure pump 141 is started. By operating the negative pressure pump 141, the low pressure chamber 124 of the separator 12 is set to a negative pressure, and the fuel circulating through the circulation passage 100 is started to be separated by the separator 12. Note that the fuel separation control start determination and the processing count n are not set to n + 1 except in the case of the first processing of this routine and the processing after the nth fuel separation control end determination in step S8. The operation of the negative pressure pump 141 is continued. When the process of step S6 ends, the process proceeds to step S7.

  In step S7, it is determined whether or not the high octane component concentration in the fuel circulating in the circulation passage 100 is equal to or higher than a predetermined threshold value CL. If this determination is NO, it is determined that the current fuel separation is completed, the process proceeds to step S8, the n-th fuel separation control end determination is performed, and the process proceeds to step S9. If this determination is YES, it is determined that the fuel circulating in the circulation passage 100 is being separated, and the process returns to step S4.

In step S9, it is determined whether or not the detected temperature detected by the second temperature sensor 126 (the temperature of the fuel circulating in the circulation passage 100) is equal to or higher than a predetermined temperature T3. The predetermined temperature T3 is obtained by conducting an experiment in advance, and is set to a value that is lower than the predetermined temperature T2 and equal to or lower than the boiling point of the temperature of the fuel circulating in the circulation passage 100. Since the radiator 16 is disposed downstream of the heat exchanger 11 during the circulation of the fuel in the circulation passage 100, the radiator outlet temperature is necessarily lower than the heat exchanger outlet temperature. The temperature sensor at the outlet of the radiator was omitted, and the temperature detected by the second temperature sensor 126 was used.
If this determination is YES, it is determined that the cooling control of the fuel temperature circulating in the circulation passage 100 is necessary, and the process proceeds to step S10 to start the cooling control of the fuel temperature. If this determination is NO, it is determined that the cooling control of the fuel temperature circulating in the circulation passage 100 is unnecessary, and the process proceeds to step S11. Here, when moving to step S11, cooling control in step S10 described later is stopped.

  In step S <b> 10, cooling control is performed so that the temperature of the fuel circulating in the circulation passage 100 becomes a low temperature suitable for discharging from the circulation passage 100. In the cooling control of the fuel temperature, the ECU 5 controls the flow rate adjusting valve 112 that controls the flow rate of the cooling water to stop the temperature rise of the fuel by the heat exchanger 11 and controls the cooling fan 161 of the radiator 16 to control the radiator 16. To cool the fuel. As a cooling control method for the fuel temperature, the ECU 5 fully closes the flow rate adjustment valve 112 to minimize the heat generation amount of the heat exchanger 11 and to set the maximum rotation amount of the cooling fan 161 to the maximum air flow rate and to the suction of the radiator 16. Control the amount of heat to the maximum. As a result, the amount of the fuel whose temperature is adjusted by circulating in the circulation passage 100 is small compared with the amount stored in the main tank 10 in a full tank. Can be cooled. When the process of step S10 ends, the process returns to step S9.

  In step S11, the start of replacement is determined, the circulation control valve 163 is closed to shut off the bypass passage 162, and the operation of the negative pressure pump 141 is stopped. When the operation of the negative pressure pump 141 is stopped, the separator 12 is stopped. At the same time, the timer t is reset to 0 and started. As a result, the operation of the high-pressure fuel pump 103 is continued, so that the low-octane fuel that has circulated in the circulation passage 100 is supplied to the low-octane fuel tank 17. Further, the mixed fuel is supplied from the main tank 10 to the first fuel passage 101. When the process of step S11 ends, the process proceeds to step S12.

  In step S12, it is determined whether or not the timer t is equal to or greater than a predetermined threshold value t1. The threshold value t1 is set in advance to the time required for the mixed fuel in the main tank 10 to be replaced with the low-octane fuel that has circulated in the circulation passage 100. If this determination is YES, it is determined that the replacement of fuel has been completed, the process proceeds to step S13 to determine completion of replacement / separation, the operation of the high-pressure fuel pump 103 is once stopped, and the process proceeds to step S1. If this determination is NO, it is determined that the fuel replacement has not been completed, and the process returns to step S12.

By repeating the above operation, the fuel is separated little by little, and high octane number fuel and low octane number fuel are produced little by little in a short time.
Further, the octane number of the high octane number fuel in the high octane number fuel buffer tank 14 varies with time as the fuel circulates in the circulation passage 100. On the other hand, the octane number of the high-octane fuel in the high-octane fuel buffer tank 14 at the time of completion of separation for each separation cycle is always stable. Therefore, since the stable octane number high-octane fuel is supplied to the high-octane fuel tank 15, the octane number of the high-octane fuel in the high-octane fuel tank 15 is stabilized. As a result, the octane number of the high octane fuel injected into the intake port 30 of the engine 2 is also stabilized.

Note that when the consumption of the low-octane component due to traveling is severe and the supply of low-octane fuel cannot catch up, the circulation control valve 163 is closed before the separation of the fuel circulating in the circulation passage 100 is completed. As a result, the fuel circulated in the circulation passage 100 is supplied to the low octane fuel tank 17. Although the high octane number component that could not be completely separated is consumed for traveling, the consumption of the high octane number component is suppressed as compared with the conventional case where the mixed fuel before separation is consumed for traveling.
In addition, when the low octane number fuel consumption due to traveling is small and the low octane number fuel tank 17 is full, the fuel separation is stopped. Alternatively, the overflow from the low-octane fuel tank 17 is supplied to the main tank 10 while continuing the fuel separation.

  Thereby, the high octane number component in the mixed fuel can be efficiently separated by performing the above operation according to the traveling state and the stocked state of the low octane number fuel and the high octane number fuel. Moreover, the octane number of the high octane fuel and the low octane fuel supplied to the engine 2 can be stabilized, the capacity of the low octane fuel tank 17, the high octane fuel buffer tank 14, and the high octane fuel tank 15 can be reduced, and the system can be downsized. .

  According to this embodiment, the following effects are produced.

According to the present embodiment, the ECU 5 controls the temperature of the fuel flowing through the circulation passage 100 by controlling the cooling fan 161 and the flow rate adjustment valve 112 of the radiator 16. That is, the fuel flowing through the circulation passage 100 is circulated and supplied to the heat exchanger 11 where the temperature can be adjusted by the control of the flow rate adjusting valve 112 to be heated. And the heated fuel which distribute | circulates the circulation path 100 is circulated, and it isolate | separates into a high octane number fuel and a low octane number fuel. Thereafter, the separated fuel flowing through the circulation passage 100 is circulated and cooled by the radiator 16 that can be controlled to adjust the temperature.
Here, since the amount of fuel flowing through the circulation passage 100 is a part (small amount) of the fuel stored in the main tank 10 in a full tank, the heat mass of the fuel flowing through the circulation passage 100 is small. The temperature responsiveness of the flowing fuel is improved. For this reason, the ECU 5 can adjust the temperature of the fuel flowing through the circulation passage 100 efficiently and with good responsiveness.
Therefore, it is possible to reliably raise the temperature of the fuel before separation to a temperature necessary for separation in a short time, and it is possible to reliably cool the fuel after separation to a temperature at which there is no problem. Also, the separation efficiency is good during separation.

  A heat exchanger 11 and a radiator 16 are disposed in the circulation passage 100. For this reason, the temperature of the fuel flowing through the circulation passage 100 increases on the downstream side of the heat exchanger 11 and decreases on the downstream side of the radiator 16 and is not constant in the circulation passage 100. According to the present embodiment, the ECU 5 adjusts the temperature of the fuel flowing through the circulation passage 100 based on the temperature of the fuel at a plurality of different locations in the circulation passage 100. Therefore, the ECU 5 can accurately grasp the temperature of the fuel flowing through the circulation passage 100. For this reason, ECU5 can adjust the temperature of the fuel which distribute | circulates the circulation path 100 more efficiently with sufficient responsiveness.

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 to be mixed with gasoline is not limited to ethanol, but may be methanol or butanol.

DESCRIPTION OF SYMBOLS 1 ... Fuel separation system 2 ... Engine 5 ... ECU (temperature control means)
DESCRIPTION OF SYMBOLS 10 ... Main tank 11 ... Heat exchanger 16 ... Radiator (cooling means)
100 ... circulation passage 101 ... first fuel passage (fuel passage)
112 ... Flow control valve

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 circulation passage for separating the mixed fuel supplied from the main tank through a fuel passage into a high octane fuel and a low octane fuel, and circulating the separated low octane fuel by bypassing the main tank ;
A heat exchanger that is provided in the middle of the circulation passage and exchanges heat between the fuel flowing through the circulation passage and a cooling medium that cools the internal combustion engine;
A flow rate adjusting valve for controlling the flow rate of the cooling medium flowing through the heat exchanger;
A cooling means provided in the middle of the circulation passage for cooling the fuel flowing through the circulation passage;
A fuel separation system for an internal combustion engine, comprising: temperature adjusting means for adjusting a temperature of fuel flowing through the circulation passage by controlling at least one of the flow rate adjusting valve or the cooling means.   2. The internal combustion engine according to claim 1, wherein the temperature adjusting unit adjusts the temperature of the fuel flowing through the circulation passage based on the temperature of the fuel at a plurality of different locations in the circulation passage. Fuel separation system.

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