JP2009185676A - Fuel supply device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inject heated fuel at an early stage in low temperature start of an engine. <P>SOLUTION: A heating delivery 35 is provided between a delivery pipe 33 and a fuel injection valve 21. A coil 40 for induction heating is disposed at an outside of the heating delivery 35. Fuel in the heating delivery 35 is heated by supplying high frequency alternating current to the coil 40 by a high frequency power source circuit 41 and heating the heating delivery 35 by induction heating. Since the heating delivery 35 itself can be made generate heat by induction heating, and fuel in the heating delivery 35 can be efficiently heated, time until temperature of the fuel is raised to startable temperature can be shortened. Since fuel in the heating delivery 35 provided near a fuel injection valve 21 is heated, time until fuel heated in the heating delivery 35 injected from injection start can be shortened. Consequently, heated fuel can be injected at the early stage and startability can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel supply device for an internal combustion engine having a function of heating fuel of the internal combustion engine.

  In recent years, in response to social demands such as CO2 emission reduction and the use of alternative fuels for oil, internal combustion engines that can use gasoline, alcohol (ethanol, methanol, etc.), and alcohol-mixed fuels that are a mixture of gasoline and alcohol can be used as fuels. The demand for onboard vehicles is increasing. However, alcohol has a higher flash point and a greater latent heat of vaporization (harder to vaporize) than gasoline, so when using alcohol fuel containing alcohol (alcohol or alcohol-mixed fuel), startability at low temperatures In particular, when a fuel having a high alcohol concentration is used, starting at a low temperature is expected to be difficult.

  As a countermeasure, as described in Japanese Patent Application Laid-Open No. 7-77130, in a fuel supply system that distributes fuel supplied from a fuel tank to a fuel injection valve via a delivery pipe, the fuel tank In some cases, a heater such as a heating wire or nichrome wire for heating the fuel is provided in the middle of a fuel passage connecting the delivery pipe and the delivery pipe.

In addition, as described in Patent Document 2 (Japanese Patent Laid-Open No. 2003-206821), there is also a fuel injection valve provided with a heater for heating the fuel.
Japanese Patent Laid-Open No. 7-77130 (page 3, FIG. 2, etc.) JP 2003-206821 A (2nd page, FIG. 1 etc.)

  However, in the technique disclosed in Patent Document 1, the fuel passage is heated by the heat of a heater (heating element) such as a heating wire disposed on the outer peripheral side of the fuel passage to heat the fuel in the fuel passage. It cannot be heated, and the time until the temperature of the internal combustion engine is raised to a temperature at which the internal combustion engine can be started is increased. In addition, since the heater is arranged in the fuel passage further upstream than the delivery pipe arranged upstream of the fuel injection valve, even if the fuel is heated by the heater at the low temperature start of the internal combustion engine, it takes a while from the start of injection. In the meantime, low-temperature unheated fuel downstream from the heater is injected, and then the fuel heated by the heater reaches the fuel injection valve and is injected, so the fuel heated by the heater from the start of injection The time until the fuel reaches the fuel injection valve and is injected becomes longer. For these reasons, when the internal combustion engine is started at a low temperature, the heated fuel (fuel that has been heated to a temperature that can be started) cannot be injected at an early stage, and the startup time required to complete the startup becomes longer. is there.

  Further, in the technique of Patent Document 2 described above, since the heater is disposed inside the fuel injection valve, the fuel heated by the heater can be injected from the beginning of the injection at the time of low temperature start of the internal combustion engine. There is a possibility that the precision fitting part and the resin part inside the valve will be damaged by the high heat of the heater and the fuel injection valve will fail.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to enable the fuel that is heated at the time of cold start of the internal combustion engine to be injected at an early stage, and to improve the startability at the time of cold start. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that can be improved and can prevent a failure of a fuel injection valve due to fuel heating.

  In order to achieve the above object, an invention according to claim 1 is directed to a fuel supply device for an internal combustion engine that supplies fuel supplied from a fuel tank to a fuel injection valve via a delivery, between the delivery and the fuel injection valve. A heating delivery is provided, and this heating delivery is heated by induction heating to provide an induction heating means for heating the fuel in the heating delivery.

  In this configuration, since the heating delivery itself can generate heat by induction heating and the fuel in the heating delivery can be heated, the heating delivery can be heated efficiently and the fuel in the heating delivery can be heated efficiently. The time until the temperature is raised to a temperature at which the temperature can be started (fuel temperature raising time) can be shortened. Furthermore, in order to heat the fuel in the heating delivery provided between the delivery and the fuel injection valve, the time from the start of injection until the fuel heated in the heating delivery reaches the fuel injection valve and is injected (heating) (Fuel arrival time) can be shortened. By both the effect of shortening the fuel temperature rise time and the effect of shortening the heated fuel arrival time, fuel that has been heated at the time of low-temperature start of the internal combustion engine (fuel that has been heated to a startable temperature) is injected at an early stage. As a result, the start time required to complete the start-up can be shortened, and the startability at the low-temperature start can be improved. Further, since the heating delivery upstream of the fuel injection valve is heated, it is possible to prevent the fuel injection valve from being broken due to heating.

  In this case, when a plurality of fuel injection valves are connected to the heating delivery as in claim 2, the length of the fuel flow path from the fuel inlet of the heating delivery to each of the fuel injection valves is substantially the same. good. In this way, the fuel heated in the heating delivery can be distributed almost evenly to each fuel injection valve, and the temperature of the fuel injected from each fuel injection valve can be made substantially uniform. It is possible to prevent variation in combustibility between the two.

  By the way, when the internal combustion engine is started at a low temperature, even if the fuel in the heating delivery is heated to a temperature at which the fuel temperature can be started before the injection starts, if the volume of the heating delivery is too small, The fuel that has been heated to the startable temperature within the heating delivery is consumed at an early stage after the start of injection, and the fuel that has been heated to the startable temperature cannot be continuously injected until the start is completed. There is sex. On the other hand, if the volume of the heating delivery becomes too large, it takes a long time to raise the fuel temperature in the heating delivery to a temperature at which it can be started.

  Therefore, as in claim 3, the volume of the heating delivery is a volume corresponding to the amount of fuel required to start the internal combustion engine at a low temperature (the integrated value of the fuel injection amount required from the start to the completion of the start). It is better to configure as follows. In this way, when the internal combustion engine is started at a low temperature, the fuel whose temperature has been raised to a startable temperature in the heating delivery can be continuously injected until the start is completed, and the volume of the heating delivery is minimized. The fuel temperature in the heating delivery can be raised to a temperature at which the fuel can be quickly started with a limited size.

  Further, as in claim 4, alcohol concentration determination means for detecting or estimating the alcohol concentration of the fuel supplied to the fuel injection valve, and temperature information of the internal combustion engine (temperature of the internal combustion engine or temperature information related thereto) ) For detecting the internal combustion engine temperature information, the fuel pressure detecting means for detecting the fuel pressure in the heating delivery, and the fuel temperature detecting means for detecting the fuel temperature in the heating delivery. Alternatively, the target fuel temperature is set by the target fuel temperature setting means based on the estimated alcohol concentration of the fuel, the temperature information of the internal combustion engine detected by the internal combustion engine temperature information detection means, and the fuel pressure detected by the fuel pressure detection means. The induction heating means is controlled by the fuel heating control means so that the fuel temperature in the heating delivery is raised to the target fuel temperature when the internal combustion engine is started at a low temperature. Unishi and may be.

  Generally, the startable fuel temperature changes according to the alcohol concentration of the fuel and the temperature of the internal combustion engine. Further, the fuel temperature at which vapor is generated changes according to the fuel pressure. Therefore, if the target fuel temperature is calculated based on the alcohol concentration of the fuel, temperature information of the internal combustion engine (for example, cooling water temperature, oil temperature, etc.) and the fuel pressure, the target fuel that can be started within a range in which vapor generation can be prevented. The temperature can be set. Then, by controlling the induction heating means to raise the fuel temperature in the heating delivery to the target fuel temperature when the internal combustion engine is started at a low temperature, the fuel temperature in the heating delivery is started quickly while preventing the generation of vapor. The temperature can be raised to a possible temperature.

  In this case, as in claim 5, after the fuel temperature in the heating delivery is raised to the target fuel temperature, the induction heating means is controlled so as to maintain the fuel temperature in the heating delivery at the target fuel temperature. good. In this way, the fuel temperature in the heating delivery can be stably maintained near the target fuel temperature.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 (internal combustion engine temperature information detecting means) for detecting the cooling water temperature and a knock sensor 29 for detecting knocking vibration are attached to the cylinder block of the engine 11. A crank angle sensor 28 that outputs a pulse signal every time the crankshaft 27 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 27. Based on the output signal of the crank angle sensor 28, the crank angle and engine The rotation speed is detected.

  The engine 11 can use any of gasoline, alcohol (ethanol, methanol, etc.), and alcohol mixed fuel obtained by mixing alcohol with gasoline as fuel, and refuel any of these gasoline, alcohol, alcohol mixed fuel. The engine 11 is supplied. A fuel pump 31 for pumping fuel is provided in the fuel tank 30 for storing fuel, and a fuel pipe 32 is connected to the fuel pump 31 via a filter 34. The fuel discharged from the fuel pump 31 is sent to the delivery pipe 33 through the fuel pipe 32, and is distributed from the delivery pipe 33 to the fuel injection valve 21 of each cylinder through the heating delivery 35 (see FIG. 2). The fuel supply system from the fuel tank 30 to the fuel injection valve 21 is provided with an alcohol concentration sensor 36 (alcohol concentration determination means) for detecting the alcohol concentration of the fuel at an appropriate location.

  As shown in FIG. 2, a plurality of (for example, two) heating delivery 35 is connected to the delivery pipe 33, and a plurality of (for example, two) fuel injection valves 21 are connected to each heating delivery 35. . Two communication passages 37 provided on both sides of the upper portion of the heating delivery 35 are connected to the delivery pipe 33, respectively, and the fuel flowing into the communication passage 37 from the delivery pipe 33 flows into the fuel flow provided in the upper center of the heating delivery 35. They merge at the inlet 38 and flow into the heating delivery 35. On the other hand, fuel injection valves 21 are respectively connected to two fuel outlets 39 provided on both lower sides of the heating delivery 35, and the length of the fuel flow path from the fuel inlet 38 of the heating delivery 35 to each fuel injection valve 21. Are made to be almost the same.

  The volume of the heating delivery 35 is a volume corresponding to the amount of fuel required to start the engine 11 at a low temperature (the integrated value of the fuel injection amount required from the start to the start completion). In this embodiment, For example, the volume corresponding to the amount of fuel for six injections of the fuel injection valve 21 is set.

  The heating delivery 35 is formed in a cylindrical shape with a metal material (for example, iron, stainless steel, etc.) having a relatively large resistance value suitable for induction heating, and an induction heating coil 40 is disposed outside the heating delivery 35. Yes. The coil 40 is connected to the high frequency power supply circuit 41, and a high frequency alternating current is passed through the coil 40, whereby the heating delivery 35 disposed in the coil 40 is heated by high frequency induction heating, and the fuel in the heating delivery 35 is heated. It is supposed to be. These coils 40 and the high-frequency power supply circuit 41 serve as induction heating means in the claims.

  The heating delivery 35 includes a fuel pressure sensor 42 (fuel pressure detecting means) for detecting the fuel pressure in the heating delivery 35 and a fuel temperature sensor 42 (fuel temperature detecting means) for detecting the fuel temperature in the heating delivery 35. It is attached.

  As shown in FIG. 1, the outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 44. The ECU 44 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 21 according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  Further, the ECU 44 executes a fuel heating control routine of FIG. 3 to be described later, so that when the engine 11 is started, a predetermined fuel heating region (for example, the coolant temperature is lower than a predetermined value and the alcohol concentration of the fuel is a predetermined value). If the fuel heating region is determined, it is determined that it is difficult to start unless the fuel is heated, and the alcohol concentration of the fuel, the cooling water temperature, A target fuel temperature is calculated based on the fuel pressure. Then, the high frequency alternating current supplied to the coil 40 is controlled by the high frequency power supply circuit 41 so as to raise the fuel temperature in the heating delivery 35 to the target fuel temperature, and the heating delivery 35 is heated by high frequency induction heating to be heated. The fuel in 35 is heated. After the fuel temperature in the heating delivery 35 has risen to the target fuel temperature, the energization of the coil 40 is turned on / off by the high frequency power supply circuit 41 so as to maintain the fuel temperature in the heating delivery 35 at the target fuel temperature. The high frequency induction heating of the heating delivery 35 is turned on / off.

Hereinafter, the processing content of the fuel heating control routine of FIG. 3 executed by the ECU 44 will be described.
The fuel heating control routine shown in FIG. 3 is executed at a predetermined cycle while the ECU 44 is powered on (when the ignition switch is on), and serves as fuel heating control means in the claims. When this routine is started, first, at step 101, it is determined whether or not the engine 11 has been started (before starting or during starting).

  If it is determined in step 101 that the engine 11 has not been started yet, the process proceeds to step 102 where the alcohol concentration of the fuel, the coolant temperature, the fuel pressure in the heating delivery 35, After reading the fuel temperature or the like in the heating delivery 35, the process proceeds to step 103, and whether or not the fuel heating region (for example, the region where the coolant temperature is lower than the predetermined value and the alcohol concentration of the fuel is higher than the predetermined value). Determine.

  If it is determined in step 103 that it is not in the fuel heating region, it is determined that the fuel can be started without heating the fuel, and the routine proceeds to step 108 where the coil 40 is energized by the high frequency power supply circuit 41. Keep it off and do not heat the fuel.

  On the other hand, if it is determined in step 103 that the fuel heating region is set, it is determined that it is difficult to start the fuel unless the fuel is heated, and the process proceeds to step 104, where the alcohol concentration of the fuel, the cooling water temperature, and the heating delivery are determined. The target fuel temperature is calculated by a map or a mathematical formula based on the fuel pressure in 35. The processing in step 104 serves as a target fuel temperature setting means in the claims.

  In general, the startable fuel temperature varies depending on the alcohol concentration of the fuel and the engine temperature. Further, the fuel temperature at which vapor is generated changes according to the fuel pressure. Therefore, if the target fuel temperature is calculated based on the alcohol concentration of the fuel, the coolant temperature (engine temperature information), and the fuel pressure, it is possible to set a target fuel temperature that can be started within a range in which vapor generation can be prevented. . In step 104, the cooling water temperature is used as the engine temperature information. However, the oil temperature or the engine temperature may be used instead of the cooling water temperature.

  Thereafter, the routine proceeds to step 105, where it is determined whether or not the fuel temperature in the heating delivery 35 is lower than the target fuel temperature, and when it is determined that the fuel temperature in the heating delivery 35 is lower than the target fuel temperature. In Step 106, the high-frequency alternating current applied to the coil 40 is controlled by the high-frequency power circuit 41 so that the fuel temperature in the heating delivery 35 is raised to the target fuel temperature, and the heating delivery 35 is heated by high-frequency induction heating. The fuel in the heating delivery 35 is heated. As a result, the temperature of the fuel in the heating delivery 35 is raised to a temperature at which it can be quickly started while preventing the generation of vapor.

  Thereafter, when it is determined in step 105 that the fuel temperature in the heating delivery 35 is equal to or higher than the target fuel temperature, the routine proceeds to step 107, where the high frequency is maintained so as to maintain the fuel temperature in the heating delivery 35 at the target fuel temperature. The power supply circuit 41 turns on / off the energization of the coil 40 to turn on / off the high frequency induction heating of the heating delivery 35. Thereby, the fuel temperature in the heating delivery 35 is stably maintained near the target fuel temperature.

  Thereafter, cranking of the engine 11 is started, fuel injection of the fuel injection valve 21 and ignition of the spark plug 22 are started, and when it is determined in step 101 that the start-up is completed, the process proceeds to step 108. Then, the coil 40 is turned off by the high frequency power supply circuit 41 to stop the heating of the fuel.

  In the present embodiment described above, since the heating delivery 35 itself can generate heat by high-frequency induction heating and the fuel in the heating delivery 35 can be heated, the fuel in the heating delivery 35 can be efficiently heated. The time until the temperature is raised to a temperature at which the temperature can be started (fuel temperature raising time) can be shortened. Furthermore, in order to heat the fuel in the heating delivery 35 provided between the delivery pipe 33 and the fuel injection valve 21, the fuel heated in the heating delivery 35 from the start of injection reaches the fuel injection valve 21 and is injected. It is possible to shorten the time until the heating time (heating fuel arrival time). By both the effect of shortening the fuel temperature rise time and the effect of shortening the heating fuel arrival time, the fuel heated at the time of low temperature start of the engine 11 (fuel that has been heated to a startable temperature) is injected at an early stage. As a result, the start time required to complete the start-up can be shortened, and the startability at the low-temperature start can be improved. Further, since the heating delivery 35 upstream of the fuel injection valve 21 is heated, it is possible to prevent the fuel injection valve 21 from being broken due to heating.

  Further, in this embodiment, the length of the fuel flow path from the fuel inlet 38 of the heating delivery 35 to each fuel injection valve 21 is made substantially the same, so that the fuel heated in the heating delivery 35 is converted to each fuel. The fuel can be distributed almost evenly to the injection valves 21 and the temperature of the fuel injected from each fuel injection valve 21 can be made substantially uniform, so that it is possible to prevent the startability from varying among the cylinders.

  Further, in the present embodiment, the volume of the heating delivery 35 becomes a volume corresponding to the amount of fuel necessary for starting the engine 11 at a low temperature (the integrated value of the fuel injection amount required from the start to the start completion). Therefore, when the engine 11 is started at a low temperature, the fuel whose temperature has been raised to the startable temperature in the heating delivery 35 can be continuously injected until the start is completed, and the volume of the heating delivery 35 is minimized. Thus, the fuel temperature in the heating delivery 35 can be raised to a temperature at which it can be started quickly.

  In the above embodiment, the alcohol concentration sensor 36 detects the alcohol concentration of the fuel. However, in the case of a system that does not include the alcohol concentration sensor, for example, the air-fuel ratio feedback correction amount during the previous operation, The alcohol concentration of the fuel may be estimated based on at least one of an air-fuel ratio shift amount, combustion stability (engine rotation fluctuation), engine torque, and the like.

  In addition, the shape and attachment method (connection method) of the heating delivery 35 are appropriately changed, and the control method for heating the fuel in the heating delivery 35 by heating the heating delivery 35 by induction heating is appropriately changed. It goes without saying that it is also good.

  In addition, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, but includes an in-cylinder injection type engine, and both an intake port injection fuel injection valve and an in-cylinder injection fuel injection valve. It can also be applied to dual-injection engines.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is sectional drawing of a heat delivery and its peripheral part. It is a flowchart explaining the flow of a process of a fuel heating control routine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 21 ... Fuel injection valve, 26 ... Cooling water temperature sensor (internal combustion engine temperature information detection means), 30 ... Fuel tank, 33 ... Delivery pipe, 35 ... Heating delivery, 36 ... Alcohol concentration sensor (alcohol (Concentration determination means), 37 ... communication passageway, 38 ... fuel inlet, 39 ... fuel outlet, 40 ... coil (induction heating means), 41 ... high frequency power circuit (induction heating means), 42 ... fuel pressure sensor (fuel pressure detection) Means), 43 ... fuel temperature sensor (fuel temperature detection means), 44 ... ECU (target fuel temperature setting means, fuel heating control means)

Claims (5)

In a fuel supply device for an internal combustion engine that supplies fuel supplied from a fuel tank to a fuel injection valve via a delivery,
A heating delivery provided between the delivery and the fuel injection valve;
An internal combustion engine fuel supply apparatus comprising: an induction heating unit configured to heat the heating delivery by induction heating to heat the fuel in the heating delivery.   A plurality of fuel injection valves are connected to the heating delivery, and the length of the fuel flow path from the fuel inlet of the heating delivery to each fuel injection valve is substantially the same. The fuel supply device for an internal combustion engine according to claim 1.   3. The fuel supply device for an internal combustion engine according to claim 1, wherein the volume of the heating delivery is configured to correspond to a volume of fuel necessary for starting the internal combustion engine at a low temperature. Alcohol concentration determination means for detecting or estimating the alcohol concentration of fuel supplied to the fuel injection valve;
Internal combustion engine temperature information detecting means for detecting temperature information of the internal combustion engine;
Fuel pressure detecting means for detecting the fuel pressure in the heating delivery;
Fuel temperature detection means for detecting the fuel temperature in the heating delivery;
Based on the alcohol concentration of the fuel detected or estimated by the alcohol concentration determination means, the temperature information of the internal combustion engine detected by the internal combustion engine temperature information detection means, and the fuel pressure detected by the fuel pressure detection means Target fuel temperature setting means for setting
4. A fuel heating control means for controlling the induction heating means so as to raise the fuel temperature in the heating delivery to the target fuel temperature when the internal combustion engine is started at a low temperature. The fuel supply device for an internal combustion engine according to any one of the above.   The fuel heating control means controls the induction heating means so as to maintain the fuel temperature in the heating delivery at the target fuel temperature after the fuel temperature in the heating delivery has been raised to the target fuel temperature. The fuel supply device for an internal combustion engine according to claim 4.

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