JP5387475B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that uses a low volatility fuel such as alcohol fuel.

  As a conventional technique, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2007-224878), a control device for an internal combustion engine using alcohol fuel is known. Since alcohol fuel is difficult to vaporize particularly at low temperatures, the internal combustion engine of the prior art is provided with a vaporization chamber for vaporizing the fuel at start-up. The vaporizing chamber has a sealed structure that is blocked from the outside, and is connected to the intake passage through a throttle passage. Further, the vaporizing chamber is provided with a starting fuel injection valve for injecting fuel therein and a heater for heating the injected fuel.

  When starting the internal combustion engine, first, the heater is operated when a start signal is output to the internal combustion engine, and then fuel is injected from the start fuel injection valve into the vaporization chamber when an appropriate time has elapsed. To do. When fuel is injected, the vaporization chamber is in a decompressed state due to the intake negative pressure due to cranking. As a result, the injected fuel is vaporized by receiving the heat of the heater in the vaporization chamber in the decompressed state, and is supplied to each cylinder through the intake passage. As described above, in the prior art, fuel is vaporized in the vaporizing chamber at the time of starting, thereby ensuring startability at the time of cold starting or the like.

JP 2007-224878 A JP 2007-270654 A

  By the way, in the above-described prior art, after starting the heater at the start, fuel is injected into the vaporizing chamber to generate vaporized fuel. However, in this case, after the start signal is output to the internal combustion engine, the heater is heated, the injected fuel is heated, and the vaporization chamber is depressurized. As a result, vaporized fuel is generated. For this reason, in the prior art, there is a problem that it takes time to generate the vaporized fuel at the time of starting, and the vaporized fuel cannot be quickly supplied into the cylinder.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to quickly supply vaporized fuel into a cylinder even in a situation where the fuel is difficult to vaporize, such as at low temperature start. Another object of the present invention is to provide a control device for an internal combustion engine that can improve startability.

A first invention is a fuel tank for storing fuel;
A fuel injection valve for injecting fuel in the fuel tank into the intake passage and / or the combustion chamber;
A vaporized fuel tank connected to the intake passage and storing vaporized fuel vaporized by the fuel;
In-tank fuel supply means for supplying fuel in the fuel tank to the vaporized fuel tank;
A normally-closed vaporized fuel supply valve that opens and closes a connection between the vaporized fuel tank and the intake passage;
A first vaporized fuel generating means for driving the fuel supply means in the tank with the vaporized fuel supply valve closed during operation of the internal combustion engine to generate vaporized fuel in the vaporized fuel tank;
Start control that opens the vaporized fuel supply valve while performing cranking and supplies vaporized fuel stored in the vaporized fuel tank to the intake passage during operation when an internal combustion engine start request is generated Means,
If the internal combustion engine does not start even if vaporized fuel is supplied to the intake passage, a negative pressure is generated that generates a negative pressure in the vaporized fuel tank using the cranking and then closes the vaporized fuel supply valve. Generating means;
Second vaporized fuel generating means for driving the fuel supply means in the tank after the vaporized fuel supply valve is closed by the negative pressure generating means;
When new vaporized fuel is generated in the vaporized fuel tank by the second vaporized fuel generation means, the vaporized fuel supply valve is opened while cranking is performed, and the new vaporized fuel is supplied to the intake air. Restart control means for supplying the passage;
It is characterized by providing.

  The second invention includes auxiliary fuel injection means for driving the fuel injection valve when vaporized fuel is supplied by the restart control means.

A third invention includes a throttle valve provided in the intake passage upstream of the vaporized fuel supply valve,
The negative pressure generating means is configured to hold the throttle valve in a fully closed state when generating a negative pressure in the vaporized fuel tank.

4th invention is provided in the position which can connect the inside and external space of the said vaporization fuel tank, and is provided with the normally-closed air introduction valve which opens together with the said vaporization fuel supply valve at the time of supply of vaporization fuel,
The negative pressure generating means is configured to open the vaporized fuel supply valve and close the atmosphere introduction valve when generating a negative pressure in the vaporized fuel tank.

  In the fifth invention, alcohol fuel is used as the fuel.

  According to the first invention, vaporized fuel can be generated in the vaporized fuel tank by the first vaporized fuel generating means during operation of the internal combustion engine. And after an engine stop, vaporized fuel can be stored using the natural pressure reduction which arises in a tank. Thereby, the start control means can quickly supply the vaporized fuel into the cylinder at the start, and can improve the startability even at the low temperature start. In addition, when the vaporized fuel in the tank is insufficient at the time of starting, the negative pressure can be generated in the tank using the cranking by the negative pressure generating means. And the 2nd vaporized fuel production | generation means can produce | generate vaporized fuel efficiently in a short time by this negative pressure state. Therefore, the restart control means can quickly supply the newly generated vaporized fuel into the cylinder, and can smoothly perform the restart after the vaporized fuel is once insufficient.

  According to the second invention, the auxiliary fuel injection means can drive the fuel injection valve when the vaporized fuel is supplied by the restart control means. Thereby, at the time of restart after the shortage of vaporized fuel, in addition to the newly generated vaporized fuel, the injected fuel can also be supplied into the cylinder, and the internal combustion engine can be started more reliably.

  According to the third invention, the negative pressure generating means can hold the throttle valve in the fully closed state when generating the negative pressure in the vaporized fuel tank. Thereby, a large negative pressure can be efficiently generated in the vaporized fuel tank.

  According to the fourth aspect of the invention, the air introduction valve is opened when the vaporized fuel is supplied, and air can flow into the tank by the amount of vaporized fuel that has flowed out of the vaporized fuel tank. Accordingly, the vaporized fuel can be supplied smoothly. Further, when generating a negative pressure in the vaporized fuel tank, the air introduction valve can be closed by the negative pressure generating means, and the vaporized fuel tank can be kept sealed from the outside other than the intake system. .

  According to the fifth aspect of the present invention, even when alcohol fuel that is difficult to vaporize at low temperatures is used, vaporized fuel is stored in the vaporized fuel tank during operation of the internal combustion engine, and the vaporized fuel is supplied at the time of start-up. Can be improved.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a block diagram which shows the control system of the system in Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 1 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 2 of this invention, it is a flowchart which shows the control performed by ECU.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
The first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system of the present embodiment includes an engine 10 as an internal combustion engine mounted on an FFV (Flexible Fuel Vehicle). Although FIG. 1 illustrates a four-cylinder engine, the internal combustion engine of the present invention is not limited to four cylinders. The engine 10 includes an intake passage 12 that sucks intake air into a combustion chamber of each cylinder, and an exhaust passage 14 through which exhaust gas is discharged from the combustion chamber.

  In the intake passage 12, an air cleaner 16, a throttle valve 18 and a surge tank 20 are provided in order from the upstream side. The throttle valve 18 is configured by an electronically controlled butterfly valve that is opened and closed between a fully closed position and a fully opened position, and adjusts the amount of intake air flowing through the intake passage 12 according to the opening degree. The surge tank 20 forms a space having a certain extent in the middle of the intake passage 12 in order to exhibit an attenuation effect of intake pulsation and the like. The downstream side of the surge tank 20 is connected to the intake port 24 of each cylinder via an intake manifold 22 composed of a plurality of intake pipes. The surge tank 20, the intake manifold 22 and the intake port 24 constitute a part of the intake passage 12.

  Each cylinder of the engine 10 is provided with an intake port injection valve 26 that injects fuel into the intake port 24 and an in-cylinder injection valve 28 that directly injects fuel into the combustion chamber (inside the cylinder). Further, each cylinder is provided with an ignition plug 30 (see FIG. 2) for igniting the vaporized fuel, and an intake valve and an exhaust valve (not shown). The injection valves 26 and 28 are configured to be supplied with alcohol fuel stored in a liquefied state in a fuel tank 32 of the vehicle.

  The engine 10 also includes a starter motor 34 that rotationally drives the crankshaft at the start. When the driver of the vehicle turns on the starter switch, an engine start request is issued to the ECU 60 described later. Thereby, the ECU 60 executes the operation (cranking) for starting the starter motor 34 and rotating the crankshaft, and stops the cranking when the engine is started, that is, when it shifts to the independent operation.

  Next, the fuel vaporization system mounted on the engine 10 will be described. The present embodiment is characterized in that vaporized fuel generated during operation of the engine is stored in a tank, and this vaporized fuel is used at the next start. The fuel vaporization system includes a vaporized fuel tank 36, an in-tank injection valve 38, a vaporized fuel supply valve 40, an air introduction valve 42, a relief valve 44, and the like described below.

  The vaporized fuel tank 36 is formed as a pressure-resistant container having a sealed structure, and is configured to store vaporized fuel obtained by vaporizing alcohol fuel in the fuel tank 32. The vaporized fuel tank 36 is installed at a position where heat is easily conducted from the engine 10 in, for example, the engine room. The in-tank injection valve 38 injects (supplies) the fuel stored in the fuel tank 32 into the vaporized fuel tank 36, and constitutes the in-tank fuel supply means of the present embodiment. The in-tank injection valve 38 is constituted by a general fuel injection valve similar to the injection valves 26 and 28, for example, and the fuel injection amount is controlled in accordance with a control signal. The fuel injected from the in-tank injection valve 38 is vaporized in the vaporized fuel tank 36 to become vaporized fuel.

  The vaporized fuel tank 36 is connected to the surge tank 20 on the downstream side of the throttle valve 18. The connecting portion is provided with a vaporized fuel supply valve 40 constituted by a normally closed solenoid valve or the like. When the vaporized fuel supply valve 40 is closed, the vaporized fuel tank 36 and the surge tank 20 are disconnected, and vaporized fuel can be stored in the vaporized fuel tank 36. Further, when the vaporized fuel supply valve 40 is opened, the tanks 20 and 36 are communicated with each other, and the vaporized fuel stored in the vaporized fuel tank 36 is supplied to the surge tank 20.

  The vaporized fuel tank 36 is provided with an air introduction valve 42 at a position where the inside of the tank can communicate with the external space. The atmosphere introduction valve 42 is constituted by a normally closed electromagnetic valve or the like, and the vaporized fuel tank 36 is released to the atmosphere when the valve is opened. At the time of supplying the vaporized fuel, the vaporized fuel supply valve 40 and the atmosphere introduction valve 42 are opened together with a slight time difference, and the atmosphere is introduced into the vaporized fuel tank 36 from the atmosphere introduction valve 42 by the amount of the vaporized fuel supplied. The These valves 40 and 42 are kept closed except when vaporized fuel is supplied. The air introduction valve 42 is connected to the intake passage 12 between the air cleaner 16 and the throttle valve 18. For this reason, when the air introduction valve 42 is opened, air that has been cleaned by the air cleaner 16 and is not affected by the negative intake pressure is introduced into the vaporized fuel tank 36.

  Further, the vaporized fuel tank 36 is provided with a normally closed relief valve 44 constituted by, for example, a check valve, a reed valve or the like. The relief valve 44 releases the pressure to the outside (for example, the intake passage 12) when the pressure in the vaporized fuel tank 36 exceeds a predetermined operating pressure. The operating pressure of the relief valve 44 is, for example, a large value. It is set to a pressure of about atmospheric pressure or a pressure about several tens of kPa higher than atmospheric pressure. This setting is based on the premise that, for example, the vaporized fuel tank 36 is maintained at a temperature of about room temperature or slightly higher than that, and the saturated vapor pressure of the fuel becomes a pressure corresponding to this temperature region. Accordingly, the relief valve 44 is configured to release the air in the tank to the outside when the fuel injected into the vaporized fuel tank 36 is vaporized. The relief valve 44 also has a function as a safety valve that prevents the pressure in the tank from becoming excessive when the vaporized fuel tank 36 is sealed.

  Next, the control system of the engine 10 will be described with reference to FIG. FIG. 2 is a configuration diagram showing a control system of the system according to the first embodiment of the present invention. As shown in this figure, the system of the present embodiment includes a sensor system including a plurality of sensors 46 to 56 and an ECU (Electronic Control Unit) 60 that controls the operating state of the engine 10.

  First, the sensor system will be described. The crank angle sensor 46 outputs a signal synchronized with the rotation of the crankshaft of the engine 10, and the ECU 60 can detect the engine speed and the crank angle based on this output. it can. The air flow sensor 48 detects the amount of intake air, and the water temperature sensor 50 detects the temperature of engine cooling water. The tank pressure sensor 52 detects the pressure in the vaporized fuel tank 36, and the tank temperature sensor 54 detects the temperature in the vaporized fuel tank 36. Further, the fuel property sensor 56 detects the alcohol concentration in the fuel as the property of the fuel.

  The sensor system includes various sensors (for example, an air-fuel ratio sensor for detecting the exhaust air-fuel ratio, a throttle sensor for detecting the opening degree of the throttle valve 18) other than the sensors 46 to 56, which are necessary for controlling the vehicle and the engine. An accelerator opening degree sensor for detecting the accelerator opening degree) is included, and these sensors are connected to the input side of the ECU 60. The present invention does not necessarily require the tank temperature sensor 54. For example, the tank temperature sensor 54 is not used, and the tank temperature is based on the engine temperature, operation history, heat conduction characteristics to the vaporized fuel tank 36, and the like. The internal temperature may be estimated.

  On the other hand, on the output side of the ECU 60, various actuators including a throttle valve 18, injection valves 26, 28, and 38, a spark plug 30, a starter motor 34, a vaporized fuel supply valve 40, an air introduction valve 42, and the like are connected. . The ECU 60 detects the operation information of the engine by the sensor system, and controls the operation by driving each actuator based on the detection result. Specifically, the engine speed and the crank angle are detected based on the output of the crank angle sensor 46, and the intake air amount is detected by the air flow sensor 48. Further, while performing the normal fuel injection control described below, the ignition timing is determined based on the crank angle, and the spark plug 30 is driven.

  The normal fuel injection control is executed during the operation of the engine except when vaporized fuel supply control, which will be described later, is executed, and includes fuel injection control at start-up. In this fuel injection control, the fuel injection amount is calculated based on the intake air amount, the engine speed, the engine coolant temperature, etc., and the fuel injection timing is determined based on the crank angle, and then the injection valves 26 and 28 are driven. To do. In this case, the ratio of the injection amounts of the intake port injection valve 26 and the in-cylinder injection valve 28 is variably set according to the operating state of the engine and the properties of the fuel. Further, the ECU 60 executes vaporized fuel generation control and vaporized fuel supply control described below as control of the fuel vaporization system.

[Operation of Embodiment 1]
(Vaporized fuel generation control)
The vaporized fuel generation control is to vaporize the fuel in the vaporized fuel tank 36 during the operation of the engine 10 (preferably during the operation after the warm-up is completed) to generate vaporized fuel. More specifically, in the vaporized fuel generation control, fuel is injected from the in-tank injection valve 38 with the vaporized fuel supply valve 40 and the air introduction valve 42 closed. At this time, the fuel injection amount is determined so that all of the injected fuel is vaporized based on the temperature in the vaporized fuel tank 36, the alcohol concentration in the fuel, and the like. The injected fuel quickly evaporates and becomes vaporized fuel while expelling air in the tank from the relief valve 44. At this time, the relief valve 44 can prevent the vaporization of the fuel from being suppressed by the air pressure in the tank, and can promote the generation of the vaporized fuel. As a result, the vaporized fuel tank 36 is finally filled with vaporized fuel.

  By the vaporized fuel generation control described above, vaporized fuel can be stored in the vaporized fuel tank 36 during engine operation. And the vaporized fuel tank 36 can hold | maintain at least one part of vaporized fuel in a gaseous-phase state also at the time of the cold after an engine stop using the natural pressure reduction produced in a tank. The vaporized fuel generation control is preferably executed only when the temperature in the vaporized fuel tank 36 is equal to or higher than a predetermined determination temperature at which vaporized fuel can be generated.

(Vaporized fuel supply control)
In the vaporized fuel supply control, the vaporized fuel supply valve 40 and the air introduction valve 42 are opened when the engine is started, and the vaporized fuel stored in the vaporized fuel tank 36 is supplied to the surge tank 20. More specifically, first, the ECU 60 detects that a start request has occurred when the starter switch is turned on, and starts cranking. As a result, an intake negative pressure is generated in the surge tank 20 due to cranking. Therefore, the ECU 60 opens the vaporized fuel supply valve 40 and the air introduction valve 42 and takes the vaporized fuel in the vaporized fuel tank 36 into the intake negative. The surge tank 20 is supplied by pressure.

  At this time, air flows from the air introduction valve 42 into the vaporized fuel tank 36 by the amount of vaporized fuel that has flowed out, so that vaporized fuel can be supplied smoothly. When opening the atmosphere introduction valve 42, if the pressure in the vaporized fuel tank 36 is equal to or higher than the atmospheric pressure, the vaporization fuel supply valve 40 is first opened and then the atmosphere introduction valve 42 is opened. . On the other hand, when the pressure in the tank is lower than the atmospheric pressure, the air introduction valve 42 is first opened and then the vaporized fuel supply valve 40 is opened. Thereby, it is possible to prevent the vaporized fuel in the tank from flowing out into the atmosphere and the air from flowing back from the surge tank 20 into the vaporized fuel tank 36.

  The vaporized fuel supplied from the vaporized fuel tank 36 to the surge tank 20 flows into the cylinder via the intake port 24, and is ignited and burned in the cylinder. As a result, when the combustion in each cylinder continues, the engine speed increases and the engine shifts to a self-sustained operation. The ECU 60 stops the cranking when it is confirmed by the increase in the engine speed that the self-sustained operation is started. Further, the vaporized fuel supply valve 40 and the air introduction valve 42 are closed, and the vaporized fuel supply control is ended. Then, normal fuel injection control for injecting fuel from the intake port injection valve 26 and the in-cylinder injection valve 28 is started.

  As described above, when the vaporized fuel stored during the operation of the engine is used, the vaporized fuel can be quickly supplied into the cylinder as compared with the case where the vaporized fuel is generated at the time of starting. Even at a low temperature start that is difficult to achieve, startability can be improved. Note that the vaporized fuel supply control is preferably executed only when the engine temperature at the time of starting (for example, the temperature of engine cooling water or the like) is equal to or lower than a predetermined determination temperature that requires vaporized fuel.

  The above-described vaporized fuel supply control can exert an effect by storing a sufficient amount of vaporized fuel during operation of the engine. However, for example, when an operation that is stopped in a short time after the engine is started (so-called short trip operation) is repeated, the amount of vaporized fuel stored in the vaporized fuel tank 36 tends to be insufficient. If the engine is cold started in this state, there is a problem that a sufficient amount of vaporized fuel is not supplied to the intake system and the startability is deteriorated. For this reason, in the present embodiment, if the engine does not start even when vaporized fuel is supplied, it is determined that the vaporized fuel is insufficient, and vaporized fuel is newly generated and then restarted. Fuel replenishment control is executed.

(Vaporized fuel replenishment control)
In the vaporized fuel supplement control, first, when it is determined that there is not enough vaporized fuel, the vaporized fuel supply valve 40 is opened, the air introduction valve 42 is closed, and the throttle valve 18 is held in the fully closed position. As a result, the inside of the vaporized fuel tank 36 is sealed from the outside other than the intake system. Then, cranking is continued in this state. As a result, a large negative pressure is generated by cranking on the downstream side of the throttle valve 18, and this negative pressure also acts in the vaporized fuel tank 36 via the surge tank 20 and the like. The pressure drops rapidly. At this time, when the throttle valve 18 is fully closed, a large negative pressure can be efficiently generated in the vaporized fuel tank.

  Next, the ECU 60 closes the vaporized fuel supply valve 40 and temporarily stops cranking when the pressure in the vaporized fuel tank 36 is sufficiently reduced. Thereby, the inside of the vaporized fuel tank 36 is sealed in a reduced pressure state, and the fuel is easily vaporized. For this reason, the ECU 60 drives the in-tank injection valve 38 to inject fuel into the vaporized fuel tank 36. Since the injected fuel quickly becomes vaporized fuel under a reduced pressure atmosphere, the ECU 60 restarts cranking at a point in time when a predetermined time when it can be considered that vaporized fuel has been sufficiently generated has elapsed. 40 is opened. Thereby, the vaporized fuel newly generated in the tank is supplied into the surge tank 20 by the intake negative pressure. Therefore, even when the vaporized fuel is insufficient at the start, the engine 10 can be started smoothly.

[Specific Processing for Realizing Embodiment 1]
Next, specific processing for realizing the above-described control will be described with reference to FIGS. 3 and 4. First, FIG. 3 is a flowchart showing vaporized fuel generation control executed by the ECU in the first embodiment of the present invention. The routine shown in FIG. 3 is repeatedly executed during operation of the engine.

  In the routine shown in FIG. 3, first, the temperature T in the vaporized fuel tank 36 is detected by the tank temperature sensor 54 (step 100), and it is determined whether or not this tank temperature T is higher than the determination temperature T1 (step 100). 102). Here, the determination temperature T1 is set corresponding to the lower limit value of the temperature at which vaporized fuel can be generated, and is a determination temperature for permitting fuel injection in the tank. When the determination in step 102 is satisfied, since the temperature of the fuel is easily vaporized, the amount of fuel injected into the vaporized fuel tank 36 is calculated, and the vaporized fuel supply valve 40 and the air introduction valve 42 are closed. The inner injection valve 38 is driven (step 104). Thereby, vaporized fuel is stored in the vaporized fuel tank 36.

  Next, FIG. 4 is a flowchart showing vaporized fuel supply control and vaporized fuel replenishment control executed by the ECU in the first embodiment of the present invention. The routine shown in this figure is repeatedly executed during operation of the engine. In the routine shown in FIG. 4, first, it is determined whether or not the ignition switch (IGSW) is turned on (step 200). When this determination is satisfied, it is determined whether or not an engine start request has occurred (step 200). Step 202). If a start request is generated, the starter motor 34 is activated and cranking is started (step 204).

  Next, the vaporized fuel supply valve 40 and the air introduction valve 42 are opened, and vaporized fuel is supplied from the vaporized fuel tank 36 to the surge tank 20 using the intake negative pressure generated by cranking (step 206). In the case where the vaporized fuel is supplied only at the cold start, it is determined whether or not the temperature in the tank is equal to or higher than the determination temperature immediately before executing step 206. If this determination is satisfied, the process proceeds to step 208. If the determination is not satisfied, the process proceeds to step 210.

  In the next process, it is determined whether or not the engine has been started (step 208). Specifically, in step 208, it is determined that the engine has been started, for example, when the engine speed exceeds a predetermined determination speed corresponding to the cranking speed. When the engine is started, the vaporized fuel supply valve 40 and the air introduction valve 42 are closed, the vaporized fuel supply control is terminated, and the routine proceeds to normal fuel injection control (step 210).

  On the other hand, in step 208, if the engine speed is equal to or lower than the determination speed, the process waits until the engine speed increases. However, if the predetermined time has elapsed since the start of cranking with this standby operation continued, it is determined that the engine will not start due to a lack of vaporized fuel, and vaporization is performed after step 212. Fuel replenishment control is executed.

  In the vaporized fuel replenishment control, as described above, first, a negative pressure is generated in the vaporized fuel tank 36 (step 212). Then, the pressure in the vaporized fuel tank 36 (tank pressure) P is detected by the tank pressure sensor 52, and it is determined whether or not the tank pressure P is equal to or lower than a predetermined determination pressure P0 (step 214). Here, for example, the determination pressure P0 is set as a pressure value corresponding to a negative pressure state in which the fuel is easily vaporized in the vaporized fuel tank 36, and is stored in the ECU 60 in advance. Even if the pressure in the tank is high, the fuel is easily vaporized if the temperature is high by that amount. For this reason, the determination pressure P0 may be variably set according to the temperature so that the higher the temperature in the tank, the higher the pressure value.

  If the determination in step 214 is satisfied, the vaporized fuel tank 36 is in a sufficiently negative pressure state, so the vaporized fuel supply valve 40 is closed to seal the tank (step 216), and the starter motor 34 is stopped (step 218). Then, the in-tank injection valve 38 is driven to inject fuel into the vaporized fuel tank 36 (step 220). In the next process, it is determined whether or not a predetermined time has passed when it can be considered that vaporized fuel has been sufficiently generated, and the process waits until this determination is satisfied (step 222). When the determination in step 222 is satisfied, the starter motor 34 is restarted (step 224), and the vaporized fuel supply valve 40 and the atmosphere introduction valve 42 are opened to supply vaporized fuel to the intake system (step 226).

  As described above in detail, according to the present embodiment, when the vaporized fuel in the vaporized fuel tank 36 is insufficient at the time of starting, negative pressure is easily generated in the vaporized fuel tank 36 using cranking. be able to. And by this negative pressure state, vaporized fuel can be produced | generated efficiently in a short time. Therefore, the newly generated vaporized fuel can be quickly supplied into the cylinder, and the restart after the vaporized fuel is once insufficient can be smoothly performed.

  In the first embodiment, steps 100 to 104 shown in FIG. 3 show a specific example of the first vaporized fuel generating means in claim 1. Steps 200 to 206 shown in FIG. 4 show a specific example of the start control means in claim 1, and step 212 shows a specific example of the negative pressure generating means. Further, step 220 shows a specific example of the second vaporized fuel generating means, and steps 224 and 226 show a specific example of the restart control means.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. Although the present embodiment employs substantially the same configuration and control as in the first embodiment (FIGS. 1, 2, and 3), when supplying newly generated vaporized fuel at start-up, the fuel A feature is that the auxiliary injection is performed by the injection valve. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
In the present embodiment, the auxiliary fuel injection control is executed when restarting after the vaporized fuel is once insufficient. In the auxiliary fuel injection control, either one or both of the intake port injection valve 26 and the in-cylinder injection valve 28 are driven, and the injected fuel is supplied into the cylinder in addition to the vaporized fuel.

[Specific Processing for Realizing Embodiment 2]
Next, specific processing for realizing the above-described control will be described with reference to FIG. FIG. 5 is a flowchart showing the control executed by the ECU in the second embodiment of the present invention. The routine shown in this figure is executed repeatedly during the operation of the engine instead of the routine shown in FIG. 4 of the first embodiment. In the routine shown in FIG. 5, first, in steps 300 to 326, processing similar to that in steps 200 to 226 shown in FIG. 4 is executed. In step 328, when newly generated vaporized fuel is supplied to the surge tank 20, at least one of the intake port injection valve 26 and the in-cylinder injection valve 28 is driven, and auxiliary fuel injection control is executed.

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as in the first embodiment. In particular, in this embodiment, since the auxiliary fuel injection is performed, at the time of restart after the shortage of vaporized fuel, the injected fuel is supplied into the cylinder in addition to the newly generated vaporized fuel. And the engine can be started more reliably.

  In the second embodiment, steps 300 to 306 shown in FIG. 5 show a specific example of the start control means in claim 1, and step 312 shows a specific example of the negative pressure generating means. Step 320 shows a specific example of the second vaporized fuel generation means in claim 1, steps 324 and 326 show a specific example of the restart control means, and step 328 shows a specific example of the auxiliary fuel injection means in claim 2. ing.

  In the embodiment, the surge tank 20 has been described as an example of the supply portion of the vaporized fuel to the intake passage 12. However, the present invention is not limited to this, and the vaporized fuel tank 36 may be connected to any part of the intake passage 12 and the vaporized fuel may be supplied to this part as long as it is downstream of the throttle valve 18. .

  In the embodiment, the vaporized fuel tank 36 is arranged in a place where heat from the engine 10 is easily transmitted. However, the present invention is not limited to this, and the vaporized fuel tank 36 may be positively heated by the heat generated by the engine 10. For example, a cooling water pipe may be provided between the engine 10 and the vaporized fuel tank 36, and the vaporized fuel tank 36 may be heated by the engine cooling water. Further, a heat conducting member such as a heat pipe may be provided between the exhaust passage 14 and the vaporized fuel tank 36, and the vaporized fuel tank 36 may be heated by the exhaust heat. With these configurations, the saturated vapor pressure of the fuel in the vaporized fuel tank 36 can be increased, and the amount of vaporized fuel that can be stored can be increased.

  Further, in the embodiment, the engine 10 including both the intake port injection valve 26 and the in-cylinder injection valve 28 has been described as an example. However, the present invention is not limited to this, and the present invention may be applied to an internal combustion engine that does not include any one of the injection valves 26 and 28 but includes only the other.

  In the embodiment, the engine 10 using alcohol fuel has been described as an example. However, the present invention is not limited to this, and can be applied to normal gasoline and various fuels obtained by adding components other than alcohol to gasoline.

10 Engine (Internal combustion engine)
12 Intake passage 14 Exhaust passage 16 Air cleaner 18 Throttle valve 20 Surge tank (intake passage)
22 Intake manifold (intake passage)
24 Intake port (intake passage)
26 Intake port injection valve (fuel injection valve)
28 In-cylinder injection valve (fuel injection valve)
32 Fuel tank 34 Starter motor 36 Vaporized fuel tank 38 Injection valve in tank (fuel supply means in tank)
40 Vaporized fuel supply valve 42 Air introduction valve 44 Relief valve 52 Tank pressure sensor 54 Tank temperature sensor 56 Fuel property sensor 60 ECU

Claims (5)

A fuel tank for storing fuel;
A fuel injection valve for injecting fuel in the fuel tank into the intake passage and / or the combustion chamber;
A vaporized fuel tank connected to the intake passage and storing vaporized fuel vaporized by the fuel;
In-tank fuel supply means for supplying fuel in the fuel tank to the vaporized fuel tank;
A normally-closed vaporized fuel supply valve that opens and closes a connection between the vaporized fuel tank and the intake passage;
A first vaporized fuel generating means for driving the fuel supply means in the tank with the vaporized fuel supply valve closed during operation of the internal combustion engine to generate vaporized fuel in the vaporized fuel tank;
Start control that opens the vaporized fuel supply valve while performing cranking and supplies vaporized fuel stored in the vaporized fuel tank to the intake passage during operation when an internal combustion engine start request is generated Means,
If the internal combustion engine does not start even if vaporized fuel is supplied to the intake passage, a negative pressure is generated that generates a negative pressure in the vaporized fuel tank using the cranking and then closes the vaporized fuel supply valve. Generating means;
Second vaporized fuel generating means for driving the fuel supply means in the tank after the vaporized fuel supply valve is closed by the negative pressure generating means;
When new vaporized fuel is generated in the vaporized fuel tank by the second vaporized fuel generation means, the vaporized fuel supply valve is opened while cranking is performed, and the new vaporized fuel is supplied to the intake air. Restart control means for supplying the passage;
A control device for an internal combustion engine, comprising:   The control apparatus for an internal combustion engine according to claim 1, further comprising auxiliary fuel injection means for driving the fuel injection valve when vaporized fuel is supplied by the restart control means. A throttle valve provided in the intake passage upstream of the vaporized fuel supply valve;
The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the negative pressure generating means is configured to hold the throttle valve in a fully closed state when generating a negative pressure in the vaporized fuel tank. A normally closed air introduction valve which is provided at a position where the inside of the vaporized fuel tank and the external space can communicate with each other, and which opens together with the vaporized fuel supply valve when vaporized fuel is supplied;
The negative pressure generating means is configured to open the vaporized fuel supply valve and close the atmosphere introduction valve when generating a negative pressure in the vaporized fuel tank. The control device for an internal combustion engine according to any one of the preceding claims.   The control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein alcohol fuel is used as the fuel.

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