JP2009156056A - Engine start control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device for an engine capable of suppressing deterioration of emission as well as securing starting performance when the engine is started after oil supply during engine stopping. <P>SOLUTION: A start control device of the engine 100 equipped with a fuel injection valve 41 supplied with fuel in a fuel tank 45 via fuel pipes 42, 46 sets a fuel injection amount based on a property of the fuel and injects the fuel from the fuel injection valve 41. The start control device comprises fuel property learning means S102, S103 for determining the property of the fuel during engine operation and updating the fuel property as a learning value, an oil supply determining means S112 for determining whether the fuel is supplied into the fuel tank 45 during engine stopping or not, and a first-time start control means S114 for setting the fuel injection amount based on the fuel property learning value before the oil supply and starting the engine. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine start control device that sets a fuel injection amount based on fuel properties.

  Fuels having different vaporization characteristics (hereinafter referred to as “fuel properties”), such as light fuel and heavy fuel, are used for vehicle engines. In order to cope with this difference in fuel properties, engines that detect fuel properties and control the fuel injection amount based on the detected fuel properties are widely known. However, an engine that detects the fuel property during engine operation has a problem that when the fuel is supplied when the engine is stopped, the fuel property of the supplied fuel cannot be specified until the engine is started.

Patent Document 1 discloses an engine that determines whether or not fuel is supplied while the engine is stopped, and determines a fuel injection amount at the time of starting the engine based on a result of the fuel supply determination. That is, in the engine described in Patent Document 1, when it is determined that fuel has been refueled while the engine is stopped, the fuel injection amount is increased from that of light fuel so as to be compatible with heavy fuel with the worst vaporization characteristics. Start the engine. Thereby, regardless of the fuel properties of the fuel supplied when the engine is stopped, it is possible to ensure the engine starting performance and driving performance.
JP-A-7-286549

  By the way, even when the fuel is supplied when the engine is stopped, the fuel before refueling remains between the fuel injection valve and the fuel pipe, so the engine is started like the engine described in Patent Document 1. Therefore, there are cases where it is not possible to cope with the actual fuel properties of the fuel used. In other words, if the fuel remaining in the fuel injection valve or the like is a light fuel that is easily vaporized, the air-fuel ratio becomes over-rich if the engine is started by controlling the fuel injection so that it matches the heavy fuel. Emissions get worse.

  Therefore, the present invention has been made paying attention to such a problem, and in the engine start when the fuel is supplied when the engine is stopped, the engine capable of ensuring the start performance and suppressing the deterioration of the emission. An object of the present invention is to provide a fuel injection control device.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes a fuel injection valve (41) to which fuel in a fuel tank (45) is supplied via a fuel pipe (42, 46), and sets the fuel injection amount based on the fuel property of the fuel. A start control device for an engine (100) that injects fuel from an injection valve (41), wherein the fuel property learning means (S102, S102) determines the fuel property of the fuel during engine operation and updates the fuel property as a learning value. S103), a fuel supply determination means (S112) for determining whether or not fuel has been supplied into the fuel tank (45) while the engine is stopped, and a fuel property learning value before fuel supply in the case of the first engine start after fuel supply. And an initial start control means (S114) for starting the engine by setting the fuel injection amount based on the above.

  According to the present invention, when the engine is started for the first time after refueling, the fuel injection amount is set based on the fuel property learning value before refueling. Therefore, even if the fuel is supplied while the engine is stopped and the fuel before refueling remains between the fuel injection valve and the fuel pipe, the engine starting performance can be ensured and the emission deteriorates. Can be suppressed. In this way, in order to consider the fuel before refueling remaining in the fuel injection valve, fuel is injected in vain compared to the conventional method of setting the fuel injection amount as heavy fuel every time the engine is started after refueling The fuel efficiency is improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an engine according to the first embodiment.

  The engine 100 is a port injection engine that injects fuel into an intake port, and is disposed in front of the vehicle. This engine 100 forms an intake port 2 and an exhaust port 3 in a cylinder head 1 as shown in FIG. The intake port 2 and the exhaust port 3 communicate with the combustion chamber 4.

  An intake manifold 21 is connected to the intake port 2. An intake passage 22 is connected to the intake manifold 21.

  The intake passage 22 allows air taken from outside to flow to the intake port 2 via the intake manifold 21. An air flow meter 23 and a throttle valve 24 are sequentially arranged in the intake passage 22 from the upstream side of the intake passage.

  The air flow meter 23 is a hot wire type air flow meter. The air flow meter 23 detects the amount of intake air taken into the engine 100.

  The throttle valve 24 is installed in the intake passage 22 on the downstream side of the air flow meter 23. The throttle valve 24 adjusts the amount of intake air introduced into the combustion chamber 4 by changing the intake flow area of the intake passage 22. The intake air that has passed through the throttle valve 24 is distributed to each cylinder of the engine 100 via the intake manifold 21.

  A fuel injection device 40 is installed in the intake manifold 21. The fuel injection device 40 is a device that injects fuel into the intake port, and includes a fuel injection valve 41, a delivery pipe 42, a pressure regulator 43, a fuel pump 44, and a fuel tank 45.

  The fuel injection valve 41 is installed in the intake manifold 21 and is provided for each cylinder of the engine 100. The fuel supplied to the fuel injection valve 41 is stored in the fuel tank 45. The fuel tank 45 is disposed at the rear of the vehicle. The fuel stored in the fuel tank 45 is discharged from a fuel pump 44 provided in the fuel tank. The discharged fuel flows through the fuel pipe 46 arranged under the floor of the vehicle from the rear of the vehicle toward the front, and is supplied to the delivery pipe 42. The delivery pipe 42 is provided with a pressure regulator 43. The pressure regulator 43 adjusts the fuel pumped from the fuel pump 44 to a predetermined pressure. The pressure regulator 43 supplies fuel from the return pipe 47 to the fuel tank 45 when the fuel pressure is higher than a predetermined value with respect to the suction negative pressure so as to make the differential pressure between the suction negative pressure of the engine and the fuel pressure constant. The fuel pressure is adjusted by returning to step (1). Then, the fuel adjusted to a predetermined pressure by the pressure regulator 43 is supplied to the fuel injection valve 41 via the delivery pipe 42. The fuel injection valve 41 injects fuel according to the engine operating state into the intake manifold to form an air-fuel mixture.

  The fuel tank 45 is provided with a fuel level sensor 48 that detects the amount of fuel stored in the fuel tank.

  On the other hand, an exhaust manifold 31 is connected to the exhaust port 3. An exhaust passage 32 is connected to the intake manifold 31. A three-way catalyst 33 is disposed in the exhaust passage 32. An air-fuel ratio sensor 34 is installed in the exhaust passage 32 upstream of the three-way catalyst 33. The air-fuel ratio sensor 34 detects the oxygen concentration in the exhaust flowing in the exhaust passage and outputs it to the controller 50 described later.

  The engine 100 also includes an intake valve 5 that opens and closes the intake port 2 and an exhaust valve 6 that opens and closes the exhaust port 3 in the cylinder head 1.

  The intake valve 5 is driven by an intake camshaft (not shown). When the intake valve 5 opens the intake port 2, the air-fuel mixture formed in the intake port is introduced into the combustion chamber 4, and the introduced air-fuel mixture is ignited by an ignition plug 7 installed in the upper portion of the combustion chamber and explosive combustion To do. The exhaust valve 6 installed in the cylinder head 1 is driven by an exhaust camshaft (not shown), and the exhaust valve 6 opens the exhaust port 3 so that the exhaust generated by combustion is discharged to the exhaust port 3. The exhaust gas flows through the exhaust passage 32, is purified by the three-way catalyst 33, and is discharged to the outside.

  The engine 100 includes a controller 50 for determining the fuel property of the fuel injected from the fuel injection valve 41 and controlling the fuel injection amount based on the fuel property. The controller 50 includes a microcomputer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). In addition to the air flow meter 23, the air-fuel ratio sensor 34, and the fuel level sensor 48, the controller 50 receives output signals from sensors that detect engine operating conditions such as the accelerator pedal sensor 51, the ignition switch 52, and the crank angle sensor 53. To do. The controller 50 determines the fuel property based on the detection signals from the various sensors described above, and controls the fuel injection valve 41 and the like.

  In the engine 100 configured as described above, since fuels having different fuel properties such as light fuel and heavy fuel are used, the fuel property of the fuel supplied to the fuel injection valve 41 is based on the air-fuel ratio feedback correction amount. The fuel injection amount is adjusted based on the fuel properties.

  By the way, in the conventional method of detecting the fuel property during engine operation, when fuel is supplied when the engine is stopped, the fuel property of the supplied fuel cannot be specified until the engine is started. For this reason, the conventional engine determines whether or not fuel has been refueled while the engine is stopped. When it is determined that fuel has been refueled, the heavy fuel having the worst vaporization characteristics regardless of the fuel properties of the refueled fuel. The engine start performance is ensured by starting the engine by increasing the fuel injection amount so as to meet the above requirements.

  However, even when fuel is supplied when the engine is stopped, the fuel before refueling remains in the fuel injection valve and the fuel pipe. Therefore, when the fuel remaining in the fuel injection valve is light fuel that is easily vaporized, the engine is started by controlling the fuel injection so that it matches the heavy fuel as in the conventional method. Even if the performance can be ensured, the air-fuel ratio becomes over-rich, so that there is a problem that the emission deteriorates.

  Therefore, in the engine 100 according to the present embodiment, when fuel is supplied while the engine is stopped, the fuel properties learned and stored before refueling are taken into account before refueling remaining in the fuel injection valve 41 and the like. By determining the fuel injection amount based on the engine and starting the engine, the starting performance is ensured and the deterioration of the emission is suppressed.

  Control executed by the controller 50 of the engine 100 of this embodiment will be described with reference to FIGS.

  FIG. 2 is a flowchart showing a control routine for determining fuel properties. This control is performed together with the start of engine operation, and is performed at a constant cycle, for example, a cycle of 10 milliseconds until the end of engine operation.

  In step S101, the controller 50 determines whether or not the engine 100 is idling after being warmed up based on detection values of the air flow meter 23, the accelerator pedal sensor 51, the crank angle sensor 53, and the like. When the engine 100 is idling after being warmed up, the routine proceeds to step S102 in order to determine the fuel property. In other cases, the process ends without determining the fuel property.

In step S102, the controller 50 determines the fuel property f _new of the fuel injected from the fuel injection valve 41 based on the air-fuel ratio feedback correction amount when the air-fuel ratio is feedback controlled according to the detection value of the air-fuel ratio sensor 34. Determination is made, and the process proceeds to step S103. For example, when the fuel injection amount during operation is determined on the assumption that the fuel is light fuel, the fuel property f _new of the current fuel is heavy fuel when the feedback correction amount exceeds the reference range. Is determined. Similarly, when the fuel injection amount is determined on the assumption that the fuel is heavy fuel, when the feedback correction amount exceeds the reference range, it is determined that the fuel property f _new of the current fuel is light fuel. To do.

In step S103, the controller 50 learns the fuel property f _new determined in step S102, stores it as the fuel property learned value f _learn , and ends the process.

As described above, in the present embodiment, during idle operation after the engine 100 is warmed up, the fuel property f _new of the fuel injected from the fuel injection valve 41 is determined, and the fuel property f _new is updated as the learning value f _learn. To do. The engine 100 configured as described above starts the engine according to the flowcharts shown in FIGS. 3 to 5 when fuel is supplied while the engine is stopped.

  FIG. 3 is a flowchart showing the control executed by the controller 50 when the engine is started. This control is performed when the engine is started.

  In step S111, the controller 50 determines whether or not there is an engine start request based on the output signal from the ignition switch 52.

  When the ignition switch 52 is switched from OFF to ON, it is determined that there is an engine start request, and the process proceeds to Step S112. In other cases, it is determined that there is no engine start request, and the process is terminated.

  In step S112, the controller 50 determines whether or not fuel has been supplied into the fuel tank while the engine is stopped based on the amount of fuel detected by the fuel level sensor 48.

  When the deviation between the fuel amount in the fuel tank when the engine is restarted after the engine is stopped and the fuel amount in the fuel tank before the engine is stopped is larger than a predetermined value, it is determined that the fuel is supplied while the engine is stopped, The process moves to step S113. In other cases, it is determined that fuel is not being supplied while the engine is stopped, and the process proceeds to step S116.

  In step S113, the controller 50 determines whether or not it is the first engine start after refueling. This can be determined by counting the number of starts after refueling based on the output signal from the ignition switch 52, and is reset to zero when refueling. And when it is the first engine start after refueling, it moves to step S114. On the other hand, when the engine is started for the second time after refueling, the process proceeds to step S115.

  In step S114, the controller 50 executes initial start control. Details of the initial start control will be described later with reference to FIG.

  In step S115, the controller 50 executes start control after the first time. Details of the starting control after the first time will be described later with reference to FIG.

In step S116, the controller 50 executes normal start control. This normal start control is executed when the engine is started when fuel is not being supplied. When the fuel is not supplied, there is no change in the fuel property in the fuel tank, so the fuel injection amount is set based on the learned value f _learn of the fuel property before the engine is stopped. For example, when the learned value f _learn of the fuel property before the engine is stopped is heavy fuel, the fuel injection amount is set larger than that in the case of light fuel.

  Next, the initial start control will be described with reference to FIG. FIG. 4 is a flowchart showing the initial start control executed by the controller 50.

  When the engine is started for the first time after being refueled while the engine is stopped, initial start control is performed as shown in FIG.

  In step S141, the controller 50 determines whether or not a predetermined time (for example, three months) has elapsed since the fuel was supplied into the fuel tank until the first engine start.

  The time from when the fuel is supplied until the first engine start is measured, and when this measured time has passed three months, the process proceeds to step S144. In step S144, the controller 50 sets the fuel injection amount on the assumption that the fuel is heavy fuel, and injects the fuel from the fuel injection valve 41 based on the fuel injection amount. As described above, when the engine is started after a long period of time after refueling, the fuel injection amount is set assuming that the fuel is heavy fuel. The fuel remaining in the fuel injection valve 41 or the like This is because even if it is a light fuel, it will change to a heavy fuel over time.

  On the other hand, when the time from the fuel supply to the first engine start does not exceed 3 months, the process proceeds to step S142.

In step S142, similarly to the normal start control in step S116, the controller 50 sets the fuel injection amount based on the fuel property learning value f _learn before refueling, and controls the fuel injection valve 41 to inject fuel.

When the engine is started immediately after refueling or the like, the fuel before refueling remains in the fuel injection valve 41, the fuel pipe 46, etc., even if fuel having a property different from that of the fuel before refueling is refueled. . Therefore, when the engine is started for the first time after refueling, the fuel injection amount is not set as heavy fuel, and fuel injection is performed based on the fuel property learning value f _learn before refueling, that is, the fuel property of the fuel before refueling. Set the amount.

  After the engine is started in step S142, in step S143, the controller 50 calculates the fuel consumption integrated value S by integrating the amount of fuel consumed during engine operation, and ends the process. The fuel consumption integrated value S can be calculated based on the fuel injection pulse of the fuel injection valve 41 set according to the engine operating state. This fuel consumption integrated value S is used in the starting control after the first time described later.

As described above, at the time of the first engine start after refueling, the fuel before refueling remaining in the fuel injection valve 41 and the like is taken into account, and fuel injection is basically performed based on the fuel property learning value f _learn before refueling. Set the amount. After the engine is started in this way, when the engine 100 enters a warm-up idle operation state, the fuel property f _new is determined according to the flowchart of FIG. 2, and the fuel property learning value f _learn is updated. However, since the fuel before refueling remains in the fuel injection valve 41 or the like, whether the fuel property learning value f _learn updated after refueling is the result of determining the fuel property of the fuel before refueling or after refueling. It cannot be determined whether the fuel property of the fuel has been determined. Therefore, when the engine is started for the first time after refueling, the fuel property learning value f _learn is updated and the engine is stopped. Thereafter, when the engine is restarted, fuel injection is performed based on the fuel property learning value f _learn as in the initial start control. Setting the amount may degrade start-up performance and emissions.

For example, in the case where the fuel before refueling is light fuel and the refueled fuel is heavy fuel, the first engine start after refueling and the fuel properties (light fuel) before refueling during the engine operation ). After that, when there is no opportunity to determine the fuel properties and all the light fuel before refueling has been consumed and switched to the heavy fuel after refueling, the engine 100 stops and the first time the engine is started after the second refueling. When the engine is started with the same control as the start control, the fuel injection amount is set as light fuel based on the fuel property learning value f _learn even though the actual fuel is heavy fuel. If the amount is insufficient, the starting performance will deteriorate.

Therefore, in the engine start after the second refueling, if the fuel property learning value f _learn is updated after refueling, whether the updated learned value f _learn is the fuel property of the fuel before refueling, or after refueling The fuel injection amount is set based on the fuel property learning value f _learn according to the result and the deterioration of the starting performance and the emission is suppressed.

  The first and subsequent start control performed at the second and subsequent engine start after refueling will be described with reference to FIG. FIG. 5 is a flowchart showing the starting control after the first time executed by the controller 50.

In step S151, the controller 50 determines whether or not the fuel property learning value f _learn has been updated after refueling. When the fuel property learning value f _learn is updated after refueling, it is determined whether the updated fuel property learning value f _learn is the fuel property of the fuel before refueling or the fuel property of the fuel after refueling. Therefore, the process proceeds to step S152. In cases other than that described here, process flow proceeds to Step S154.

In step S152, the controller 50 determines whether the fuel-consumption cumulative value S when the fuel property learned value f _learn is updated after refueling is larger than a predetermined value S _0. Here, the reference predetermined value S ₀ is determined from the capacities of the fuel injection valve 41, the delivery pipe 42, and the fuel pipe 46, and is set based on the sum of the capacities, for example.

When the fuel consumption integrated value S is larger than the predetermined value S ₀ , the fuel property of the fuel after refueling is determined after all the fuel before refueling remaining in the fuel injection valve 41 or the like is consumed. _Assuming that the fuel property learning value f _learn has been updated, the process proceeds to step S153. On the other hand, when the fuel consumption integrated value S is smaller than the predetermined value S ₀ , the fuel property of the fuel before refueling is determined and the fuel property learning value f _learn is updated, and the process proceeds to step S154. .

In step S153, the controller 50 sets the fuel injection amount based on the fuel property learning value f _learn updated after refueling. Then, the controller 50 controls the fuel injection valve 41 so as to inject the fuel with the set fuel injection amount, starts the engine 100, and ends the process. Since matching the fuel property by the fuel property and fuel property learned value f _learn of the fuel injected from the fuel injection valve 41 when the engine is started, the fuel injection by setting the fuel injection amount based on the fuel property learned value f _learn Even so, the starting performance and emission of the engine 100 are not deteriorated.

  In step S154, the controller 50 sets the fuel injection amount on the assumption that the fuel is heavy fuel, controls the fuel injection valve 41 to inject the fuel, and starts the engine.

When the fuel property learning value has not been updated after refueling (No in S151) or when the fuel property of the fuel before refueling is learned (No in S152), it is injected from the fuel injection valve 41 when the engine is started. The fuel property of the fuel to be obtained does not necessarily match the fuel property based on the fuel property learning value f _learn . In such a case, the engine 100 is started by giving priority to the starting performance and the driving performance by setting the fuel injection amount so as to be suitable for the heavy fuel.

  In step S155, after the engine is started in step S154, the controller 50 continues to calculate the fuel consumption integrated value S from the previous start and ends the process.

  As described above, the following effects can be obtained in the first embodiment.

  Even when the fuel is supplied while the engine is stopped, the fuel before refueling remains between the fuel injection valve 41 and the fuel pipe 46. Therefore, the engine 100 does not refuel before the first engine start after refueling. The fuel injection amount is set based on the fuel property learning value. Therefore, at the time of the first engine start after refueling, start performance can be ensured, and deterioration of emissions can be suppressed. In addition, in the engine 100, since the fuel before refueling remaining in the fuel injection valve 41 is taken into consideration, the fuel injection amount is not set as heavy fuel every time the engine is started after refueling unlike the conventional method. In addition, it is possible to reduce unnecessary fuel injection and improve fuel efficiency.

  Also, when starting the engine for the first time after refueling, if the engine start is started after a long time has elapsed since the fuel was refueled in the fuel tank, the fuel injection amount is set assuming that the fuel is heavy fuel. . Therefore, even when the fuel remaining in the fuel injection valve 41 or the like and the supplied fuel are changed to heavy fuel due to changes over time, the startability at the time of starting the engine can be ensured and the deterioration of the emission is suppressed. can do.

Further, when the engine start is performed for the second and subsequent times after refueling, and the fuel property learning value is updated after refueling, the fuel consumption integrated value S at the time of learning value update is greater than the predetermined value S ₀ , and Only when it is determined that the fuel property of the fuel has been learned, the fuel injection amount is set based on the fuel property learning value. Therefore, even when the engine is started for the second time after refueling, it is possible to ensure the starting performance at the time of starting the engine and to suppress the deterioration of the emission.

(Second Embodiment)
The engine 100 of the second embodiment is substantially the same as that of the first embodiment, but is partially different in the way of determining fuel properties during engine operation. That is, the fuel property is determined based on the degree of change in the rotational speed immediately after the engine is started, and the difference will be mainly described below.

  FIG. 6 is a flowchart showing a control routine for fuel property determination in the second embodiment. This control is performed together with the start of engine operation.

  In step S201, the controller 50 determines whether or not it is within a predetermined period immediately after the engine is started. This predetermined period is a period from when fuel is injected into the first cylinder at the time of starting the engine until fuel is sequentially injected into the other cylinders to make a round. If it is a predetermined period immediately after the engine is started, the process proceeds to step S202 to determine the fuel property. If not, the process ends without determining the fuel property.

  The fuel property is judged within such a predetermined period because the engine temperature is relatively low immediately after the engine is started and the difference in vaporization characteristics between heavy fuel and light fuel becomes large. Because it is easy to do.

  In step S202, the controller 50 calculates the engine rotation speed change degree ΔW for each cylinder, and proceeds to step S203. The engine rotation speed change degree ΔW is an angular acceleration calculated from a difference between the maximum angular velocity in the expansion stroke and the angular velocity at the compression top dead center. The angular speed used for the engine rotational speed change degree ΔW is calculated based on the output signal of the crank angle sensor 53.

In step S203, the controller 50 determines the fuel property f _new based on the engine rotational speed change degree ΔW, and proceeds to step S204.

  For example, if the fuel injected from the fuel injection valve 41 is a heavy fuel that is difficult to vaporize, a part of the heavy fuel injected from the fuel injection valve 41 remains as a wall flow in the intake port. Therefore, even if this heavy fuel is injected in the same amount as the light fuel, the ratio of fuel to the intake air (mixture concentration) is lower in the case of heavy fuel than in the case of light fuel. Therefore, when the fuel injected from the fuel injection valve 41 is a heavy fuel, the maximum angular velocity in the expansion stroke and the angular velocity at the compression top dead center are lower than in the case of injecting the light fuel, thereby the engine. The rotational speed change degree ΔW also decreases.

Therefore, in the present embodiment, it is determined whether the fuel is heavy fuel or light fuel based on the engine rotation speed change degree ΔW that changes due to the fuel property. That is, when one of the calculated engine rotation speed change degrees ΔW of each cylinder is larger than the predetermined value ΔW ₀ , it is determined that the fuel injected from the fuel injection valve 41 is light fuel. On the contrary, when all the engine rotation speed change degrees ΔW of the respective cylinders are smaller than the predetermined value ΔW _0, it is determined that the fuel injected from the fuel injection valve 41 is heavy fuel.

In step S204, the controller 50 learns the fuel property f _new determined in step S203, stores it as the fuel property learning value f _learn , and ends the process. As described above, in this embodiment, within a predetermined period immediately after the engine start, it is determined fuel property f _{new new} fuel injected from the fuel injection valve 41 based on the engine rotational speed variation degree [Delta] W, the fuel property f _{new new} It is updated as the learning value f _learn .

  The engine 100 configured as described above starts the engine according to the flowcharts shown in FIGS. 3 to 5 as in the first embodiment when fuel is supplied while the engine is stopped.

  As described above, the engine 100 according to the second embodiment can obtain the same effects as those of the first embodiment.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

It is a schematic block diagram of the engine of 1st Embodiment. It is a flowchart which shows the control routine which determines a fuel property. It is a flowchart which shows the control routine performed at the time of engine starting. It is a flowchart which shows first time starting control. It is a flowchart which shows starting control after the first time. It is a flowchart which shows the control routine of fuel property determination of 2nd Embodiment.

Explanation of symbols

100 Engine 23 Airflow meter 34 Air-fuel ratio sensor 41 Fuel injection valve 42 Delivery pipe (fuel piping)
43 Pressure regulator 44 Fuel pump 45 Fuel tank 46 Fuel pipe (fuel piping)
47 Return pipe 48 Fuel level sensor 50 Controller 51 Accelerator pedal sensor 52 Ignition switch 53 Crank angle sensors S101 to S103, S201 to S204 Fuel property learning means S112 Oil supply determination means S114 Initial start control means S143, S155 Fuel consumption integrated value calculation means S115 First and subsequent starting control means

Claims (11)

An engine start control device that includes a fuel injection valve to which fuel in a fuel tank is supplied via a fuel pipe, sets a fuel injection amount based on the fuel property of the fuel, and injects fuel from the fuel injection valve. And
Fuel property learning means for determining the fuel property of the fuel during engine operation and updating the fuel property as a learning value;
Refueling determination means for determining whether fuel has been refueled in the fuel tank while the engine is stopped;
In the case of the first engine start after refueling, initial start control means for setting the fuel injection amount based on the fuel property learning value before refueling and starting the engine;
An engine start control device comprising: Fuel consumption integrated value calculating means for calculating a fuel consumption integrated value of fuel consumed during engine operation after refueling;
If the fuel property learning value is updated after refueling for the second and subsequent engine starts after refueling, the updated fuel is consumed when the fuel consumption integrated value at the time of learning value update is greater than the predetermined integrated value. Starting control means after the first time to start the engine by setting the fuel injection amount based on the property learning value;
The engine start control device according to claim 1, further comprising: When the fuel consumption integrated value at the time of learning value update is smaller than a predetermined integrated value, the starting control unit after the first time sets the fuel injection amount as the fuel is heavy fuel and starts the engine.
The engine start control device according to claim 2. The fuel consumption integrated value calculating means calculates a fuel consumption integrated value based on a fuel injection pulse set in accordance with an engine operating state;
The engine start control device according to claim 2 or claim 3, wherein The predetermined integrated value is set based on a capacity between the fuel injection valve and the fuel pipe.
The engine start control device according to any one of claims 2 to 4, wherein the engine start control device is provided. The initial start control means sets the fuel injection amount as the fuel is heavy fuel and starts the engine when starting the engine after a predetermined period of time has elapsed since refueling.
The engine start control device according to any one of claims 1 to 5, characterized in that: The fuel property learning means determines the fuel property based on the feedback correction amount of the air-fuel ratio during idle operation after engine warm-up.
The engine start control device according to any one of claims 1 to 6, characterized in that: The fuel property learning means determines the fuel property based on the degree of change in engine rotation speed within a predetermined period immediately after engine startup.
The engine start control device according to any one of claims 1 to 6, characterized in that: The degree of change in engine rotation speed is the difference between the maximum angular velocity in the expansion stroke and the angular velocity at the compression top dead center for at least one cylinder.
The engine start control device according to claim 8. The predetermined period immediately after the engine start is a period from when fuel is injected into the first cylinder at the time of engine start until fuel is sequentially injected into the other cylinders to make a round.
The engine start control device according to claim 8 or 9, characterized in that The engine start control method includes a fuel injection valve to which fuel in a fuel tank is supplied via a fuel pipe, sets a fuel injection amount based on the fuel properties of the fuel, and injects fuel from the fuel injection valve. And
A fuel property learning step of determining the fuel property of the fuel during engine operation and updating the fuel property as a learning value;
A refueling determination step of determining whether fuel has been refueled in the fuel tank while the engine is stopped;
In the case of the first engine start after refueling, an initial start control step of setting the fuel injection amount based on the fuel property learning value before refueling and starting the engine;
An engine start control method comprising:

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