control device

Abstract

To provide a control device capable of determining injection timing of fuel containing alcohol.SOLUTION: A control device calculates a second temperature in a combustion chamber at timing when a piston is located at a top dead center on the basis of first pressure detected by a cylinder inner pressure sensor at closing timing of an intake valve, a second pressure detected by the cylinder inner pressure sensor at timing when the piston is located at the top dead center and a first temperature detected by an intake temperature sensor. The control device corrects injection timing of fuel by an injector on the basis of the second temperature.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] As an invention related to a conventional control device, for example, a control device for an internal combustion engine described in Patent Document 1 is known. The control device for an internal combustion engine described in Patent Document 1 controls the fuel injection timing based on the engine temperature, alcohol concentration, and load of the internal combustion engine. Thereby, the control device for an internal combustion engine described in Patent Document 1 can ensure a stable and good combustion state after a cold start of an internal combustion engine using fuel containing alcohol.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, in fuel containing alcohol, it is important to determine the fuel injection timing.

[0005] Therefore, an object of the present invention is to provide a control device capable of determining the fuel injection timing of fuel containing alcohol.

Means for Solving the Problems

[0006] A first aspect of the present invention is a control device for an internal combustion engine, where the internal combustion engine includes a main body, a piston, an intake valve, an injector, a cylinder pressure sensor, and an intake air temperature sensor, the main body is provided with a combustion chamber and a cylinder space, the piston reciprocates within the cylinder space, The intake valve opens and closes the intake port connected to the combustion chamber. The injector injects a fuel containing alcohol into the combustion chamber. The in-cylinder pressure sensor detects the pressure in the combustion chamber and the cylinder space, The intake air temperature sensor detects the temperature of the intake air flowing into the combustion chamber. The control device calculates the second temperature inside the combustion chamber at the time the piston is at top dead center, based on the first pressure detected by the in-cylinder pressure sensor when the intake valve is closed, the second pressure detected by the in-cylinder pressure sensor when the piston is at top dead center, and the first temperature detected by the intake air temperature sensor. The control device corrects the timing at which the injector injects the fuel based on the second temperature. It is a control device.

[0007] A second aspect of the present invention is, When the second temperature rises, the control device advances the timing at which the injector injects the fuel. This is the control device described on the first side.

[0008] A third aspect of the present invention is, The aforementioned internal combustion engine further comprises a camshaft and a cam angle sensor. The camshaft operates the intake valve, The cam angle sensor detects the phase of the camshaft, The control device detects the timing when the intake valve closes based on the phase detected by the cam angle sensor. The control device calculates the second temperature based on the compression ratio obtained by dividing the sum of the volume of the combustion chamber and the volume of the cylinder space at the time when the intake valve is closed by the volume of the combustion chamber, the first pressure, the second pressure, and the first temperature. The control device is as described on either the first or second side.

[0009] The fourth aspect of the present invention is, When the injector injects the fuel, it is between 90° before top dead center in the compression process and 0° before top dead center in the compression process. It is the control device according to any one of the first to third aspects.

[0010] The fifth aspect of the present invention is A control device for an internal combustion engine, The internal combustion engine includes a main body, a piston, an intake valve, an injector, a cylinder pressure sensor, and an intake air temperature sensor. The main body is provided with a combustion chamber and a cylinder space. The piston reciprocates within the cylinder space. The intake valve opens and closes an intake port connected to the combustion chamber. The injector injects fuel containing alcohol into the combustion chamber. The cylinder pressure sensor detects the pressure in the combustion chamber and the cylinder space. The intake air temperature sensor detects the temperature of the intake air flowing into the combustion chamber. When the first pressure detected by the cylinder pressure sensor rises at the time when the intake valve closes, the control device advances the injection timing of the fuel by the injector. When the second pressure detected by the cylinder pressure sensor rises at the time when the piston is located at top dead center, the control device advances the injection timing of the fuel by the injector. When the first temperature detected by the intake air temperature sensor rises, the control device advances the injection timing of the fuel by the injector. It is a control device.

Advantages of the Invention

[0011] According to the present invention, the injection timing of fuel containing alcohol can be determined.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a schematic view of an internal combustion engine 10. [Figure 2] Figure 2 is a schematic diagram of the internal combustion engine 10. [Figure 3] Figure 3 is a table showing the relationship between the water temperature and the injection frequency, injection timing, and injection ratio. [Figure 4] Figure 4 is a table showing the relationship between the water temperature and the injection frequency, injection timing, and injection ratio. [Figure 5] Figure 5 is a flowchart executed by the control device 100.

Embodiments for Carrying Out the Invention

[0013] (Embodiment) [Structure of Internal Combustion Engine]

[0014] The structure of the internal combustion engine 10 according to an embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 are schematic diagrams of the internal combustion engine 10. FIG. 1 shows the internal combustion engine 10 when the piston 18 is at the top dead center. FIG. 2 shows the internal combustion engine 10 when the intake valve 20 closes.

[0015] In FIGS. 1 and 2, the directions in which the piston 18 moves are defined as the upward direction and the downward direction. However, the upward and downward directions in this specification are directions defined for convenience of explanation and may not coincide with the upward and downward directions when the internal combustion engine 10 is actually used.

[0016] The internal combustion engine 10 is used, for example, as a power source for an automobile. The internal combustion engine 10 is, for example, a four-stroke engine. The fuel for the internal combustion engine 10 contains alcohol. The fuel for the internal combustion engine 10 is a mixture of gasoline and alcohol, or alcohol. Although the internal combustion engine 10 in Figure 1 has one cylinder, it is generally an engine with multiple cylinders. When the internal combustion engine 10 is an engine with multiple cylinders, the multiple cylinders may be arranged in one row, two rows, or four rows. The internal combustion engine 10 comprises a body 12, a crankshaft 14, a connecting rod 16, a piston 18, an intake valve 20, a camshaft 21, an exhaust valve 22, a camshaft 23, a spark plug 24, and an injector 29.

[0017] The main body 12 is provided with a combustion chamber Sp and a cylinder space Sy. The main body 12 includes a cylinder block 12a, a cylinder head 12b, and a crankcase 12c. The cylinder block 12a is provided with a cylinder space Sy. The cylinder space Sy has a cylindrical shape with a central axis extending along the vertical axis.

[0018] The cylinder head 12b is located on top of the cylinder block 12a. The cylinder head 12b is fixed to the cylinder block 12a. The cylinder head 12b is provided with a combustion chamber Sp. The combustion chamber Sp is located above the cylinder space Sy. The combustion chamber Sp is connected to the cylinder space Sy.

[0019] The cylinder head 12b is provided with an intake port p1 and an exhaust port p2. The intake port p1 and exhaust port p2 are connected to the combustion chamber Sp. The intake port p1 is part of the intake path R1. The intake path R1 is the path through which air passes. The exhaust port p2 is part of the exhaust path R2. The exhaust path R2 is the path through which exhaust gases pass. Thus, the internal combustion engine 10 is provided with a combustion chamber Sp, an intake path R1 connected to the combustion chamber Sp, and an exhaust path R2.

[0020] The injector 29 is fixed to the cylinder head 12b. The injector 29 injects alcohol-containing fuel into the combustion chamber Sp. Thus, the internal combustion engine 10 is a direct-injection engine for a Flexible Fuel Vehicle (FFV).

[0021] The crankcase 12c is located below the cylinder block 12a. The crankcase 12c is fixed to the cylinder block 12a.

[0022] The crankshaft 14 is supported by the cylinder block 12a and the crankcase 12c. The crankshaft 14 can rotate about a rotation axis perpendicular to the vertical axis. The piston 18 is located within the cylinder space Sy. The piston 18 has a cylindrical shape.

[0023] The connecting rod 16 connects the crankshaft 14 and the piston 18. As a result, when the crankshaft 14 rotates, the piston 18 moves up and down. That is, the piston 18 reciprocates within the cylinder space Sy. The combustion chamber Sp mentioned above is the space enclosed by the piston 18 and the cylinder head 12b when the piston 18 is at top dead center, as shown in Figure 1.

[0024] The intake valve 20 is supported by the cylinder head 12b. The intake valve 20 opens and closes the intake port p1 which is connected to the combustion chamber Sp. When the intake valve 20 is open the intake port p1, air flows from the intake path R1 into the combustion chamber Sp. The camshaft 21 is rotated by the crankshaft 14. The camshaft 21 operates the intake valve 20.

[0025] The exhaust valve 22 is supported by the cylinder head 12b. The exhaust valve 22 opens and closes the exhaust port p2, which is connected to the combustion chamber Sp. When the exhaust valve 22 is open, exhaust gas flows out of the combustion chamber Sp into the exhaust path R2. The camshaft 23 is rotated by the crankshaft 14. The camshaft 23 operates the exhaust valve 22.

[0026] The spark plug 24 is fixed to the cylinder head 12b. The spark plug 24 includes a center electrode and a ground electrode. The center electrode and ground electrode are exposed to the combustion chamber Sp. A high voltage is applied between the center electrode and the ground electrode of the spark plug 24 by an ignition coil (not shown). This generates a spark between the center electrode and the ground electrode of the spark plug 24, igniting the fuel in the combustion chamber Sp.

[0027] The internal combustion engine 10 further includes a control device 100, an intake air temperature sensor 102, an in-cylinder pressure sensor 104, and a cam angle sensor 106.

[0028] The intake air temperature sensor 102 is located in the intake air path R1. The intake air temperature sensor 102 detects the temperature of the intake air flowing into the combustion chamber Sp.

[0029] The in-cylinder pressure sensor 104 is located in the cylinder head 12b. The in-cylinder pressure sensor 104 detects the pressure in the combustion chamber Sp and the cylinder space Sy.

[0030] The camshaft angle sensor 106 is located on the cylinder head 12b. The camshaft angle sensor 106 detects the phase of the camshaft.

[0031] The control device 100 is an ECU (Engine Control Unit). The control device 100 controls the timing of fuel injection by the injector 29 based on the temperature detected by the intake air temperature sensor 102, the pressure detected by the in-cylinder pressure sensor 104, and the phase detected by the cam angle sensor 106.

[0032] [Operation of control device 100] Next, the operation of the control device 100 will be explained with reference to the drawings. Figures 3 and 4 are tables showing the relationship between water temperature, injection number, injection timing, and injection ratio. Figure 3 is a table when fuel with 100% ethanol is used. Figure 4 is a table when fuel with 22% ethanol and 78% gasoline is used.

[0033] In Figures 3 and 4, the injection timing refers to the time when fuel is injected at X° before top dead center in the compression stroke. Let's explain X° before top dead center in the compression stroke. We define the crank angle when the piston 18 is at top dead center in the compression stroke as 0°. X° before top dead center in the compression stroke is the time when the crank angle is X° backward from the time when the crank angle is 0° in the compression stroke.

[0034] Furthermore, in the injection timing, multiple numbers are listed, for example, 160 / 120 / 15-30. This indicates that the first injection timing is 160° before top dead center in the compression stroke, the second injection timing is 120° before top dead center in the compression stroke, and the third injection timing is 15° to 30° before top dead center in the compression stroke.

[0035] Alcohol has a higher boiling point than gasoline. Therefore, when the temperature of the internal combustion engine 10 is low (hereinafter simply referred to as the low-temperature state), fuel containing alcohol is less likely to atomize. In Figures 3 and 4, the low-temperature state means that the water temperature of the internal combustion engine 10 is 35°C or lower when the internal combustion engine 10 is started, and 30°C or lower when the internal combustion engine 10 is under normal control. When the internal combustion engine 10 is started, the combustion elements such as fuel injection amount, throttle opening, and ignition timing are operated at fixed values ​​for each engine water temperature. When the internal combustion engine 10 is under normal control, the combustion elements such as fuel injection amount, throttle opening, and ignition timing are mainly controlled by feedback so that they match the target rotational speed / stoichiometric air-fuel ratio. In contrast, near 0° before top dead center in the compression stroke, the temperature of the combustion chamber Sp is high. Therefore, fuel containing alcohol is more likely to atomize.

[0036] Therefore, in low-temperature conditions, the control device 100 injects fuel into the combustion chamber Sp by the injector 29 at a time around 0° before top dead center in the compression stroke, as shown in Figures 3 and 4. This injection corresponds to the third injection in Figures 3 and 4. Thus, the timing of fuel injection by the injector 29 is between 90° before top dead center in the compression stroke and 0° before top dead center in the compression stroke. At this time, the control device 100 changes the timing of fuel injection by the injector 29 based on the alcohol concentration of the fuel, the water temperature of the internal combustion engine 10, and whether it is during startup or normal control, as shown in the graphs in Figures 3 and 4.

[0037] When the alcohol concentration of the fuel decreases, the fuel is more likely to atomize. Therefore, when the alcohol concentration of the fuel decreases, the control device 100 advances the timing of the third fuel injection by the injector 29. Specifically, the timing of the third injection in Figure 4 is later than the timing of the third injection in Figure 3. Also, when the water temperature of the internal combustion engine increases, the fuel is more likely to atomize. Therefore, when the water temperature of the internal combustion engine 10 increases, the control device 100 advances the timing of the third fuel injection by the injector 29. Specifically, when the water temperature in Figure 4 is between 5°C and 30°C, the timing of the third injection is earlier than when the water temperature in Figure 3 is between -5°C and 0°C. To achieve this control, the control device 100 performs the calculations described below.

[0038] The temperature inside the combustion chamber Sp at the time when the piston 18 shown in Figure 1 is at top dead center is defined as the second temperature T2, the volume of the combustion chamber Sp is defined as the second volume V2, and the pressure inside the combustion chamber Sp is defined as the second pressure P2. In the compression stroke shown in Figure 2, the temperature inside the combustion chamber Sp and the cylinder space Sy at the time when the valve closes is defined as the first temperature T1, the sum of the volume of the combustion chamber Sp and the volume of the cylinder space Sy is defined as the first volume V1, and the pressure inside the combustion chamber Sp and the cylinder space Sy is defined as the first pressure P1. At this time, the change in the state of the gas from the state in Figure 1 to the state in Figure 2 is an adiabatic compression stroke. Therefore, the following equation (1) holds true, where k is the specific heat ratio and ε is the compression ratio (V1 / V2).

[0039] T2 = T1 × (V1 / V2) k-1 =T1×(P2 / P1) ε-1 ...(1)

[0040] Here, the first temperature T1 is the temperature inside the combustion chamber Sp and the cylinder space Sy at the time when the valve closes during the compression stroke, and therefore corresponds to the temperature of the intake air flowing into the combustion chamber Sp. In other words, the temperature detected by the intake air temperature sensor 102 corresponds to the first temperature T1. Furthermore, the control device 100 can determine the timing when the intake valve 20 closes based on the phase detected by the cam angle sensor 106. Therefore, the control device 100 identifies the pressure detected by the in-cylinder pressure sensor 104 at the time when the intake valve 20 closes as the first pressure P1. In addition, the control device 100 can determine the timing when the piston 18 is at top dead center based on the phase detected by the cam angle sensor 106. Therefore, the control device 100 identifies the pressure detected by the in-cylinder pressure sensor 104 at the time when the piston 18 is at top dead center as the second pressure P2.

[0041] Furthermore, the control device 100 can detect the timing of the intake valve 20 closing based on the phase detected by the cam angle sensor 106. Therefore, the control device 100 can also determine the position of the piston 18 at the time the intake valve 20 closes. Thus, the control device 100 can also determine the first volume V1 at the time the intake valve 20 closes. In addition, the second volume V2 of the combustion chamber Sp is a predetermined value. Therefore, the control device 100 can also determine the compression ratio ε.

[0042] As described above, the control device 100 can acquire the first temperature T1, the first pressure P1, the second pressure P2, and the compression ratio ε. Based on the first pressure P1 detected by the in-cylinder pressure sensor 104 when the intake valve 20 is closed, the second pressure P2 detected by the in-cylinder pressure sensor 104 when the piston 18 is at top dead center, the compression ratio ε, and the first temperature T1 detected by the intake air temperature sensor 102, the control device 100 calculates the second temperature T2 in the combustion chamber Sp at the time when the piston 18 is at top dead center.

[0043] From experiments, it has been found that if the temperature of the combustion chamber Sp and cylinder space Sy is around 230°C, fuel with a 100% ethanol content will ignite without any problems. In other words, if the control device 100 can calculate the second temperature T2 (compression end temperature), it can identify the time when the temperature of the combustion chamber Sp and cylinder space Sy will rise above 230°C. Therefore, the control device 100 should inject fuel into the injector 29 at the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C. In this way, the control device 100 corrects the timing of fuel injection by the injector 29 based on the second temperature T2. Specifically, when the second temperature T2 rises, the control device 100 advances the timing of fuel injection by the injector 29. When the second temperature T2 falls, the control device 100 retards the timing of fuel injection by the injector 29.

[0044] Incidentally, the above control performed by the control device 100 can be rephrased as follows: When the first pressure P1 detected by the in-cylinder pressure sensor 104 rises at the time the intake valve 20 closes, the second temperature T2 rises. Therefore, the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes earlier. So, when the first pressure P1 detected by the in-cylinder pressure sensor 104 rises at the time the intake valve 20 closes, the control device 100 advances the timing at which the injector 29 injects fuel. On the other hand, when the first pressure P1 detected by the in-cylinder pressure sensor 104 falls at the time the intake valve 20 closes, the second temperature T2 falls. Therefore, the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes later. Therefore, when the intake valve 20 closes and the first pressure P1 detected by the in-cylinder pressure sensor 104 decreases, the control device 100 retards the timing at which the injector 29 injects fuel.

[0045] Furthermore, when the second pressure P2 detected by the in-cylinder pressure sensor 104 rises when the piston 18 is at top dead center, the second temperature T2 rises. Consequently, the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes earlier. Therefore, when the second pressure P2 detected by the in-cylinder pressure sensor 104 rises when the piston 18 is at top dead center, the control device 100 advances the timing at which the injector 29 injects fuel. On the other hand, when the second pressure P2 detected by the in-cylinder pressure sensor 104 falls when the piston 18 is at top dead center, the second temperature T2 falls. Consequently, the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes later. Therefore, when the second pressure P2 detected by the in-cylinder pressure sensor 104 falls when the piston 18 is at top dead center, the control device 100 retards the timing at which the injector 29 injects fuel.

[0046] Furthermore, when the first temperature T1 detected by the intake air temperature sensor 102 rises, the second temperature T2 also rises. Consequently, the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes earlier. Therefore, when the first temperature T1 detected by the intake air temperature sensor 102 rises, the control device 100 advances the timing at which the injector 29 injects fuel. On the other hand, when the first temperature T1 detected by the intake air temperature sensor 102 falls, the second temperature T2 falls. Consequently, the time when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes later. Therefore, when the first temperature T1 detected by the intake air temperature sensor 102 falls, the control device 100 retards the timing at which the injector 29 injects fuel.

[0047] Next, the specific operations performed by the control device 100 will be explained with reference to the drawings. Figure 5 is a flowchart of the operations performed by the control device 100. The control device 100 executes the flowchart in Figure 5 by reading a program stored in a memory device (not shown).

[0048] The control device 100 acquires first information (step S1). The first information is, for example, the rotational speed of the internal combustion engine 10 and the load applied to the internal combustion engine 10.

[0049] Next, the control device 100 determines whether the water temperature of the internal combustion engine 10 is below a predetermined temperature (step S2). Specifically, the control device 100 determines whether the water temperature detected by a water temperature sensor (not shown) is below a predetermined temperature. The predetermined temperature is 35°C at startup and 30°C during normal control. In step S2, the control device 100 determines whether the internal combustion engine 10 is in a low-temperature state. If the water temperature is below the predetermined temperature, the process proceeds to step S3. If the water temperature is not below the predetermined temperature, the process proceeds to step S7.

[0050] Next, the control device 100 determines, based on the first information, the timing and number of times the injector 29 will inject fuel (step S3).

[0051] Next, the control device 100 acquires second information (step S4). The second information consists of the first pressure P1, the second pressure P2, the first temperature T1, the first volume V1, and the second volume V2. The control device 100 detects the timing when the intake valve 20 closes based on the phase detected by the cam angle sensor 106. The control device 100 then identifies the sum of the volume of the combustion chamber Sp and the volume of the cylinder space Sy at this time as the second volume V2.

[0052] Next, the control device 100 calculates the second temperature T2 (compression end temperature) based on the first pressure P1, second pressure P2, first temperature T1, first volume V1, and second volume V2 (step S5). The control device 100 uses equation (1) to calculate the second temperature T2. However, the control device 100 may also calculate the second temperature T2 by referring to a table corresponding to equation (1).

[0053] Next, the control device 100 corrects the timing at which the injector 29 injects fuel, which was determined in step S3, based on the second temperature T2 (step S6). A storage unit (not shown) stores a table showing the relationship between the correction amount for the timing at which the injector 29 injects fuel and the second temperature T2. The correction amount is the advance or retard amount relative to the timing determined in step S3. The control device 100 corrects the timing at which the injector 29 injects fuel by referring to this table. After this, the process proceeds to step S8.

[0054] If the water temperature is not below a predetermined temperature, the control device 100 determines, based on the first information, the timing and number of times the injector 29 will inject fuel (step S7). After this, the process proceeds to step S8. In other words, no correction of the injection timing is performed.

[0055] In step S8, the control device 100 determines whether or not to terminate this process (step S8). The control device 100 determines whether or not to terminate this process by determining whether or not to stop the internal combustion engine 10. If this process is not terminated, the process returns to step S2.

[0056] [effect] The control device 100 can determine the injection timing of the alcohol-containing fuel. More specifically, the boiling point of alcohol is higher than that of gasoline. Therefore, when the temperature of the internal combustion engine 10 is low (hereinafter simply referred to as the low-temperature state), the alcohol-containing fuel is difficult to atomize. In contrast, around 0° before top dead center in the compression stroke, the temperature of the combustion chamber Sp is high. Therefore, the alcohol-containing fuel is easily atomized.

[0057] Therefore, in low-temperature conditions, the control device 100 injects fuel into the combustion chamber Sp by the injector 29 at a time when the piston 18 is approximately 0° before top dead center during the compression stroke. In order to appropriately determine the injection timing, the control device 100 calculates the second temperature T2 in the combustion chamber Sp at the time when the piston 18 is at top dead center, based on the first pressure P1 detected by the in-cylinder pressure sensor 104 when the intake valve 20 is closed, the second pressure P2 detected by the in-cylinder pressure sensor 104 when the piston 18 is at top dead center, and the first temperature T1 detected by the intake air temperature sensor 102.

[0058] From experiments, it has been shown that if the temperature of the combustion chamber Sp and cylinder space Sy is around 230°C, a fuel with a 100% ethanol content will ignite without any problems. In other words, if the control device 100 can calculate the second temperature T2 (compression end temperature) as described above, it can identify the time when the temperature of the combustion chamber Sp and cylinder space Sy will rise above 230°C. Therefore, the control device 100 should inject fuel into the injector 29 when the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C. Accordingly, the control device 100 corrects the timing of fuel injection by the injector 29 based on the second temperature T2. As a result, the control device 100 can determine the injection timing of alcohol-containing fuel.

[0059] Incidentally, as the second temperature T2 rises, the time at which the temperature of the combustion chamber Sp and cylinder space Sy rises above 230°C becomes earlier. Therefore, when the second temperature T2 rises, the control device 100 advances the timing at which the injector 29 injects fuel. In this way, the control device 100 can determine the injection timing of the alcohol-containing fuel.

[0060] According to the control device 100, even in an internal combustion engine 10 employing a variable valve timing mechanism, the injection timing of alcohol-containing fuel can be determined. More specifically, in an internal combustion engine 10 employing a variable valve timing mechanism, the timing of the intake valve 20 closing changes. As a result, the second volume V2 changes. Therefore, the control device 100 detects the timing of the intake valve 20 closing based on the phase detected by the cam angle sensor 106. This allows the control device 100 to calculate the second volume V2. As a result, the control device 100 can accurately calculate the second temperature T2 based on equation (1). Thus, according to the control device 100, even in an internal combustion engine 10 employing a variable valve timing mechanism, the injection timing of alcohol-containing fuel can be determined.

[0061] According to the control device 100, the injection timing of alcohol-containing fuel can also be determined for the following reasons. More specifically, the control device 100 corrects the timing of fuel injection by the injector 29 based on the second temperature T2. The second temperature T2 is calculated based on the first pressure P1, the second pressure P2, and the first temperature T1. Therefore, when the first pressure P1, the second pressure P2, and the first temperature T1 change, the second temperature T2 also changes. Specifically, when the first pressure P1 increases, the second temperature T2 increases. When the second pressure P2 increases, the second temperature T2 increases. When the first temperature T1 increases, the second temperature T2 increases. In this way, when the first pressure P1, the second pressure P2, or the first temperature T1 increases, the time when the temperature of the combustion chamber Sp and the cylinder space Sy rises above 230°C becomes earlier.

[0062] Therefore, when the intake valve 20 closes and the first pressure P1 detected by the in-cylinder pressure sensor 104 rises, the control device 100 advances the timing at which the injector 29 injects fuel. When the piston 18 is at top dead center and the second pressure P2 detected by the in-cylinder pressure sensor 104 rises, the control device 100 advances the timing at which the injector 29 injects fuel. When the intake air temperature sensor 102 detects the first temperature T1 rises, the control device 100 advances the timing at which the injector 29 injects fuel. As described above, the control device 100 can determine the injection timing of alcohol-containing fuel.

[0063] (Other embodiments) The control device according to the present invention is not limited to the control device 100, but can be modified within the scope of its gist.

[0064] The vehicle may be a four-wheeled vehicle, a three-wheeled vehicle, or a two-wheeled vehicle. A two-wheeled vehicle is a lean vehicle, in which the body tilts in the same direction as the direction of travel in the corner. A three-wheeled vehicle may be a lean vehicle, or it may be a vehicle that rolls in the opposite direction to the direction of travel in the corner.

[0065] If the internal combustion engine 10 does not have a variable valve timing mechanism, it does not need to have a cam angle sensor 106. In this case, the second volume V2 is the sum of the volume of the combustion chamber Sp and the volume of the cylinder space Sy when the piston 18 is at bottom dead center.

[0066] The internal combustion engine 10 may also be equipped with an alcohol concentration sensor. The alcohol concentration sensor detects the concentration of alcohol contained in the fuel (alcohol concentration). The control device 100 may acquire the alcohol concentration in step S4. In this case, when the alcohol concentration decreases, the control device 100 advances the timing at which the injector 29 injects fuel. When the alcohol concentration increases, the control device 100 retards the timing at which the injector 29 injects fuel.

[0067] Note that the injection timing in the table in Figure 3 is listed as 15-30. This means that when the rotational speed of the internal combustion engine 10 is less than 400 rpm, fuel is injected at 15° before top dead center in the compression stroke, and when the rotational speed of the internal combustion engine 10 is 400 rpm or more, fuel is injected at 30° before top dead center in the compression stroke. When the rotational speed of the internal combustion engine 10 is less than 400 rpm, since not much time has passed since the start of combustion, fuel is injected at a timing when the temperature of the combustion chamber Sp is high. On the other hand, when the rotational speed of the internal combustion engine 10 is 400 rpm or more, since the rotational speed is increasing, fuel is injected at a timing that makes premixing easier. [Explanation of Symbols]

[0068] 10: Internal combustion engine 12: Main unit 18: Piston 20: Intake valve 21,23: Camshaft 22: Exhaust valve 29: Injector 100: Control device 102: Intake air temperature sensor 104: In-cylinder pressure sensor 106: Cam angle sensor R1: Intake path R2: Exhaust path Sp: Combustion chamber Sy: Cylinder space p1: Intake port p2: Exhaust port

Claims

1. A control device for an internal combustion engine, The aforementioned internal combustion engine comprises a main body, a piston, an intake valve, an injector, an in-cylinder pressure sensor, and an intake air temperature sensor. The main body is provided with a combustion chamber and a cylinder space. The piston reciprocates within the cylinder space, The intake valve opens and closes the intake port connected to the combustion chamber. The injector injects a fuel containing alcohol into the combustion chamber. The in-cylinder pressure sensor detects the pressure in the combustion chamber and the cylinder space, The intake air temperature sensor detects the temperature of the intake air flowing into the combustion chamber. The control device calculates the second temperature inside the combustion chamber at the time the piston is at top dead center, based on the first pressure detected by the in-cylinder pressure sensor when the intake valve is closed, the second pressure detected by the in-cylinder pressure sensor when the piston is at top dead center, and the first temperature detected by the intake air temperature sensor. The control device corrects the timing at which the injector injects the fuel based on the second temperature. When the second temperature rises, the timing of the fuel injection by the injector is advanced. The timing at which the injector injects the fuel is from 90° before top dead center in the compression stroke to 0° before top dead center in the compression stroke. Control device.

2. The aforementioned internal combustion engine further comprises a camshaft and a cam angle sensor. The camshaft operates the intake valve, The cam angle sensor detects the phase of the camshaft, The control device detects the timing when the intake valve closes based on the phase detected by the cam angle sensor. The control device calculates the second temperature based on the compression ratio obtained by dividing the sum of the volume of the combustion chamber and the volume of the cylinder space at the time the intake valve closes by the volume of the combustion chamber, the first pressure, the second pressure, and the first temperature. The control device according to claim 1.

3. The control device, when starting the internal combustion engine and when the water temperature of the internal combustion engine is below a predetermined temperature, sets the number of fuel injections by the injector to multiple times and injects fuel. The control device corrects the timing of fuel injection by the injector only for the last injection among the multiple injections, which takes place near the top dead center of the compression stroke. The injection ratio of the last injection in which the timing correction of the fuel injection by the injector is performed is set to be greater than the injection ratio of the other injections in the multiple injections in which the timing correction of the fuel injection by the injector is performed. The control device according to claim 1.

4. A control device for an internal combustion engine, The aforementioned internal combustion engine comprises a main body, a piston, an intake valve, an injector, an in-cylinder pressure sensor, and an intake air temperature sensor. The main body is provided with a combustion chamber and a cylinder space. The piston reciprocates within the cylinder space, The intake valve opens and closes the intake port connected to the combustion chamber. The injector injects a fuel containing alcohol into the combustion chamber. The in-cylinder pressure sensor detects the pressure in the combustion chamber and the cylinder space, The intake air temperature sensor detects the temperature of the intake air flowing into the combustion chamber. When the first pressure detected by the in-cylinder pressure sensor rises at the time the intake valve closes, the control device advances the timing at which the injector injects the fuel. When the second pressure detected by the in-cylinder pressure sensor rises at the time the piston is at top dead center, the control device advances the timing at which the injector injects the fuel. When the first temperature detected by the intake air temperature sensor rises, the control device advances the timing at which the injector injects the fuel. Control device.

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