Start control device for engine

Abstract

To achieve stable combustion over a wide air-fuel ratio.SOLUTION: A start control device for an engine, in which fuel containing alcohol is directly injected into a cylinder, changes fuel injection setting in accordance with a cooling water temperature. At the cooling water temperature of equal to or higher than B°C, the start control device for the engine performs collective injection in an intake stroke, and at the cooling water temperature of lower than B°C, the start control device for the engine performs injection in the former stage of a compression stroke when performing multi-stage injection in the compression stroke.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an engine start control device. [Background technology]

[0002] In recent years, flexible fuel vehicles (FFVs) that can use a mixture of conventional fuels such as gasoline and diesel and alternative fuels such as ethanol in any ratio have become popular. FFVs use fuels such as E85 (a mixture of 85% ethanol and 15% gasoline) and E100 (a 100% ethanol fuel).

[0003] Ethanol has a higher flash point than gasoline, so if a mixed fuel with a high ethanol concentration or ethanol fuel is used, when the temperature of the combustion chamber of the cylinder (engine temperature) is low, the injected fuel will not vaporize easily and combustion will not occur properly.

[0004] In view of this, a technique is known in which fuel is injected in the latter stage of the compression stroke to promote vaporization of the fuel by utilizing adiabatic compression in the cylinder. For example, a technique is known in which the fuel injection end timing of the fuel injection valve is set to the compression stroke during the start of the internal combustion engine and / or for a predetermined period after the start when the alcohol concentration of the fuel is equal to or higher than a predetermined value and the engine temperature, etc., is equal to or lower than a predetermined value. In addition, a technique is known in which the fuel is supplied into the cylinder within the range from the intake stroke to the compression stroke when the temperature state of the engine body is a low temperature state equal to or lower than a predetermined temperature and the load state of the engine body is equal to or higher than a predetermined load, and the amount of fuel injected by the fuel injection valve during the compression stroke is made larger than the amount of fuel injected during the intake stroke when the concentration of the special fuel in the fuel is higher than a predetermined value. Furthermore, in a direct injection engine in which fuel containing alcohol is directly injected into a cylinder, a technique is also known in which, during a cold start from a state in which the temperature of the direct injection engine is below a predetermined temperature, a first fuel injection is performed into the cylinder during a period in the latter half of the compression stroke after the start of cranking, and the timing of the fuel injection performed after combustion in the cylinder is advanced from the timing of the first fuel injection. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-037968 A [Patent Document 2] JP 2014-206117 A [Patent Document 3] JP 2013-224621 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is also known to increase the air-fuel ratio to improve fuel economy, but when fuel is injected in the latter stage of the compression stroke, misfires may be more likely to occur when the air-fuel ratio is increased.

[0007] An object of the present invention is to provide an engine starting control system that can achieve stable combustion over a wide range of air-fuel ratios. [Means for solving the problem]

[0008] In one embodiment, the engine start control device is an engine start control device in which fuel containing alcohol is directly injected into a cylinder, and changes a fuel injection setting according to a coolant temperature. When the coolant temperature is equal to or higher than B°C, the engine start control device performs a batch injection during the intake stroke, and when the coolant temperature is lower than B°C, the engine start control device performs an injection before the compression stroke when performing a multi-stage injection during the compression stroke.

[0009] According to one embodiment, stable combustion can be achieved over a wide range of air-fuel ratios. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an example of the configuration of an engine cylinder and a starting control device. [Diagram 2] FIG. 2 is a functional block diagram showing an example of a functional configuration of an ECU of the engine start control device. [Diagram 3] FIG. 3 is a diagram showing an example of the relationship between temperature and the alcohol concentration of fuel and engine start control. [Figure 4] FIG. 4 is a graph showing changes in engine speed. [Diagram 5] FIG. 5 is a flowchart showing an example of a flow of processing performed by the ECU of the engine start control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following, a coordinate axis may be displayed with the Z-axis direction being the direction in which a piston 12 of an engine 1 described later slides. First, a schematic configuration of an engine in an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a vertical cross-sectional view showing an example of the configuration of an engine cylinder and a start control device. The engine 1 is mounted on a vehicle such as a four-wheeled automobile.

[0012] 1, engine 1 includes a cylinder formed by combining a cylinder 10 having a bore wall surface 22 and a cylinder head 23 with a piston 12. The cylinder head 23, the piston 12, and the bore wall surface 22 form a combustion chamber 13. Note that engine 1 is a direct injection engine that directly injects fuel into combustion chamber 13. Also, engine 1 may include multiple cylinders.

[0013] The cylinder head 23 is equipped with an intake valve 15 and an exhaust valve 17. The intake valve 15 introduces air flowing through the intake port 14 into the combustion chamber 13. The exhaust valve 17 exhausts combustion gas generated in the combustion chamber 13 through the exhaust port 16. Note that there may be multiple intake valves 15 and multiple exhaust valves 17.

[0014] An injector 19 and a spark plug 18 are installed in the cylinder head 23 facing the inside of the combustion chamber 13. The injector 19 forms an air-fuel mixture by injecting fuel supplied from the fuel pipe 11 into the combustion chamber 13 to which air has been introduced from the intake port 14. The spark plug 18 is installed directly above the combustion chamber 13, between the intake valve 15 and the exhaust valve 17, and ignites the air-fuel mixture in the combustion chamber 13.

[0015] During the intake stroke, when intake valve 15 opens and piston 12 descends in the negative direction of the Z axis, air is drawn into combustion chamber 13 through intake port 14. Then, during the compression stroke following the intake stroke, piston 12 ascends in the positive direction of the Z axis, compressing the air drawn into combustion chamber 13.

[0016] The piston 12 is disposed below the combustion chamber 13, and slides along a bore wall surface 22 of the combustion chamber 13. The other end of a connecting rod 20 connected below the piston 12 is connected to a crankshaft 21.

[0017] The explosive force of the mixture generated in the combustion chamber 13 generates an up-and-down movement of the piston 12. The up-and-down movement of the piston 12 is converted into a rotational movement of the crankshaft 21, which generates a driving force for a vehicle equipped with the engine. The crankshaft 21 transmits the driving force to driving wheels (not shown), for example, via a reduction gear (not shown).

[0018] The crank angle sensor 31 measures the rotation angle of the crankshaft 21. The crank angle sensor 31 is installed near the crankshaft 21. The crank angle sensor 31 measures, for example, the rotation angle of a disk with slits provided around it that is installed around the crankshaft 21 and rotates together with the crankshaft 21, using an optical element such as a phototransistor, an electromagnetic pickup, or the like.

[0019] The air-fuel ratio sensor 32 measures the oxygen concentration in the exhaust gas. The air-fuel ratio sensor 32 is installed, for example, in the exhaust port 16. As the air-fuel ratio sensor 32, for example, an O2 sensor or an A / F sensor is used.

[0020] The water temperature gauge 33 measures the temperature of the cooling water for the engine 1 .

[0021] The alcohol concentration sensor 34 detects the concentration of alcohol in the fuel in the fuel pipe 11 .

[0022] The engine 1 may also include other sensors, such as an in-cylinder pressure sensor that measures pressure fluctuations in the combustion chamber 13.

[0023] The engine 1 is controlled by an ECU 25 (Electronic Control Unit). The ECU 25 includes a microcontroller unit (microcomputer), which includes, for example, a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). The ECU 25 is connected to various sensors, such as a crank angle sensor 31, an air-fuel ratio sensor 32, a water temperature gauge 33, and an alcohol concentration sensor 34, shown in FIG. 1, and receives detection signals from the connected sensors. The ECU 25 functions as a start control device in the embodiment by working in conjunction with these sensors.

[0024] The ECU 25 implements a temperature acquisition unit 41, a concentration acquisition unit 42, a determination unit 43, an injection control unit 44, and a crank angle detection unit 45 as functional units shown in Fig. 2 by expanding a control program stored in a ROM (Read Only Memory) or the like into a RAM (Random Access Memory) and running the program. Fig. 2 is a functional block diagram showing an example of a functional configuration of the ECU of the engine start control device. Note that some or all of these functional units may be implemented by dedicated hardware.

[0025] The temperature acquisition unit 41 acquires the temperature of the coolant from, for example, the water temperature gauge 33 shown in Fig. 1. The temperature acquisition unit 41 substitutes the acquired coolant temperature X as the engine temperature in the cylinder 10. Note that the temperature acquisition unit 41 may use a temperature acquired by another temperature sensor as the engine temperature.

[0026] The concentration acquisition unit 42 acquires the alcohol concentration of the fuel in the fuel pipe 11 from, for example, the alcohol concentration sensor 34 shown in FIG.

[0027] The determination unit 43 determines the timing of fuel injection and the fuel pressure based on the water temperature acquired by the temperature acquisition unit 41 and the alcohol concentration acquired by the concentration acquisition unit 42. Specifically, the determination unit 43 determines the timing at which the injector 19 injects fuel based on the relationship between the coolant temperature and the alcohol concentration of the fuel and the angle at which the fuel is injected as shown in Fig. 3. Fig. 3 is a diagram showing an example of the relationship between the temperature and the alcohol concentration of the fuel and the engine start control. Note that information showing the correspondence relationship between the water temperature and the alcohol concentration of the fuel and the engine start control as shown in Fig. 3 is stored in, for example, a ROM or a RAM.

[0028] The injection control unit 44 instructs the injector 19 on the timing of fuel injection, the injection rate, and the fuel pressure based on the result of the determination by the determination unit 43. At that time, the injection control unit 44 instructs the injector 19 to inject fuel at a timing determined based on the crank angle detected by the crank angle detection unit 45.

[0029] The crank angle detection unit 45 detects the current crank angle based on a change in crank angle information obtained from the crank angle sensor 31, for example, or detects that the engine 1 has started.

[0030] Next, the contents of the judgment by the judgment unit 43 will be described with reference to Fig. 3. For example, when the water temperature X is 90°C or higher, stable combustion is possible even with single injection (all-at-once injection) during the intake stroke regardless of the alcohol concentration. In this case, the judgment unit 43 determines to perform single injection when the crank angle is 200°. The water temperature of 90°C is an example of a second threshold value B°C, which will be described later.

[0031] When the water temperature X is less than 90°C, the ECU 25 determines that fuel injection is to be performed during the compression stroke so that an air-fuel mixture is formed by taking advantage of the adiabatic compression effect in the combustion chamber 13 during the compression stroke. In this case, the ECU 25 determines that fuel should be injected in separate injections (multiple injections) in order to suppress a temperature drop in the combustion chamber 13 due to the heat of vaporization, particularly in the case of a fuel containing alcohol such as ethanol, since the latent heat of vaporization of ethanol is high.

[0032] For example, when the water temperature X is equal to or higher than 40°C and lower than 90°C, the determination unit 43 determines that fuel is to be injected twice, once when the crank angle is 160° and once when the crank angle is 120°. At this time, the fuel injection ratio is, for example, 5-5, and the same amount of fuel is injected in the front and rear stages. The water temperature of 40°C is an example of a first threshold value A°C, which will be described later. Also, when the alcohol concentration in the fuel is low, for example, when the ethanol concentration is lower than 22%, the control may be such that split injection is not performed, or fuel is injected during the intake stroke.

[0033] In the above-described process, the determination unit 43 determines the timing and injection rate of fuel injection regardless of the alcohol concentration of the fuel. On the other hand, when the water temperature X is lower than 40° C., the determination unit 43 may change the injection timing and the like according to the alcohol concentration of the fuel.

[0034] For example, when the water temperature X is equal to or higher than 15° C. and lower than 40° C., the determination unit 43 determines to increase the number of injections from two to three, and to perform fuel injection in the latter stage of the compression stroke as well. The water temperature of 15° C. is an example of a third threshold value d° C., which will be described later.

[0035] In this case, the fuel injection ratio is, for example, 4:4:2. That is, the ratio of the fuel injection amount at the front stage of the compression stroke to the fuel injection amount at the rear stage of the compression stroke is 8:2.

[0036] At this time, the determination unit 43 determines the timing of the third fuel injection according to the alcohol concentration Y of the fuel. For example, when the alcohol concentration Y of the fuel is 60% or more, such as E100 fuel, the determination unit 43 determines that the third fuel injection is to be performed on the retarded side of the latter stage of the compression stroke, for example, when the crank angle is 30°. Note that the alcohol concentration of 60% is an example of a threshold value e%, which will be described later.

[0037] On the other hand, when the alcohol concentration Y of the fuel is less than 60%, such as E22 fuel, the determination unit 43 determines that the third injection is to be performed on the advanced side of the latter stage of the compression stroke, for example, when the crank angle is 80°.

[0038] Furthermore, when the water temperature X is lower than 15° C. and the alcohol concentration Y of the fuel is 60% or more, such as E100, it is necessary to inject fuel near the compression top dead center. In this case, when the ECU 25 determines that the alcohol concentration Y of the fuel is 60% or more, it determines to inject fuel at a position closer to the compression top dead center than the injection time when the water temperature X is 15° C. or more, for example, at a crank angle of 15°.

[0039] Furthermore, since the pressure inside the combustion chamber 13 is rising near the compression top dead center, it is necessary to increase the fuel pressure when injecting fuel from the injector 19. In this case, the ECU 25 determines the fuel pressure to be 20 MPa.

[0040] At this time, by injecting fuel in separate injections at the beginning of the compression stroke (when the crank angles are 160° and 120°), the airflow generated by the rising piston prevents fuel from adhering to the bore wall surface 22 and promotes premixing of the fuel and air, thereby preventing misfires.

[0041] In a lean burn condition where the air-fuel ratio is improved, misfires are likely to occur when fuel is injected near the top dead center of compression, as shown in Figure 4. Figure 4 is a graph showing the transition of engine speed.

[0042] In Fig. 4, the graph indicated by the solid line P shows the change in engine speed when fuel is injected near the top dead center of compression in a non-lean burn state. The graph indicated by the dashed line Q shows the change in engine speed when fuel is injected near the top dead center of compression in a lean burn state. As shown in Fig. 4, in a lean burn state, when fuel is injected all at once, misfires are more likely to occur after the initial explosion, resulting in large fluctuations in engine speed.

[0043] 4, the dashed line R indicates the engine speed change when fuel is injected in split injection in the lean burn state. The timings of the split fuel injection are when the crank angles are 160°, 120°, and 15°, respectively, and the fuel injection ratio is 1:1:8.

[0044] When fuel is injected in separate injections, misfires are less likely to occur than when fuel is injected all at once. In this case, as shown in Fig. 4, the fluctuation in engine speed is smaller, so the engine speed transition is closer to that when the engine is not in a lean burn state.

[0045] The split injection ratio when the water temperature X is less than 15° C. may be changed as appropriate according to the water temperature X and the alcohol concentration Y. For example, when the water temperature X is 0° C. or higher, the fuel injection ratio at each crank angle may be 2:2:6 as shown in Fig. 3. In this case, the ratio between the fuel injection amount at the front stage of the compression stroke and the fuel injection amount at the rear stage of the compression stroke is 4:6.

[0046] On the other hand, if the fuel injection ratio in the early stage of the compression stroke is further reduced, for example to 0.5:0.5:9, the premixed mixture becomes significantly leaner, making misfires more likely to occur. Therefore, even if the split injection ratio in the late stage of the compression stroke is increased, it is preferable that the ratio of the fuel injection amount in the early stage of the compression stroke to the fuel injection amount in the late stage of the compression stroke is 2:8 or less.

[0047] Also, when the water temperature X is less than 15° C. and the alcohol concentration Y of the fuel is low, for example, the ethanol concentration is less than 60%, the ECU 25 determines that the split injection in the latter stage of the compression stroke is to inject fuel on the advance side, not near the compression top dead center. In this case, the fuel injection in the latter stage of the compression stroke is performed at a timing when the crank angle is 80°, as in the case where the water temperature X is 15° C. or more and less than 40° C. Note that, since the pressure in the combustion chamber 13 is lower on the advance side than near the compression top dead center, the fuel pressure may be set to 10 MPa without increasing. Also, the timing of the fuel injection in the former stage of the compression stroke and the fuel injection ratio may be the same as in the case where the alcohol concentration Y of the fuel is 60% or more, as shown in FIG. 3.

[0048] (Flow of processing performed by the start control device) The flow of processing performed by the starting control device will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the flow of processing performed by the ECU of the engine starting control device.

[0049] The crank angle detection unit 45 detects the start of the engine based on, for example, a change in crank angle information (step S101). Next, the temperature acquisition unit 41 acquires the temperature X of the cooling water (step S102).

[0050] Then, the judgment unit 43 judges whether the water temperature X of the cooling water is less than a first threshold value A°C (step S110). If it is judged that the water temperature X is less than A°C (step S110: Yes), the process proceeds to step S111. On the other hand, if it is judged that the water temperature X is equal to or higher than A°C (step S110: No), the process proceeds to step S120. Note that the first threshold value A°C of the water temperature X is, for example, 20°C to 60°C, and preferably 40°C as shown in FIG. 3, but the specific threshold value is merely an example and is not limited thereto. The same applies to the second threshold value B°C and third threshold value d°C of the water temperature X, and the threshold value e% of the alcohol concentration Y, which will be described below.

[0051] If it is determined in step S110 that the water temperature X is lower than A° C., the determination unit 43 determines to perform multiple injections in the front and rear stages of the compression stroke (step S111), and then proceeds to step S130.

[0052] If it is determined in step S110 that the water temperature X is equal to or higher than A° C., it is determined whether or not the water temperature X is less than a second threshold value B° C. (step S120). If it is determined in step S120 that the water temperature X is less than B° C. (step S120: Yes), the determination unit 43 determines to perform multiple injection in the early stage of the compression stroke (step S121), and proceeds to step S160. On the other hand, if it is determined in step S120 that the water temperature X is equal to or higher than B° C. (step S120: No), the determination unit 43 determines to perform single injection in the intake stroke (step S122), and proceeds to step S160.

[0053] In step S130, the judgment unit 43 judges whether or not the coolant temperature X is less than the third threshold value d° C. If it is judged that the coolant temperature X is less than the third threshold value d° C. (step S130: Yes), the process proceeds to step S131. On the other hand, if it is judged that the coolant temperature X is equal to or greater than the third threshold value d° C. (step S130: No), the process proceeds to step S133.

[0054] When it is determined in step S130 that the water temperature X is less than d° C., the determination unit 43 determines to increase the injection ratio in the latter stage of the compression stroke in the multi-injection (step S131). Then, the concentration acquisition unit 42 acquires the alcohol concentration Y (step S132), and the process proceeds to step S140.

[0055] When it is determined in step S130 that the water temperature X is equal to or higher than d° C., the determination unit 43 determines to reduce the injection ratio in the latter stage of the compression stroke in the multi-injection (step S133). Then, the concentration acquisition unit 42 acquires the alcohol concentration Y (step S134), and the process proceeds to step S150.

[0056] In step S140, the judgment unit 43 judges whether the alcohol concentration Y of the fuel in the fuel pipe 11 is equal to or greater than the threshold value e%. If it is judged that the alcohol concentration Y is equal to or greater than the threshold value e% (step S140: Yes), the process proceeds to step S141. On the other hand, if it is judged that the alcohol concentration Y is less than the threshold value e% (step S140: No), the process proceeds to step S143.

[0057] When it is determined in step S140 that the alcohol concentration Y is e% or more, the determination unit 43 determines to increase the fuel pressure to, for example, 20 MPa (step S141).Then, the determination unit 43 determines to retard the injection timing in the latter stage of the compression stroke of the multiple injection, for example, by 15° (step S142), and proceeds to step S160.

[0058] When it is determined in step S140 that the alcohol concentration Y is less than e%, the determination unit 43 determines to reduce the fuel pressure to, for example, 10 MPa (step S143).Then, the determination unit 43 determines to advance the injection timing in the latter stage of the compression stroke of the multiple injection, for example, to 80° (step S144), and proceeds to step S160.

[0059] Returning to step S150, the judgment unit 43 judges whether the alcohol concentration Y of the fuel in the fuel pipe 11 is equal to or greater than the threshold value e% (step S150). If it is judged to be equal to or greater than the threshold value e% (step S150: Yes), the process proceeds to step S151. On the other hand, if it is judged to be less than the threshold value e% (step S150: No), the process proceeds to step S152.

[0060] When it is determined in step S150 that the alcohol concentration Y is e% or more, the determination unit 43 determines to retard the injection timing in the latter stage of the compression stroke of the multi-injection, for example, to 30° (step S151), and proceeds to step S160.

[0061] When it is determined in step S150 that the alcohol concentration Y is less than e%, the determination unit 43 determines to advance the injection timing in the latter stage of the compression stroke of the multi-injection, for example, to 80° (step S152), and proceeds to step S160.

[0062] Then, the injection control unit 44 controls the injector 19 to inject fuel at the fuel pressure, injection ratio, and injection timing determined by the determination unit 43 (step S160). Note that the fuel injection timing from the second time onwards may be set not to be changed from the first time if, for example, there is no change in the water temperature X or the alcohol concentration Y.

[0063] As described above, the engine start control device in the embodiment is an engine start control device in which fuel containing alcohol is directly injected into the cylinder, and changes the fuel injection setting according to the coolant temperature. When the coolant temperature is B°C or higher, the engine start control device performs a batch injection during the intake stroke, and when the coolant temperature is below B°C, the engine start control device performs injection before the compression stroke when performing multi-stage injection during the compression stroke. With this control, stable combustion can be achieved over a wide temperature range and alcohol concentration of the fuel, without the need for a temperature adjustment device or a variable valve timing mechanism.

[0064] The above-described injection timings, fuel pressures, and injection ratios are merely examples and are not limited to those shown above. For example, in the relationship between the water temperature and alcohol concentration and the fuel injection as shown in Fig. 3, the injection timing or injection ratio may be changed gradually by linear interpolation for E20 to E60 (alcohol concentration is 20% or more and less than 60%).

[0065] Furthermore, the determination unit 43 may be configured to perform only a part of the branch determinations shown in Fig. 5. For example, the determination unit 43 may be configured to omit the determination based on temperature as shown in step S120 of Fig. 5, or may be configured not to perform the determination based on alcohol concentration as shown in step S150.

[0066] Although the above configuration is for an FFV, the technology disclosed herein can be widely applied to vehicles other than FFVs, such as hybrid vehicles equipped with electric motors, that are equipped with engines supplied with fuel containing alcohol.

[0067] Although the embodiment of the present invention has been described above, the above-mentioned embodiment is presented as an example and is not intended to limit the scope of the present invention. This new embodiment can be implemented in various other forms. In addition, various omissions, substitutions, and modifications can be made without departing from the gist of the invention. In addition, this embodiment is included in the scope and gist of the invention, and is included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0068] 1 Engine 10 Cylinders 11 Fuel Pipe 12 Piston 13 Combustion chamber 14 Intake port 15 Intake valve 16 Exhaust port 17 Exhaust valve 18 Spark plug 19 Injector 20 Connecting rod 21 Crankshaft 22 Bore wall 23 Cylinder head 25 ECU 31 Crank angle sensor 32 Air-fuel ratio sensor 33 Water temperature gauge 34 Alcohol concentration sensor 41 Temperature acquisition section 42 Concentration acquisition section 43 Judgment section 44 Injection control unit 45 Crank angle detector

Claims

1. A start control device for an engine in which fuel containing alcohol is directly injected into a cylinder, comprising: The fuel injection settings are changed according to the cooling water temperature. When the cooling water temperature is above B℃, the engine will inject all the fuel at once during the intake stroke. When the cooling water temperature is lower than B°C, when performing multi-stage injection during the compression stroke, injection is performed at the early stage of the compression stroke. Engine start control device.

2. 2. The engine start control device according to claim 1, wherein when the cooling water temperature is lower than A degrees Celsius, the injection is performed in the latter stage of the compression stroke when performing multi-stage injection during the compression stroke.

3. When the cooling water temperature is equal to or higher than A°C and lower than B°C, the injection ratio at the front stage of the compression stroke and the rear stage of the compression stroke is varied within a range of 8:2 to 10:0 depending on the temperature from the high temperature side to the low temperature side when performing multi-stage injection. When the cooling water temperature is below A°C, the injection ratio between the front stage and the rear stage of the compression stroke is varied within a range of 4:6 to 2:8 depending on the temperature from the high temperature side to the low temperature side when performing multi-stage injection.

3. The engine start control device according to claim 1 or 2.

4. The fuel injection settings are changed according to the alcohol concentration. When it is determined that the alcohol concentration is equal to or higher than a predetermined threshold, when performing multi-stage injection during the compression stroke, the fuel pressure is increased and the latter stage injection is performed on the retard side in the latter stage of the compression stroke.

4. The engine start control device according to claim 3.

Images