JP2000097071A - Control device for in-cylinder direct injection engine - Google Patents

Abstract

(57) [Summary] (with corrections) [Problem] To start a cylinder direct injection engine smoothly in an extremely low temperature state. SOLUTION: At the time of engine starting cranking, the ignition of at least one or more cycles is cut to control the timing of the first explosion, and the amount of fuel required for ignition for all cylinders during the cut is controlled. Supply in advance. The number of cycles to cut off the ignition is calculated as the number of cycles necessary to supply the fuel amount from the required fuel amount calculated before the first explosion occurs, based on the cooling water temperature, the cranking rotation speed, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called "in-cylinder direct injection engine" which includes an ignition device such as a spark ignition device and directly injects a volatile fuel such as gasoline into a cylinder. And a control device for controlling fuel injection and ignition.

[0002]

2. Description of the Related Art A direct injection engine is characterized in that fuel is directly injected into a cylinder during a compression stroke.
When fuel is injected into the cylinder only during the compression stroke, when the temperature in the cylinder is still low, such as when starting the engine, the fuel injected and adhered to the inner wall surface of the cylinder, such as the inner wall surface of the cavity at the top of the piston, Does not sufficiently evaporate by the end of the compression stroke, so that good ignition cannot be obtained at the start of the engine, and as a result, there is a problem that a normal in-cylinder direct injection engine has poor startability. To solve this problem, Japanese Patent Application Laid-Open No. 64-87835 has been proposed.
Japanese Patent Application Laid-Open Publication No. H11-17583 discloses an in-cylinder direct injection engine that performs control such that fuel is injected into a cylinder during an intake stroke during startup.

[0003] However, even if such fuel injection control is performed, a sufficiently long fuel injection period (large injection amount) cannot be obtained at the time of starting in which the engine speed must be rapidly increased. In addition to the in-cylinder direct injection injector, another cold start injector is attached to the intake pipe, and fuel is injected also into the intake pipe at low temperature starting, so that the injection amount necessary for starting can be satisfied. I have.

[0004] This measure requires that a cold start injector be installed in the intake pipe in addition to the in-cylinder direct injection injector. If the injector for cold start is abolished due to a problem or the like, at extremely low temperatures (equivalent to −25 ° C. to −35 ° C.), there is a possibility that starting cannot be performed depending on a conventional fuel injection and ignition control method.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has been developed by improving a conventional control device for injection control and ignition. The object of the present invention is to provide a novel control device for fuel injection and ignition for an in-cylinder direct injection engine that can avoid a poor start condition at extremely low temperatures even when the start injector is abolished. And

[0006]

According to the present invention, there is provided a fuel injection control device described in each claim as means for solving the above-mentioned problems.

According to the present invention, the first explosion is achieved by cutting off the ignition of at least one cycle or more at the time of cranking for starting the direct injection engine at extremely low temperatures. Control the timing of the occurrence of
It is characterized in that a fuel amount necessary for ignition is supplied in advance to all cylinders during the ignition cut. Here, the number of ignition cut cycles is calculated as the number of cycles required to supply the fuel amount from the required fuel amount calculated before the first explosion occurs based on the cooling water temperature, the cranking rotation speed, and the like. .

[0010] The ignition cut makes the initial explosion slow, but during that time, the fuel required for ignition is injected into all cylinders and temporarily stored in the cylinders, and a part of them is vaporized. Therefore, when ignition is started, ignition occurs in all cylinders and no misfiring cylinder occurs. Therefore, when the rotation speed rises due to the initial explosion occurring in the first cylinder after ignition is started, even if the injection amount to other cylinders decreases due to the increase in the rotation speed, the other cylinders do not. Since the fuel stored during the ignition cut is ignited, all cylinders are ignited and the engine speed steadily increases without the undesirable effect of misfiring other cylinders as in the prior art.

When the ignition of the control device according to the first aspect of the present invention causes ignition in all the cylinders and the engine speed increases steadily, it is desirable to determine the timing of switching from the control of the start mode to the control of the post-start mode. According to claim 2, in consideration of the fact that the control target is a cryogenic start, a reference is made to a time when a sufficiently high rotational speed of about twice that in the normal start control mode is reached. It can be.

According to the third aspect of the present invention, the timing at which fuel injection into the cylinder is started is set as early as the first half of the intake stroke, and the in-cylinder pressure increases as in the second half of the compression stroke. End injection before. As a result, it is possible to avoid a decrease in the injection amount due to a shortage of the fuel pressure immediately after the start, which is a problem common to the direct injection engine.

Further, in order to improve the re-startability when the starting operation fails and the starting operation is repeated again at a very low temperature, the ignition is performed once before the restart operation is performed. By cutting off the fuel injection or ignition to the cylinders that have been fired, the operation to suppress the fuel injection to the unignited cylinders is prevented from occurring, and the injection amount to the unignited cylinders that may be misfired is reduced. Can be secured. As a result, ignition in all cylinders becomes possible, and a smooth restart is performed.

Further, as in the invention according to claim 5, by detecting the degree of increase in the number of revolutions, the properties of the fuel such as volatile are estimated, and the fuel is injected during the ignition cut according to the fuel properties. It is desirable to determine the amount of fuel into the cylinder.

[0013] Since the control device for a direct injection engine of the present invention is constructed as described above, when the cold start injector is not mounted on the intake pipe, the conventional injection system can be used as it is to achieve extremely low temperature. Sometimes, it is possible to prevent a poor start, and to ensure good startability.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The control device of the direct injection engine according to the first embodiment controls the fuel injection amount of the direct injection gasoline engine at the time of cryogenic start, and controls the ignition so as to perform ignition at the optimum timing. The opening and closing operation of the injector for injecting and supplying fuel to each cylinder is controlled by an electronic control device mainly composed of a microcomputer.

FIG. 1 is a block diagram showing in detail an engine commonly used in each embodiment of the present invention and its control device. In FIG. 1, an in-cylinder direct injection gasoline engine 1 has an intake pipe 2 and an exhaust pipe 3 connected thereto. The intake pipe 2 is provided with a throttle valve 5 which is controlled by the opening of an accelerator pedal 4, and the opening of the throttle valve 5 is detected by a throttle opening sensor 6. Further, an intake pressure sensor 8 is provided in the surge tank 7 of the intake pipe 2.

A piston 10 which reciprocates in the vertical direction in the figure is disposed in each cylinder 9 constituting the engine 1, and each piston 10 is connected to a crankshaft 12 via a connecting rod 11. A combustion chamber 26 defined by the cylinder 9 and the cylinder head 13 is formed above the piston 10. The combustion chamber 26 communicates with the intake pipe 2 and the exhaust pipe 3 when the intake valve 14 and the exhaust valve 15 are opened. I do. The exhaust pipe 3 is provided with an air-fuel ratio sensor 16 that outputs a different voltage signal according to the oxygen concentration in the exhaust gas. Note that, like a normal engine, a gear 24 of a starter 22 can be engaged with a gear 21 attached to the crankshaft 12 at the time of cranking. Further, a water temperature sensor 23 for detecting a cooling water temperature is provided in the water jacket 25 of the cylinder 9.

The direct injection engine 1 is provided with an injector 18 for directly injecting fuel into a cylinder, and the injector 18 is provided with a fuel (gasoline) from a fuel tank 19.
Is supplied through the delivery pipe 51 while being pressurized to a high pressure by the electric pump 53 and the mechanical pump 52 driven by the crankshaft 12. Further, the delivery pipe 51 is provided with a fuel pressure sensor 59 for detecting a fuel pressure in the delivery pipe. In this case, with the valve opening operation of the intake valve 14, fresh air supplied from the upstream side of the intake pipe and fuel injected by the injector 18 are mixed in the combustion chamber 26, and are spark-ignited by the spark plug 60. It burns when it comes.

On the other hand, an electronic control unit (ECU) 30 for controlling fuel injection and ignition is constituted mainly of, for example, a microcomputer system.
1, input / output interface 32, CPU 33, ROM
34, a RAM 35, a backup RAM 36, a clock generation circuit 37, and the like. The detection signal of the intake pressure sensor 8, the detection signal of the air-fuel ratio sensor 16, and the analog signal detected by the water temperature sensor 23 and the like are input to the A / D converter 31, converted into digital signals, and then transmitted to the CPU 33 via the bus 38. Is entered. Further, a detection signal of the throttle opening sensor 6 and a pulse signal (digital signal) of the crank angle sensor 20 and the like are input to the CPU 33 via the input / output interface 32 and the bus 38. CPU33
Is based on each detection signal, the intake pressure (PM), the air-fuel ratio (A
/ F), cooling water temperature (Tw), throttle opening, reference crank position, engine speed (Ne), and the like.

Further, the ECU 30 is provided with a down counter 39 for controlling the driving of the injector 18, a flip-flop 40, and an injector driving circuit 41. That is, when the fuel injection amount is calculated by a fuel injection amount control routine described later, the calculation result is set in the down counter 39, and at the same time, the flip-flop 40 is also set. As a result, power is supplied to the injector 18 by the injector drive circuit 41 to start fuel injection. The down counter 39 starts counting clock pulses, and when the value of the down counter 39 becomes “0”, the flip-flop 40 is reset. Then, when the power supply to the injector 18 is interrupted by the injector drive circuit 41, the fuel injection is stopped. That is, power is supplied to the injector 18 only for a period calculated by the ECU 30, and an amount of fuel corresponding to the calculation result is supplied to each cylinder of the engine 1.

The ECU 30 calculates the ignition timing of the ignition plug 60 based on each detection signal, and controls the ignition by energizing the coil unit 57 with the signal.

In-cylinder direct injection engine 1 constructed as described above
The control of fuel injection and ignition during startup at extremely low temperatures and the behavior of the fuel injected into the cylinder will be described in the control device for the present invention. 2 and 3 show control of fuel injection and ignition in each of the cylinders # 1 to # 4 at the time of cryogenic start according to the related art, and the behavior of fuel injected into the cylinders. As shown in FIGS. 2 and 3, after the starter starts cranking, if the first explosion occurs in cylinder # 1 (see a in FIG. 2), cylinder # 3 has already completed the intake stroke at that time. The injection period is not shortened because of the timing, and a sufficient injection amount can be obtained, so that the # 3 cylinder ignites normally near the compression top dead center (see b in FIG. 2), but the injection of the # 4 cylinder During the period, the initial explosion of the # 1 cylinder increases the rotation speed of the engine 1, so the injection period becomes shorter as the rotation speed increases, and the injection amount decreases while the fuel pressure is low. As a result, an undesirable misfire occurs. (See c in FIG. 2). Similarly, in the # 2 cylinder which reaches the injection timing when the rotation speed increases, misfire occurs due to the shortage of the injection amount (see d in FIG. 2).

Since the engine speed decreases due to misfire of the # 4 and # 2 cylinders, the injection period of the # 1 and # 3 cylinders becomes longer at this point, causing ignition (see e and f in FIG. 2). When the rotation speed increases again, # 4 and #
The two cylinders will misfire (see g and h in FIG. 2).
As a result of the repetition of such a series of operations, if the conventional direct injection engine is not provided with the cold start injector, poor starting at cryogenic start occurs.

As a countermeasure against this problem, in the injection control at the start of the direct injection engine, as described above, the fuel injection by the injector 18 is executed so that a part of the injection period is performed in the intake stroke before the compression stroke. That is, so-called "synchronous intake injection control" is adopted. In this control,
The injection period is limited from the first half of the intake stroke to the middle of the compression stroke. This is because, in the case of a direct injection engine, when the rotational speed of the mechanical high-pressure fuel injection pump has not yet risen sufficiently and the fuel pressure is low, such as when starting, the in-cylinder pressure increases during the compression stroke of the engine. If the injection pressure is higher than the injection pressure of the injector, fuel injection becomes impossible. Therefore, the period during which fuel can be injected into the cylinder is from the first half of the intake stroke to the time when the pressure in the cylinder during the compression stroke exceeds the fuel pressure. In such injection control, the injection end timing is limited, so that when the engine speed is low, it is possible to secure a long injection time, and a large amount of fuel can be injected into the cylinder. When the number of revolutions rises, the time during which injection can be performed is shortened and the injection amount cannot be increased.
In the cryogenic start without the cold start injector, the above-described poor start state occurs.

Further, in a direct injection engine, usually,
In a region where the engine speed is high, the fuel pressurized to a high pressure (about 12 MPa) by the mechanical high-pressure fuel pump 52 is injected into the cylinder, so that the injection rate (injection amount per unit time) of the injector 18 is high. Since it is set to the required value, at the start of low fuel pressure, the injection rate is significantly lower than in the case of a normal intake pipe injection engine. When the cranking rotation speed at the time of cryogenic start is low, the fuel pressure is low because the injection amount is large relative to the discharge amount of the high-pressure fuel pump that is rotationally driven by the crankshaft 12,
A long injection time is required to secure the required injection amount. For this reason, if the time during which injection can be performed becomes short when the rotation speed is increased by the initial explosion, it becomes impossible to secure a necessary injection amount, which causes a start failure.

In the present invention, in view of the above-mentioned problems in the prior art, it is possible to start the engine at an extremely low temperature without providing a cold start injector.

The operation of the first embodiment of the present invention will be described with reference to Table 1 which summarizes the ignition operation at the time of starting and the behavior of the fuel in the cylinder (ignition or misfire).

[0027]

[Table 1]

As described above, the biggest cause of poor starting at extremely low temperatures is a decrease in the injection amount due to an increase in the rotational speed after the first explosion. Therefore, in the first embodiment, a certain amount of in-cylinder wet is formed in the cylinder before the first explosion occurs in order to compensate for the shortage of the injection amount when the rotation speed increases.

As shown in Table 1, by cutting off the ignition for an arbitrary number of cycles (two times in the case of Table 1) at the time of starting, a certain amount of fuel is supplied to each cylinder before the first explosion, and thereafter, By starting the ignition control, even if the injection amount decreases when the rotation speed increases, the shortage of the fuel amount due to the decrease is compensated by the in-cylinder wet vaporization component, so that ignition can be obtained for all cylinders without misfiring. Starting is possible.

FIG. 4 is a flowchart showing a control procedure for realizing the above-described fuel injection amount control and ignition control. This processing is performed by the CPU 33 in the ECU 30 for each fuel injection timing of the injector 18 of each cylinder. Be executed.
When the routine shown in FIG. 4 starts, the CPU 33
First, in step 101, the temperature of the engine cooling water is detected by the water temperature sensor 23. And step 102
It is determined whether or not to select the cryogenic start mode based on the value of the water temperature. For example, if the water temperature is equal to or lower than the predetermined value of −20 to −25 ° C., the process proceeds to step 104. In step 103, a normal start control routine is started.

In step 104, the crank angle sensor 2
The engine speed is detected by the signal of 0, and step 1
At 05, it is determined whether or not the start mode should be selected based on the value of the rotation speed. For example, if the rotation speed is less than the predetermined value of 800 rpm, it is determined that the engine is in the start mode, and the process proceeds to step 107. Then, the routine proceeds to a routine for executing the injection control.

In the start control at room temperature, it is usually determined that the combustion has completely exploded when the engine speed is about 400 rpm or more, and the engine is switched to the post-start mode from the start mode so that the engine enters a good idle state. Is controlled to be smaller than in the start mode. However, when starting at cryogenic temperature, if the injection amount is reduced by switching to the post-start mode when the rotational speed is around 400 rpm, the injection amount becomes insufficient, misfiring occurs, and starting may fail. Therefore, in the first embodiment, as the cryogenic start mode, the determined rotational speed of “start” and “after start” is set to approximately twice the rotational speed of the normal start mode in step 103 (around 400 rpm). (Around 800 rpm).

In step 107, the values of the fuel pressure of the delivery pipe 51 and the negative pressure of the intake pipe are detected based on the signals from the fuel pressure sensor 59 and the intake pressure sensor 8. And step 10
In 8, the injection amount and injection timing per cycle of the injector 18 for each cylinder are determined based on the values of the engine coolant temperature Tw, the fuel pressure Pf, the intake pipe negative pressure PM, and the engine speed Ne. That is, the injection amount tau _st is a K ₁ is a _{constant, τ st = f (Tw,} Pf, PM, Ne, ...) × K 1 (ms
ec), and in step 109, the in-cylinder supply fuel amount Qs required in each cylinder before the first explosion occurs,
For example, 1000 mm from a map built in the ECU 30
Read as ³ . The supplied fuel amount Qs is also determined by the engine coolant temperature Tw, the fuel pressure Pf, the rotational speed Ne, and the intake pipe negative pressure P.
This is a value determined according to the value of M.

Next, based on the in-cylinder supplied fuel amount Qs and the injection amount τ _{st of the} injector 18, the number of ignition cut cycles N _IG
Is calculated from N _IG = Qs / ( _τst · Q) in step 110, and the routine proceeds to step 111, where it is determined how many cycles of the ignition cut have been executed. If the number is less than or equal to N _{IG, the} process proceeds to step 112; otherwise, the process proceeds to step 113. In step 112, a predetermined amount of injection is executed, and ignition control is not performed and step 101 is performed again.
Return to

In step 113, step 11
After executing a predetermined amount of injection in the same manner as in step 2, step 114
Then, the same ignition control as during normal startup is performed, and the routine returns to step 101. Here, the cylinder fuel supply amount is determined by the map values in step 109 Q _S is the case became 0 mm ³ and ignition cut control release. According to the processing of steps 101 to 114 described above, the injection control for improving the startability at the time of cryogenic start is properly performed.

In the first embodiment, step 108
In addition, the injection timing is determined in addition to the determination of the injection amount τ _st. However, when the purpose is to store fuel in the cylinder, the injection timing is determined in the latter half of the intake stroke (90 ° C. after the intake top dead center).
Experiments have shown that it is more effective to start the injection in the first half of the intake stroke, for example, around 10 ° C. after the intake top dead center, as compared to the case where the injection is started later. Therefore, the injection timing in step 108 is set to start the injection in the first half of the intake stroke (around 10 ° A after the intake top dead center). This injection timing is particularly effective in a direct injection engine having the piston 10 in which the cavity 71 is formed.

Next, a second embodiment of the present invention will be described. In the injection pattern according to the prior art as shown in FIG. 2, when the engine speed is increased due to the first explosion or the like, the engine cannot be started by decreasing the fuel injection amount, as described above. Judging that it is impossible,
Even if the cranking is restarted after being stopped, the conventional control may be unable to start for the same reason. Therefore, injection control for preventing such a start failure at restart at extremely low temperatures will be described with reference to FIGS.

In FIG. 2 showing the result of the conventional control, # 1
And the # 3 cylinder ignites when the required injection amount is obtained,
And, the # 2 cylinder does not ignite due to a decrease in the injection amount due to an increase in the rotational speed. In this state, if the cranking is stopped and then restarted, and if the fuel injection is started again from the # 1 cylinder, the # 1 and # 3 cylinders have a history of already ignited. While the temperature is rising and a sufficient amount of fuel is supplied into the cylinders at the time of restart, the # 1 and # 3 cylinders are reliably ignited, but the rotation speeds are accordingly increased and the # 4 and # 2 cylinders are increased. Will be misfired again and will not be able to start for the same reason as when it was first started. Also,
If the injection is continued in this state, the injection amount will be excessive,
Since the so-called plug fogging occurs in the ignited cylinder, there is a possibility that the cylinder cannot be completely started.

As a countermeasure, as shown in FIG.
When the injection is started from the cylinder, the injection of the fuel is cut off at the beginning of the restart for the cylinders ignited by the first start operation, that is, for the cylinders # 1 and # 3, and the misfired cylinder is initially started. That is, a predetermined amount of fuel is injected into the # 4 and # 2 cylinders. And # 4 and #
Until ignition is obtained in the two cylinders, fuel injection to the # 1 and # 3 cylinders is cut off, and after ignition is obtained in the # 4 and # 2 cylinders, a predetermined amount of fuel is injected to the # 1 and # 3 cylinders To start. When the injection is started from the # 4 cylinder, a predetermined amount of injection is started from the first cycle for the # 4 and # 2 cylinders, and the # 4 and # 2 cylinders for the # 1 and # 3 cylinders. It is assumed that the fuel injection is cut until ignition is obtained at.

FIG. 6 is a flowchart showing a procedure for realizing the above-described fuel injection control of the second embodiment. This processing is executed by the ECU for each fuel injection timing of each cylinder.
The processing is executed by the CPU 33 provided in the apparatus 30.

In FIG. 6, the control from step 201 to step 206 is the same as that from step 101 to step 106 in the flow chart of FIG. 4 showing the control of the first embodiment. Omitted. In step 205, when the rotation speed Ne is equal to or less than the predetermined value, it is determined that the engine is in the start mode, and the process proceeds to step 207. In accordance with the injection pattern stored in the storage device of the ECU 30, it is determined whether injection has been performed after IG _ON . It is determined whether or not the engine is restarted based on the determination as to whether the fuel injection has not been performed yet.
As in the case of the embodiment, a normal cryogenic start mode is entered as in step 107 and the subsequent steps in the flowchart of FIG.

If it is determined in step 207 that restart is to be performed because injection has already been performed, the flow advances to step 209. In the determination of step 209,
The determination is made based on the detected value of the engine speed Ne. For example,
If the rotation speed Ne is 300 rpm or more, it is determined that ignition has occurred, and if it is less than 300 rpm, it is determined that ignition has not yet occurred.
If it is determined that the ignition has occurred, the process proceeds to step 211, but if it is determined that the ignition has not occurred, the process proceeds to step 210.
Proceed to. In step 210, the injection pattern executed before the restart is read, and it is determined that the cylinder whose injection time is substantially equal in length to the predetermined injection amount has ignited. Not ignited (misfire)
Cylinder. If the cylinder to be injected next is the ignition cylinder, it is determined that the injection is cut, and the process proceeds to step 215.
If the cylinder is not ignited, it is determined that the fuel is injected, and the routine proceeds to step 211.

Steps 211 and 212 correspond to step 10 in the flowchart shown in FIG. 4 for the first embodiment.
The same processing as in Steps 7 and 108 is performed, a predetermined amount of fuel injection is performed in Step 213, ignition control is performed in Step 214, and after the injection pattern is read in Step 215, the process returns to Step 201.

Here, as a modification of the control of the second embodiment described with reference to FIGS. 5 and 6, as shown in FIGS. 7 and 8, when it is determined that the injection is cut in step 210, before the flow proceeds to step 215, Steps 216 to 2
The process of step 18 may be performed to execute fuel injection of a predetermined amount or less, cut off the ignition, and proceed to step 215. Step 20 as described above
According to the processes of Nos. 1 to 215, the injection control at the time of restarting at extremely low temperatures is appropriately performed, so that the startability is improved.

Next, a third embodiment of the present invention will be described. At the time of cryogenic start, the startability greatly changes depending on the properties of the fuel, particularly the volatility of the fuel. Therefore, it is necessary to change the fuel injection control depending on the properties of the fuel. FIG.
Fig. 8 shows the result when starting is performed by the same ignition cut control of the first embodiment using three types of fuels A, B, and C having different fuel properties at the time of starting at an extremely low temperature. . It can be seen that the degree of increase in the number of revolutions differs greatly depending on the properties of the fuel. This is because the fuel A has a higher volatility than the fuel B, so that a large amount of fuel in the cylinder evaporates when the rotation increases and becomes over-rich, so that no torque is generated. In addition, the generation of the first explosion is delayed because the fuel C is less volatile than the fuel B, but the rise of the rotation is improved by that much. Therefore, in the third embodiment, the nature of the fuel is determined based on the degree of increase in the rotational speed after the occurrence of the first explosion, and this is reflected in the injection control at the time of cryogenic start.

Although a flowchart showing a procedure for realizing the injection control according to the third embodiment is not shown, the flowchart of the third embodiment is different from the flowchart of the first embodiment shown in FIG. The other procedure is the same as that of FIG. 4 except that a step for determining the property of the fuel is inserted between step 105 and step 105. In the step inserted as a feature of the third embodiment, for example, the rotational speed is 300 rp.
The time required to increase from m to 800 rpm (post-start mode) is read, and the nature of the fuel is determined based on the length of the time.

For example, when the injection amount is set based on the properties of commonly used fuel, the time required for the rotation speed to increase from 300 rpm to 800 rpm by the base fuel is determined. Based on the above, it is determined that the fuel is more volatile if it is longer than that, and is less volatile if it is shorter. Then, in consideration of the properties of the fuel, the in-cylinder supply fuel amount in steps 108 and 109 is determined at the next extremely low temperature start.

In determining the amount of in-cylinder fuel to be supplied, if it is determined that the volatility of the fuel relative to the base fuel is good, the in-cylinder supply amount is set to be smaller than that of the base fuel, and the volatility is poor. If it is determined that it is larger than the base fuel. However, in this case, irrespective of the fuel properties such as good or bad volatility, the injection amount and injection timing determined in step 108 of the flowchart of FIG. It is assumed that only the value of the in-cylinder supplied fuel amount is changed.

As another means for judging the fuel property, the A / F sensor 1 shown in FIG.
6 may be used. Normally, during acceleration / deceleration during engine operation, feedback control is performed based on the output of the A / F sensor in order to set the A / F in the cylinder to an appropriate value. In this case, the fuel property is an important factor as a parameter of the feedback control. If the output value of the A / F sensor greatly deviates when the control is performed with the preset fuel property parameter in this control. It is determined that the fuel property has changed, and the parameters of the fuel property are corrected based on the output of the A / F sensor.

As a correction method, for example, fuel increase control is performed at the time of acceleration. At this time, especially when the fuel is highly volatile with respect to the fuel properties of the base fuel during the period from immediately after start-up to half-warm-up, A / A The output of the F sensor shifts to the rich side, and if the fuel has poor volatility, it shifts to the lean side. Therefore, the parameter of the fuel property is corrected based on the state of the deviation of the output value. Therefore, using this determination value, before the cryogenic start in the first embodiment, the in-cylinder fuel supply amount before the first explosion is corrected based on the fuel properties in the same manner as the above-described correction.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram combining a cross-sectional view of an in-cylinder direct injection engine body common to each embodiment of the present invention and a block diagram of a control device.

FIG. 2 is a time chart showing a conventional fuel injection and ignition control pattern.

FIG. 3 is a longitudinal sectional view showing a comparison between initial states of an expansion (combustion) stroke of each cylinder in a direct injection engine with a conventional control system.

FIG. 4 is a flowchart illustrating a control routine according to the first embodiment of the present invention.

FIG. 5 is a time chart showing a control pattern of fuel injection and ignition in a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating a control routine according to a second embodiment.

FIG. 7 is a time chart showing a control pattern of fuel injection and ignition in a modification of the second embodiment.

FIG. 8 is a flowchart showing a main part of a control routine in a modification of the second embodiment shown in FIG. 7;

FIG. 9 is a diagram showing comparison of results of examining how the engine speed rises for three types of fuels A, B, and C having different volatility as a premise of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... In-cylinder direct injection engine 6 ... Throttle opening degree sensor 8 ... Intake pressure sensor 18 ... Injector 20 ... Crank angle sensor 23 ... Cooling water temperature sensor 26 ... Combustion chamber (in a cylinder) 30 ... Electronic control unit (ECU) 52 ... Mechanical high-pressure fuel pump 53 ... Electric fuel pump 59 ... Fuel pressure sensor 60 ... Spark plug

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02P 5/15 F02P 5/15 E (72) Inventor Nobuo Imatake 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture Stock Inside the Japan Auto Parts Research Institute (72) Inventor Kimitaka Saito 14 Iwatani, Shimoba Kakucho, Nishio City, Aichi Prefecture Inside the Japan Auto Parts Research Institute (72) Inventor Nobuhiko Koga 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto 3G022 AA00 AA03 CA01 EA00 FA03 FA08 GA00 GA02 GA05 GA07 GA08 GA09 GA12 3G084 AA00 AA03 BA13 BA15 BA16 CA01 DA09 DA13 EA11 EB02 EB24 EC02 EC03 FA14 FA29 FA33 FA34 FA36 FA38 FA03 HA03 HA04 KA04 LA00 LA03 LB04 MA11 MA19 MA24 NA08 NB02 NB06 NB11 NE23 PA07Z PA11Z PB02Z PB08Z PD02Z PE01Z PE02Z PE04Z PE05Z PE08 Z PF16Z

Claims (5)

[Claims] In an in-cylinder direct injection engine without an injector for supplying fuel to an intake pipe, a fuel injection amount of an injector for directly injecting fuel into a cylinder and an ignition for igniting fuel are determined. A control device for controlling,
As a control for starting injection and ignition at cryogenic temperature different from normal start control, during cranking, ignition is prohibited for at least one cycle before the first explosion occurs,
A control device for an in-cylinder direct injection engine, characterized in that only fuel injection is performed into each cylinder during that time, and fuel injection and ignition are performed in combination after an ignition cut cycle is completed. 2. The method according to claim 1, wherein a reference rotation speed for determining which of the start mode and the post-start mode is to be executed is changed to a normal start control mode for starting at an extremely low temperature. A control device for an in-cylinder direct injection engine, wherein the rotation speed is set to approximately twice the rotation speed of the determination. 3. The control device for a direct injection engine according to claim 1, wherein the fuel injection start timing is set in the first half of the intake stroke. 4. The in-cylinder direct injection engine according to claim 1, wherein at the time of restart after the start has failed, at least one of injection and ignition to a cylinder ignited when the start has failed is cut off. Control device. 5. The method according to claim 1, wherein the fuel property is determined based on an increase in the number of revolutions after the initial explosion or an output value of an A / F sensor during operation of the engine, and based on the determined value before the first explosion due to ignition cut. A control device for an in-cylinder direct-injection engine, wherein the in-cylinder injection amount for each cylinder is changed.