JPH02196149A - Fuel supply controller for two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a sudden increase of output torque and any impact attending on this each from occurring by reopening a fuel supply after once stopping it at time of decelerating drive, while after reopening of the fuel supply, feeding only partial cylinders with fuel as long as the specified period. CONSTITUTION:In this multicylinder 2-cycle internal combustion engine, a feed valve 11, an exhaust valve 13 and an air blast valve 15 are adjacently installed in its combustion chamber 10. In this case, the air blast valve 15 is controlled as follows, namely, first of all, after a fuel supply is stopped at time of decelerating drive, it is controlled by a fuel supply-cut resetting means A so as to reopen the fuel supply in succession. After reopening of the fuel supply, fuel is fed to only partial cylinders as long as the preset period, and successively it is controlled by a fuel supply control means B so as to feed all cylinders with fuel after the elapse of the specified period. With this constitution, a sudden increase of output torque and any impact attending on this each are prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply control device for a two-stroke internal combustion engine.

[Conventional technology]

In a two-stroke internal combustion engine, a large amount of burned gas remains in the cylinder, and only a small portion of the cylinder is occupied by fresh air, especially during low load operation. The fuel supply 9 causes the air-fuel mixture formed by this fresh air and the supplied fuel to reach a predetermined temperature,
For example, it is calculated based on the intake air %it so as to reach the standard air-fuel ratio. However, in order to reduce fuel consumption in such a two-stroke internal combustion engine, when the fuel supply is stopped during low-speed operation, the residual burnt gas in the cylinder is sequentially expelled by fresh air into the exhaust passage. The burnt gas gradually decreases and the cylinder is finally filled with fresh air. When the fuel supply is restarted in such a state, the amount of fuel supplied at this time is determined based on the amount of fresh air supplied into the cylinder at this time, that is, the amount of fresh air that occupies only a small part of the inside of the cylinder. As a result, the air-fuel mixture in the cylinder becomes quite lean, resulting in a misfire. In order to prevent such misfires, when the fuel supply is resumed, the amount of fuel supplied must be determined relative to the total amount of fresh air in the cylinder, and in this way, a large amount of burned gas remains. It is necessary to greatly increase the amount of fuel supplied compared to during steady operation.
(See Publication No. 3).

[Problem to be solved by the invention]

However, if the amount of fuel supplied is greatly increased when the fuel supply is restarted in this way, the engine will generate a large output torque as soon as the fuel supply is restarted, thus giving a shock to the driver. There is a problem that it is not possible to ensure the drivability of the vehicle.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, as shown in the block diagram of the invention in FIG. 1, in a multi-cylinder two-stroke internal combustion engine, fuel supply is stopped during deceleration operation, and then fuel supply is restarted. It comprises a fuel supply cut return means A, and a fuel supply control means B that supplies fuel only to partial cylinders for a predetermined period after resuming fuel supply, and then supplies fuel to all cylinders after this period has elapsed. .

[For production]

Since partial cylinder operation is performed when the fuel supply is resumed, the output torque does not increase suddenly and no large shock occurs.

〔Example〕

FIGS. 2 and 3 show a six-cylinder, two-stroke internal combustion engine. This two-stroke internal combustion engine has the first cylinder 1, the second cylinder 2.
It has six cylinders: No. 3 cylinder, No. 4 cylinder, No. 4 cylinder, No. 5 cylinder, and No. 6 cylinder 6. Each cylinder has a similar structure,
Therefore, referring to FIG. 3, the structure of the first cylinder 1 will be mainly explained. Referring to FIG. 3, 7 is a cylinder block, 8 is a piston that reciprocates within the cylinder block 7, 9 is a cylinder head fixed on the cylinder block 7, and 10 is a cylinder formed between the piston 8 and the cylinder head 9. 11 is an intake valve, 12 is an intake port, 13 is an exhaust valve, 14 is an exhaust port, and 15 is an air blast valve that injects fuel together with compressed air into the combustion chamber 10. Although not shown in the drawings, an ignition plug is arranged at the center of the inner wall surface of the cylinder head 9. The air supply port 12 is connected to a surge tank 17 via an air supply branch pipe 16, and the surge tank 17 is connected to an engine-driven mechanical supercharger 18 and an air supply duct 1.
9, connected to an air cleaner 22 via an air flow meter 20 and an air supply duct 21.

A throttle valve 23 is arranged within the air supply duct 19 .

The ignition order of the 6-cylinder 2-stroke internal combustion engine shown in Figs. 2 and 3 is 1-6-2-4-3-5, and the following ignition order is every other cylinder: 1st cylinder, 2nd cylinder, 2nd cylinder, etc. The third cylinder 3 is referred to as a tenth cylinder group, and the fourth cylinder, which has an ignition order of every other cylinder, the fifth cylinder 5, and the sixth cylinder 6 are referred to as a second cylinder group. As shown in FIG. 2, each exhaust port 14 of the first cylinder group is connected to a common first exhaust manifold 24,
Each exhaust port 14 of the second cylinder group is connected to a common second exhaust manifold 25.

FIG. 4 shows an enlarged sectional view of the air blast valve 15. Fourth
Referring to the figure, a compressed air passage 31 that extends straight is formed in the housing 30 of the air blast valve 15, and the tip of this compressed air passage 31 has a combustion chamber 10 (see FIG. 3).
A nozzle opening 32 located inside is formed. An on-off valve 33 is disposed within the compressed air passage 31, and a valve body 34 for controlling opening and closing of the nozzle port 32 is integrally formed at the outer end of the on-off valve 33. A movable core 36 that is disposed coaxially with the on-off valve 33 and urged toward the on-off valve 33 by a compression spring 35, and a solenoid 37 for attracting the movable core 36 are arranged within the housing 30. The inner end of the on-off valve 33 is brought into contact with the end surface of the movable core 36 by a compression spring 38, and the spring force of the compression spring 38 is applied to the compression spring 35.
Since the spring force is stronger than the spring force of the nozzle port 32, the on-off valve 33
It is closed by a valve body 34. When the solenoid 37 is energized, the movable core 36 moves toward the on-off valve 33, and as a result, the valve body 34 of the on-off valve 33 opens the nozzle opening. On the other hand, from the compressed air passage 31
A compressed air passage 39 extending obliquely is branched off from the compressed air passage 39, and this compressed air passage 39 is connected to a compressed air supply port 40. A fuel injection valve 41 is attached to the housing 30 , and fuel is injected into the compressed air passage 39 from a nozzle hole 42 of the fuel injection valve 41 .

As shown in FIG. 3, an air blasting air passage 43 is branched from the air supply duct 21 between the air flow meter 20 and the air cleaner 22.
3 is an engine-driven vane pump 44 and a compressed air passage 4
5 to a compressed air distribution chamber 46. This compressed air distribution chamber 4G is connected to a compressed air supply port 40 of an air blast valve 15 provided for each cylinder. In the compressed air passage 45, there is a pressure regulating valve 47 for maintaining the compressed air pressure in the compressed air distribution chamber 46 at a predetermined constant pressure.
is arranged, and excess compressed air is returned into the air supply duct 21 via the compressed air return passage 48. Therefore, the compressed air passage 3139 of the air blast valve 15 is filled with compressed air at a constant pressure.

FIG. 5 shows the opening period of the air supply valve 11 and the exhaust valve 13, the period of fuel injection from the fuel injection valve 41, and the opening period of the valve body 34 of the on-off valve 33, that is, the opening period of the air blast valve 15. . As shown in FIG. 5, in the embodiment shown in FIGS. 2 and 3, the exhaust valve 13 opens before the intake valve 11 and closes before the intake valve 11. Moreover, as shown in FIG. 5, before the valve body 34 of the on-off valve 33 opens, that is, the air blast valve 1
5 opens the compressed air passage 39 from the fuel injection valve 41.
Fuel is injected into the compressed air inside. Next, when the air blast valve 15 opens, the injected fuel is injected from the nozzle port 32 into the combustion chamber 10 together with compressed air. On the other hand, as shown in FIG. 3, a mask wall 49 is formed on the inner wall surface of the cylinder head 9 to cover the opening of the air intake valve 11 on the exhaust valve 13 side during the full opening period of the air intake valve 11. Therefore, when the air supply valve 11 opens, fresh air flows from the air supply boat 12 to the exhaust valve 1.
The air is supplied into the combustion chamber 10 through the opening of the intake valve 11 on the side opposite to the air intake valve 3. As a result, the fresh air flows along the peripheral wall surface of the combustion chamber 10 as shown by arrow S, thus achieving good loop scavenging.

As shown in FIG. 3, the air blast valve 15 is an electronic control unit.A child control unit 50 is composed of a digital computer, and is connected to a ROM (ROM) (ROM) connected to each other by a bidirectional bus 51.
read-only memory) 52. RAM (Random Access Memory) 53. It is equipped with a CPU (microprocessor) 541, a human power port 55, and an output port 56. A throttle switch 57 is connected to the throttle valve 23 and detects that the throttle valve 23 is in the idling position, and an output signal of the throttle switch 57 is sent to the human-powered boat 55 . Further, the air flow meter 20 generates an output voltage proportional to the amount of intake air, and this output voltage is A
The signal is input to the input port 55 via the D converter 58. Further, connected to the human power port 55 are a cylinder discrimination sensor 59 that detects, for example, that the No. 1 cylinder 1 is at compression top dead center, and a crank angle sensor 60 that generates an output pulse every time the crankshaft rotates 15 degrees, for example. be done. Therefore, from the output signal of the cylinder discrimination sensor 59, it is determined which cylinder's air blast valve 15 should be operated next, and on the other hand, from the output pulse of the rank angle sensor 60, the engine speed can be calculated. Output capo=) 56 is a drive circuit 61. ．．
62 to the solenoid 37 of the corresponding air blast valve 15 and the fuel injection valve 41.

In a two-stroke internal combustion engine as shown in FIGS. 2 and 3, a part of the burnt gas in the combustion chamber 10 becomes fresh air regardless of whether ignition combustion occurs or not. The air is scavenged by Therefore, when the fuel supply is stopped during deceleration operation, the amount of fresh air in the combustion chamber 10 gradually increases. In this case, if the period during which the fuel supply is stopped is relatively short, the amount of burned gas remaining in the combustion chamber 10 when the fuel supply is restarted is relatively large, and therefore the amount of burned gas remaining in the combustion chamber 10 is relatively large. The amount of fresh air that occupies the 10 range is relatively small. Therefore, in this case, if the fuel calculated based on the intake air amount is supplied when the fuel supply is restarted, an ignitable mixture is formed, so that the mixture can be ignited and burned without misfire. However, if the fuel supply is stopped for a long time, the combustion chamber 10 will be filled with fresh air, so even if the fuel calculated based on the intake air amount is supplied, the air-fuel mixture in the combustion chamber 10 will become extremely low. It becomes diluted, thus causing misfires. Therefore, in one embodiment of the present invention, if fuel supply has been stopped or stopped for a long time, when restarting fuel supply, only some cylinders are supplied with the fuel, and in the embodiment shown in FIG. Fuel is supplied only to the first cylinder group to operate only the first cylinder group, and then after a while, fuel is also supplied to the remaining cylinders, in the embodiment shown in FIG. 2, the second cylinder group to operate all cylinders. I have to. In this case, when fuel supply is resumed to only some cylinders, the amount of fuel supplied to those cylinders is increased, and ignition combustion can be restarted without causing misfire. By the way, when the supply of fuel is resumed to only some cylinders, if ignition combustion is immediately performed in these cylinders, there is no need to increase the amount of fuel thereafter. However, there are cases where these cylinders cannot be immediately ignited and burned, so the amount of fuel is kept increasing for a while.

That is, in the event of a misfire, the supplied fuel will accumulate in the combustion chamber 10, and in this case, if the amount of supplied fuel is increased, the amount of fuel accumulated in the combustion chamber 10 will rapidly increase, so even if a misfire occurs, it will be quicker. Ignition combustion can be carried out at the appropriate time.

Next, fuel injection control will be described with reference to the time chart shown in FIG. 6 and the flow charts shown in FIGS. 7 and 8.

FIG. 7 shows a control routine for flags F1 and F2, and this routine is executed by interrupts at regular intervals.

Referring to FIG. 7, first, in step 100, it is determined based on the output signal of the throttle switch 59 whether or not the throttle valve 23 is at the idling opening. If the opening is idling, the process proceeds to step 101 where the engine speed N is set to a predetermined constant value N0, for example 15.
It is determined whether or not it is higher than 00r, p, m. N
>No, the process advances to step 102 and flag F1 is set. That is, when the throttle valve 23 is at the idling opening and N > No, it is determined that the fuel injection is to be stopped during deceleration operation, and at this time, the flag F is set.
l is set. When the flag F1 is set, fuel injection is stopped as shown in FIG.

Next, in step 103, the count value of the counter C1 is incremented by one. That is, when the fuel injection is stopped, the counter C1 starts counting up. Next, in step 104, it is determined whether the count value of the counter C1 is larger than a predetermined constant value A (FIG. 6). When C1>A, step 10
5, flag F2 is set. On the other hand, when it is determined in step 100 that the throttle valve 23 is open, or in step 101, the N'-No.
If it is determined that this is the case, the process proceeds to step 106, where the flag F1 is reset, and then the counter C1 is cleared. At this time, the fuel supply is restarted as shown in FIG.

FIG. 8 shows the fuel injection control routine.

This routine is executed every 360 crank angles, for example every compression top dead center of the No. 1 cylinder 1.

Referring to FIG. 8, first, in step 200, it is determined whether the flag F1 is set. If flag F1 is set, step 201
As described above, fuel injection from the fuel injection valve 41 of the air blast valve 15 of the gold cylinder is stopped. On the other hand, if the flag F1 is reset, the process proceeds to step 202, where it is determined whether the flag F2 is set.

As shown in FIG. 6(A), when the count value of the counter C1 exceeds A after the flag F1 is set, that is, when a predetermined time t has passed after the flag F1 was set, the flag F2 is set. This fixed time t represents the time until the inside of the combustion chamber 10 is almost filled with fresh air after the fuel supply is stopped, and this time t is determined in advance through experiments and stored in the R[1M 52. In other words, the flag F2 is set when the combustion chamber 10 is almost filled with fresh air after the fuel supply is stopped.

Returning to FIG. 8 again, when the flag F1 is reset and fuel injection is started, the process proceeds from step 200 to step 202. At this time, if the flag F2 is set, the process proceeds to step 203, where the count value of the counter C2 becomes 1. is incremented by Next, in step 204, it is determined whether the count value of the counter C2 has become larger than a predetermined constant value B (FIG. 6), that is, whether the engine has rotated a predetermined number of times after the fuel supply is resumed. It is determined whether or not. When C2≦B, the process proceeds to step 205 and the air blast valve 15 of a partial cylinder, for example, the first cylinder group
Fuel is supplied only from The basic fuel injection time TAU is stored in advance in the ROM 52 as a function of the engine load Q/N and the engine speed N, as shown in FIG. Fuel is injected from the fuel injection valve 41 of the air blast valve 15 of the first cylinder group only during the time TAU-, which is the time TAU multiplied by the increase correction coefficient K. This increase correction coefficient is predetermined so that the air-fuel ratio of the air-fuel mixture in the combustion chamber 10 can be ignited. On the other hand, if it is determined in step 204 that C2>B, the process proceeds to step 206, where the flag F2 is reset, and then, in step 207, the counter C2 is cleared. Then step 20
Proceeding to step 8, fuel is supplied to all cylinders. At this time, fuel injection is performed based on the basic fuel injection time T AU shown in FIG. 9, and therefore no increase correction is performed.

On the other hand, if flag F2 is reset when flag F1 is reset and fuel supply is restarted, the process jumps from step 202 to step 208, and all-cylinder operation is started immediately as shown in FIG. 6(B). to move to. At this time, as described above, fuel injection is performed based on the basic fuel injection time T A tJ shown in FIG. 9, and therefore, no increase correction is performed.

〔Effect of the invention〕

By performing partial cylinder operation when fuel supply is restarted after fuel supply is stopped during deceleration operation, sudden generation of output torque can be suppressed, thereby preventing the occurrence of shock.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the invention, Fig. 2 is a plan view of a two-stroke internal combustion engine, Fig. 3 is a side sectional view of the two-stroke internal combustion engine, Fig. 4 is an enlarged side sectional view of the air blast valve, and Fig. 5. 6 is a time chart, FIG. 7 is a flowchart for controlling flags, and FIG. 8 is a diagram showing fuel injection control. FIG. 9 is a flowchart showing a map of fuel injection time. 10... Combustion chamber, 11... Air supply valve, 13...
・Exhaust valve, 15...Air blast valve. 15... Air blast valve Figure 4 Air blast valve (A) Figure (B)

Claims (1)

[Claims] In a multi-cylinder two-stroke internal combustion engine, there is provided a fuel supply cut return means for stopping the fuel supply during deceleration operation and then restarting the fuel supply, and supplying fuel only to partial cylinders for a predetermined period after restarting the fuel supply. A fuel supply control device for a two-stroke internal combustion engine, comprising a fuel supply control means for supplying fuel to all cylinders after the period has elapsed.