JPS626090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fuel supply system for a supercharged engine.

In addition to naturally aspirated air, a supercharged engine uses a supercharger to pressurize the intake air and force a large amount of air and fuel into the combustion chamber, increasing the filling efficiency of the air-fuel mixture and combusting the air-fuel mixture. The purpose is to increase energy and improve engine output. In such a supercharged engine, there is a main intake passage for natural intake and an auxiliary intake (supercharging) for supercharging.
It is known from JP-A-56-18024 to provide separate passages and communicate them with the combustion chamber by means of a main intake port and an auxiliary intake (supercharging) port. This configuration has the advantage that even a small-capacity supercharger can perform effective supercharging. In order to further increase turbocharging efficiency, a timing valve is installed downstream of the supercharger in the auxiliary intake passage that opens and closes the auxiliary intake passage in synchronization with engine rotation, and supercharging is performed through the auxiliary intake passage at the end of the intake stroke. There is also known an intake system in which the timing of opening and closing of an auxiliary intake passage is controlled. However, in these supercharged engines, the air passing through the auxiliary intake passage is subjected to adiabatic compression by the supercharger, and the temperature of the supercharged air increases accordingly.
This causes problems such as decreased filling efficiency and knocking during high-load operation. Further, when operating these supercharged engines, supercharging operation is necessary only when the engine is under high load. Therefore, supercharging air is not introduced from the auxiliary intake passage when the load is light. In such a case, it is not only pointless to supply fuel from the auxiliary fuel supply means, but also may impair the vaporization and atomization of the fuel, making it impossible to maintain the uniformity of the air-fuel mixture.

Therefore, an object of the present invention is to maintain the uniformity of the air-fuel mixture in both supercharging operation and non-supercharging operation to provide a good combustion state, and to maintain high supercharging efficiency in supercharging operation. At the same time, the fuel supply for supercharged engines can suppress the decline in charging efficiency due to temperature rise due to adiabatic compression of supercharged air, prevent knocking during high loads, and promote fuel atomization. The purpose is to provide equipment.

The present invention has a main intake passage that communicates with the combustion chamber via a main intake port, and an auxiliary intake passage that communicates with the combustion chamber via an auxiliary intake port that has a supercharger and closes later than the main intake port. a timing valve provided downstream of the supercharger for opening the auxiliary intake passage; a main fuel supply means for supplying fuel to the main intake passage; and a timing valve provided downstream of the timing valve for supplying fuel to the auxiliary intake passage. and an auxiliary fuel supply means for supplying fuel, and a fuel supply control device that supplies fuel only from the main fuel supply means during non-supercharging operation and supplies fuel from at least the auxiliary fuel supply means during supercharging operation. It is characterized by
In a preferred embodiment of the present invention, the fuel supply control device opens the timing valve at the end of the intake stroke during supercharging operation, and operates the auxiliary fuel supply means while the timing valve is open. configured.

According to the present invention, when the engine is under light load, that is, during non-supercharging operation, fuel is supplied only from the main fuel supply means. Therefore, the problem that fuel is delivered from the auxiliary fuel supply means without supercharging air being delivered, resulting in non-uniform air-fuel mixture, is solved. Further, when the engine is under high load, that is, during supercharging operation, fuel is supplied from at least the auxiliary fuel supply means. This auxiliary fuel supply means is located downstream of a timing valve that opens and closes the auxiliary intake passage, and when the timing valve is opened and the supercharged air is introduced into the combustion chamber through the auxiliary intake passage, Since fuel is injected into the air stream, the fuel is atomized by the high-speed supercharging air flow, mixes with the air, and becomes a nearly homogeneous mixture.
There is no problem of liquid fuel adhering to the wall and flowing. Further, a part of the fuel is vaporized during atomization and takes away latent heat of vaporization from the supercharged air, thereby cooling the supercharged air whose temperature has increased due to adiabatic compression. This can prevent a decrease in filling efficiency and the occurrence of knocking. Further, in the above-described preferred embodiment of the present invention, the high-pressure supercharged air is introduced into the combustion chamber at the end of the intake stroke, and the auxiliary intake port is configured to close later than the main intake port, so the main intake passage It is possible to prevent blowback and maintain high supercharging efficiency.

Furthermore, in this preferred embodiment of the invention, the auxiliary fuel supply means is operated with a phase difference with respect to the main fuel supply means, so that the fuel supply control device can provide an appropriate amount of fuel for the total intake air amount. A configuration can be adopted in which the fuel supply amount is determined and then distributed to the main auxiliary fuel supply means,
The fuel control device can be simplified compared to the case where the amounts of fuel supplied to the main and auxiliary fuel supply means are determined separately.

Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, engine E has cylinder 1
It has a piston 2 that reciprocates within the cylinder 1. A combustion chamber 3 is formed in the upper part of the cylinder 1, and the cylinder 1 is also formed with a main intake port 4, an auxiliary intake port 5, and an exhaust port 6 that open into the combustion chamber. A main intake valve 7 is combined with the main intake port 4, an auxiliary intake valve 8 is combined with the auxiliary intake port 5, and an exhaust valve 9 is combined with the exhaust port.
The main intake port 4 is connected to a main intake passage 10, and the auxiliary intake port 5 is connected to an auxiliary intake passage 11. These main intake passage 10 and auxiliary intake passage 1
1 is an intake passage 13 which both has an air cleaner 12;
connected to. A throttle valve 14 is arranged in the main intake passage 10, and a main fuel injection valve 15a is provided downstream of the throttle valve 14. An air flow rate detection device, ie, an air flow meter 16a, is disposed in the intake passage 13, and the output of the air flow rate detection device is preferably input to a control circuit 16b consisting of a microcomputer. A signal from the crank angle sensor 26 is also input to the control circuit 16b.
A supercharger 17 consisting of a vane type air pump is disposed in the auxiliary intake passage 11, and an auxiliary intake passage throttle valve 18 is provided downstream of the supercharger 17. Note that the turbocharger 17 is operated by the control circuit 16 when the throttle opening is above the set value (line A in Figure 3).
It is activated by a signal from b. Main intake passage 10
The throttle valve 14 and the throttle valve 18 of the auxiliary intake passage 11 are interlocked so that the throttle valve 18 starts to open when the throttle valve 14 opens to a predetermined opening degree. The opening degree of the throttle valve 14 is detected by the opening degree sensor 25, and its output is input to the control circuit 16b. A supercharge relief valve 19 is provided between the supercharger 17 and the throttle valve 18, and the air relieved from the supercharge relief valve 19 is returned to the auxiliary intake passage upstream of the supercharger 17 through a relief passage 20. It's starting to become easier.
A timing valve 21 is located downstream of the throttle valve 18.
is provided. This timing valve is actuated by a signal from the control circuit 16b, and by this actuation, the auxiliary intake passage 11 is directed toward the combustion chamber 3 at an appropriate time synchronized with the engine crankshaft, for example, from near the end of the intake stroke to the beginning of the compression stroke. open.
An auxiliary fuel injection valve 15 is located downstream of the timing valve.
b is provided. The main fuel injection valve 15a and the auxiliary fuel injection valve 15b inject a required amount of fuel into the main intake passage 10 and the auxiliary intake passage 11 according to a command signal from the control circuit 16b. This fuel is pressurized by a fuel pump 23 from a fuel tank 22 and supplied to each injection valve.

FIG. 2 shows the contents of the control circuit 16b, which includes the air flow meter 16a,
Signals from the crank angle sensor 26 and throttle valve opening sensor 25 are input, and the main fuel injection valve 15a
A command signal is output to the auxiliary fuel injection valve 15b. To explain the input/output relationship of this circuit 16b in detail, the signal S indicating the intake flow rate from the air flow meter 16a
1 is input to the generation circuit 100 during the total injection pulse. The crank angle sensor 26 detects the rotational position of the crankshaft, and the signal S from this sensor 26 is
2 is input to the rotation speed detection circuit 102. The rotation speed detection circuit 102 calculates the rotation speed of the crankshaft, that is, the rotation speed of the engine, from the signal S2 of the sensor 26, and outputs a rotation speed signal S5. The signal S3 from the throttle opening sensor 25 is transmitted to the reference voltage generation circuit 10.
4, and this circuit 104 is connected to the throttle valve 1.
A voltage signal S4 corresponding to the opening degree of 4 is generated. A signal S5 from the rotation speed detection circuit 102 representing the engine rotation speed is input to the total injection pulse width generation circuit 100. Further, the signal S5 from the rotation speed detection circuit 102 is also input to the comparison circuit 106. A signal S4 from the reference voltage generation circuit 104 is also input to the comparison circuit 106. The comparison circuit 106 generates a high level or low level signal S6 in accordance with the chart of the opening degree of the throttle valve 14 and the engine speed as shown in FIG. 3, for example. Third
In the figure, line A is the opening degree of the throttle valve 14 at which the throttle valve 18 opens. Therefore, when the opening degree of the throttle valve 14 exceeds line A, the supercharger 17 is activated and supercharged air is introduced. Therefore, in the operating range below line B, no fuel is injected from the auxiliary fuel injection valve, and fuel is supplied only from the main fuel injection valve.

Further, in the shaded area C delimited by line B, the auxiliary fuel intake passage 11 is opened when the auxiliary fuel injection valve 15b is opened.
This is also a desirable area to inject. Supercharger 1
Depending on the characteristics of 7 and the control method of the throttle valves 14 and 18, it may be desirable to set the range above line D in the figure, for example. In practical terms, line F
Alternatively, even if the area is placed above line A, no major inconvenience will occur. In this case, there is no need to input the signal S5 from the rotation speed detection circuit 102 to the comparison circuit 106. The output signal S6 of the comparator circuit 106 is at a high level when the operating state is in a region where fuel supply to the auxiliary intake passage 11 is desirable, that is, in the region C, and is at a low level otherwise.

Referring to FIG. 2, total injection pulse generation circuit 1
00 is the signal S from the air flow meter 16a
1 and the signal S5 from the rotation speed detection circuit 102, a pulse width corresponding to the total fuel injection amount per cycle is determined, and a pulse signal S7 having the determined pulse width is generated. This signal S7 is transmitted to the dividing circuit 10
8 is input. The division circuit 108 divides the pulse width of the total injected fuel into a pulse width corresponding to the main fuel injection amount;
Divide into pulse widths corresponding to the auxiliary fuel injection amount, each having a pulse width corresponding to the amount of fuel injected into the main intake passage (hereinafter referred to as main fuel) and the amount of fuel injected into the auxiliary intake passage (hereinafter referred to as auxiliary fuel). A pulse signal S8 and a signal S9 are output. In this case, when the signal S6 of the comparison circuit 106 is at a low level, the auxiliary fuel is not injected, so the signal 9 is not generated, and the signal S8 becomes the same as the signal S7. Furthermore, the control circuit 16b includes each fuel injection valve 15a, 1
A main fuel injection start timing setting circuit 110 and a drive circuit 11 are used to determine the fuel injection start timing of 5b.
2 is provided. Main fuel injection start timing setting circuit 1
10 inputs the signal S2 from the crank angle sensor 26, determines the timing to open the main fuel injection valve 14, and outputs a signal S10 representing the injection timing. This signal S10 is input to the drive circuit 112. A signal S8 from the division circuit 108 is also input to the drive circuit 112. The drive circuit 112 is
A command signal S11 for the main fuel injection valve 15a to open the valve and keep it open for a time corresponding to the pulse width of the pulse signal S8 of the split circuit 108.
Output. For the auxiliary fuel injection valve 15b,
Auxiliary fuel injection start timing setting circuit 11 with similar configuration
6 and a drive circuit 118 are provided, and a command signal S1
Outputs 2. The auxiliary fuel injection valve 15b is set to open when the timing valve 21 opens a predetermined time later than the main fuel injection valve 15a.
Note that the auxiliary fuel injection start timing setting circuit 116 is configured to operate when the input signal S6 from the comparison circuit 106 is at a high level.

In the above configuration, when the output signal S6 of the comparison circuit 106 is at a low level, that is, when the engine load is small, the throttle valve opening is relatively small, and the operating state is outside the region C in FIG. Since no pulse is generated in the signal S9 from the drive circuit 118 and no open command signal is issued from the drive circuit 118, the auxiliary fuel injection valve 15b does not open and no auxiliary fuel is injected. Therefore, under such operating conditions,
There is no supercharging, or only a relatively small amount of supercharging air is introduced into the combustion chamber. Fuel is supplied only from the main fuel injection valve 15a.

When the throttle opening becomes large and the operating state enters the region C of FIG. 3, the output signal S6 of the comparator circuit 106
changes to a high level. As a result, dividing circuit 1
08 is a pulse signal S8 which is divided into pulses according to the magnitude of the input pulse signal S7 and which corresponds to the main fuel amount.
A pulse signal S9 having a pulse width corresponding to the amount of auxiliary fuel is generated. Drive circuits 112 and 118
receives these signals and holds the fuel injection valves 15a, 15b open for a period of time corresponding to the pulse width of the signals S8, S9 at a predetermined timing.

As shown in FIG. 4, in the case of supercharging, the main intake port 4 is first opened, and then the main fuel injection valve 15a is opened. As a result, natural intake begins, and the air-fuel mixture is introduced into the combustion chamber 3 from the main intake port 4. Next, the auxiliary intake port 5 is opened, but at the same time, the drive circuit 1
After a period of time determined by the signal S11 from the main fuel injection valve 15a has elapsed, the main fuel injection valve 15a is closed and fuel supply is stopped. Even if the auxiliary intake port 5 is opened, while the timing valve 21 is closed, supercharging air is not introduced into the combustion chamber 3 and only natural intake occurs. At the end of this natural intake stroke, that is, just before the main intake port is closed, the timing valve 21 is opened and supercharging air is introduced. At the same time, the auxiliary fuel injection valve 15b is opened by the signal S12 from the drive circuit 118, and auxiliary fuel is injected into the auxiliary intake passage 11. The fuel comes into contact with the high-pressure, high-speed supercharged air to create a nearly homogeneous air-fuel mixture, and some of it evaporates to cool the supercharged air. Then, the auxiliary fuel injection valve 15b closes after a predetermined time period according to the pulse signal S9 has elapsed. Thereafter, after the air-fuel mixture in the auxiliary intake passage 11 is driven into the combustion chamber 3 by the supercharging air, the timing valve 21 is closed and the auxiliary intake port is closed.

According to the valve operation described above, there is no problem of so-called sucking back of high-pressure supercharging air entering the main intake passage, and supercharging efficiency is good.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a supercharged engine according to the present invention, and FIG. 2 is a control circuit 16 of the engine shown in FIG.
FIG. 3 is a graph showing the relationship between throttle opening and engine speed, and FIG. 4 is a graph showing the relationship between valve operation. Explanation of symbols, 1...Cylinder, 2...Piston, 3
...combustion chamber, 4...main intake port, 5...auxiliary intake port, 6...exhaust port, 7...main intake valve, 8...auxiliary intake valve, 9...exhaust valve, 10...main intake passage, 11...auxiliary intake passage, 14...Throttle valve, 15a, 15
b...Fuel injection valve, 16a...Air flow meter,
16b... Control circuit, 17... Supercharger, 18... Supercharging control valve, 19... Supercharging relief valve, 21... Timing valve, 25... Throttle opening sensor, 26
...Crank angle sensor.

Claims (1)

[Scope of Claims] 1. A main intake passage that communicates with the combustion chamber via a main intake port, and an auxiliary intake that communicates with the combustion chamber via an auxiliary intake port that has a supercharger and closes later than the main intake port. a timing valve provided downstream of the supercharger for opening the auxiliary intake passage; a main fuel supply means for supplying fuel to the main intake passage; and a timing valve provided downstream of the timing valve for supplying fuel to the auxiliary intake passage. and an auxiliary fuel supply means for supplying fuel, and a fuel supply control device for supplying fuel only from the main fuel supply means in non-supercharging operation, and supplying fuel from at least the auxiliary fuel supply means in supercharging operation. A fuel supply device for a supercharged engine, characterized in that: 2. The fuel supply control device opens the timing valve at the end of the intake stroke during supercharging operation;
2. The fuel supply system for a supercharged engine according to claim 1, wherein the auxiliary fuel supply means is operated when the timing valve is open.