JPS6026185Y2 - Internal combustion engine intake system - Google Patents

Description

[Detailed explanation of the idea] Industrial applications The present invention relates to an intake system for an internal combustion engine.

Conventional technology If the opening timing of the intake valve is delayed and the valve closing timing is accelerated, high charging efficiency can be ensured during low load engine operation, which can improve output and shorten the valve polymerization period. The residual gas proportion is reduced, thereby making it possible to obtain stable combustion.

However, when the engine is operated at high speed and high load, the charging efficiency deteriorates and the output decreases.

On the contrary, if the opening timing of the intake valve is accelerated and the valve closing timing is delayed, high charging efficiency can be ensured when the engine is operating at high speed and high load, resulting in high output, but charging efficiency is poor when the engine is operating at low load. As a result, the output decreases, and since the valve polymerization period becomes longer, the proportion of residual gas increases, making it difficult to obtain stable combustion.

Therefore, conventionally, the opening timing and closing timing of the intake valve have been set so as to ensure as high a charging efficiency as possible over the entire operating range of the engine and to obtain stable combustion.

Problems that the invention aims to solveHowever, today there is a need to further improve the fuel consumption rate as well as higher output, so it is possible to obtain stable combustion even when operating at lower rotation speeds, and to achieve sufficiently high output. It has become necessary to be able to obtain it.

In response to this need, research has been conducted into variable valve timing mechanisms that automatically change the intake valve opening and closing timings in response to changes in engine load, but such variable valve timing mechanisms are not reliable. However, it has not yet been put into practical use due to its poor performance.

In view of these facts, it is an object of the present invention to provide an internal combustion engine that is capable of ensuring stable combustion at a lower rotational speed than conventional engines, and is also capable of obtaining a sufficiently high output.

Means for Solving the Problems An intake system for an internal combustion engine according to the present invention includes a main intake valve and a sub-intake valve whose opening area is smaller than that of the main intake valve, and includes a first throttle valve for controlling engine load. The downstream intake passage is divided into a main intake passage and a sub-intake passage whose cross-sectional area is smaller than that of the main intake passage, and the main intake passage is connected to the combustion chamber via the main intake valve, and the sub-intake passage is connected to the combustion chamber through the main intake valve. is connected into the combustion chamber via an auxiliary intake valve.

Further, a second throttle valve is disposed within the main intake passage, the edge of one side of which is close to the inlet of the sub-intake passage when fully closed, and the edge of the other side of which is located closer to the first throttle valve than the edge of the other side. The engine is equipped with a throttle valve and a second throttle valve control device that controls the opening and closing of the second throttle valve depending on the operating state of the engine, and the second throttle valve opens when the amount of intake air is large. controlled as follows.

Example Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2, 1 is a cylinder block, 2 is a piston that reciprocates within the cylinder block 1,
3 is a cylinder head, 4 is a combustion chamber, 5 is a spark plug provided in the combustion chamber, 6 is an exhaust valve, and 7 is an exhaust port.

In FIG. 1, A, B, C, and D indicate the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, respectively.

As shown in FIG. 1, each of the cylinders A, B, C, and D has a large main intake valve 10, a main intake port 11 connected to the combustion chamber 4 via the main intake valve 10, and a small main intake port 11 connected to the combustion chamber 4 through the main intake valve 10. , and a sub-intake port 13 connected to the combustion chamber 4 via the sub-intake valve 12 and having a smaller cross-sectional area than the main intake port 11.

Note that the cross-sectional area of the sub-intake port 13 is set within a range of 30% to 60% of the cross-sectional area of the main intake port 11.

Each main intake port 11 and auxiliary intake port 13 are connected to a surge tank 31 via a corresponding branch pipe 30, while the surge tank 31 is connected to an air cleaner via a first throttle valve 32 connected to an accelerator pedal and an air flow meter 33. (not shown).

As shown in FIG. 2, a fuel injection valve 34 for injecting fuel into the branch pipe 30 is attached to the upper part of each branch pipe 30, and fuel is supplied from the fuel injection valve 34 according to the amount of intake air. is injected.

On the other hand, each branch pipe 30 consists of an inlet part 35, a main intake passage 36 and a sub-intake passage 37 branched from this inlet part 35, and as shown in FIG.
It is placed almost in line with 5.

The fuel injection valve 34 is attached to the branch pipe 30 at an angle so that the injection hole faces toward the inlet of the sub-intake passage 37, as shown in FIG.

A second throttle valve 1 is provided at the inlet of each main intake passage 36, respectively.
6 are arranged, and these second throttle valves 16 have one side edge 38 aligned with the inner edge 39 of the inlet part of the auxiliary intake passage 37 when fully closed, as shown in the first aroma cylinder A in FIG. On the other hand, the other side edge 40 is located closer to the first throttle valve 32 than the one side edge 38 .

Each second throttle valve 16 has a throttle shaft 17 extending perpendicularly to the direction in which the cylinders are arranged.
An arm 18 is fixed to the lower end of 7.

1 An arm 41 fixed to the throttle shaft 17 of the incense cylinder A
One end is connected to the arm 18 fixed to the throttle shaft 17 of the second cylinder B via the rod 42, and the arm 41
The other end is connected to the rod 19.

On the other hand, one end of the arm 43 fixed to the throttle shaft 17 of the third scent cylinder C is connected via a rod 44 to an arm 18 fixed to the throttle shaft 17 of the fourth scent MD, and the other end of the arm 43 is connected to.

This rod 19 is connected to an electromagnetic control valve 45.

On the other hand, the electromagnetic control valve 45 is controlled by an electronic control circuit 47 based on an output signal from an engine speed sensor 46.

When the engine speed is lower than the predetermined speed, the electromagnetic control valve 45
is deenergized, and at this time, the second throttle valve 16 is in a fully closed state as shown in FIG.

Therefore, at this time, the air in the surge tank 31 is supplied into the combustion chamber 4 via the auxiliary intake valve 12 together with the fuel injected from the fuel injection valve 34.

As can be seen from FIG. 1, each of the second throttle valves 16 is arranged so as to guide the air mixture flowing from the inlet portion 35 toward the sub-intake passage 37 without providing any resistance, thereby ensuring even higher filling efficiency. be able to.

On the other hand, when the engine speed becomes higher than the predetermined speed, the electromagnetic control valve 45 is energized, and as a result, the rod 19 protrudes from the electromagnetic control valve 45, so that the second throttle valve 16 is fully opened.

As mentioned above, since the inlet portion 35 and the main intake passage 36 are arranged almost in a straight line, the intake air flows mainly through the main intake valve 10 into the combustion chamber 4 without experiencing large flow resistance in the branch pipe 30. In this way, high filling efficiency can be ensured.

FIG. 3 shows the opening periods of the main intake valve 10 and the auxiliary intake valve 12.

In FIG. 3, the vertical axis F shows the valve lift, and the horizontal axis θ shows the crank angle.

Further, in FIG. 3, a curved line indicates the main intake valve 10, a curved line indicates the sub-intake valve 12, and a curved line M indicates the exhaust valve 6.

In the present invention, as shown in Fig. 3, the opening timing of the main intake valve 10 is set in the range of 15° to 200° before top dead center, and the closing timing of the main intake valve 10 is set in the range of 50° to 60° after bottom dead center. It is set in the range of °.

On the other hand, the opening timing of the auxiliary intake valve 12 is set in the range of 0° to 10' before the top dead center, and the closing timing of the auxiliary intake valve 12 is set in the range of 10° to 30° after the bottom dead center. is set to .

Furthermore, in the present invention, as shown in FIG.
It is set at 50% to 70% of the maximum valve lift.

When the amount of intake air is small, the second throttle valve 16 fully closes the main manifold branch pipe 15 as described above.

As shown in FIG. 3, when the intake stroke starts, the main intake valve 10 opens first, but as mentioned above, since the second throttle valve 16 is fully closed, the mixture in the branch pipe 30 Air is not supplied into the combustion chamber 4 via the main intake valve 10, and the air-fuel mixture in the branch pipe 30 is not supplied into the combustion chamber 4 via the auxiliary intake valve 12 until the auxiliary intake valve 12 opens. supplied to

As mentioned above, the cross-sectional area of the sub-intake port 13 is much smaller than the cross-sectional area of the main intake port 11, and thus the fuel flows at a high speed within the sub-intake port 13, promoting vaporization of fuel during this time. .

Then, the air-fuel mixture flows into the combustion chamber 4 at a high velocity, causing strong turbulence within the combustion chamber 4.

At the end of the intake stroke, even if the sub-intake valve 12 closes, the main intake valve 1
0 is open, but the second throttle valve 16 is fully closed, so the amount of air-fuel mixture blown back from the combustion chamber 4 into the main intake port 11 is small, thus achieving high charging efficiency. can be secured.

In order to reduce the amount of air-fuel mixture blown back, it is preferable to arrange the second throttle valve 16 as close to the main intake valve 10 as possible.

In this way, when the amount of intake air is small, vaporization of the fuel is promoted and strong turbulence is generated within the combustion chamber.Moreover, since the valve polymerization period is short and the residual gas proportion is small, stable combustion can be ensured.

Furthermore, since the filling efficiency is increased, high output can be obtained.

On the other hand, when the amount of intake air increases, the second throttle valve 16 is fully opened as described above, so that the intake manifold 8
The air-fuel mixture in the combustion chamber 4 is supplied to the combustion chamber 4 through both the main intake valve 10 and the auxiliary intake valve 12.

As can be seen from Figure 3, the opening timing of the main intake valve 10 is set to the so-called high-speed type, so high filling efficiency can be ensured during high-speed, high-load operation with a large amount of intake air, thus achieving high output. be able to.

FIG. 4 shows the relationship between engine output and rotational speed.

In FIG. 4, the vertical axis P shows the output, and the horizontal axis N shows the rotation speed.

In addition, in FIG. 4, the solid line indicates the case where the air-fuel mixture is supplied into the combustion chamber 4 only via the sub-intake valve 12,
The broken line shows the case where the second throttle valve 16 is kept fully open and the air-fuel mixture is supplied into the combustion chamber 4 through both the auxiliary intake valve 12 and the main intake valve 10.

Therefore, from Fig. 4, the number of revolutions is N.

In the following, the second throttle valve 16 is fully closed and the rotational speed is N.

It can be seen from the above that it is preferable to fully open the second throttle valve 16.

In this embodiment, the auxiliary intake port 13 is located closer to the main intake port 11 as shown by the broken line in FIG. placed below.

Effects of the Invention As described above, according to the present invention, the valve polymerization period during low-load operation can be shortened, so that the proportion of residual exhaust gas can be reduced.

As a result, it is possible to improve combustion during low-load operation, especially during idling operation, so that the idling speed can be lowered, and as a result, the fuel consumption rate can be improved.

Furthermore, since high charging efficiency can be ensured during low-load operation, low-speed output can be significantly improved compared to the conventional system.

Furthermore, during low-load operation, fuel vaporization is promoted and strong turbulence is generated within the combustion chamber, so stable combustion can be ensured.

On the other hand, during high-load operation, air-fuel mixture is also supplied from the main intake valve, so high-speed output can be ensured.

Further, according to the present invention, when the second throttle valve is fully closed, one side edge of the second throttle valve is closer to the inlet of the auxiliary intake passage, and the other side edge is closer to the first side edge than the one side edge. Since it is located on the throttle valve side, the air-fuel mixture that has passed through the first throttle valve is guided to the second throttle valve and smoothly flows into the auxiliary intake passage, making it possible to obtain an even higher filling rate. can.

At this time, since the fuel injection valve faces downward, fuel efficiently flows into the sub-intake passage and is smoothly guided into the combustion chamber.

Therefore, good combustion can be obtained.

[Brief Description of the Drawings] Figure 1 is a sectional plan view of the internal combustion engine according to the present invention, Figure 2 is a side sectional view of Figure 1, and Figure 3 shows the opening timing of the main intake valve and sub-intake valve. The graph shown in FIG. 4 is a graph showing the relationship between engine output and rotation speed. 4... Combustion chamber, 6... Exhaust valve, 10.
...Main intake valve, 11...Main intake port,
12...Sub-intake valve, 13...Sub-intake passage, 16...Second throttle valve.

Claims (1)

[Scope of utility model registration request] It is equipped with a main intake valve and a sub-intake valve whose opening area is smaller than that of the main intake valve, and an intake passage downstream of the first throttle valve that controls the engine load is defined as the main intake passage and has a cross-sectional area smaller than that of the main intake passage. The main intake passage is connected to the combustion chamber via the main intake valve, and the auxiliary intake passage is connected to the combustion chamber via the main intake valve. The injection is connected to the combustion chamber via the combustion chamber, and is injected into the upper part of the intake passage, which is upstream of the branching part of the intake passage between the main intake passage and the auxiliary intake passage, and toward the entrance of the auxiliary intake passage. A fuel injection valve is provided in the main intake passage with the hole facing toward the main intake passage. A second throttle valve located on the first throttle valve side is provided, and a second throttle valve control device is provided to control the opening and closing of the second throttle valve according to the operating state of the engine, and when the amount of intake air is large. An intake system for an internal combustion engine, wherein the second throttle valve is opened.