JPS6113109B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection type multi-cylinder internal combustion engine in which a fuel injection nozzle is provided in an intake manifold gathering part.

When fuel is supplied by fuel injection in a multi-cylinder internal combustion engine, the number of fuel injection nozzles used can be reduced by providing the fuel injection nozzles at the gathering part of the intake manifold that distributes intake air to each cylinder.
It is possible to simplify the structure and reduce costs. However, when adopting such a configuration, the mixture of fuel and intake air tends to become uneven when there are changes in the fuel injection amount or intake flow rate, and as a result, the distribution of fuel to each cylinder becomes uneven. Therefore, there is a problem that the air-fuel ratio becomes uneven among the cylinders. In addition, there was also the problem that the air-fuel mixture was difficult to atomize and proper combustion could not be achieved because the flow velocity was slow, especially in the low speed range.

This invention has been made in view of the above problems, and includes forming a bench lily in the gathering part of the intake manifold, providing a fuel injection nozzle to inject fuel toward the inside of the vent lily, and also forming a vent lily in the gathering part of the intake manifold. A throttle valve and a control valve that closes this intake passage only at low load are installed in the intake passage on the downstream side of the engine, and by connecting these two valves and the vicinity of the intake port with an auxiliary intake passage, the atomization of the fuel and the air-fuel mixture are improved. To provide a fuel injection multi-cylinder internal combustion engine that promotes uniformity of the air-fuel ratio, reduces variations in air-fuel ratio between cylinders, and can be expected to achieve proper combustion even in a low speed range. The present invention will be explained in detail below based on the drawings.

FIG. 1 is a bottom view showing an embodiment of the present invention applied to a four-cylinder engine with the cylinder block removed;
FIG. 2 is also a sectional view taken along the - line. In these figures, reference numeral 1 indicates a four-cylinder cylinder block, 2 a piston, 3 a cylinder head, and 4 a combustion chamber formed by these. The cylinder head 3 is provided with an intake valve 5 and an exhaust valve 6, which are driven by a known valve mechanism so as to communicate and cut off communication between the intake passage 7 and the exhaust passage 8 and the combustion chamber 4, respectively. Ru. An intake manifold 9 for guiding intake air into each combustion chamber 4 is connected to the cylinder head 3 . The intake manifold 9 includes a main intake passage 10 and a sub-intake passage 11.
The main intake passage 10 is composed of distribution parts 12, 12, . This gathering part 13 has a vertical part 13a whose lower end is connected to the distribution part 12 and guides the intake air substantially vertically, and a horizontal part 13b which is connected to the upper end of the vertical part 13a and guides the intake air horizontally. . That is, the gathering portion 13 is bent at a substantially right angle here. A bench lily 14 is formed near the upper end of the vertical portion 13a, and a throttle valve 15 and a control valve 16 are sequentially arranged in the intake passage on the downstream side of this bench lily 14. The throttle valve 15 is rotationally controlled by an accelerator mechanism (not shown). control valve 16
is rotationally controlled by a negative pressure responsive drive section 17. That is, this drive section 17 is connected to the control valve 16.
A diaphragm 19 is connected via a connecting rod 18 to a lever integrated with the diaphragm 19.
A negative pressure chamber 21 is provided with a spring 20 to return the control valve 16 in the direction of opening, and a negative pressure chamber 21 that sucks the diaphragm 19 in the direction of closing the control valve 16.
is formed, and this negative pressure chamber 21 has a negative pressure detection hole 2 opened between the throttle valve 15 and the control valve 16.
Connected to 2. Therefore, when the negative pressure between the throttle valve 15 and the control valve 16 is large (moving away from atmospheric pressure) at low load, the control valve 16 is closed, and on the other hand, when the negative pressure is small (approaching atmospheric pressure), the spring 2 closes.
0 opens the control valve 16.

The upstream opening 23 of the sub-intake passage 11 is positioned between the throttle valve 15 and the control valve 16. This auxiliary intake passage 11 includes a gathering part 24 having a diameter smaller than that of the main intake passage 10, a distribution part 25 on the downstream side thereof,
25......, the opening 23 of the gathering part 24
The intake air is guided to distribution parts 25, 25, . That is, each of the distribution parts 25, 25, . . . passes through the cylinder head 3 and is connected to an auxiliary intake port 26 that opens near the intake port of each cylinder. The auxiliary intake port 26 is opened in the intake passage 7 from the back side of the intake valve 5 so as to face the combustion chamber 4 obliquely. A bypass passage 27 is provided on the upstream side of the auxiliary intake passage 11, which bypasses the throttle valve 15 and communicates with the upstream side of the main intake passage 10. An adjustment screw 28 is attached for adjusting.

A water jacket 29 is attached to the intake manifold 9.
is provided. This water jacket 29
Cooling water is circulated through the sub-intake passage 11, which has the effect of promoting fuel atomization by heating the sub-intake passage 11.

The horizontal portion 13b on the upstream side of the intake manifold 9
The air flow meter 30 is connected to a flexible pipe 3.
1. This air flow meter 30 includes a flap 32 whose rotation angle changes depending on the intake air flow rate. The rotation angle of the flap 32 is electrically read by a potentiometer (not shown), and the fuel flow rate etc. are controlled by an electric circuit device.

33 is a fuel injection nozzle, and this nozzle is attached to the horizontal portion 13b so as to inject fuel toward the inside of the bench lily 14. That is, this fuel injection nozzle 33 is located at the horizontal portion 13b.
It is fixed to the horizontal part 13b so that fuel is injected from approximately the center of the bench lily 14 along the axis of the bench lily 14 at the bent part consisting of the vertical part 13a and the vertical part 13a.

Next, the operation of this embodiment will be explained. First, before starting the engine, the throttle valve 15 is in the fully closed position shown in FIG.
It comes to the fully open position with a bias of 0. When the engine is started in this state, the negative pressure on the downstream side of the throttle valve 15 increases (moves away from atmospheric pressure), so the drive unit 1
The diaphragm 19 of No. 7 is drawn toward the negative pressure chamber 21, and the control valve 16 is closed. Therefore, intake air is supplied into the combustion chamber 4 through the sub-intake passage 11. As the throttle valve 15 opens, the negative pressure in the negative pressure detection hole 22 also decreases (approaches atmospheric pressure), so the control valve 16
will gradually open up. Therefore, intake air is supplied from the sub-intake passage 11 and the main intake passages 10 and 7.
As a result, even during low-load operation where irregular combustion is likely to occur, the proportion of intake air passing through the auxiliary intake passage 11 increases, and the intake air passing through this auxiliary intake passage flows from the auxiliary intake port 26 at high speed into the combustion chamber 4 at a constant rate. Since the fuel is oriented and injected, a strong vortex is generated within the combustion chamber 4. This stabilizes combustion, enables smooth engine operation, and improves acceleration performance.

Fuel is supplied from the fuel injection nozzle 33 into the bench lily 14 while its injection amount is controlled in accordance with the operating state. This bench lily 14
Since the inner diameter is narrowed at , the intake flow rate increases. Therefore, atomization of the fuel injected into the bench lily 14 is promoted. Also bench lily 14
Since the cross-sectional area of the flow path through which the intake air passes is small, the fuel injected from the fuel injection nozzle 33 is spread throughout this cross-sectional area, and the fuel is mixed uniformly. This air-fuel mixture flows through the sub-intake passage 11 and the main intake passage 10.
The fuel is distributed to each cylinder in the respective distribution parts 25 and 12 and supplied to each combustion chamber 4. At this time, the atomization and uniformity of the air-fuel mixture are good, so variations in the mixture ratio between cylinders are reduced.

In this embodiment, the fuel injection nozzle 33 is provided to inject fuel from approximately the center of the bench lily 14 along the axis of the bench lily 14, so that the fuel is injected at the position where the intake flow velocity is highest. , fuel atomization is further promoted. Furthermore, since the fuel is injected along the flow direction of the intake air, the fuel is less likely to adhere to the wall surface of the intake passage. As a result, the uniformity of the air-fuel mixture is further improved, and the variation in air-fuel ratio between cylinders is further reduced. Note that the injection port of the fuel injection nozzle 33 only needs to face the bench lily 14, and most of the nozzle 33 is located within the horizontal portion 13b, so even if a relatively large nozzle 33 is used, the flow of intake air will be obstructed. Never.

As explained above, in this invention, a bench lily is formed in the gathering part of the intake manifold, and a fuel injection pump is provided to inject fuel toward the inside of this bench lily, so that the fuel is injected into the part where the intake flow velocity is high. Atomization of fuel is promoted. Further, the cross-sectional area of the bench lily portion is small, and the injected fuel is thoroughly distributed within this cross-sectional area, thereby improving the uniformity of the air-fuel mixture. Therefore, the air-fuel ratio of the air-fuel mixture distributed to each cylinder is made uniform among the cylinders, and combustion in each cylinder is uniform, which is advantageous from the viewpoint of exhaust gas countermeasures.
In addition, a throttle valve and a control valve that closes the passage only at low load are installed in the intake passage at the lower end of the bench lily, and a sub-intake passage is connected between these two valves and the vicinity of the intake port of each cylinder, causing irregular combustion. It has the advantage of stable combustion and smooth operation even during easy low-load operation.

[Brief explanation of the drawing]

Fig. 1 is a bottom view showing an embodiment of the present invention with the cylinder block removed, and Fig. 2 is a bottom view showing an embodiment of the present invention with the cylinder block removed.
FIG. 7...Intake passage, 9...Intake manifold, 11
... Sub-intake passage, 13 ... Gathering part, 14 ... Bench lily, 15 ... Throttle valve, 16 ... Control valve, 26
...Sub-intake port, 33...Fuel injection nozzle.

Claims (1)

[Claims] 1. A bench lily 14 is formed in the intake passage of the collecting part 13 of the intake manifold 9, and a fuel injection nozzle 33 for injecting fuel directed into the bench lily 14 is provided. A throttle valve 15 and a control valve 16 that closes this intake passage only at low load are provided, and an opening is provided between these two valves 15 and 16 and into the intake passage 7 near the intake port of each cylinder, oriented toward the combustion chamber. A fuel injection multi-cylinder internal combustion engine in which a sub-intake port 26 is connected to a sub-intake passage 11.