JPH0759922B2 - Intake device for 4-cycle internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has three intake valves adjacent to each other for one cylinder, and a fuel injection valve is provided in a communication chamber communicating with these intake valves. The present invention relates to an intake system for a four-cycle internal combustion engine that supplies fuel.

(Background of the Invention) There is a four-cycle internal combustion engine in which three adjacent intake valves are provided for one cylinder. In this type of engine, it is considered that the intake passages communicating with each intake valve are communicated with each other in a communication chamber, and the fuel is supplied to the communication chamber by using one fuel injection valve. In this case, since there are three intake passages connected to the communication chamber, combustion is likely to adhere to the inner wall surface of the intake passage, and the distribution to the three intake passages is likely to be uneven. Therefore, it is necessary to prevent the fuel from adhering to the inner wall of the intake passage, promote atomization of the fuel, and obtain preferable combustion with respect to changes in operating conditions.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is a four-cycle internal combustion engine in which three intake valves adjacent to each other are arranged so as to surround a cylinder center line, and each intake valve Guides the intake passage to the side of the combustion chamber, communicates these intake passages with each other in the communication chamber, and when fuel is supplied to this communication chamber by the fuel injection valve, the atomization of the fuel is good and each intake valve It is an object of the present invention to provide an intake system for a four-cycle internal combustion engine in which the supply of air-fuel mixture to the engine is preferable.

(Structure of the Invention) According to the present invention, an object of the present invention is to arrange three intake valves adjacent to each other so as to surround a cylinder center line, and to connect each intake passage connected to each intake valve to the side of the combustion chamber. In a four-cycle internal combustion engine in which these intake passages are communicated with each other in a communication chamber, a four-cycle internal combustion engine is provided with one fuel injection valve that directs fuel into the communication chamber in the direction of the central intake passage, and the communication chamber is used as a cylinder head. Formed and opened on the side surface of the cylinder head, the partition wall between the intake passages is retracted to the intake valve side to expand the communication chamber from the cylinder head side surface to the inside of the cylinder diameter when viewed from the cylinder center line direction, and the center Of the intake passages of the communication chamber are displaced downward from the intake passages on both sides, and the lower wall and the upper wall of the communication chamber are respectively located in the center of the intake passages when viewed from a direction substantially orthogonal to the intake passages and the cylinder center line. This is achieved by an intake system for a four-cycle internal combustion engine, characterized in that it is smoothly connected to the lower wall and the upper wall of the passage.

(Operation) The fuel injected from the fuel injection valve into the communication chamber is distributed to the intake passage of each intake valve together with the intake air. The fuel is injected while spreading toward the central intake valve direction, but the central intake passage is offset below the intake passages on both sides, and the partition wall of each intake passage is sufficiently oriented toward the intake valve side. Since it is retracted, the communication chamber can be sufficiently expanded to the inside of the cylinder diameter when viewed from the cylinder center line direction. The lower wall and the upper wall of the communication chamber are lowered so as to smoothly connect to the central intake passage, so that the fuel injected from the fuel injection valve is unlikely to adhere to the inner wall of the communication chamber or the inner wall of the central intake passage. And the atomization is accelerated. Therefore, the supply of fuel to the three intake valves becomes preferable, and the combustion becomes stable.

(Embodiment) FIG. 1 is a plan view in which a first embodiment of the present invention is partially sectioned, FIG. 2 is a sectional view taken along the line II-II, and FIG. 3 is a torque characteristic diagram. In FIGS. 1 and 2, reference numeral 10 is a cylinder body, 12 is a cylinder head, and 14 is a piston, which form a combustion chamber 16. The cylinder head 12 is provided with two exhaust valves 18 (18a, 18b) per cylinder and three intake valves 20 (20a, 20b, 20c) adjacent to each other. These exhaust / intake valves 18 and 20 are respectively the overhead camshafts 22 and 24,
It is opened and closed by a well-known swing arm type two-head camshaft type valve operating mechanism including swing arms 26, 28 and the like. 30
Is a cylinder head cover, 32 is an exhaust passage communicating with the exhaust valve 18, and 34 in FIG. 1 is a spark plug. The ignition part of the spark plug 34 faces near the center of the combustion chamber 16.

36 is a surge tank, and 38 is an intake pipe connecting the surge tank 36 and the cylinder head 12 for each cylinder. In the intake pipe 38, a first intake pipe line 40a and a second intake pipe line 40b are formed. The first intake conduit 40a and the second intake conduit 40b have substantially the same diameter, and the valve shaft 42 passing through these conduits 40a, 40b is
A butterfly type control valve 44 for opening and closing the second intake pipe line 40b is attached. The control valve 44 is controlled to open and close in response to operating conditions such as an operating load and an increase / decrease in engine speed.

Downstream sides of the first and second intake pipe lines 40 are connected to a communication chamber 46 provided in the cylinder head 12, and the communication chamber 46 communicates with the three intake valves 20. Here, the communication chamber 46 is a cylinder head.
The intake passages 21 (21a, 21b, 21c) that open to the side surface of 12 and are guided to the side of the combustion chamber 16 from each intake valve 20 and reach the communication chamber 46 are sufficiently short. That is, the partition walls 23 (23a, 23b) of these intake passages 21 retract toward the intake valve 20 side, and the communication chamber 46
Extends from the side surface of the cylinder head 12 to the inside of the cylinder diameter when viewed from the cylinder center line direction. Therefore, the communication room 46
Is wide enough and its lower and upper walls are wide enough.

On the other hand, in the three intake passages 21, the central intake passage 21b is displaced downward from the intake passages 21a, 21c on both sides, and the lower wall and the upper wall of the communication chamber 46 are respectively the lower wall of the central intake passage 21b and the lower wall of the central intake passage 21b. It is smoothly continuous to the upper wall.

Reference numeral 48 is an electromagnetic fuel injection valve. As shown in FIG. 2, the injection valve 48 is located between the distribution pipe 50 arranged in the upper part of the intake pipe 38 and the upper part of the communication chamber 46 of the cylinder head 12, and its injection port is shown in FIG. As can be seen, the intake valve 20b in the center of the plan view
Be oriented. This injection valve 48 opens at a predetermined timing by an electric signal output by a controller (not shown), and intermittently injects the fuel in the distribution pipe 50 pressurized to a predetermined pressure into the communication chamber 46. .

The operation of the first embodiment is as follows. During low load / low speed operation, the control valve 44 is closed and the intake air is guided to the communication chamber 46 from the first intake pipe line 40a. Therefore, strong turbulence is generated in the communication chamber 46, and atomization of fuel is promoted. At high load and high speed operation, the control valve 44 opens and intake air is in the first and second intake pipe lines 40.
Enter the communication room 46 from a and 40b. At this time, the intake flow velocity becomes high, so that a strong turbulent flow is generated in the communication chamber 46, and atomization of the fuel is promoted.

The fuel injected from the fuel injection valve 48 passes through the communication chamber 46 and spreads toward the central intake passage 21b, but the partition wall 23 is sufficiently short so that the communication chamber 46 is sufficiently close to the intake valve 20 side and the communication chamber Since 46 is sufficiently wide, this lower wall is sufficiently wide, and this lower wall smoothly continues to the central intake passage 21b which is offset downward from the outer intake passages 21a and 21c. Therefore, the fuel is less likely to hit the upper and lower walls of the communication chamber 46,
It also becomes difficult to adhere to the inner wall surface of the central intake passage 21b. For this reason, atomization of the fuel is promoted, and stable combustion becomes possible.

In FIG. 3, the solid line A shows the torque characteristic when the control valve 44 is kept open, and shows that the torque decrease is remarkable due to the reduction of the intake inertia effect at medium and low speeds. A chain line B indicates a control valve 44.
Is a torque characteristic when is closed. By opening and closing the control valve 44 in the medium speed range, these two characteristics A and B can be combined to improve the torque characteristics.

FIG. 4 is a plan view in which the second embodiment is partially sectioned. In this embodiment, the first intake pipe 40a in the first embodiment has a smaller diameter than the second intake pipe 40b. According to this embodiment, the injection port of the injection valve 48 has the first and second intake pipe lines.
It is deviated to the side of the second intake pipe line 40b from the wall between 40a and 40b. As a result, when the control valve 44 is opened at high load and high speed, the intake air flowing into the communication chamber 46 from the second intake pipe line 40b hits the fuel injected from the injection valve 48 better than in the first embodiment, and the fuel is injected. The atomization of is further promoted.

Further, since the second intake pipe 40b has a small diameter, it is possible to increase the torque due to the intake inertia from a lower speed than in the first embodiment. Further, since the deviation amount of the first intake pipe line 40a with respect to the communication chamber 46 becomes larger than that in the first embodiment, the control valve 44
When the engine is closed at a low speed, the vortex flow generated in the communication chamber 46 becomes stronger, and when the intake valve 20 is opened, a stronger swirl (intake vortex flow) is generated in the combustion chamber 16 due to this vortex flow. Therefore, the combustion at low speed is stabilized, and the effect of smoothing the low speed operation becomes more remarkable.

FIG. 5 is a partially sectional plan view of the third embodiment. In this embodiment, the first intake pipe 40a is arranged in the center while the second intake pipe 40a is arranged in the second position.
The intake pipe 40b is divided into two parts, and the control valves 44,
Was set up.

According to this embodiment, the intake air passing through the first intake pipe at the time of low load / low speed when the control valve 44 is closed hits the fuel injected from the injection valve 48 favorably, and the atomization especially at low load / low speed is This is further improved as compared with the first and second embodiments.

FIG. 6 is a partial cross-sectional plan view of the fourth embodiment, and this embodiment includes first, second and third intake pipe lines 40a, 40b, 40c, and the first intake pipe line 40a is sandwiched between the first and second intake pipe lines 40a, 40b, 40c. 2, 3rd intake pipe line 40b, 40
Control valves 44a and 44b having different opening and closing timings are arranged in c.

According to this embodiment, not only the atomization at low speed is promoted as in the third embodiment (FIG. 5), but also the torque characteristic can be improved at the same time. That is, FIG. 7 is a Tokule characteristic diagram of the fourth embodiment, in which the solid line A indicates the characteristic when the control valves 44a and 44b are kept open, and the broken line B indicates the control valves 44a and 44b in the low speed range.
The characteristic when both are closed is also the characteristic when the chain line C is the characteristic when only the control valve 44b is opened in the medium speed range. Control valves 44a, 44
These characteristics A, B, C by opening and closing b at different operating speeds
By combining the above, it is possible to improve the torque in the medium speed range as compared with the first to third embodiments.

FIG. 8 is a partially sectional plan view of the fifth embodiment, which is the first intake pipe 40 in the fourth embodiment (FIG. 6).
The positions of a and the second intake pipe line 40b are interchanged.

According to this embodiment, as in the fourth embodiment (FIG. 6), not only the torque in the medium speed range can be increased, but also the swirl is generated in the low speed range as in the second embodiment (FIG. 4). Since it is strengthened, the rotation during low speed operation becomes smoother.

In FIGS. 4, 5, 6, and 8, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will not be repeated.

(Effects of the Invention) As described above, according to the present invention, when each intake passage communicating with each of the three intake valves is communicated with the communication chamber and fuel is injected from the fuel injection valve into this communication chamber, the central intake passage Are displaced downward from the intake passages on both sides, the partition walls of each intake passage are retracted to the intake valve side, and the communication chamber is enlarged from the cylinder head side surface to the inside of the cylinder diameter when viewed from the cylinder center line direction, making it sufficiently wide. Therefore, the atomization of the fuel is promoted in the wide communication chamber, and since the communication chamber is close to the intake valve, the atomized fuel in the communication chamber can be smoothly guided to the intake valve. Further, since the lower wall and the upper wall of the communication chamber are smoothly connected to the central intake passage as viewed from the direction substantially orthogonal to the intake passages and the cylinder center line, the fuel is less likely to adhere to the lower wall of the communication chamber. Atomization of the fuel is promoted and is well guided to each intake passage.

[Brief description of drawings]

FIG. 1 is a plan view in which a first embodiment of the present invention is partially sectioned, FIG. 2 is a sectional view taken along the line II-II, and FIG. 3 is a torque characteristic diagram. Further, FIGS. 4, 5, 6 and 8 are partially sectional plan views of other embodiments, and FIG. 7 is a torque characteristic diagram of the embodiment of FIG. 16 ... Combustion chamber, 20a, 20b, 20c ... Intake valve, 21a, 21b, 21c ... Intake passage, 22, 24 ... Cam shaft, 23a, 23b ... Partition wall, 46 ... Communication chamber, 47 ... ... intake passage.

Claims (1)

[Claims] 1. Three adjacent intake valves are arranged so as to surround a cylinder center line, and each intake passage connected to each intake valve is guided to the side of the combustion chamber, and these intake passages are connected to each other in a communication chamber. In a four-cycle internal combustion engine that communicates with each other, one fuel injection valve that directs fuel into the communication chamber by directing toward the central intake passage is provided, and the communication chamber is formed in the cylinder head and opened on the side surface of the cylinder head. , The partition wall between the intake passages is retracted to the intake valve side to expand the communication chamber from the cylinder head side surface to the inside of the cylinder diameter when viewed from the cylinder center line direction, and the central intake passage is formed from the intake passages on both sides. The lower wall and the upper wall of the communication chamber to the lower wall and the upper wall of the central intake passage, respectively, when viewed from a direction substantially orthogonal to the intake passages and the cylinder center line. Characterized by being continuous 4
Intake device for a cycle internal combustion engine.