JPS6325169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-stroke internal combustion engine, such as a diesel engine, equipped with a fuel injection valve.

Generally, there are various factors that govern the output performance of a four-stroke engine, and among them, the intake and exhaust processes are one of the important factors.

However, in conventional mushroom valve type four-cycle internal combustion engines, even if the four-valve type is used, with two intake valves and two exhaust valves each, as the rotational speed increases, it is difficult to get enough air into the cylinders for performance reasons. Therefore, there is a problem in that the engine performance deteriorates, the exhaust temperature rises, or the heat load around the combustion chamber increases, and the maximum output of the engine is kept low. In particular, this trend has become more noticeable recently as engines have become more powerful and rotated at higher speeds.

This invention relates to a four-stroke internal combustion engine in which a piston is slidably provided in a cylinder, and an intake port, an exhaust port, and a fuel injection valve are provided in a cylinder head, and the piston is provided in the cylinder at the bottom dead center of the piston. , a second intake port is provided, and a communication hole is provided in the middle of the passage of the second intake port, the two openings having different half-rotation positions, and one operation of the four-cycle internal combustion engine
The passage opens and closes approximately in synchronization with the opening and closing of the second intake port at the bottom dead center portion of the piston's intake stroke, and the second intake port opens and closes slightly near the bottom dead center of the piston's explosion stroke. The structure includes a rotary control valve that opens the passage when the opening piston reaches the bottom dead center and closes the passage almost in synchronization with the closing of the second intake port, so that there is enough air inside the combustion chamber of the cylinder. It is an object of the present invention to provide a four-cycle internal combustion engine that can increase output and reduce heat load around a combustion chamber by feeding fresh air and performing efficient scavenging.

Hereinafter, one embodiment of the present invention will be described with reference to the attached FIGS. 1 to 4.

Reference numeral 1 in FIG. 1 is a cylinder block.
In cylinder 2 of this cylinder block 1,
A piston 4 is slidably provided through a cylinder liner 3. A connecting rod 5 is rotatably provided at one end of the piston 4, and the other end of the connecting rod 5 is rotatably provided relative to the crankshaft 6. Further, a cylinder head 9 having an intake port 7 and an exhaust port 8 is fixed to the upper end of the cylinder block 1, and these intake and exhaust ports 7 and 8 are connected by a camshaft and springs 10 and 11 (not shown). Intake valve 12 and exhaust valve 1 that open and close intake and exhaust ports 7 and 8
3 are provided respectively. Note that the intake/exhaust ports 7, 8 are connected to the intake pipe 1 via piping 14, 15.
6, are connected to the exhaust pipe 17, and
The cylinder head 9 is provided with a well-known fuel injection valve (not shown).

Further, the cylinder liner 3 is provided with a second intake port 18 that opens so as to be in contact with one end of the upper part of the piston 4 in the figure, which is located at the bottom dead center. This second intake port 18 is connected to the intake pipe 16 via a passage 19 provided in the cylinder block 1 and a pipe 20. Therefore, when the piston 4 is located near the bottom dead center, the second intake port 18 is opened and the air is drawn from the intake pipe 16 to the cylinder 2.
When air is sent into the combustion chamber S and the piston 4 is positioned other than near the bottom dead center, the second intake port 18 is closed by the piston 4. Furthermore, in order to open and close the second intake port 18 at more appropriate times, a camshaft is provided in the middle of the passage 19, and in synchronization with this, the second intake port 18 is opened and closed at a more appropriate time. A rotary control valve 21 that can be rotated once in the direction is provided. That is, the rotary control valve 21 has a substantially dogleg-shaped passage extending from an opening on one side of the outer periphery to an opening on the other side, and the two openings have different half-turn positions. A communication hole 21a is provided, and a passage 19 is provided corresponding to the communication hole 21a. Moreover, the second intake port 18 of the passage 19
The passage 19a connected to the piping 20 has the same diameter as the passage 21a, and the passage 19b connected to the piping 20 has a larger diameter than the passage 21a. And the second
In the intake stroke from FIG. and the passage 19 as shown in solid line in FIG.
a and the passage 21a are made to coincide with each other. In other words, as shown in FIG. 4, during the intake stroke, the open area of the second intake port 18 and the rotary control valve 2
This is done so that the open area of 1 is the same as that of 1. On the other hand, during the explosion stroke from a to b in FIG.
The passage 19a and the passage 21 are
The passage 19a and the passage 21a begin to be connected when the piston 4 reaches the bottom dead center as shown by the two-dot chain line in FIG. At this time, since the passage 19b has a larger diameter than the passage 21a, the passage 19b and the passage 21a are already connected. Then, as the piston 4 moves upward and the second intake port 18 is gradually closed, the connection area between the passage 19a and the passage 21a increases, and the open area of the second intake port 18 and the rotary control valve 2 increase.
The open area of 1 matches. After that, the open area of the rotary control valve 21 decreases due to the decrease in the connecting area between the passage 19b and the passage 21a, and as a result, the second intake port 18 and the rotary control valve 21 are connected to each other as shown in FIG.
are closed at the same time.

Next, the operation of the four-stroke internal combustion engine configured as described above will be explained. As shown in FIG. 2a, when fuel is injected into the combustion chamber S from a fuel injection valve (not shown) and an explosion occurs, the piston 4 rotates while rotating the crankshaft 6 in the direction B in the figure. moves downward. When the exhaust valve 13 is opened just before the end of the explosion stroke, the pressure in the combustion chamber S drops to zero due to the reaction of the exhaust pulse when the piston 4 reaches near the bottom dead center or slightly past the bottom dead center. Or it becomes negative pressure. At this time, that is, when the piston 4 reaches the bottom dead center, the rotary control valve 21 is opened, so air flows in from the second intake port 18 to lower the exhaust temperature and perform scavenging efficiently. This promotes exhaustion. Thereafter, as the piston 4 rises, the pressure within the combustion chamber S increases, but at that time the second intake port 18 is blocked by the piston 4, so exhaust gas does not flow back. Furthermore, as shown in FIG. 2c, the exhaust and intake overlaps occur in a conventional manner. However, in this case, since air has already been introduced, the overlap can be reduced. Next, intake is performed, and as shown in FIG. 2d, when the piston 4 is located near the bottom dead center, the second intake port 18
Air flows in from the intake port 7, thereby making it possible to sufficiently compensate for the air that cannot enter through the intake port 7. As a result, the opening time of the intake valve 7 after the bottom dead center of the piston 4 can be made shorter than in the conventional case (the portion shown by the two-dot chain line in FIG. 4). This can increase the effective compression ratio at startup, which is advantageous for cold startup.

Note that a compressor may be provided in the piping 20 or the intake pipe 16 in order to allow more air to flow into the combustion chamber S from the second intake port 18. Also,
In the above embodiment, the number of intake ports 7 and the number of exhaust ports 8 are the same, but the number of exhaust ports is not limited to this, and the number of exhaust ports is greater than the number of intake ports, for example, the number of exhaust ports is three, and the number of intake ports is one. It may be used as ke. In this case, as shown in Fig. 5, the opening area of the exhaust valve becomes larger due to the increase in the number of exhaust ports, so the exhaust resistance can be reduced, and moreover, intake is sufficiently carried out from the second intake port.
Therefore, the performance of the engine can be further improved.

As explained above, the four-stroke internal combustion engine of the present invention is a four-stroke internal combustion engine in which a piston is slidably provided in a cylinder, and an intake port, an exhaust port, and a fuel injection valve are provided in the cylinder head. A second intake port is provided in the cylinder at the bottom dead center portion of the piston, and a communication hole is provided in the middle of the passage of the second intake port, the two openings having different half-rotation positions, and 1 per operation of a 4-stroke internal combustion engine.
The passage opens and closes approximately in synchronization with the opening and closing of the second intake port at the bottom dead center portion of the piston's intake stroke, and the second intake port opens and closes slightly near the bottom dead center of the piston's explosion stroke. Since the structure includes a rotary control valve that opens the passage when the opening piston reaches the bottom dead center and closes the passage in approximately synchronization with the closing of the second intake port, air intake is prevented. The temperature of the exhaust gas can be lowered by the air flowing in from the second intake port.
Since combustion gas is prevented from blowing out from the intake port, there is no loss of explosion energy, and the scavenging efficiency of exhaust gas can be improved, thereby increasing the output of the four-stroke internal combustion engine. The heat load around the combustion chamber can be reduced, and the maximum output can be improved. In addition, as a result of sufficient intake air, the opening time of the intake valve after the bottom dead center of the piston can be shortened, and the piston can compress air from an early stage, increasing the net compression stroke volume. can do. Furthermore, since the scavenging efficiency is increased by the air flowing in from the second intake port, the overlap can be reduced and the escape of the piston from the intake and exhaust valves can be reduced, thereby reducing the shape of the combustion chamber. It has the effect of making it better.

[Brief explanation of the drawing]

The attached FIGS. 1 to 4 show one embodiment of the present invention, with FIG. 1 being a longitudinal sectional front view thereof, and FIG. 2 showing the relationship between the second intake port and the rotary control valve in each stroke, and a is the explosion stroke diagram, b is the exhaust stroke diagram, c
is an intake/exhaust overlap stroke diagram, d is an intake stroke diagram, Figure 3 is an enlarged view of the circular part in Figure 1, and Figure 4 is an opening diagram of the intake valve, exhaust valve, second intake port, and rotary control valve. A diagram showing the area, FIG. 5, is a diagram similar to FIG. 4 of another embodiment of the present invention. 2...Cylinder, 4...Piston, 7...Intake port, 8...Exhaust port, 9...Cylinder head, 1
2... Intake valve, 13... Exhaust valve, 18... Second intake port, 19... Passage, 21... Rotary control valve, 21a... Passage (communication hole).

Claims (1)

[Claims] 1. In a four-stroke internal combustion engine in which a piston is slidably provided in a cylinder and an intake port, an exhaust port, and a fuel injection valve are provided in the cylinder head, a second piston is provided in the cylinder at the bottom dead center portion of the piston. An intake port is provided, and a communication hole is provided in the middle of the passage of the second intake port, the two openings having different half-rotation positions, and one rotation in one direction in one operation of the four-cycle internal combustion engine. During the bottom dead center portion of the piston's intake stroke, the passage is opened and closed almost in synchronization with the opening and closing of the second intake port, and near the bottom dead center of the piston's explosion stroke, the second intake port slightly opens and the piston moves downward. A four-stroke internal combustion engine characterized in that a rotary control valve is provided that opens the passage when the engine reaches a dead center and closes the passage in substantially synchronization with the closing of the second intake port.