JPS6233066Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (1) Industrial field of application The present invention is mainly concerned with internal combustion engines suitable for small vehicles such as motorcycles, and in particular with a combustion chamber, an intake passage and an exhaust passage opening thereto, and The present invention relates to an intake system for a four-stroke internal combustion engine, which includes an intake valve and an exhaust valve provided in an intake passage and an exhaust passage to open and close the intake passage and the exhaust passage.

(2) Prior Art Conventional internal combustion engines have already been proposed in which a sealed replenishment chamber is communicated in the middle of an intake passage and the replenishment chamber is utilized to improve engine performance.

(3) Problems to be solved by the invention When the effective capacity of the replenishment chamber is increased in the conventional proposals, the atomized fuel in the air-fuel mixture sucked into the replenishment chamber liquefies and stagnates in the chamber. If a large amount of it is discharged into the combustion chamber at once due to vehicle tilting, it may cause irregular combustion in the engine or narrow the control hole or the connecting passage between it and the chamber. There are problems such as inhibiting the breathing action of the chamber.

An object of the present invention is to provide an intake system for an internal combustion engine that can eliminate the above-mentioned problems.

B. Structure of the invention (1) Means for solving the problem In order to achieve the above object, the invention provides a combustion chamber, an intake passage and an exhaust passage that open to the combustion chamber, and a combustion chamber that opens and closes the intake passage and the exhaust passage. An intake system for an internal combustion engine, comprising an intake valve and an exhaust valve arranged as shown in FIG. Disposed above the control hole, the replenishment chamber includes a guiding slope capable of guiding the liquid fuel that has entered the chamber toward the bottom of the chamber, and a guiding slope that allows the liquid fuel to collect at the bottom of the chamber. A discharge port is formed at the lower part of the inner surface of the chamber to discharge the gas, and the discharge port and the control hole are communicated with each other via a connecting pipe disposed below the replenishment chamber. It is said that

(2) Effect When the atomized fuel in the air-fuel mixture that has entered the replenishment chamber liquefies and adheres to the inner surface of the replenishment chamber, it is guided by the guiding slope and efficiently collected at the bottom of the replenishment chamber.

The liquid fuel collected at the bottom of the replenishment chamber is quickly discharged little by little from the discharge port, through the connection pipe and control hole, into the suction passage without stagnating at the bottom, which can cause irregular combustion in the engine. There is no need to constrict control holes or the like to impede the respiration function of the replenishment chamber.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, in FIGS. 1 and 2, a four-stroke internal combustion engine E moves up and down within the cylinders of the cylinder block 1 and the cylinder head 2, which is superimposed and bonded to the upper surface of the cylinder block 1, as usual. A combustion chamber 1a is formed on the lower surface of the cylinder head 2 so as to face the piston P, and an ignition plug 11 is provided in the combustion chamber 1a, deviating to one side from the center of the combustion chamber 1a. The electrode 11a is facing.
Further, the cylinder head 2 is formed with an intake passage 3a and an exhaust passage 3b, and these passages 3a, 3
b is opened into the combustion chamber 1a. The suction passage 3a has an intake valve 4a that opens and closes the passage 3a, and the exhaust passage 3b has an exhaust valve 4 that opens and closes the passage 3b.
b are provided at an angle with respect to the cylinder axis LL. These valves 4a, 4b are operated by rotary cams 5a, 5b provided on the cylinder head 2 via rocker arms 6a, 6b, and alternately open the suction passage 3a and exhaust passage 3b in conjunction with the vertical movement of the piston P. It is designed to open and close. As usual, the suction passage 3a is connected to an intake pipe 12a connected to the carburetor C, and the exhaust passage 3b is connected to an exhaust pipe 12b connected to an exhaust muffler (not shown).

Below the suction passage 3a, a control hole 7 having an equal diameter over the entire length is bored in the thick wall portion of the cylinder head 2, which communicates the suction passage 3a with the outside. The opening end of the control hole 7 on the suction passage 3a side opens below the center line of the suction passage 3a, in the inner wall surface of the lower half of the suction passage 3a, close to the umbrella part of the suction valve 4a. At the same time, it is oriented in a substantially tangential direction of the peripheral wall of the combustion chamber 1a and toward the electrode 11a of the ignition plug 11. The open end of the control hole 7 outside the cylinder head 2 is communicated via a connecting pipe 8 and a flexible connecting tube 9 to a closed replenishment chamber 10 having a required volume. The replenishment chamber 10 is disposed above the control hole 7, and the inner bottom surface of the replenishment chamber 10 is configured to absorb liquid fuel generated by liquefying the atomized fuel in the air-fuel mixture that has entered the chamber 10. It is formed into a conical guiding slope 10a that can be guided toward. In addition, a discharge port 10b is opened at the lowest part of the inner bottom surface of the replenishment chamber 10, that is, at the center, for quickly discharging the liquid fuel that collects therein without causing it to stagnate. 10 is connected to the connecting pipe 9 disposed below.

Next, the operation of this embodiment will be explained mainly with reference to FIG.

During the intake stroke of the engine, when the intake valve 4a is opened and the piston P descends as shown in FIG. Combustion chamber 1 through 3a
inhaled by a. During this time, the negative intake pressure in the suction passage 3a also acts on the replenishment chamber 10 through the control hole 7, the connecting pipe 8, and the flexible conduit 9, so that the inside of the replenishment chamber 10 is temporarily maintained at a negative pressure.

Next, the engine moves to the compression stroke, and even if the suction valve 4a is closed (the exhaust valve 4b is also closed) as shown in FIG. is connected, and the mixture flows into the replenishment chamber 10 through the control hole 7, the connecting pipe 8 and the conduit 9 as shown by the arrow, and this causes the internal pressure of the suction passage 3a and the replenishment chamber 1 to
This continues until the internal pressure of 0 is balanced, and the required amount of air-fuel mixture is filled into the replenishment chamber 10.

In this state, the engine enters the suction stroke again, the suction valve 4a is opened, and the piston P descends. This time, as shown in FIG. The air-fuel mixture stored in the combustion chamber 1a is drawn into the combustion chamber 1a. As a result, a large amount of air-fuel mixture is sucked into the combustion chamber 1a, and the suction efficiency is improved. The above operations are repeated while the engine is running.

In this embodiment, by specifying the configuration of the control hole 7, the respiration effect of the replenishment chamber 10 is made more powerful, and its effect becomes more pronounced.
That is, due to the opening and closing of the suction valve 4a, the suction passage 3
The pulsating pressure waves generated in the suction passage 3a are densest near the cap of the suction passage 3a due to pulsation and inertia effects, and there is little pressure propagation loss. By opening into the suction passage 3a, the opening end is subjected to a stronger pressure change than other parts of the suction passage 3a, and the breathing action by the control hole 7 is performed strongly.
The flow of the air-fuel mixture in the lower half of the center line is
Since the flow of the air-fuel mixture flowing through the upper half is less obstructed by the stem of the suction valve 4a, the lower half of the suction passage 3a has a higher flow rate of the air-fuel mixture than the upper half. The air-fuel mixture that flows smoothly and has a large flow rate passes through the control hole 7 opened in the lower half and flows into the replenishment chamber 10 based on the strong breathing action, and is injected from there into the suction passage 3a. Ru. In addition, in the high-speed rotation range of the engine, the intake flow rate of the mixture is large, and the mixture in the suction passage 3a is sufficiently atomized, but on the other hand, the throttle valve is partially opened and the engine is operated at low or medium speeds. When the intake air flow rate is within the range, the intake flow rate is small, and the liquid fuel that cannot be atomized flows along the lower half wall surface of the intake passage 3a. However, the opening end of the control hole 7 on the suction passage 3a side is
As mentioned above, below the center line of the suction passage 3a,
Since it is opened in the inner wall surface of the lower half of the passage 3a, the air-fuel mixture in the replenishment chamber 10 is vigorously injected into the intake passage 3a from this opening, and at this time, the liquid fuel is blown away and the mist is The liquid fuel can be prevented from flowing into the combustion chamber 1a, the ignitability of the air-fuel mixture can be improved, and low-speed performance can be improved.

The opening end of the control hole 7 on the suction passage 3a side is
In the substantially tangential direction of the peripheral wall of the combustion chamber 1a and the ignition plug 11
Since the air-fuel mixture is directed toward the electrode 11a of the spark plug 11, a relatively large amount of the air-fuel mixture is injected into the combustion chamber 1a from the control hole 7 even in the low to medium speed range of the engine. 11a to reliably eliminate the residual exhaust gas around the electrode 11a, it flows along the inner wall of the combustion chamber 10 to generate a strong swirling flow, and as a result, the intake air Even in the low to medium speed operating range of the engine where the amount of fuel is small, uniform mixing of the atomized fuel and air can be promoted, and the ignition performance of the ignition plug 11 for the mixture can be improved. Overall, a significant improvement in combustion efficiency is achieved.

Furthermore, since the control hole 7 is formed in the thick part of the cylinder head 2, suction resistance does not increase in the suction passage 3a even though the control hole 7 is specially provided, especially in the high-speed operating range of the engine. The suction efficiency does not decrease, the control hole 7 is less affected by engine vibrations, etc., the hole 7 can be easily machined, and the cylinder head 2 is connected to the control hole 7.
Its rigidity is not impaired even by the formation of .

Furthermore, the control holes 7 are of substantially equal diameter over their entire length, thereby minimizing the pressure drop of the fluid passing through the holes 7 to the replenishment chamber. 10 breathing actions can be performed more smoothly.

By the way, a part of the atomized fuel contained in the air-fuel mixture sucked into the replenishment chamber 10 is transferred to the chamber 1.
Although the liquid fuel may contact the inner wall of the chamber 10 and become liquid, the liquid fuel is efficiently collected at the lowest part of the bottom of the chamber 10 by the guiding inclined surface 10a.
The collected liquid fuel is then transferred to the outlet 1
0b, through the connecting pipe 9, the connecting pipe 8, and the control hole 7, into the suction passage 3a, so it will not cause irregular combustion in the engine, and the control hole 7, etc., will be narrowed. There is no interference with the breathing action of the supply chamber 10.

FIG. 4 shows a case where the above-mentioned intake system is applied to a gasoline engine E for a motorcycle, in which two control holes (not shown) open to the intake passage, and two control holes communicating with each of the two control holes are shown in FIG. Conduit 9a, 9b
are connected to one supply chamber 10. In Fig. 4, A is the air cleaner, C is the carburetor, F is the frame, M is the transmission, and Ma is the exhaust muffler.

Figures 5 and 6 A and B are graphs showing the test results of 90 c.c. gasoline engines equipped with the intake system of the present invention and conventional engines without it, respectively. Figure 5 shows the output characteristics. According to this figure, when the engine speed is in the range of 6000 to 6500 RPM, the output increases by 26% when the throttle valve opening Oth of carburetor C is 1/4. The throttle valve opening Oth is also 1/2.
15.2% when the throttle valve opening Oth is 4/4
It can be seen that when the engine is fully open, the output increases by 6.7%.

In addition, the graph in Figure 6A shows changes in the volumetric efficiency of the engine due to motoring tests, and it shows that when the rotational speed of the engine exceeds 5000 RPM, the volumetric efficiency of the device of the present invention is higher and the suction efficiency is correspondingly higher. Figure 6 (b) shows the change in volumetric efficiency of the engine due to the firing test, which shows that the engine with the supply chamber 10 is almost the same as the one without. In fact, it tends to exceed this, which indicates that the combustion of the present invention is performed well despite the intake of a large amount of air-fuel mixture.

C Effect of the invention As described above, according to the invention, the combustion chamber 1a,
Suction passage 3a and exhaust passage 3b open thereto
and an intake valve 4a and an exhaust valve 4b provided in the intake passage 3a and the exhaust passage 3b to open and close them, and a required volume is supplied to the intake passage 3a through a control hole 7 opened therein. Since the sealed replenishment chamber 10 is communicated with the engine, during the intake stroke of the engine, the air-fuel mixture stored in the replenishment chamber 10 can be automatically sucked into the combustion chamber 1a, thereby improving the intake efficiency of the engine as a whole. It is effective in increasing the suction efficiency in low and medium load operating ranges of engines where the absolute amount of intake air is small. Further, since the replenishment chamber 10 does not specifically bypass the suction passage 3a, the piping structure is simple and there are few restrictions on the installation location.

Further, the replenishment chamber 10 is connected to the control hole 7.
The supply chamber 10 is located higher up, and the supply chamber 10 has a
a guiding slope 10 capable of guiding liquid fuel that has entered the chamber 10 toward the bottom of the chamber 10;
a, and a discharge port 10b that opens at the lower part of the inner surface of the chamber 10 to discharge the liquid fuel that collects at the bottom of the chamber 10, and the discharge port 10b.
and the control hole 7 are communicated through the connecting pipe 9 disposed below the replenishment chamber 10, so that the atomized fuel in the air-fuel mixture sucked into the replenishment chamber 10 is liquefied. Even if it adheres to the inner surface of the replenishment chamber 10, it can be efficiently collected at the bottom of the replenishment chamber 10 by the guiding slope 10a, and the collected liquid fuel is transferred from the discharge port 10b to the connecting pipe 9, Since it is quickly discharged little by little into the suction passage 3a through the control hole 7, it will not cause irregular combustion in the engine, and the control hole 7 etc. will be narrowed to inhibit the breathing action of the supply chamber 10. Nothing.

[Brief explanation of the drawing]

The drawings show an embodiment of the device according to the present invention, and FIG. 1 is a longitudinal sectional view of the head of a four-stroke internal combustion engine equipped with the present invention, and FIG. 2 is a bottom view of the cylinder head taken along the line shown in FIG. 1. Figures 3A, 3B, and 3C are explanatory diagrams showing the operating states of the device of the present invention, and Figure 4 shows the internal combustion engine with the device of the present invention applied to a motorcycle.
A partial side view of a motorcycle; Figure 5 is a graph of test results comparing the engine equipped with the device of the present invention with a conventional engine in terms of output status; Figure 6 A and B show volumetric efficiency due to motoring and firing. 2 is a graph of test results comparing an engine equipped with the device of the present invention with a conventional engine. 1a... combustion chamber, 3a... suction passage, 3b...
Exhaust passage, 4a... Suction valve, 4b... Exhaust valve, 7
... Control hole, 9 ... Connection pipe, 10 ... Supply chamber, 10a ... Guidance slope, 10b ... Discharge port.

Claims (1)

[Scope of utility model registration request] The combustion chamber 1a includes a combustion chamber 1a, an intake passage 3a and an exhaust passage 3b opening thereto, and an intake valve 4a and an exhaust valve 4b provided in the intake passage 3a and the exhaust passage 3b to open and close them. In an intake system for an internal combustion engine in which a closed replenishment chamber 10 of a required volume is communicated through a control hole 7 opened therein, the replenishment chamber 10 is disposed above the control hole 7, and the replenishment chamber 10 is disposed above the control hole 7, The chamber 10 has a guide slope 10a that can guide the liquid fuel that has entered the chamber 10 toward the bottom of the chamber 10, and a guide slope 10a that can guide the liquid fuel that has entered the chamber 10 toward the bottom of the chamber 10. A connecting pipe 9 is formed with a discharge port 10b opening at the lower part of the inner surface, and the discharge port 10b and the control hole 7 are arranged below the supply chamber 10.
An intake system for an internal combustion engine that communicates with the