JPS5934848B2 - Crank chamber compression type 2-stroke engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crank chamber compression type two-stroke engine, and its purpose is to scavenge burnt gas generated in the combustion chamber in this type of two-stroke engine.
At the beginning of the scavenging stroke, the scavenging stroke is mainly carried out with a lean mixture with a small amount of fuel components, including the case where only air is used, and then with a rich mixture with a relatively large amount of fuel components. This reduces the amount of unburned air-fuel mixture that flows out from the engine and improves the ignitability of the fuel during combustion5.
There are many things.

The first embodiment of the present invention will be explained below with reference to the drawings.
In FIG. 1, reference numeral 10 indicates a cylinder, and reference numeral 20 indicates a piston.

The cylinder 10 is fixed at 30 to the upper part of the crankcase 11, and has an intake hole 12, an exhaust hole 13, and 4 exhaust holes on its peripheral wall.
Scavenging holes 14a to 14d and fuel supply holes 31 are provided.

The fuel supply hole 31 is provided in the lower blade than the scavenging holes 14a to 14d, and when its inner end is selectively opened to the combustion chamber R1, the communication hole 35 and the communication hole 21 provided in the peripheral wall of the piston 20 are connected to the crack chamber R2. 2, and its outer end communicates selectively through the fuel chamber R provided in the cylinder 10, as shown in FIG.
It is connected to the center of 3. The fuel chamber R3 is formed in a cylindrical shape, and as shown in FIG. 3, an inlet 32 is provided in the upper end of the fuel chamber R3 in the tangential direction, communicating with the carburetor 33 via a reed valve 34. Note that this vaporizer 33 has a known configuration. (See FIGS. 1 to 3) The piston 20 is fitted into the cylinder 10, and a communication hole 21 is bored in the peripheral side wall corresponding to the fuel supply hole 31.
Further, a vent hole 22 is provided in the peripheral side wall corresponding to the intake hole 12 .

Therefore, the location of the communication port 21 is such that negative pressure in the crank chamber R2 can be applied to the fuel supply hole 31 after the scavenging is completed when the piston moves upward, and at the same time, the negative pressure in the crank chamber R2 can be applied to the fuel supply hole 31 before the scavenging starts when the piston moves downward. This is the position where positive pressure inside can be applied to the fuel supply hole 31. Note that reference numeral 15 in the figure indicates a throttle valve that controls the amount of air supplied to the intake hole 12 via the intake pipe 17 and the reed valve 16.

The operation of this embodiment configured in this way will be explained with reference to FIG. 4.Is the piston 20 immortal? BI) When in C (position shown in Fig. 1), exhaust hole 13, scavenging hole 1
4a to 14d and the fuel supply hole 31 are open to the combustion chamber R1, so exhaust, scavenging, and fuel (rich mixture) supply are performed at the same time.

When the piston 20 moves up, the fuel supply hole 31 is first closed by the circumferential wall of the piston 20, and then the scavenging holes 14a to 14d are closed by the circumferential wall of the piston 20. At this time, a negative pressure is generated in the crank chamber R2, and an amount of air determined by the opening degree of the throttle valve 15 flows from the intake hole 12 into the crank chamber R2 through the vent hole 22. However, after the scavenging holes 14a to 14d are closed, the fuel supply hole 31 and the communication hole 21 of the piston 20 match, and the negative pressure in the crank chamber R2 is applied to the fuel supply hole 31. This negative pressure is applied to the fuel chamber R3 from the fuel supply hole 31, and the air-fuel mixture remaining in the fuel chamber R3 is sucked into the crank chamber R2 through the communication hole 21.
A rich air-fuel mixture generated in the carburetor 33 having a second throttle valve (not shown) that operates in conjunction with the throttle valve 15 is transferred to the reed valve 34
The fuel is sucked into the fuel chamber R3 through the fuel chamber R3. At this time, the rich air-fuel mixture flows into the fuel chamber R from the inlet 32 in the form of a vortex. In this way, where the rich air-fuel mixture is sucked into the fuel chamber R3, the piston 20 rises and the fuel supply hole 31 is closed again by the circumferential side wall of the piston 20.

Therefore, the rich mixture is stored in the fuel chamber R3, and the residual rich mixture flows into the crank chamber R2, resulting in a lean mixture (
(similar to air) is produced. At this time, fuel chamber R3
The fuel in the rich mixture inside the cylinder is accelerated to vaporize by the heat of the cylinder peripheral wall. (Note that the exhaust hole 13 is closed while the fuel supply hole 31 and the communication hole 21 of the piston are aligned.)
Thereafter, when the piston 20 that has risen to the top dead center TDC descends due to explosion, the lean air-fuel mixture is compressed in the crank chamber R2.

Therefore, when the fuel supply hole 31 matches the communication hole 21, the compressed lean mixture in the crank chamber R2 flows into the fuel chamber R3 through the fuel supply hole 31, and the rich mixture in the fuel chamber R3 flows into the fuel chamber R3. Pressurized. Note that the exhaust hole 13 opens into the combustion chamber R1 during this pressurization, and the burnt gas is ejected to the outside. Therefore, before the piston 20 opens the scavenging holes 14a to 14d, the fuel supply hole 31 is closed to the crank chamber R2 by the peripheral side wall of the piston 20, so that the fuel chamber R3
A pressurized concentrated air-fuel mixture is sealed and stored inside.

Thereafter, the scavenging holes 14a to 14d open, the lean air-fuel mixture pressurized in the crank chamber R2 flows into the combustion chamber R1, and the residual burnt gas is discharged to the outside through the exhaust hole 13. After that, the fuel supply hole 31 opens into the combustion chamber R1, so the pressurized rich mixture in the fuel chamber R3 is vigorously jetted out from the fuel supply hole 31 into the combustion chamber R1, and is more efficient than the lean mixture that has flowed in earlier. The mixture is well mixed and has a predetermined concentration, resulting in good ignitability during the next combustion. Also at this time, exhaust hole 1
From No. 3, only the lean air-fuel mixture (scavenging air) that first flowed out from the scavenging holes 14a to 14d flows out to the outside, and the flow of unburned gas into the exhaust gas is reduced. Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 8. In this embodiment, a pair of recesses 23 provided in the outer circumferential wall of the piston 20 are provided in the circumferential wall of the cylinder 10. A pair of auxiliary chambers R4, R4 are formed which communicate with the fuel chamber R3 via 23.

- The piston 20 is provided with a pair of second communication holes 24, 24 for selectively communicating the auxiliary chamber R4 with the crank chamber R2. Furthermore, the auxiliary chambers R4, R4 are provided lower than the fuel chamber R3, and do not directly open into the combustion chamber R1.

Further, the recesses 23, 23 are provided in the upper blade than the communication hole 21, and the second communication holes 24, 24 are provided in the lower blade than the communication hole 21. The rest of the structure is substantially the same as the first embodiment described above, so the same parts are given the same reference numerals and the explanation thereof will be omitted.
To explain with reference to the figure, the piston 20 is at the bottom dead center BI)
When in position C (position shown in Figure 5), exhaust hole 1
3. Since the scavenging holes 14a to 14d and the fuel supply hole 31 open into the combustion chamber R1, exhaust, scavenging, and fuel supply are performed simultaneously.

Also, at this time, since the subchambers R4, R4 communicate with the fuel chamber R3 through the recesses 23, 23, the air in the subchambers R4, R4 is accompanied by the rich air-fuel mixture remaining in the fuel chamber R3. It flows into the combustion chamber R. When the piston 20 rises, first the auxiliary chambers R4 and R4 are closed by the circumferential wall of the piston 20, then the fuel supply hole 31 is closed to the combustion chamber R1, and then the scavenging holes 14a and 14d are closed.
is closed. At this time, a negative pressure j is generated in the crank chamber R2, and an amount of air determined by the opening degree of the throttle valve 15 from the intake hole 12 passes through the reed valve 16 and flows into the crank chamber R.
I'm exiled within 2. However, immediately after the scavenging holes 14a to 14d are closed, the fuel chamber R3 and the auxiliary chambers R4, R4 coincide with the communication hole 21 and the second communication holes 24, 24, respectively, and the negative pressure in the crank chamber R2 is reduced to the fuel chamber R3 and the subchamber R4, R4. These are provided to subchambers R4 and R4, respectively. Therefore, the rich mixture in the fuel chamber R3 and the lean mixture remaining in the auxiliary chambers R4 and R4 are sucked into the crank chamber R2, and the carburetor 33
The rich air-fuel mixture generated in is passed through the reed valve 34 to the fuel chamber R3.
sucked inside. While the rich air-fuel mixture is being drawn into the fuel chamber R3, the auxiliary chambers R4 and R4 are closed again by the circumferential wall of the piston 20, and the fuel chamber is filled with the rich air-fuel mixture into the fuel chamber R3. R3 is again closed to the crank chamber R2 by the circumferential wall of the piston 20. As a result, a rich air-fuel mixture is stored in the fuel chamber R3, and the auxiliary chamber R4
, R4 are applied with negative pressure. (The exhaust hole 13 is closed while the fuel supply hole 31 and the communication hole 21 of the piston are aligned.) Thereafter, when the piston 20, which has risen to the top dead center TDC, descends due to the explosion, the crank chamber R2 Inside, the lean mixture is compressed.

Therefore, when the fuel supply hole 31 matches the communication hole 21, the compressed air-fuel mixture in the crank chamber R2 flows through the fuel supply hole 31.
The rich mixture in the fuel chamber R3 is pressurized, and the auxiliary chambers R4, R4 are connected to the second communication holes 24, 24.
When it matches, the compressed air-fuel mixture in the crank chamber R2 flows into the auxiliary chambers R4 and R4. The exhaust hole 13 opens into the combustion chamber R1 during this pressurization, and the burnt gas is ejected to the outside. Therefore, before the piston 20 opens the scavenging holes 14a to 14d, both the fuel supply hole 13 and the auxiliary chambers R4 and R4 force S are closed to the crank chamber R2 by the peripheral side wall of the piston 20, so that the fuel chamber R3 A pressurized rich air-fuel mixture is sealed in the subchambers R4, R4, and a pressurized lean air-fuel mixture is sealed in the auxiliary chambers R4 and R4.

Thereafter, the scavenging holes 14a to 14d open, the lean air-fuel mixture pressurized in the crank chamber R2 flows into the combustion chamber R1, and the residual burnt gas is discharged to the outside through the exhaust hole 13. Thereafter, the fuel supply hole 31 opens into the combustion chamber R1, and the sub-chambers R4, R4 communicate with the fuel chamber R2 via the recess 2323 provided in the piston 20, so that the rich fuel stored in the fuel chamber R3 is removed. The air-fuel mixture is injected into the combustion chamber R1 by its own blade, and is pushed out by the pressurized lean air-fuel mixture in the auxiliary chambers R4 and R4, and reliably flows into the combustion chamber R1. Therefore, a predetermined amount of fuel is reliably and vigorously supplied into the combustion chamber R1, and is efficiently mixed with the air in the combustion chamber, resulting in good ignitability during combustion. In addition, in this second embodiment,
Since the auxiliary chambers R4 and R4 are provided, the gas that flows into the crank chamber R2 when the piston rises can be almost exclusively air, and the amount of unburned gas flowing out from the exhaust hole 13 during scavenging can be further reduced. I can do it. As detailed above,
In the present invention, as illustrated in each of the above-mentioned embodiments of the needle trowel,
When the fuel supply hole 31 (opening of the fuel chamber R3) is connected to the communication hole 2 of the piston 20 during the crank chamber compression stroke (during the downward movement of the piston)
When communicating with the crank chamber R2 through 1, the crank chamber R
2'ζ Due to the compressed lean mixture generated in the fuel chamber R2
When the fuel supply hole 31 communicates with the crank chamber R2 through the communication hole 21 of the piston 20 during the combustion chamber compression stroke (when the piston moves upward), the negative energy generated in the crank chamber R2 is compressed. Depending on the pressure, from the vaporizer 33 to the reverse city valve 3
At the beginning of the scavenging stroke, the air sucked into the crank chamber R2 is used to perform scavenging, and then the air is drawn into the fuel chamber R3.
The feature is that the rich mixture inside the combustion chamber is injected into the combustion chamber R1, which makes it possible to reduce the amount of unburned mixture flowing out from the exhaust hole, and also to reduce the ignition of fuel during combustion. You can make your sexuality look better.

Further, when the present invention is implemented as in the second embodiment, the amount of unburned gas flowing out from the exhaust hole is further reduced, so that the compressed state in the crank chamber supplied to the pre-chamber is diluted. The rich air-fuel mixture in the fuel chamber can be smoothly supplied into the combustion chamber by air, thereby improving the ignitability of the fuel in the combustion chamber.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing a first embodiment of the present invention, Fig. 2 is a cross-sectional bottom view taken along line 2-2 in Fig. 1, and Fig. 3 is a cross-sectional bottom view taken along line 3-3 in Fig. 2. FIG. 4, a longitudinal sectional view taken along the line, is an explanatory diagram of the operation of the first embodiment, and is a diagram showing the timing of opening and closing of each hole. Further, FIG. 5 is a vertical sectional view showing the second embodiment of the present invention, and FIG.
The figure is a cross-sectional plan view showing the state of communication between the fuel chamber and the sub-chamber, FIG. 7 is a cross-sectional plan view showing the state of communication between the sub-chamber and the crank chamber, and FIG.
The figure is an explanatory diagram of the operation of the second embodiment, and is a diagram showing the opening/closing timing of each hole and subchamber. Explanation of symbols: 10...Cylinder, 11...Crankcase, 12...
...Intake hole, 13...Exhaust hole, 14a, 14
d...Scavenging hole, 15... Throttle valve, 17
...Intake pipe, 20...Piston, 21
...Communication hole, 23...Recess, 24...
...Second communication hole, 31...Fuel supply hole (opening of fuel chamber), 33...Carburizer, 34...
... Reed valve (check valve), R1 ... Combustion chamber, R
2... Crank chamber, R3... Fuel chamber,
R4... Antechamber.

Claims (1)

[Scope of Claims] 1. In a crank chamber compression type two-stroke engine, an intake pipe is attached to the intake hole of the engine for introducing a relatively lean air-fuel mixture, including the case where only air is present, into the crank chamber, and one part of the cylinder peripheral wall is installed. A fuel chamber to which a relatively rich air-fuel mixture is supplied through a check valve is provided in the engine, and this fuel chamber is opened to the inner circumferential wall of the cylinder located at the lower blade of the scavenging hole of the engine. Through a communication hole provided in the piston peripheral wall, communication is made into the crank chamber so that it can be opened and closed during the crank chamber compression stroke and during the combustion chamber compression stroke, and the timing of opening and closing is determined based on the compression generated in the crank chamber during the crank chamber compression stroke. The air-fuel mixture in the first fuel chamber is compressed by the air-fuel mixture, and during the combustion chamber compression stroke, the air-fuel mixture is set to be sucked into the fuel chamber through the reverse valve by the negative pressure generated in the crank chamber during the scavenging stroke. A two-stroke engine characterized in that initially, scavenging is performed mainly by a lean mixture sucked into a crank chamber through the intake hole, and then a rich mixture in the fuel chamber is supplied into a combustion chamber. 2. At least one auxiliary chamber is formed in a side part of the fuel chamber, and the auxiliary chamber is opened to an inner circumferential wall of the cylinder located below the opening of the fuel chamber, while the piston is formed on the circumferential wall of the piston at an indestructible point. A recess is provided that communicates the opening of the sub-chamber with the fuel chamber when the piston reaches the vicinity, and the opening of the sub-chamber is intermittently communicated with the crank chamber through a communication hole provided in the peripheral wall of the piston. The communication timing is set so that the compressed air-fuel mixture generated in the crank chamber is applied to the sub-chamber during the crank chamber compression stroke and before the time when the recess communicates the opening of the sub-chamber with the fuel chamber, and then Claim 1, characterized in that when the opening of the fuel chamber opens into the combustion chamber, the opening of the auxiliary chamber communicates with the fuel chamber through a recess of the piston. Crank chamber compression type two-stroke engine as described.