JP2584582Y2 - 2 cycle engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-cycle engine, and more particularly to a two-cycle engine having a scavenging system in which scavenging gas is forcibly supplied from outside by a scavenging pump.

[0002]

2. Description of the Related Art With the recent development of electronic control technology in automobile engines, for example, as disclosed in Japanese Utility Model Laid-Open No. 3-35210, scavenging air is forcibly supplied from the outside by a scavenging pump and fuel is injected by a fuel injection system. Supply,
It has become possible to realize a two-stroke engine in which oil is stored in a lower part of a crankcase, and a two-stroke engine which has a simple structure and can be mounted on an automobile has been developed.

In such a two-stroke engine, as shown in FIG. 4, oil in a crank chamber 22 is supplied to a scavenging port 23 and an exhaust port 24 in a skirt portion of the piston 21 separately from a piston ring above the piston 21. An oil ring 25 for preventing inflow is provided. The oil ring 25 is fitted in an oil ring groove 26 formed below the scavenging port 23 with the piston 21 located at the top dead center. Also,
An oil drop hole 27 penetrating from the inner periphery of the oil ring groove 26 to the inside of the piston 21 is formed, and when the piston 21 moves down, the oil that has been scraped off by the oil ring 25 and accumulated in the lower portion of the oil chamber smoothly flows into the crank chamber. 22. That is, if the piston 11 moves down while the oil remains in the lower portion of the oil ring 25, the pressure in the oil reservoir will increase and the scraping of the oil will be insufficient.

Further, in the above publication, oil scraped by the piston ring when the piston 21 moves down enters the scavenging port 23 and the exhaust port 24, and the oil which has entered the scavenging port 23 during the scavenging removes the oil. In order to solve the problems such as returning to the combustion state and causing the oil entering the exhaust port 24 to incompletely burn by the exhaust heat to generate white smoke, the oil is disposed below the scavenging port 23 or the exhaust port 24. A storage recess 28 is provided, and the oil ring groove 26 is provided.
The upper part to form an oil return hole 29 through the piston inner, Oy when the piston 21 rises to near the top dead center
A configuration is disclosed in which the oil in the reservoir sump 28 is surely returned to the crank chamber 22 through an oil return hole 29 by scavenging pressure or exhaust pressure due to exhaust blow-down.

[0005]

The oil ring 2 provided on the skirt of the piston 21 as described above.
When the oil return hole 29 is formed at the upper position of the oil reservoir 5, the oil in the oil reservoir recess 28 can be surely returned to the crank chamber 22. However, the scavenging port 23 has a gap between the piston 21 and the cylinder 30 and the oil return hole. 29, the scavenging gas also escapes into the crank chamber 22 together with the oil, the blow-by gas pressure in the crank chamber 22 increases, and the oil is removed by the blow-by gas. There has been such a problem that the engine output cannot be effectively improved due to an increase in the amount or an increase in pumping loss due to an increase in piston back resistance.

In view of such a conventional problem, the present invention reliably returns the oil collected in the oil sump recess to the crank chamber and prevents scavenging air from flowing into the crank chamber to prevent an increase in blow-by gas. It is an object of the present invention to provide a two-stroke engine that can be used.

[0007]

In the two-stroke engine of the present invention, a scavenging pump is connected to a scavenging port on the peripheral surface of a cylinder, oil is stored in a lower portion of a crank chamber, and an upper portion of a piston is provided in a piston.
Piston rings, in 2-cycle engines were respectively disposed oil ring to the skirt portion of the piston, the oil reservoir forms a recess in the lower edge of the apertured scavenging port or the exhaust port to the cylinder circumference, the oil ring of the piston An oil return hole penetrating into the piston from the outer peripheral surface of the piston is formed at an upper position, a sealing ring is disposed at a position above the oil return hole , and the piston is at a top dead center.
When near the oil reservoir,
Is located below, and the sealing ring is located above.
And the piston has moved below the top dead center by a predetermined position.
The seal ring against the oil sump recess
Characterized in that it is located below .

[0008]

According to the present invention, the oil scraped from the cylinder peripheral surface by the piston ring during the downward movement of the piston does not enter the scavenging port or the exhaust port, but accumulates in the oil sump recess at the lower edge thereof. Since the scavenging is performed in the state, the oil is not returned to the combustion chamber and burned with the scavenging. Next, when the piston moves upward and approaches the top dead center, the sealing ring is positioned above the oil sump recess, so the scavenging pressure or the exhaust pressure causes the scavenging port to move between the oil sump recess, the cylinder peripheral surface and the piston. Flows toward the crank chamber through the gap and the oil return hole, whereby the oil collected in the oil reservoir recess is reliably and promptly returned to the crank chamber. Next, when the piston starts to move downward, the sealing ring is located immediately below the scavenging port and the oil reservoir recess, so that the sealing ring passes through the gap between the cylinder peripheral surface and the piston and the oil return hole. Thus, it is possible to prevent the scavenging air from flowing into the crank chamber and increase the blow-by gas.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

First, the overall system of the two-stroke engine of this embodiment will be described with reference to FIG.

Reference numeral 1 denotes a cylinder chamber, on which a scavenging port 2 and an exhaust port 3 are provided on the peripheral surface, and an ignition plug 4 and a fuel injector 5 are provided on an upper wall. An air filter 6, a scavenging pump 7, and a scavenging system 9 including a throttle valve 8 are connected to the scavenging port 2, and the exhaust port 3 is connected to the muffler 1
0 or open to the atmosphere via an exhaust purification catalyst or the like. A piston 11 is fitted into the cylinder chamber 1 so as to be vertically movable,
It is connected via a connecting rod 12 to a crankshaft 14 arranged in a crankcase 13. Crank chamber 1
An oil for lubrication is stored in a lower part of the cylinder 3. A piston ring 15 including a top ring 15a and a second ring 15b is mounted on an upper portion of the piston 11.

As shown in detail in FIGS. 1 and 2, an oil ring 16 is fitted to an oil ring groove formed on the outer peripheral surface of the skirt of the piston 11, so that oil in the crank chamber 13 is released. Peripheral surface of cylinder chamber 1 and piston 1
1 to prevent the gas from flowing into the scavenging port 2 and the exhaust port 3. Therefore, the oil ring 16
Is the scavenging port 2 with the piston 11 at the top dead center.
And is located below the exhaust port 3. Note that a compression ring may be fitted instead of the oil ring 16.

Oil reservoir recesses 17 and 18 are formed in the lower edges of the scavenging port 2 and the exhaust port 3, respectively, and are located above the oil ring 16 in the skirt portion of the piston 11 from the outer peripheral surface of the piston to the inside of the piston. Is formed with an oil return hole 19 penetrating therethrough. The oil return hole 19 is provided so as to face the oil reservoir recesses 17 and 18 when the piston 11 is located near the top dead center. Further, a sealing ring 20 composed of a compression ring or the like is located above the oil return hole 19.
Are arranged. When the piston 11 is located near the top dead center, the sealing ring 20 is disposed so as to face the lower or intermediate portion of the scavenging port 2 or the exhaust port 3.

In the above configuration, the piston 11 is
When the piston ring 15 moves downward as shown by the arrow, oil on the peripheral surface of the cylinder chamber 1 is scraped off by the piston ring 15 and pushed down.
When approaching and passing further, the oil may be scraped off at the lower edge of the scavenging port 2 or the exhaust port 3 and may enter the interior. In this embodiment, the oil may enter the scavenging port 2 or the exhaust port 3. Instead, the oil is stored in the oil storage recesses 17 and 18 provided at the lower edge thereof.

In this state, scavenging is performed by lowering the upper end surface of the piston 11 to a position below the scavenging port 2 and the exhaust port 3. Therefore, the oil reservoir recesses 17, 18
The oil stored therein is not returned to the cylinder chamber 1 with scavenging and burns.

Next, when the piston 11 moves upward and approaches the top dead center, as shown in FIG. 2, the sealing ring 20 is located above the oil storage recesses 17 and 18, so that the scavenging pressure and the exhaust pressure are reduced. Exhaust pressure due to blowdown and reflected waves from the exhaust system cause the oil to pass through the scavenging port 2 and the exhaust port 3, pass through the oil reservoir recesses 17 and 18, the clearance between the peripheral surface of the cylinder chamber 1 and the piston 11, and the oil return hole 19 to crank. Room 1
3 and a flow toward the oil sump 1
The oil collected in 7 and 18 is reliably and promptly returned to the crank chamber 13.

Next, when the piston 11 starts to move downward, as shown in FIG. 1, the sealing ring 20 immediately moves the scavenging port 2, the exhaust port 3, and the oil storage recesses 17, 1 and 2.
8, the sealing ring 2
At 0, the gap between the peripheral surface of the cylinder chamber 1 and the piston 11 is closed, so that the scavenging air is prevented from leaking to the crank chamber 13 through this gap and the oil return hole 19, and an increase in blow-by gas can be eliminated. .

Thus, there is no possibility that the oil mist is taken out together with the blow-by gas to increase the oil consumption. In addition, an increase in the blow-by gas pressure in the crank chamber 13 causes a large back resistance when the piston 11 is lowered, so that the pumping loss increases and the output does not decrease. Further, since scavenging gas does not leak, useless work of the scavenging pump is reduced, which contributes to reduction of mechanical loss and improvement of fuel efficiency.

In the above embodiment, an example is shown in which both the scavenging port 2 and the exhaust port 3 are provided on the peripheral surface of the cylinder chamber 1, but the present invention provides a two-stroke engine in which only one of them is provided. It is needless to say that the same effect can be obtained.

[0020]

According to the two-stroke engine of the present invention,
As described above, the oil scraped from the cylinder peripheral surface by the piston ring during the downward movement of the piston does not enter the scavenging port or the exhaust port, but accumulates in the oil sump recess at the lower edge thereof and is scavenged in that state. Therefore, the oil does not return to the combustion chamber with the scavenging and burns, and when the piston moves upward and approaches the top dead center, the sealing ring is positioned above the oil reservoir recess, so that scavenging pressure and exhaust Oil collected in the oil reservoir recess by pressure or the like can be reliably and promptly returned to the crank chamber through the oil return hole. Further, as soon as the piston starts to move downward, the gap between the cylinder peripheral surface and the piston is closed by the sealing ring immediately, and it is possible to prevent the scavenging air from passing through the oil return hole to the crank chamber and increasing the blow-by gas. It is possible to reduce the amount of oil consumption by reducing the amount of oil taken out by blow-by gas, and to prevent the blow-by gas pressure in the crank chamber from increasing and the piston back resistance to increase, thereby preventing the output from decreasing due to pumping loss. Since there is no scavenging leak, wasteful work of the scavenging pump is reduced, and effects such as contributing to improved fuel efficiency are exhibited.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a two-stroke engine according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the embodiment in an oil discharge state.

FIG. 3 is a configuration diagram of an entire system of a two-cycle engine of the embodiment.

FIG. 4 is a longitudinal sectional view of a main part of a main part of a conventional two-stroke engine.

[Description of Signs] 1 Cylinder chamber 2 Scavenging port 3 Exhaust port 11 Piston 13 Crank chamber 16 Oil ring 17 Oil reservoir recess 18 Oil reservoir recess 19 Oil return hole 20 Seal ring

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code FI F16J 1/08 F16J 1/08 (56) References JP-A 3-35210 (JP, U) JP-A 58-111334 (JP) , U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01M 11/00 F01M 1/06 F01M 3/00 F02F 1/22 F02F 3/00

Claims (1)

(57) [Scope of request for utility model registration] 1. A scavenging pump is connected to a scavenging port on the peripheral surface of a cylinder, oil is stored in a lower portion of a crank chamber, and
Piston rings at the top, in a two stroke engine respectively disposed oil ring to the skirt portion of the piston,
An oil reservoir recess is formed at the lower edge of the scavenging port or exhaust port opened on the cylinder peripheral surface, and an oil return hole is formed at a position above the oil ring of the piston and penetrates from the piston outer peripheral surface into the piston. Place a sealing ring above the oil return hole , and
When near the top dead center,
Ring below, and sealing ring above.
And the piston has moved below the top dead center by a predetermined position.
When in position, seal ring against oil sump recess
A two-stroke engine, wherein the engine is positioned below the engine.