JPS62113812A - Two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To realize a reduction of lubricating oil consumption, the improvement of combustion property, and the like, by making the lubricating oil together with a mixed gas fed to a crankcase flow in an oil separating chamber at a high speed through a slender scavenging passage, and separating and recovering the oil from the mixed gas thereby. CONSTITUTION:The lubricating oil is fed from an oil jet 40 to the lower stream of a throttle valve 14, and fed together with the mixed gas to an internal combustion engine. In this case, when a piston 5 goes down and an intake passage 12 is closed, the mixed gas flows in a pulsation at a high speed from a new gas flow inlet 21 through a relatively slender route, the first scavenging passage 20, and the fuel component is evaporated. Furthermore, the mixed gas flows in a cylindrical oil separating chamber 22, and the mixed gas only flows in a pair of second scavenging passage 28, and then, flows in a combustion chamber 6 through a pair of scavenging ports 29. On the other hand, the lubricating oil is separated from the mixed gas by a centrifugal force, and recovered to an oil recovery tank 32 through an oil recovery passage 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-stroke internal combustion engine, and in particular, the reciprocating movement of a piston draws a mixture of air and fuel as well as lubricating oil into the crank chamber of the internal combustion engine. The present invention relates to a two-stroke internal combustion engine in which an air-fuel mixture is supercharged indoors and is lubricated with lubricating oil.

[Conventional technology]

In a two-stroke internal combustion engine, a swirl chamber is provided in a part of the scavenging passage that communicates between the crank chamber and the inside of the cylinder, particularly in a position close to the fresh air inlet at the bottom of the crank chamber, so that the air/fuel mixture flows through the scavenging passage. It is already known that when fuel passes through this vortex chamber on the way from the crank chamber to the cylinder, a strong vortex is generated in the vortex chamber to promote vaporization of the fuel (Japanese Patent Application Laid-Open No. 59-1992). -65556).

In addition, the elongated first scavenging passage led from the crank chamber,
The air-fuel mixture is connected to a second scavenging passage that is disposed close to the exhaust passage and guided by the cylinder, and heats the air-fuel mixture as it passes through these scavenging passages to promote vaporization of the fuel. A two-stroke internal combustion engine is already known (Japanese Patent Application Laid-Open No. 113718/1983)6 [Problems to be Solved by the Invention] In a two-stroke internal combustion engine equipped with a carburetor, air and fuel are normally separated by the reciprocating movement of a piston. The mixture and lubricating oil for lubricating the crankshaft, cylinders, etc. are supplied to the crank chamber. However, in the two-stroke internal combustion engine disclosed in Japanese Patent Application Laid-open No. 59-65556, the fuel mixture in the swirl chamber is Since the purpose is to vaporize the mixture, the vortex chamber is installed close to the bottom of the crank chamber, and as a result of the air-fuel mixture having a faster flow rate than the fresh air inlet flowing into the vortex chamber, The components of the lubricating oil are also mixed with the fuel, and therefore it is difficult to separate the components of the lubricating oil. Further, even if the lubricating oil is separated, there is no means for recovering the lubricating oil, so the lubricating oil is wasted. Furthermore, in the two-stroke internal combustion engine disclosed in JP-A-54-113718, vaporization of fuel is promoted in the elongated first scavenging passage, but this scavenging passage is not intended to separate lubricating oil. There is no specific means for recovering the lubricating oil.

In a two-stroke internal combustion engine that does not have a means to recover lubricating oil, not only is the lubricating oil wasted and uneconomical, but it also causes incomplete combustion in the cylinder combustion chamber, producing smoke and odor in the exhaust gas. There are also problems such as deterioration of the catalyst in the exhaust system. Therefore, the present invention aims to solve the above-mentioned problems by recovering the lubricating oil supplied to the crank chamber in this type of two-stroke internal combustion engine.

[Means for solving problems]

In order to solve such problems, according to the present invention,
In a two-stroke internal combustion engine, a mixture of air and fuel and lubricating oil are sucked into the crank chamber of the two-stroke internal combustion engine by the reciprocating motion of the piston, and the air-fuel mixture is supercharged in the crank chamber and is lubricated by the lubricating oil. , one end of a relatively elongated first scavenging passageway opening at the bottom of the crank chamber; A two-stroke internal combustion engine is provided, characterized in that the two-stroke internal combustion engine is arranged so as to open substantially opposite to the oil separation chamber, and further includes means for recovering lubricating oil collected in the oil separation chamber.

[For production]

According to the present invention, the lubricating oil supplied to the crank chamber together with the air-fuel mixture flows at high speed into the oil separation chamber through the elongated scavenging passage, and is separated from the air-fuel mixture in the oil separation chamber.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In Fig. 1, 1 is a crankcase, 2 is a cylinder block fixed on the crankcase l, 3 is a cylinder head fixed on the cylinder block 2, and 4 is reciprocating within a cylinder bore 5 in the cylinder block 2. A piston, 6 is a combustion chamber formed between the cylinder head 3 and the piston 4, 7 is a spark plug, 8 is a crank chamber formed in the crankcase 1, 9 is a balance weight, 10 is a connecting rod, 11 is an intake air 12 is an intake passage opening into the wall surface of the cylinder 5, 13 is a carburetor, 14 is a carburetor throttle valve, 17 is an exhaust pipe, and 18 is an exhaust passage.

The relatively elongated first scavenging passage 20 opens at the bottom of the crank chamber 8 at a fresh air intake port 21 at one end thereof, and extends from there in an arc shape outside the crank chamber 8 of the crankcase l, and the other end is connected to the crankcase. It is connected to an oil separation chamber 22 provided at a position close to the cylinder block 2 at the upper part of the cylinder block 1 . This oil separation chamber 22 is a cylindrical chamber approximately parallel to the crankshaft, and the first scavenging passage 20 is connected tangentially at approximately the center of the cylindrical separation chamber 22, as is clear from FIGS. 1 and 2. has been done. Inside the separation chamber 22, there are many holes 23a (Fig. 2) almost concentrically with the separation chamber 22.
A pipe 23 having a diameter is provided. This pipe 23
A pair of second scavenging passages 28.28 of equal length are respectively connected to both ends of the scavenging passages 28.28, and these second scavenging passages 28.28 are substantially opposed to each other in the engine cylinder 5 at a portion of a pair of scavenging boats 29.29. It is arranged so that it opens.

The first scavenging passage 20 is tangentially connected to the cylindrical oil separation chamber 22 from below to above on the side closer to the crank chamber 8 . At the lower right side of the oil separation chamber 22 in FIG. An oil recovery passage 25 is connected through the oil recovery passage 25, and this oil recovery passage 25 extends downward and connects to the upper part 35 of the recovery tank 32.
It is connected to the. The recovered oil tank 32 is built in the upper space of the new oil tank 30, and the oil 34 accumulated in the recovered oil tank 32 is configured to mix with the new oil 31 in the new oil tank 30 through the regenerated oil filter 33. There is. The oil inlet 36 is connected to the throttle valve 11 of the carburetor 13 via an oil supply passage 37.
It is connected to the downstream oil jet 40. On the other hand, the air-fuel mixture that has flowed into the recovery oil tank 32 is returned through a return passage 39 that communicates with the ports 1-41 downstream of the throttle valve 11.

The upper part of the cylindrical oil separation chamber 22 adjoins a heating chamber 26 formed in the cylinder rad 2 via a relatively thin peripheral wall section. This heating chamber 26 opens to the exhaust passage 18 through an opening 26a, and a part of the exhaust gas passing through the exhaust passage 8 flows into the heating chamber 26 and heats the wall surface of the cylindrical oil separation chamber 22 due to the temperature of the exhaust gas. It looks like this.

A throttle valve 14 provided downstream of a mixture supply device 13 such as a carburetor operates in conjunction with an accelerator pedal (not shown) to control the flow of air/fuel mixture. ff1l
do. On the other hand, lubricating oil for lubricating the internal combustion engine is supplied downstream of the throttle valve 14 from the oil jet 40, and is supplied to the internal combustion engine together with the air/fuel mixture.

During the upward stroke of the piston 5, the piston 5 enters the intake passage 12.
When the wall opening is opened, the air-fuel mixture is drawn into the crank chamber 8 of the crankcase 1 through the intake passage 12.

Next, when the piston 5 closes the wall opening of the intake passage 12 during the downward stroke of the piston 5, the mixture containing lubricating oil is compressed and supercharged by the downward movement of the piston 5, and the bottom of the crank chamber 8 is compressed and supercharged. The fresh air flows at a high speed while pulsating through the relatively elongated first scavenging passage 22 from the fresh air inlet 21 that is open to the rear, and most of the fuel components are vaporized. Further, the oil flows tangentially into the center of the cylindrical oil separation chamber 22, and the heating chamber 2
6, and while reducing the flow rate, only the air/fuel mixture passes through the hole 23a of the pipe 23 and almost reaches the pair of second scavenging passages 28, 28 connected to both sides of the pipe 23. The second scavenging passage 2 is divided into two equal parts.
8.28, and when the pair of scavenging ports 29.29 open during the downward stroke of the piston 5, the air-fuel mixture flows into the combustion chamber 6 at a low speed. In this way, the new air-fuel mixture flowing in at a low speed does not stir the high-temperature exhaust gas remaining in the combustion chamber 6, and stratification with the exhaust gas is achieved. It moves to the compression stroke, where it is adiabatically compressed and self-ignites and burns.

On the other hand, the lubricating oil that has flowed into the cylindrical oil separation chamber 22 through the elongated first scavenging passage 22 is further separated from the fuel/air mixture by centrifugal force, is adsorbed by an oil adsorbent, and then passes through the oil recovery passage 25. The oil is collected in the recovery oil tank 32. The lubricating oil accumulated in the recovered oil tank 32 tries to descend due to gravity, but is filtered by the regenerated oil filter 33 provided at the bottom, and is filtered into the new oil tank 3 at the bottom.
It is replenished to 1. In this example, the temperature of the exhaust gas was used as a means to heat the air-fuel mixture, but other means, such as a positive temperature coefficient heating element (PTC heater), etc., could be used to achieve high output in cold conditions. The air-fuel mixture may be heated in the region to promote vaporization of the fuel.

Needless to say, it is also a good idea to send it to someone else.

〔Effect of the invention〕

a) Lubricating oil can be efficiently recovered over the entire operating range of a two-stroke internal combustion engine, and the recovered lubricating oil can be used again with new lubricating oil. This significantly reduces lubricant consumption and eliminates problems such as piston ring sticking and combustion chamber hot spots caused by carbon buildup and adhesion due to lubricant combustion. Furthermore, since the small amount of lubricating oil that cannot be recovered can self-ignite and burn, problems with smoke and odor are completely eliminated.

b) Since the low-velocity air-fuel mixture divided into two equal parts can flow into the combustion chamber 6 in a predetermined direction in the entire operating range, stable self-ignition without relying on the ignition plug 7 can be performed in the operating range up to a predetermined load. . In the operating range above a predetermined load, the air-fuel mixture is stably introduced to the ignition plug 7, so that ignition can be performed reliably.

C) The elongated first scavenging passage 20 reduces the pulsation of positive and negative pressure in the crank chamber, and also allows the exhaust gas to flow back to the scavenging boat 29. Therefore, the oil separation chamber 22 can be maintained at a nearly positive pressure, so that the oil separation The lubricating oil that has been removed continues to flow into the recovery oil passage 25. Therefore, the recovered lubricating oil can be transferred to the recovery oil tank 3 without installing a special recovery pump or the like.
It can lead to 2.

d) Also, as shown in the example, the recovery oil tank 3
By arranging the lubricating oil 2 at the upper part of the new oil tank 30, the lubricating oil passes through the oil filter 33 by gravity, and the recovered lubricating oil can be regenerated without providing a special filter pump or the like.

e) In addition, as in the example, the air-fuel mixture that leaked out together with the recovered lubricating oil and the fuel contained in the recovered lubricating oil can be sucked into the engine again, so that hydrocarbons (HC)
can be prevented from being discharged. In this case, the recovered air-fuel mixture and fuel may be adsorbed once in a canister (not shown) of the fuel tank and then purged at the same time.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a two-stroke internal combustion engine of the present invention, and FIG. 2 is a schematic sectional view taken along line 1--2 in FIG. l... Crank case 2... Cylinder block 3... Cylinder rad 8... Crank chamber 12... Intake passage 18... Exhaust passage 20... Elongated first scavenging passage 21... Fresh air inlet 22...Oil separation chamber 23...Porous pipe 28...Second scavenging passage 32...Oil recovery tank 1・Crankcase 2o Elongated first
Scavenging passage 2・・Cylinder block 21・・ Fresh air inflow daily meter ・Number cylinder 22・Oil separation chamber 8・Crank chamber 23・・Porous pipe 12 Intake passage 28・・
Second scavenging passage 18 and exhaust passage 32
Oil recovery tank Fig. 1 s2

Claims (1)

[Claims] 1. A mixture of air and fuel and lubricating oil are drawn into the crank chamber of a two-stroke internal combustion engine by the reciprocating movement of the piston;
In a two-stroke internal combustion engine in which the air-fuel mixture is supercharged in the crank chamber and is lubricated with lubricating oil, one end of the relatively long first scavenging passage opens at the bottom of the crank chamber, and the other end is connected to the oil separation chamber. At least a pair of second scavenging passages of equal length connected to the oil separation chamber are arranged so as to open substantially opposite to the engine cylinder, and the lubricating oil collected in the oil separation chamber is recovered. A two-stroke internal combustion engine characterized in that a means is provided. 2. The oil separation chamber has a substantially cylindrical shape that is substantially parallel to the crankshaft, the first scavenging passage is tangentially connected to the substantially central part of the cylindrical oil separation chamber, and the pair of second scavenging passages are connected to the cylindrical oil separation chamber. The two-stroke internal combustion engine according to claim 1, wherein the two-stroke internal combustion engine is axially connected to substantially the center of both ends of the oil separation chamber. 3. A pipe having a number of holes through which the air-fuel mixture passes is inserted concentrically into the cylindrical oil separation chamber, and the pair of second scavenging passages are connected to both ends of the pipe. A two-stroke internal combustion engine according to range 2. 4. The two-stroke internal combustion engine according to claim 1, wherein a part of the wall surface of the oil separation chamber is formed of an oil adsorbent, and the lubricating oil is recovered via the oil adsorbent. 5. The two-stroke internal combustion engine according to claim 1, further comprising means for heating the wall surface of the oil separation chamber. 6. The means for collecting lubricating oil includes a collecting oil tank for storing the lubricating oil collected from the oil separation chamber, and a new oil tank connected to the collecting oil tank via an oil filter, and the means for collecting the collected lubricating oil A two-stroke internal combustion engine according to claim 1, wherein the lubricating oil is mixed with new lubricating oil and used again as lubricating oil.