JPS62113809A - Two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the consumption of lubricating oil, by making the residuel oil of the lubricating oil fed with the air into a crankcase flow in an oil recovery tank through an oil recovery passage together with the supercharged air, and separating and recovering the lubricant component from the supercharged air. CONSTITUTION:When a piston 5 goes up and an intake passage 12 is opened, the intake air containing the lubricating oil is inhaled to a crankcase 8 through the intake passage 12. On the other hand, when the piston 5 goes down and the intake passage 12 is closed, the intake air containing the lubricating oil flows in an oil recovery passage 20 through a check valve 22 from a new air flow inlet 21 at the bottom of the crankcase 8. Then, the intake air flows in a cylindrical centrifugal separator chamber 25 in an oil recovery tank 24 through an oil cooler 23, where the lubricant is removed. After that, the lubricating oil in the oil recovery tank 24 is inhaled into an oil pump 32 through an oil passage 31, and injected into the intake passage 12 of each cylinder from an oil jet 34 through a filter 33.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a two-stroke internal combustion engine, and in particular, air is drawn into the crank chamber by the reciprocating motion of the piston, and lubricating oil is taken into the crank chamber along with the air. The present invention relates to a two-stroke internal combustion engine in which air is supercharged indoors and lubrication is performed 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).

[Problem that the invention seeks to solve]

In a 22-stroke internal combustion engine, the reciprocating movement of the piston normally creates a mixture of air and fuel, or in a fuel-injected 2-stroke internal combustion engine, air is drawn into the crank chamber, and at the same time, lubrication is created to lubricate the crankshaft, cylinders, etc. Oil is also supplied to the crank chamber.
The purpose of the two-stroke internal combustion engine disclosed in No. 5556 is to vaporize the fuel in the mixture in the swirl chamber, so even if some lubricating oil is separated in the swirl chamber, this lubricating oil is recovered. Since there are no special measures, lubricating oil is wasted. 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. Also, there are problems such as deterioration of the exhaust system catalyst. 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,
Air is sucked into the crank chamber by the reciprocating movement of the piston,
In a two-stroke internal combustion engine, lubricating oil is taken into the crank chamber along with air, and the air is supercharged in the crank chamber while lubrication is carried out with the lubricating oil. An oil recovery passage is provided with a check valve to prevent lubrication, the other end of the oil recovery passage is connected to an oil recovery tank, and a scavenging passage connected to the oil recovery tank is opened into the cylinder combustion chamber to prevent lubrication. A two-stroke internal combustion engine is provided, characterized in that supercharged air from which oil components have been separated is supplied to a cylinder combustion chamber.

[For production]

According to the present invention, the residual portion of the lubricating oil supplied to the crank chamber together with the air mixes with the supercharging air, passes through the oil recovery passage, and flows into the oil recovery tank. Here, the lubricating oil component is separated from the supercharged air and collected at the bottom of the oil recovery tank.

〔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 1, 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 fuel injection nozzle, 8 is a crank chamber formed in the crankcase 1, 9 is a balance weight, 10
11 is a connecting rod, 11 is an intake pipe, 12 is an intake passage opening into the wall surface of the cylinder 5, 14 is a throttle valve, 17 is an exhaust pipe, and 18 is an exhaust passage.

One end of the oil recovery passage 20 opens at the bottom of the crank chamber 8 at a fresh air flow 21 . The oil recovery passage 20 is equipped with a check valve 22 such as a reed valve that prevents air from flowing back into the crank chamber 8 . A heat exchanger 23 such as an oil cooler is provided in the middle of the oil recovery passage 20. The heat exchanger 23 has a well-known structure in which a space is formed with a large number of pipes through which cooling water flows, and serves to maintain the temperature of the air in the scavenging passage at an appropriate temperature.

The other end of the oil recovery passage 20 is tangentially connected to a cylindrical centrifugal separator 25 formed at the top of the oil recovery tank 24 . This allows air containing lubricating oil to flow tangentially into the cylindrical portion 25 .

The oil recovery tank 24 has an upper cylindrical portion 25 with a lower side expanding into a conical shape, and is separated from a lower oil reservoir portion by a partition wall 28.

The recovered lubricating oil falls by gravity from the oil hole 29 of the partition wall 28, passes through the buff full plate 27, and accumulates in the lower part of the oil recovery tank 24. The lubricating oil 35 recovered in the oil recovery tank 24 is supplied to the intake passage 12 again by an oil jet 34 via an oil passage 31 and an oil filter 33 by an oil pump 32.

The first scavenging passage 40 penetrates the upper cylindrical portion 25 of the oil recovery tank 24 from above the central axis and extends to the upper part of the partition wall 27 . The other end of the first scavenging passage 40 is connected to a connecting part 41, and a second scavenging passage 42 extends from the connecting part 41. It is open to Note that a pair of second scavenging passages 42 are provided for each cylinder,
It is desirable that the pair of scavenging boats 43 open on the wall surface of the cylinder combustion chamber 5 so as to face each other.

It is desirable that the oil recovery tank 24 has a volume necessary as a damping volume for the supercharged intake air, and when this two-stroke internal combustion engine has multiple cylinders, the crank chamber 8 of each cylinder has a partition wall (not shown) or a seal. (not shown), etc., and the oil recovery passages 20 of each cylinder are arranged at equal angular intervals in a cylindrical centrifugal separation part 25 at the upper part of the oil recovery tank 24. Preferably, the connection is tangential to 25.

A throttle valve 14 in the intake pipe 11 operates in conjunction with an accelerator pedal (not shown) to control the flow rate of intake air. On the other hand, lubricating oil for lubricating the internal combustion engine is injected downstream of the rethrottle valve 14 by the oil jet 34 as described above, and is supplied to the internal combustion engine together with intake air. During the upward stroke of the piston 5, this piston 5 enters the intake passage 1.
When the wall opening of 2 is opened, the intake air containing lubricating oil passes through the intake passage 12 and enters the crank chamber 8 of the crankcase L.
inhaled into the body. Next, during the downward stroke of the piston 5, the piston 5 closes the wall opening of the intake passage 12, and
The intake air containing lubricating oil is compressed and supercharged by the downward movement of the piston 5, and lubricates each bearing part, and is passed from a fresh air flow 21 opened at the bottom of the crank chamber 8 to an oil recovery passage via a check valve 22. 20 and flows tangentially through the oil cooler 23 into the cylindrical centrifugal separation chamber 25 of the oil recovery tank 24, creating a strong swirling flow that separates the lubricating oil from the supercharged intake air. The separated lubricating oil falls along the puffful plate 27 and mixes with the stocked lubricating oil. First scavenging passage 40 in the center of centrifugal separation section 25 for supercharged intake air only
The air flows out from the second scavenging passage 42 of each cylinder connected to the connecting portion 41 and flows into the cylinder combustion chamber 6 at a low speed from the scavenging boat 43 that opens into the cylinder 5 . As a result, the exhaust gas remaining in the combustion chamber 6 is scavenged without stirring and is kept in a stratified form, and the intake air is heated by the high-temperature exhaust gas. Next, the fuel injection nozzle 7 starts injecting fuel from before the top dead center of the piston 4, and the injected fuel mixes with the intake air whose temperature has increased, and the fuel is also heated by the high-temperature exhaust gas and is insulated. Compression results in autoignition combustion.

The oil recovery tank 24 is formed as a closed pressurized tank. The lubricating oil collected in the oil recovery tank 24 is sucked and pressurized from the oil passage 31 by the oil pump 32, passes through the filter 33, is injected into the intake passage 12 of each cylinder from the oil jet 34, and mixes with the intake air. The oil flows into the crank chamber 8 and lubricates the piston 4, the small and large ends of the connecting rod 10, the bearings of the crankshaft journal, and the like.

In addition, although the above-mentioned embodiment describes the case where the fuel injection nozzle 7 is provided in the cylinder head 3, the first scavenging passage 40
Alternatively, fuel may be injected into the second scavenging passage 42, and an ignition plug (not shown) may be provided in the cylinder head 3 to ignite and burn the fuel.Alternatively, fuel may be ignited to assist self-ignition. Good too. Additionally, cooling fins (not shown) may be attached to the bottom of the oil recovery tank 24 to cool the lubricating oil stock. Furthermore, a forced separation oil supply method may be adopted as a lubricating oil supply method.

〔Effect of the invention〕

a) Since lubricating oil can be efficiently recovered in the entire operating range of a two-stroke internal combustion engine and can be used again, lubricating oil consumption can be significantly reduced. Since pressurized air containing almost no carbon is supplied, it is possible to prevent carbon deposition and adhesion due to combustion of lubricating oil.

b) Since the lubricating oil component flows into the oil recovery passage 20 together with the pressurized air, the lubricating oil can be recovered without using a special oil recovery pump.

C) The blow-by gas that has flowed into the crank chamber 8 is treated as it is at the same time without providing any special means.

d) Since the internal pressure inside the recovered oil tank 24 is increased by pressurized air, it is easy to supply the lubricating oil in the recovered oil tank 24 using the pressure pump 32, etc., and the foaming of the lubricating oil is also reduced. do.

e) When replacing the lubricating oil, only the lubricating oil in the recovered oil tank 24 needs to be replaced, and maintenance is easy.

[Brief explanation of drawings]

The figure is a schematic sectional view of a two-stroke internal combustion engine of the present invention. l...Crank case 2...Cylinder block 3...Cylinder head 8...Crank chamber 12...Intake passage 18...Exhaust passage 20...Oil recovery passage 21...New air flow population 22...Check valve 24...Oil recovery tank 25...Centrifugal separation section 40...First scavenging passage 41...Connection part 42...Second scavenging passage 43...Scavenging boat 1・Crankcase 22 ・Check valve 2・
・Cylinder block 24・Oil recovery tank 3
・Cylinder head 25・Centrifugal separation section 20・
・Oil recovery passage 43 Scavenging port 216. Fresh air inlet

Claims (1)

[Claims] 1. Air is sucked into the crank chamber by the reciprocating motion of the piston, and lubricating oil is also taken into the crank chamber along with the air.
In a two-stroke internal combustion engine in which air is supercharged in the crank chamber and lubrication is performed with lubricating oil, an oil recovery device is provided with a check valve that opens at one end at the bottom of the crank chamber and prevents backflow into the crank chamber. A passage is provided, the other end of the oil recovery passage is connected to an oil recovery tank, and a scavenging passage connected to the oil recovery tank is opened to a cylinder combustion chamber, so that lubricating oil components are separated in the oil recovery tank. A two-stroke internal combustion engine characterized in that supercharged air is supplied to a cylinder combustion chamber. 2. The two-stroke internal combustion engine according to claim 1, further comprising means for supplying the lubricating oil collected in the oil recovery tank to the crank chamber again. 3. The oil recovery tank has at least a cylindrical portion,
2. A two-stroke internal combustion engine according to claim 1, wherein the oil recovery passage is connected to the oil recovery tank so that air containing lubricating oil flows tangentially into the cylindrical portion. 4. The two-stroke internal combustion engine according to claim 1, wherein the oil recovery tank has a volume necessary as a damping volume for supercharged intake air. 5. The two-stroke internal combustion engine has multiple cylinders, the crank chambers of each cylinder are separated from each other, and the oil recovery passage of each cylinder is formed by a cylindrical portion of one oil recovery tank having at least a cylindrical portion in part. 5. A two-stroke internal combustion engine according to claim 4, wherein the two-stroke internal combustion engine is tangentially connected to. 6. The two-stroke internal combustion engine according to claim 1, wherein a heat exchanger is provided in the oil recovery passage to cool the supercharged air passing through the oil recovery passage.