JPH0323317A - Two-cycle engine with supercharger - Google Patents

Abstract

PURPOSE:To aim at high powered output of an engine by connecting an oil supply system to the upstream side of an intake supercharger of an intake system, in a two-cycle engine with supercharger branch oiling type which supplies oil to the intake system from the oil supply system separately provided from a fuel supply system. CONSTITUTION:At a crank case 4 which is provided under a cylinder body 2 of an engine 1, an intake passage 14 which is provided with a check valve 15 of a reed valve type is formed, and a carburetor 17, a supercharger 18 and an air filter 19 are connected in order toward the upstream at an intake pipe 16 which is connected to the intake passage 14. In this case, an oil hose 31 which is led from the under part of an oil tank 30 is connected to the intake side of an oil pump 32, and the exhaust side is connected to an injection nozzle 34 which is arranged at the upstream side of the supercharger 18 by the oil hose 32. Consequently, micro-clearance inside the supercharger 18 is made sealable by oil, and supercharging efficiency is raised so as to improve the output of the engine 1.

Description

Detailed Description of the Invention (Field of Industrial Application) The invention relates to a two-stroke engine with a supercharger that uses a separate oil supply system for lubrication and is equipped with a supercharger in the intake system. (Prior art) A supercharger is known as a means of increasing the output of an engine without increasing its displacement.This supercharger uses part of the engine power to drive a compressor, and this compressor It sends compressed intake air to the engine cylinders to increase engine output. By the way, the compressors that make up this type of supercharger include vane type, roots type, screw type, etc. All types of compressors generally receive the rotation of the engine crankshaft via a belt or gears. It is rotated and driven. For example, a screw type compressor pumps intake air by rotating two screw-shaped rotors in opposite directions. ) and II of the other rotor! A small clearance is secured between the first part (flute) and a small clearance is also provided between both rotors and the inner wall of the housing.
In addition, even in vane type and roots type compressors, there is a small clearance between the vanes or rotors and the inner wall of the housing, and between the rotors. (Problem to be solved by the invention) However, if a minute clearance is provided between the compressor rotors or between the rotors and the inner wall of the housing as described above, intake air will leak through this clearance. , the supercharging efficiency deteriorates. By the way, as a lubrication method for two-stroke engines, a separate oil supply system is often adopted in which oil is supplied to the intake system from an oil supply system that is separate from the fuel supply system. It is conceivable that it could be used as a sealant for supercharger compressors. The present invention has been made based on the above viewpoint, and its purpose is to provide a two-stroke engine with a supercharger that can increase overcoagulation efficiency and obtain higher output. (Means for Solving the Problems) In order to achieve the above object, the present invention adopts a separate oil supply system in which oil is supplied to the intake system from an oil supply system that is installed separately from the fuel supply system, and supercharges the intake system. A two-stroke engine with a supercharger that is equipped with a charger is characterized in that the oil supply system is connected to the upstream side of the supercharger in the intake system. (Function) According to the present invention, since oil is supplied to the supercharger from the upstream side thereof, the minute clearance provided in the compressor that constitutes the supercharger is sealed by oil, and the clearance is closed. The amount of intake air passing through and leaking is suppressed to a small amount, and as a result, the supercharging efficiency of the intake air is increased, further improving engine output. (Example) An example of the present invention will be described below based on the attached drawings. The drawing is a cutaway side view of a two-stroke engine 1 with a supercharger according to the present invention. In the drawing, 2 is a cylinder body, and a cylinder head 3 and a crankcase 4 are attached to the upper and lower parts of the cylinder body, respectively. There is. A piston 6 is slidably fitted into a cylinder 5 formed within the cylinder body 2, and a scavenging passage 7 and an exhaust passage 8 are formed in the cylinder body 2.
still. One end of the scavenging passage 7 opens into the crank chamber S in the crankcase 4, and the other end opens into the cylinder 5 as a scavenging port 9. Further, one end of the exhaust passage 8 opens into the cylinder 5 as an exhaust boat 10,
An exhaust pipe (not shown) is connected to the other end of the exhaust passage 8. On the other hand, a long crankshaft 11 is rotatably arranged in the crankcase 4 in a direction perpendicular to the plane of the drawing, and the crankshaft 11 and the piston 6 are connected via a connecting rod 12. Further, a spark plug l3 is screwed onto the top of the cylinder head 3. Incidentally, the crankcase 4 is formed with an intake passage 14, and the intake passage 14 is provided with a Riet valve type check valve 15 that allows intake air to flow only toward the crank chamber S side. An intake pipe 16 is connected to this intake passage l4, and a carburetor 17, a supercharger 18, and an air filter 19 are sequentially connected to the intake pipe 16 toward the upstream side. The supercharger 18 has a screw type compressor 20.
The rotor is constructed by rotatably disposing two long screw-shaped rotors 22 and 23, upper and lower, in an elliptical housing 21 in the direction perpendicular to the plane of the drawing. The upper rotor 22 is a male rotor, and four lobes 22a with a semicircular cross section are formed continuously in the axial direction on the outer periphery of the rotor.
A gear 24 is connected to the end of the rotor 22.
Further, the lower rotor 23 is a female rotor, and six flutes (grooves) 23a are continuously formed in the axial direction on the outer periphery of the rotor 23. A gear 25 that meshes with the gear 24 is connected. still,
Both gears 24 and 25 have the same diameter (same pitch diameter) and have the same number of teeth.Furthermore, at the extending end facing outside the housing 2l of the lower rotor 23, there is a A small diameter subrocket 26 is connected to the subrocket 26, and an endless chain 28 is connected between the subrocket 26 and a large diameter subrocket 27 connected to the crankshaft l1.
is wrapped around it. When the engine 1 is driven and the crankshaft l1 rotates, this rotation is caused by the subrocket 27 and the chain 28.
The rotation of the crankshaft 11 (rotor 23) is further transmitted to the upper rotor 22 via gears 25 and 24, and at the same time, the rotation of the crankshaft 11 (rotor 23) is transmitted to the lower rotor 23 via the sprocket 26 and rotated. The rotor 22 is driven to rotate at the same speed as the rotor 23. As a result, both rotors 22, 23 are rotated independently and in opposite directions, and during these rotations, the lobes 22a of the rotor 22 are rotated by the flutes 23 of the other rotor 23.
a..., but a minute clearance is formed between each lobe 22a and each flute 23a in the engaged state. Also, a small clearance is formed between each lobe 22a and each flute 23a and the inner wall of the housing 21. By the way, the two-stroke engine l according to this embodiment employs a separate oil supply system as a lubrication system, and the oil hose 3l leading out from the lower part of the oil tank 30, which is installed separately from the engine l, is connected to the suction of the oil bomb 32. An oil hose 33 leading out from the discharge side of the oil bomb 32 is connected to an injection nozzle 34 installed upstream of the supercharger 18 in the intake system of the engine 1. The oil pump 32 is an electromagnetic oil pump whose discharge amount is determined according to the rotational speed of the engine 1 (crankshaft 11). When the engine 1 is driven and the piston 6 moves up from the bottom dead center in the cylinder 5, negative pressure is generated in the crank chamber S, and the intake air (air) is drawn by this negative pressure. After being sucked into the air filter 19 and purified there, it flows to the supercharger 18 side, but before reaching the supercharger 18, the oil in the oil tank 30 is pumped into the intake air from the injection nozzle 34 by the oil pump 32. In order to be supplied, intake air containing mist of oil is drawn into the compressor 20 of the supercharger l8. Therefore, in the compressor 20, the oil contained in the intake air increases the clearance between each lobe 22a and each flute 23a of both rotors 22, 23, and the clearance between these lobes 22a, flutes 23a, and the housing 2.
1, the amount of intake air that leaks through these clearances is suppressed to a small level, and as a result, the volumetric efficiency of the compressor 20 and
In other words, the supercharging efficiency of the intake air by the supercharger l8 is increased, and the intake air efficiently compressed by the compressor 20 reaches the carburetor l7. Note that within the compressor 20, oil not only performs the sealing function as described above, but also performs an original lubricating function. In the carburetor 17, a mist of fuel is mixed with the oil-containing intake air to form an air-fuel mixture, but since this air-fuel mixture is pressurized, a large amount of the air-fuel mixture flows through the intake pipe l6 and the check valve. It is filled into the crank chamber S from the intake passage l4 through the valve l5. Therefore, when the piston 6 moves downward from the top dead center in the cylinder 5 in the previous cycle, the scavenging boat 9 and the exhaust boat 10 remain closed by the piston 6,
The air-fuel mixture filled in the crank chamber S is primarily compressed by the descending piston 6. Then, when the piston 6 moves further down inside the cylinder 5 and opens the scavenging port 9 and the exhaust port IO, the primary compressed air-fuel mixture in the crank chamber S flows from the scavenging passage 7 into the cylinder 5. The exhaust gas generated by combustion of the air-fuel mixture in the previous cycle is pushed out to the exhaust passage 8 side. Thereafter, when the piston 6 passes the bottom dead center and moves upward again, and the scavenging boat 9 and the exhaust boat 10 are both closed by the piston 6, the air-fuel mixture in the cylinder 5 is compressed by the rising piston 6, and the piston 6 When the mixture reaches near top dead center, the mixture is ignited and combusted by an electric spark generated by the ignition plaque 13. When the piston 6 descends in the cylinder S due to the high combustion pressure generated by the combustion of this air-fuel mixture, the above-mentioned intake of intake air starts again, and from then on, the same action as above is repeated continuously, but as described above. Since the intake air is pressurized by the supercharger 18 and a large amount of air-fuel mixture is filled into the engine cylinder 5, the output of the engine 1 can be increased without increasing the displacement. The oil contained in the air-fuel mixture fulfills its original function of lubricating each sliding part within the engine. As described above, in this embodiment, the efficiency of supercharging the intake air by the supercharger 18 is increased due to the sealing function of the oil, so that the output of the engine 1 is further increased.

In the above embodiments, a two-stroke engine equipped with a supercharger using a screw type compressor was described, but the present invention is applicable to a two-stroke engine using a vane type, roots type, or any other type of compressor. Of course, this applies to the following. Further, in this embodiment, a two-stroke engine using a carburetor in the intake system has been described, but the present invention can also be applied to a fuel injection type two-stroke engine using an injector. Furthermore, the drive system for the supercharger's compressor can include a gear transmission mechanism in addition to a chain transmission mechanism using chains, belts, etc. (Effects of the Invention) As is clear from the above description, according to the present invention, a separate oil supply system is adopted in which oil is supplied to the intake system from an oil supply system installed separately from the fuel supply system, and a supercharger is installed in the intake system. In the two-stroke engine with a supercharger, the oil supply system is connected to the upstream side of the supercharger in the intake system, so oil is supplied to the supercharger from the upstream side of the supercharger, and the supercharger is configured. The effect is that the minute clearance provided in the compressor is sealed with oil, and the amount of intake air that passes through the clearance and leaks is suppressed to a small amount, increasing the supercharging efficiency, thereby further improving engine output. is obtained.

[Brief explanation of the drawing]

Claims (1)

[Claims] In a two-stroke engine with a supercharger, which employs a separate oil supply system in which oil is supplied to the intake system from an oil supply system that is separate from the fuel supply system, the oil supply system is connected to the intake system. A two-stroke engine with a supercharger, characterized in that the engine is connected to the upstream side of the supercharger.