JPS6138162A - Decompressor for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the pulling force of starter by providing a decompression path coupling between intake path and cylinder while arranging a decompression valve in said path and opening said valve while interlocking with a recoil starter. CONSTITUTION:Upon pulling of handle 40 of recoil starter 14 when starting an engine, a rod 22 will move to open a decompression valve 32. Consequently, the cylinder 29 and an intake path 30 are communicated through a decompression path 26. Here, the piston 28 will never compress the mixture gas in the cylinder 29 until said path 26 is choked by the piston 28. Consequently, the compression ratio will drop considerably thus to reduce the compression force of engine. As a results, the pulling force of handle 40 of recoil starter 14 can be reduced. While the tensile force functioning onto a rope coupled to the handle 40 can also be reduced thus to prevent cutting of rope.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a decompression device for an internal combustion engine equipped with a recoil starter, which is often used in manual starters for small internal combustion engines.

(Prior art) In an internal combustion engine equipped with a conventional recoil starter, the operator pulls the handle of the recoil starter, rotates the pinion gear of the recoil starter with a lobe connected to the hand, and the rotation of the pinion gear starts the internal combustion engine. It is set to start.

However, when starting, the handle of the recoil starter must be pulled against the compressive force of the Kahen Fμ, and the pulling force of the Han Fμ is large, making starting not only a national disaster for women and others with weak arms. There is a problem in that the tensile force acting on the p-p causes the lobe to break.

(Object of the invention) The present invention reduces the tensile force of the recoil starter at the time of starting,
It is an object of the present invention to provide a decompression device for an internal combustion engine that can easily cause the internal combustion engine to move with a small tensile force and can prevent the lobe of a recoil starter from being cut.

(Structure of the Invention) The present invention provides, in an internal combustion engine having a recoil starter with a built-in pinion gear that moves during starting, a decompression passage connecting an intake passage or an exhaust passage of the internal combustion engine to a cylinder. A decompression device for an internal combustion engine is provided with a decompression valve interposed therein, and a connecting member that opens the decompression valve at the time of starting in conjunction with the movement of the binion gear of the recoil starter.

(Example) In FIG. 1 showing a small general-purpose two-stroke engine to which the present invention is applied, 2 is a cylinder block. A mounting base 4 is formed on the cylinder block 2, and the entire engine is arranged horizontally. 6 is an igniter, 8 is a plug γ, IO is a spark plug, and 12 is a carburetor.

At the rear end of the cylinder block 2, for example, a Pendix-type glue-coil μ starter 14 is provided. A window hole 16 is formed in the side surface of the recoil starter 14, and a tip portion 20 of a friction spring 18 that moves forward in response to a starting operation protrudes from the window hole 16 to the outside.

One end of a rod 22 (connection section side) is connected to the tip 20, and the other end of the rod 22 is connected to an arm 24. The rod 22 is arranged along the side surface of the cylinder block 2.

A decompression passage 26 is formed in the cylinder block 2 as shown in FIG. One end of the decompression passage 26 opens into the inner wall of the cylinder 29 corresponding to the end of the compression stroke of the pinuton 28, and the other end communicates with the intake passage 80. 8
1 is an air cleaner provided in the carburetor 12.

This decompression passage 26 is bent into a substantially rectangular shape, and a decompression valve 8 is provided at the bent part of the decompression passage 26.
2 is interposed. The decompression valve 32 has a cylindrical shape as shown in FIG. 8, and has an annular groove 84 formed in the center.
Fit the tip of the setscrew 31 to the cylinder block 2.
It is rotatably mounted on the The arm 24 is fixed to the tip of the valve 82fl projecting from the V-ring block 2 with a set screw 86, and is rotated by movement of the rod 22. A passage 38 is formed at the base end of the /<μ valve 82, and when the arm 24 is pushed by the rod 22 to the state shown by the two-dot chain line in FIG. The valve is opened by communicating with the decompression passage 26, and the valve is closed in other states. Note that 35 is an exhaust passage and 37 is a muffler.

As shown in FIG. 4, the recoil starter 14 has a handle 40- projecting from its upper surface, and the base end 42 of the friction spring 18 is formed into an annular shape with a portion cut away. As shown in FIG. 5, the recoil starter 14 is attached to the cylinder block 2 by screwing the center shaft 44 thereto. A pulley 46 is rotatably provided on the central shaft 44, and a rope 48 connected to the hand/l/40 pulls the hand/L'40 in the direction of arrow R (see Fig. 4). It is wrapped so that it rotates.

A spiral spline 50 is integrally formed on the right end surface of the pulley 46 in FIG.
A pinion gear 52 is fitted to the outer periphery of 0. The pinion gear 52 is biased toward the pulley 46 by a compression coil spring 58. The proximal end portion 42 of the friction spring 180 is fitted into the pinion gear 52, which prevents the pinion gear 52 from rotating together with the pulley 46 due to the frictional force of the proximal end portion 42. When the hand/I/40 is pulled and the pulley 46 is rotated, the pinion gear 52 is stopped at the base end 42, so it moves along the Svirah μ spline 50 in the direction of arrow A, as shown by the two-dot chain line. It meshes with the ring gear 54 and transmits the rotational force of the pulley 46 to the ring gear 54 to perform the function of starting the engine.

Therefore, the friction spring 18 moves in the direction of the arrow along with the pinion gear 52, and this movement of the friction spring 18 causes the tip end 20 (FIG. 4,
The rod 22 connected to the arm 24 moves forward.
The decompression bap 82, which can be rotated with a relatively small operating force, is opened while increasing the moving force by the lever action.

Next, the operation will be explained. When the hand A/40 of the recoil starter 14 is pulled when starting the engine, the pinion gear 5
2 moves, the rod 22 moves, and the decompression valve 32 opens. When the decompression valve 32 opens, the cylinder 29 and the intake passage 80 communicate through the decompression passage 26, and the piston 28 does not compress the air-fuel mixture in the cylinder until the piston 28 closes the decompression passage 26.

Therefore, the compression ratio decreases significantly and the compression force of the engine also decreases significantly. When the compression force decreases, the cranking force required for starting, that is, the hand/l of the recoil starter 14
/40 tensile force is significantly reduced.

When the engine is rotated at a predetermined speed by the recoil starter 14, even if the recoil starter 14 returns to its original state and the deconzo valve 32 is closed, the engine will continue to rotate at least several times due to the inertia of the crankshaft, flywheel μ, etc. The rotation should continue to rotate, while the carrot starts.

(Effects of the Invention) As explained above, according to the present invention, in an engine having a recoil starter 14 incorporating a pinion gear 52 that moves during startup, a decompression passage 26 connecting an intake passage 80 and a cylinder 29 is provided, A decompression valve 32 is interposed in this decompression passage 26, and a rod 22 is provided that opens the decompression valve 32 at the time of starting in conjunction with the movement of the pinion gear 52 of the recoil starter 14. When the handle 40 is pulled, the rod 22 opens the decompression valve 82 in conjunction with the movement of the pinion gear 52, significantly reducing the compression ratio and causing engine cranking. can significantly reduce the tensile force of

Therefore, it is possible to reduce the tensile force of the recoil starter 14 required to start the engine, so that even women with weak physical strength can easily start the engine.
By reducing the tensile force acting on the rope 148 connected to the rope 40, the rope 48 can be prevented from breaking.

(Another embodiment) (1) The decompression passage 26 is connected to the cylinder 29 and the intake passage 30.
The cylinder 29 and the exhaust passage 8 are not limited to those that communicate with each other.
5 may be communicated with each other. However, if the decompression passage 26 is connected to the intake passage 80, the cylinder 29
Since the air-fuel mixture in the intake passage 80KR flows through the intake passage, wasteful consumption of fuel can be prevented, but if it is connected to the exhaust passage 85, the air-fuel mixture will be discharged unburned when the decompression valve 32 is opened. be done.

(2) The connecting member is not limited to the rod 22, and for example, a wire can also be used. Further, the rod 22 is not necessarily connected to the friction ring 18, but may be a bushing rod 60 that is movable by abutting against the end surface of the pinion gear 52, as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a side view of a two-stroke engine to which the present invention is applied, FIG. 2 is a partially cutaway view of FIG.
The figure is a 1-1 sectional view of FIG. 2, FIG. 4 is a front view of the recoil starter as viewed from the ■ arrow in FIG. 2, and FIG. 5 is a sectional view taken along the line N in FIG. 4. 14... Recoil starter, 22... Rod (connection I material) 26... Decompression passage, 29...
・Cylinder, 80...Intake passage, 82...Decompression valve, 84...Passage, 52...Pinion gear

Claims (1)

[Claims] In an internal combustion engine having a recoil starter with a built-in pinion gear that moves during startup, a decompression passage is provided that connects the intake passage or exhaust passage of the internal combustion engine to the cylinder, and a decompression valve is interposed in this decompression passage, and the recoil A decompression device for an internal combustion engine, comprising a connecting member that opens a decompression valve at the time of starting in conjunction with movement of a pinion gear of a starter.