JPH0263109B2 - - Google Patents

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 a conventional internal combustion engine equipped with a recoil starter, the operator pulls the recoil starter handle.
A rope connected to the handle rotates the pinion gear of the recoil starter, and the rotation of this pinion gear starts the internal combustion engine.

However, when starting, the handle of the recoil starter must be pulled against the compression force of the internal combustion engine, and the pulling force on the handle is large, making it difficult for women and others with weak arms to start. There is a problem with the rope breaking due to force.

(Objective of the Invention) The present invention reduces the pulling force of the recoil starter during startup, enables the internal combustion engine to be started easily with a small pulling force, and also provides a decompression system for the internal combustion engine that prevents the rope of the recoil starter from breaking. The purpose is to provide equipment.

(Structure of the Invention) The present invention engages with a spiral spline attached integrally with the recoil reel of a recoil starter, and a pinion gear moves in the axial direction by a friction spring and meshes with a gear on the engine side. In an internal combustion engine having a bendix-type recoil starter for starting the engine, 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 starter is installed in the decompression passage. This decompression device for an internal combustion engine is characterized in that it is provided with a connecting member that opens a decompression valve at the time of starting in conjunction with a friction spring that moves together with a pinion gear of a 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, so that the entire engine can be placed horizontally. 6 is an ignition coil, 8 is a plug cord, 10 is a spark plug, and 12 is a carburetor.

A Bendix type recoil starter 14 is provided at the rear end of the cylinder block 2. 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 (connecting member) is connected to the tip 20, and the other end of the rod 22 is connected to the arm 2.
It is connected to 4. The rod 22 is arranged along the side of the cylinder block 2.

A decombination 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 piston 28, and the other end communicates with the intake passage 30. 31 is an air cleaner provided in the carburetor 12.

This decompression passage 26 is bent into a substantially L shape, and a decompression valve 32 is interposed in the bent portion of the decompression passage 26. As shown in FIG. 3, the decompression valve 32 has a cylindrical shape and is rotatably attached to the cylinder block 2 by fitting the tip of a set screw 38 into an annular groove 34 formed in the center. The arm 24 is fixed to the distal end of the valve 32 protruding from the cylinder block 2 with a set screw 36, so that it can be rotated as the rod 22 moves. A passage 38 is formed at the base end of the valve 32, and when the arm 24 is pushed by the rod 22 to the state shown by the two-dot chain line in FIG. 2 and the valve 32 rotates, the passage 33 and the decompression passage are 26, the valve is opened, and 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 the top surface, and the base end 42 of the friction spring 18 is formed into a partially cut-out ring shape. Recoil starter 1
4 is attached to the cylinder block 2 by screwing the central shaft 44 to the cylinder block 2, as shown in FIG. central axis 4
4 is rotatably provided with a recoil reel 46, and a rope 48 connected to the handle 40 is wound around the recoil reel 46 so that the recoil reel 46 that pulls the handle 40 rotates in the direction of arrow R (FIG. 4). It is attached. recoil reel 46
A spiral spline 50 is integrally formed on the right end surface of FIG.
A pinion gear 52 is fitted to the outer periphery of 0.
The pinion gear 52 is biased toward the recoil reel 46 by a compression coil spring 58. In addition, the pinion gear 52 has a friction spring 1.
The base end portions 42 of the pinion gears 8 and 8 are fitted together, and the frictional force of the base end portions 42 prevents the pinion gear 52 from rotating together with the recoil reel 46. When the recoil reel 46 is rotated by pulling the handle 40, the pinion gear 52 is prevented from rotating at the base end 42, so it moves along the spiral spline 50 in the direction of arrow A, and the ring gear rotates as shown by the two-dot chain line. 5
4 and transmits the rotational force of the recoil reel 46 to the ring gear 54 to start the engine.

Therefore, the friction spring 18 moves in the direction of arrow A together with the pinion gear 52, and the movement of the friction spring 18 causes the rod 22 connected to the tip 20 (FIGS. 4 and 1) to move.
moves forward, and opens the decompression valve 32, which can be rotated with a relatively small operating force while increasing the moving force by the lever action of the arm 24.

Next, the operation will be explained. When the handle 40 of the recoil starter 14 is pulled when starting the engine, the rod 22 moves as the pinion gear 52 moves, and the decompression valve 32 opens. When the decompression valve 32 opens, the decompression passage 26
The piston 28 does not compress the air-fuel mixture in the cylinder until the cylinder 29 and the intake passage 30 communicate with each other and 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 compressive force is reduced, the cranking force required during starting, that is, the pulling force on the handle 40 of the recoil starter 14 is significantly reduced.
When the engine is rotated at a predetermined rotation speed by the recoil starter 14, even if the recoil starter 14 returns to its original state and the decompression valve 32 closes, the engine will continue to operate due to the inertia of the crankshaft, flywheel, etc. It will continue to rotate for at least several revolutions, during which time the engine will start.

(Effects of the Invention) As described above, according to the present invention, the pinion gear 52 is engaged with the spiral spline 50 attached integrally with the recoil reel 46 of the recoil starter 14, and the pinion gear 52 is moved in the axial direction by the friction spring 18. However, in an internal combustion engine having a Bendex type recoil starter that starts the engine by meshing with a gear on the engine side, the intake vent 30 (or exhaust vent 3
5) and a decompression passage 2 connecting the cylinder 29 and the cylinder 29.
6, and a decompression valve 32 is interposed in this decompression passage 26, and the decompression valve 32 is interlocked with the friction spring 18 that moves together with the pinion gear 52 of the recoil starter 14 to operate the decompression valve 3 at the time of starting.
2 is provided, so when the handle 40 of the recoil starter 14 is pulled during startup, the rod 2 is opened in conjunction with the movement of the pinion gear 52.
2, the decompression valve 32 is opened to significantly reduce the compression ratio, thereby significantly reducing the cranking force of the engine, that is, the tensile force of the handle 40 of the recoil starter 14.

Therefore, the tensile force of the recoil starter 14 required when starting the engine is reduced so that even women with weak arms can easily start the engine, and the tensile force acting on the rope 48 connected to the handle 40 is reduced. This can prevent the rope 48 from breaking.

There are also the following effects.

(A) Since the friction spring 18 for moving the pinion gear in the axial direction is directly interlocked and connected to the connecting member (rod 22) for operating the decompression valve, a new lever for operating the decompression valve is installed inside the recoil starter 14. There is no need to provide members such as rollers and actuating rollers, and the number of parts can be reduced.

(B) Since it is not necessary to engage the starter rope 48 with a roller for operating the decompression valve, wear of the starter rope 48 can be prevented.

(C) Since the connecting member is connected to the friction spring 18, the friction spring 18 can absorb the shock caused when the rope is pulled too strongly during startup.

(Another embodiment) (1) The decompression passage 26 is not limited to one that communicates between the cylinder 29 and the intake passage 30;
and the exhaust passage 35 may be communicated with each other. However, the decompression passage 26 is replaced by the intake passage 30.
When the air-fuel mixture in the cylinder 29 is connected to the intake passage 30, it is possible to prevent fuel from being wasted, but the exhaust passage 35
When the decompression valve 32 is opened, the air-fuel mixture is discharged unburned.

(2) The connecting member is not limited to the rod 22; for example, a wire may also be used.

[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 plan view taken in the direction of the arrows in Fig. 1, Fig. 3 is a cross-sectional view taken in Fig. 2;
The figure is a front view of the recoil starter as seen from the arrow in Figure 2.
FIG. 5 is a cross-sectional view of FIG. 4. 14...
Recoil starter, 22...rod (connection member),
26...Decompression passage, 29...Cylinder, 30
...Intake passage, 32...Decompression valve, 34
...Aisle, 52...Pinion gear.

Claims (1)

[Claims] 1 A Bendex type motor that starts the engine by engaging a spiral spline attached to the recoil reel of the recoil starter, causing the pinion gear to move in the axial direction by a friction spring and meshing with the gear on the engine side. In an internal combustion engine having a recoil starter, a decompression passage connecting the intake passage or exhaust passage of the internal combustion engine and the cylinder is provided, a decompression valve is interposed in the decompression passage, and a friction valve that moves together with the pinion gear of the recoil starter is provided. A decompression device for an internal combustion engine, comprising a connecting member that opens a decompression valve at the time of startup in conjunction with a spring.