JPH11294130A - Decompressor device of 4-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use the central part of a cam shaft as a lubricating oil path by rotatably fitting a control lever member of a decompressor means for letting the cylinder pressure escape when an engine is started to a cam shaft through a shaft member, and locating the shaft member in a place eccentric from the center of the cam shaft. SOLUTION: When the engine rotating speed is low, a decompressor 6 wraps a part of the peripheral surface of a cam shaft 2 in contact with a cam 4. In this case, a tappet contact projecting part 8 of the decompressor 6 projects over the base circle of the cam 4 to push up a tappet, thereby lifting an exhaust valve to perform decompression. When the engine rotating speed is increased at the time of starting an engine, the decompressor 6 defeats the energizing force of a return spring by the centrifugal force produced by the rotation, so that the decompressor 6 is pivoted clockwise on a pin 7 pivoted in a place eccentric from the center of the cam shaft 2 to release the decompression state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-cycle engine decompressor for assisting in reducing the start of an engine.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, a conventional four-stroke engine decompressor device has a camshaft 2 rotatably mounted inside a crankcase.
A cam 4 for transmitting a rotational force is fitted to a tappet 5 of a valve, and a lever 1 having an auto decompression function is fitted thereto.
3 is attached. This lever 13 is connected to the camshaft 2
Is pivotally supported via a through-pin 15 in a recessed portion 14 formed in the center of the engine, and is urged by a twist spring 16 in a counterclockwise direction, in other words, in a direction of the camshaft 2. When the engine is started, it comes into contact with the tappet 5 to push up the valve, and when the engine is operating, the tappet 5 and the cam 4 can be separated from the tappet 5 by centrifugal force.

[0003] The decompressor device for a four-stroke engine having the above-described structure allows the cylinder pressure during compression to escape to the outside when the engine is started, thereby making the rotation of the crankshaft smooth and easy. And

As prior art documents of this kind, there are JP-A-60-259714 and JP-A-6-294309.

[0005]

In the conventional decompressor for a four-stroke engine, since the concave portion 14 at the center of the camshaft 2 is formed as described above, the lever is provided at the center of the camshaft 2. 13 will be located. Therefore, there is a problem that the center portion of the camshaft 2 is formed in a hollow portion, and this hollow portion cannot be used as a lubricating oil passage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a four-stroke engine decompressor device that can utilize a central portion of a camshaft as a lubricating oil passage.

[0007]

According to the first aspect of the present invention, in order to achieve the above object, the cylinder pressure during compression is released by the decompressor means when the engine is started,
In one that facilitates rotation of a crankshaft, the decompressor means includes a camshaft that operates a follower of a valve via a cam member during operation of the engine, and a deflector that contacts the follower when the engine is started. A control lever member that separates the follower and the cam member from each other so that the follower and the cam member can come into contact with each other during operation of the engine; and A spring member for bringing the control lever member into contact with the cam shaft, the control lever member being rotatably mounted on the cam shaft via a plurality of shaft members, and each shaft member being positioned at a position eccentric from the center of the cam shaft. It is characterized by.

It is to be noted that the control lever member can be formed to have a substantially semicircular cross section. Further, a follower contact convex portion may be provided on the surface of the control lever member.

Here, the engine in the claims includes all four-cycle engines having a camshaft. In addition, the valve is mainly an exhaust valve, but does not particularly exclude an intake valve as disclosed in JP-A-60-259714. In addition, the follower is formed of a tappet such as a mushroom type or a roller type, but may be any applicable one. Further, the cam member may be located above or below the follower as long as it can release the cylinder pressure during compression. The control lever member of the decompressor means is not particularly limited as long as it covers a part of the peripheral surface of the camshaft, but is substantially semicircular in cross section, substantially U-shaped in cross section, and substantially C-shaped in cross section. It is preferable to form it into a plate shape, a block shape, a lever shape, or the like having a substantially U-shaped cross section or a substantially V-shaped cross section.

A single follower contact protrusion may be provided on the surface of the control lever member, or a plurality of follower contact protrusions may be provided at predetermined intervals. The follower contact convex portion is formed in a cylindrical shape, a conical shape, a truncated conical shape, a pyramid shape, a truncated pyramid shape, or the like, and may have a flat end or a rounded end. Further, as the spring member, a single or plural coil springs, torsion springs, twisting springs, or the like can be appropriately used. The term rotatable includes rotatable and swingable. Further, the plurality of shaft members may be formed of a pair of pins, or may be formed of both free ends such as a C-shaped member. Each shaft member is located at a position shifted radially outward from the center portion of the camshaft, in other words, at a portion that does not interfere with the substantially central portion of the camshaft, specifically, at a location such as both sides of the peripheral surface of the camshaft. It just needs to be located. Further, the present invention, at least on-road, off-road, or various motorcycles such as scooters, various four-wheeled vehicles such as wagons, lawnmowers, outboard motors,
It is applicable to general-purpose engines, boats, personal watercrafts, and the like.

According to the first aspect of the present invention, since the plurality of shaft members rotatably supporting the control lever member are located at positions radially away from the center of the cam shaft, the center of the cam shaft is provided. Does not interfere with the plurality of shaft members. Therefore,
Even if the center portion of the camshaft is formed in a hollow portion and this hollow portion is used as a fluid passage such as a lubricating oil passage, fluid does not flow through the fluid passage or leaks from the fluid passage. .

According to the second aspect of the present invention, since the control lever member has a substantially semi-circular cross section, the surface area of the control lever member covering a part of the camshaft is widened, and the follower contact convex portion is provided. The possible area increases. Therefore, a plurality of follower contact protrusions are provided on the surface of the control lever member, and the decompression function can be improved. Further, according to the third aspect of the present invention, since a plurality of follower contact protrusions are provided on the surface of the control lever member, the valve opening time can be set more freely than in the case where there is a single follower contact protrusion. be able to.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 5, the decompressor device of the four-stroke engine according to the present embodiment includes a decompressor unit 1 for releasing a cylinder pressure during compression to the outside at the time of starting the engine. It comprises a camshaft 2, a decompressor 6, and a return spring 11.

As shown in FIGS. 1 to 3, the camshaft 2 has a lubricating oil passage 3 having a circular vertical section at the center thereof in the axial direction (FIG. 1).
(In the left-right direction of the engine), and is rotatably mounted on both inner sides of a crankcase (not shown) of the engine via a plurality of bearings. An egg-shaped cam 4 is fitted on the cam shaft 2, and a tappet 5 is positioned directly above the cam 4 so that an exhaust valve (not shown) is brought into contact with the cam 4 and the tappet 5. Move up and down to open and close.

As shown in FIGS. 1 and 2, the decompressor 6 is formed in a semicircular shape in longitudinal section, and is pivotally mounted on both sides of the peripheral surface of the camshaft 2 via a pair of pins 7 from above. When the engine is started, it is in contact with and adjacent to the cam 4 and covers a part of the peripheral surface of the camshaft 2. At the center of the surface of the decompressor 6, a tappet contact projection 8 having a semicircular vertical section is provided, and the tappet contact projection 8 functions to contact and push up the tappet 5 when the engine is started. A through hole 9 is formed in each side of the decompressor 6, and a pin 7 penetrates each through hole 9 through a small gap, and each pin 7 is attached to the side of the camshaft 2. Hole 1
It is buried tight to zero. Each pin 7 and each mounting hole 10
Are located on both sides of the camshaft 2 away from the lubricating oil passage 3,
It functions so as not to affect the flow guiding operation of the lubricating oil passage 3 (see FIG. 2).

Further, the return spring 11 is provided as shown in FIG.
As shown in FIG. 1, the camshaft 2 is mounted on the peripheral surface of the camshaft 2 by press-fitting through one of the mounting pins 12. The return spring 11 has one long bent end inserted into the insertion hole of the decompressor 6, and the other short bent end inserted into the insertion hole of the camshaft 2. The return spring 11 configured as described above functions to bias the decompressor 6 counterclockwise when the engine is started, thereby restricting the swing of the decompressor 6.

In the above configuration, when the engine is stopped or cranked for starting (by a starter motor or kick), the rotational speed of the engine is low. A part of the peripheral surface of the camshaft 2 is covered while the decompressor 6 is in contact with 4 (see the solid line in FIG. 1 and FIG. 3). At this time, the tappet contact projection 8 of the decompressor 6 protrudes from the cam 4 base circle and pushes up the tappet 5, and the exhaust valve is lifted and decompressed (decompression ON).
Status). Due to this decompression, the cylinder pressure at the time of compression escapes to the exhaust pipe, and cranking becomes extremely easy.

When the engine starts and the rotation speed increases and the camshaft 2 rotates at a predetermined rotation speed or more, the centrifugal force generated by the rotation of the engine causes the decompressor 6 to overcome the spring force of the return spring 11 and the decompressor 6 Swings clockwise around the pin 7 (see the arrow in FIG. 1) to release the decompression state (see the broken line in FIG. 1 and FIG. 5). By releasing the decompression state, normal compression is performed (decompression OFF state).

According to the above configuration, the decompression can be easily turned on and off by utilizing the centrifugal force generated by the rotation of the engine. In addition, since each pin 7 and each mounting hole 10 are located on both sides of the camshaft 2 radially away from the lubricating oil passage 3, the lubricating oil passage 3 communicates with each pin 7 and each mounting hole 10 mutually. I have nothing to do. Therefore,
Unlike the decompressor device disclosed in Japanese Patent Application Laid-Open No. 0-259714, the central portion of the camshaft 2 is formed in a hollow portion, and this hollow portion can be largely used as the lubricating oil passage 3.

Further, there is no need to perform complicated processing (for example, drilling of a concave portion) inside the camshaft 2 or the like.
As compared with the decompressor device of the publication, the configuration is quite simple and the number of parts is reduced. Therefore, remarkable simplification of the configuration, reduction in the number of parts, and cost reduction can be expected. Further, since the decompressor 6 is formed to have a semicircular cross section so as to cover a part of the peripheral surface of the camshaft 2 as widely as possible, a plurality of tappet contact projections 8 are provided on the surface of the decompressor 6. Can be juxtaposed in the circumferential direction. This makes it possible to further improve the decompression function.

[0021]

As described above, according to the first aspect of the present invention, there is an effect that the central portion of the camshaft can be used as a fluid passage such as a lubricating oil passage. Further, according to the second or third aspect of the present invention, it is possible to provide a plurality of follower contact protrusions on the surface of the control lever member to improve the decompression function or set the valve opening time appropriately. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a decompressor device for a four-cycle engine according to the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is an explanatory perspective view showing an operation state of decompression in the embodiment of the decompressor device for the four-cycle engine according to the present invention.

FIG. 4 is an enlarged perspective explanatory view showing the return spring of FIG. 3;

FIG. 5 is a perspective explanatory view showing a decompression releasing state in the embodiment of the four-cycle engine decompressor device according to the present invention.

FIG. 6 is an explanatory sectional view showing a conventional decompressor device of a four-cycle engine.

FIG. 7 is an explanatory view showing a conventional decompressor device of a four-cycle engine.

[Explanation of symbols]

 Reference Signs List 1 decompressor means 2 cam shaft 3 lubricating oil passage 4 cam (cam member) 5 tappet (follower) 6 decompressor (control lever member) 7 pin (shaft member) 8 tappet contact protrusion (follower contact protrusion) 9 Through hole 10 Mounting hole 11 Return spring (spring member)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02N 17/08 F02N 17/08 C

Claims (3)

[Claims] 1. A decompressor device for a four-cycle engine, wherein a cylinder pressure during compression is released by a decompressor means at the start of an engine to facilitate rotation of a crankshaft. A cam shaft for operating the follower through a cam member, and contacting the follower at the time of starting the engine to separate the follower and the cam member, and moving away from the follower during operation of the engine. A control lever member that allows the follower and the cam member to come into contact with each other; and a spring member that makes the follower contact the control lever member when the engine is started. A decompression system for a four-stroke engine, wherein the shaft member is rotatably mounted via a shaft member, and each shaft member is located at a position eccentric from the center of the camshaft. Tsu support apparatus. 2. The decompressor device for a four-stroke engine according to claim 1, wherein said control lever member is formed to have a substantially semicircular cross section. 3. The decompressor device for a four-stroke engine according to claim 1, wherein a follower contact convex portion is provided on a surface of said control lever member.