JPS5916489Y2 - Internal combustion engine with decompression device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an internal combustion engine having a combustion engine which makes the combustion chamber in a non-compressed state at the time of start-up to facilitate rotation at the time of start-up. and transmits the displacement of the actuator guided and moved by the guide groove of the decompression reel rotating in conjunction with the rope pulley of the recoil starter to the decompression shaft to move the decompression shaft from the decompression release position to the decompression position. This invention relates to a mounting structure for the decompression reel in a decompression device with a new structure, in which the decompression reel is mounted on a weight part of a flywheel attached to one end of an engine shaft and a crank pulley attached to a boss part of the flywheel. By mounting the recoil starter so that they overlap each other in the axial direction of the engine, the length of the recoil starter mounting portion in the axial direction of the engine can be shortened, thereby promoting miniaturization and weight reduction of the internal combustion engine. The purpose of this invention is to provide an internal combustion engine equipped with a combustion engine.

Hereinafter, an internal combustion engine with a decompression device according to the present invention will be explained based on the embodiment shown in FIGS. 1 and 4. FIG. 1 shows a vertical water-cooled easel engine with a decompression device according to an embodiment of the present invention; Z is shown.

In FIG. 1, reference numeral 1 denotes an engine body, 2 an engine shaft, 3 a piston, and 4 a flywheel attached to one end 2a of the engine shaft 2. In FIG.

The flywheel 4 has a dish-shaped cross section with a short cylindrical weight part 4a extending in the axial direction on its side circumference, and has a dish-shaped concave part 4C facing outward. It is attached to engine shaft 2.

Symbols 5, 5... are weight portions 4a of the flywheel 4
A flywheel blade for a cooling fan, which is attached to integrally protrude from the side surface of the engine body 1 in
7 is a fan case disposed on the side of the engine body 1 so as to surround the outside of the flywheel 4;
The radiator device is shown disposed within the fan case 6 in an upper position.

Further, reference numeral 18 denotes a coil starter installed between the engine shaft 2 and the fan case 6 so as to be able to freely engage with the engine shaft 2, and a rope pulley attached to the outer wall surface of the fan case 6. 19 and the flywheel 4
It consists of a crank pulley 12 attached to a boss portion 4b.

The flywheel blades 5, 5, . . . can also be attached so as to integrally protrude from the side surface of the weight portion 4a on the recoil starter 18 side.

The crank pulley 12 is formed into a cylindrical shape with a bottom,
It is fastened and fixed to the concave side end surface of the boss portion 4b of the flywheel 4 with its open end surface 12b facing outward.

On the other hand, the rope pulley 19 is rotatably supported by a shaft member 15 attached to the fan case 6 through a no-coil starter cover 14 coaxially with the engine shaft 2, and its boss portion 11b is connected to the crank pulley. The inner side surface thereof is closely opposed to the open end surface 12 b of the crank pulley 12 so as to overlap slightly with the crank pulley 12 in the axial direction.

The rope pulley 19 and crankboo 1112 are engaged with each other by the dog 17 when the rope pulley rotates in the engine starting direction (direction of arrow A in FIG. 2), so that the engine shaft 2 is rotated together with the crankboo 1112. act.

On the other hand, after the engine has started, the dog 17 is disengaged, only the crank pulley 12 continues to rotate together with the flywheel 4, and the rope pulley 19 is moved in the opposite direction by the return spring 13 to the position before starting (Fig. 2, arrow B). direction).

A combination device X to be installed in the internal combustion engine according to the embodiment of the present invention is disposed between the rope boob 1119 of the recoil starter 18 and the exhaust valve tappet 39 (FIG. 2).

As shown in FIG. 2, the decompression device They are connected by an intermediate member Y having a link 32 and a combined yoke shaft 31, which will be described in detail later.

The decompression shaft 30 is constituted by a rotatably supported straight rod of an appropriate length, and one end 30a of the decompression shaft 30 has an angular sliding surface 38a close to the decompression shaft axis and an angular sliding surface 38a located at an appropriate distance from the axis. A corner protrusion 38 is formed having a circumferential surface 38b separated by a distance.

The combined shaft 30 is disposed such that a corner sliding surface 38a of one end 30a thereof is closely opposed to the lower surface of the tappet 39 at the lowest position.

Therefore, by rotating the decompression shaft 30, the corner sliding protrusion 3 is removed.
When the circumferential surface 38b of the exhaust valve 8 is opposed to the lower surface of the tappet 39, the tappet 39 can be lifted upward by the circumferential surface 38b and the exhaust valve can be maintained in the open state, that is, in the valve operating state. When the corner sliding surface 38a of the corner sliding protrusion is opposed to the lower surface of the tappet 39, the locking action on the exhaust valve is released.

On the other hand, a lever member 5 is attached to the other end 30b of the decompression shaft 30.
0 is fixed.

This lever member 50 is always biased by a return spring 51 so as to rotate in the direction of arrow H (the direction in which the lever is released).

Note that this combination shaft 30 is designed to maintain its rotational position during decompression by the frictional force between the lower surface of the tappet 39 and the circumferential surface of the square sliding protrusion 38b, so that the frictional force between the two is released. When the decompression shaft 30 is rotated in the direction of arrow H by the spring force of the return spring 51, the decompression shaft 30 returns to the decompression release position. do.

Next, the detailed structure and function of the guide groove 41 will be explained with reference to FIGS. 2 to 4. In the following explanation,
When the recoil starter 18 starts the engine, the rope pulley 19 and decompletion reel 40, which rotate based on the bowing operation of the starter rope 36 (Fig. 2), are rotated in the forward direction or in the direction of rotation (arrow A in Fig. 2).
direction) is called the forward rotation direction, and the rope pulley 19 is rotated in the opposite rotation direction, that is, in the direction in which the starter rope 36 is wound.
and when the rotation of the decomp reel 40 is reverse rotation, and the direction of rotation (the direction of arrow B in FIG. 2) is the reverse rotation direction.

Also, when the decomp reel 40 rotates in the forward direction, the apparent travel of the actuator 33 relative to the decomp reel guide groove 41 is referred to as forward travel, and its travel direction (arrow A' in FIGS. 3 and 4). The direction) is called the forward running direction, and the opposite direction, that is, the apparent running of the actuator 33 relative to the decomp reel guide groove 41 when the decomp reel 40 rotates in the reverse direction is called the reverse running direction. (The direction of arrow B' in FIGS. 3 and 4) is called the reverse running direction.

The structure and function of the decompression reel guide groove 41 will be explained below according to the above definition. FIG. 3 shows a developed view of the decompression reel guide groove 41.

In FIG. 3, the large black arrow indicates the (apparent) normal running locus of the actuator 33 with respect to the guide groove 41, and the thick arrow indicates the guide groove 41.
The (apparent) reverse travel locus of the actuator 33 with respect to FIG.

In addition, in Fig. 3, the white groove part is a low-bottom groove part with a low groove bottom, the side diagonal line groove part is a high-bottom groove part with a high groove bottom, and the one-sided diagonal line groove part is formed between a low-bottom groove part and a high-low groove part. The slope grooves are shown respectively.

First, the planar configuration of this guide groove 41 will be explained. As shown in FIGS.
, a second circumferential groove 43 and a third circumferential groove 44 are formed on both sides of the first circumferential groove 42, and the first circumferential groove 42 and second circumferential groove 43 are made to communicate with each other during forward rotation of the decomp reel. The first diagonal groove 45, the second circumferential groove 4 when the comb reel rotates forward.
3 and the third circumferential groove 44 across the first circumferential groove 42, and a third diagonal groove 4 that makes the third circumferential groove 44 and the first circumferential groove 42 communicate with each other during forward rotation of the combination reel.
7.

In this case, the groove lengths of the second circumferential groove 43 and the third circumferential groove 44 and the relative positional relationship between them in the rotational direction are as follows:
is appropriately set between the first oblique groove 45 and the second oblique groove 46 so as to be able to communicate in the first circumferential groove 42 in the forward running direction of the actuator.

Next, the cross-sectional structure of the guide groove 41 is shown in FIGS. 3 and 4A.
To explain with reference to B and C, when the recoil starter is not operated, the actuator 33 is located at a position a between the first diagonal groove 45 and the second diagonal groove 46 within the first circumferential groove 42 of the decomp reel 40. The decomp reel 40 is positioned.

In this case, the position a becomes the starting position when the actuator 33 apparently moves relative to the guide groove 41, and
2 is a low-degree groove portion 42a starting from this start position a and moving forward in the normal running direction (arrow A') of the actuator 33.
, one side wall 42h (upright wall) of the first oblique groove 45, a high bottom groove part 42k, a slope groove part 4 that slopes downward toward the front.
2e, a low bottom groove 42d, one side wall 42f (upright wall) of the second oblique groove 46, a slope groove 42b that slopes downward toward the front of the high bottom groove 42C1, and has a shape that returns to the starting position a. It becomes.

The second circumferential groove 43 is a low-bottom groove portion 43 that is continuous with the first oblique groove 45.
Following a, an upwardly sloping slope groove 4 is sequentially located in front of it.
3 b, high bottom groove portion 43 C1 has one side wall 43 d (upright wall) of the second oblique groove 46 , a non-grooved portion 43 e, a low bottom groove portion 43 f and a non-grooved portion 43 g, and returns to the first oblique groove 45 It has a shape.

The third circumferential groove 44 is a low-bottom groove portion 44 that is continuous with the second oblique groove 46.
Continuing from a, there is an up-sloping slope groove 44 b continuing to the third diagonal groove 47 in front of the third diagonal groove 47 , a high-bottomed groove portion 44 which becomes the main part of the third diagonal groove 47 , and C1 one side wall 44 d of the third diagonal groove 47 (an upright wall). ), non-groove portion 44 e, low bottom groove portion 44 f, non-groove portion 44
g, and has a shape that returns to the low bottom groove portion 44a.

The boundary between the high bottom groove part 43C of the second circumferential groove 43 and the low bottom groove part 42d of the first circumferential groove 42 is an upright wall 42m, and the third oblique groove 47 and the low bottom groove part of the first circumferential groove 42 The boundary with 42 d is also an upright wall 42 n.

Note that the low-bottom groove portion 43 f of the second circumferential groove 43 and the low-bottom groove portion 44 f of the third circumferential groove 44 have no guiding function for the actuator 33 and are simply formed for rotational balance of the combination reel 40. .

Next, the movement path of the actuator 33 within this guide groove 41 will be explained based on FIGS. 2 to 4.
3 is appropriately set relative to the decomp reel 40 so that it is always at the start position a in the first circumferential groove 42 at the center when the recoil starter 18 is not activated.

In this state, the starter rope 3 of the coil starter 18
6 and rotate the lobe pulley knob 40 in the forward rotation direction (direction of arrow A).

When the decomp reel 40 rotates in the normal direction, the actuator 33 moves (apparently) within the guide groove 41 in the normal running direction shown by arrow A' in FIGS. 3 and 4.

The actuator 33 rotates during one rotation of the decomp reel 40.
From the start position a of the circumferential groove 42, it enters the second circumferential groove 43 via the first oblique groove 45, and further reaches the low bottom groove portion 44a of the third circumferential groove 44 via the second oblique groove 46.

At this time, the actuator 33 is attached to the vertical side wall 42 h of the first oblique groove 45
It moves from the first circumferential groove 42 into the second circumferential groove 43 while passing through the second oblique groove 46 and falls from the high bottom groove 43C to the low bottom groove 46a at the upright wall 42m.

When the decomp reel 40 rotates one more time, the actuator 33
is from the position d of the low bottom groove part 44a of the third circumferential groove 44 to the third
It enters the low-bottom groove portion 42 d of the first circumferential groove 42 via the oblique groove 47 and returns to the position d of the third circumferential groove 44 via the low-bottom groove portion 46 a of the second circumferential groove 46 (this The travel path of the actuator 33 during the second rotation is hereinafter referred to as the circulation path X).

After this, no matter how many times the decomp reel 40 is rotated, the actuator 33 always circulates within the circulation path X and does not move into other paths.

At this time, when the actuator 33 passes through the third oblique groove 47, the actuator 33
At point 2n, it falls from the high-bottom groove 44C to the low-bottom groove 42d of the first circumferential groove 42, and is guided by the vertical side wall 42f of the second diagonal groove to fall from the first circumferential groove 42 to the third circumferential groove 44.
move within.

That is, the actuator 33 moves from the first circumferential groove 42 to the second circumferential groove 43 only once during the recoil starter starting operation, and thereafter circulates along the circulation path X.

On the other hand, when the decomp reel 40 is reversely rotated in the direction of arrow B with the return rotation of the recoil starter 18, the actuator 33 moves inside the guide groove 41 in the direction shown by arrow B' in FIGS. 3 and 4. Drive in the opposite direction (apparently).

In this case, the actuator 33 is guided by the vertical side wall 46b of the second diagonal groove 46 when it is in the third circumferential groove 44, and by the vertical side wall 46b of the second diagonal groove 46 when it is in the first circumferential groove 42. It reaches directly into the low bottom groove part 42d of the first circumferential groove 42, and further extends into the first circumferential groove 42.
It passes through the slope groove part 42 e and the high bottom groove part 42 k of the circumferential groove 42 to reach the start position a in the first circumferential groove 42 .

When the decomp reel 40 further rotates in the reverse direction in the direction of arrow B from the state in which the actuator 33 has returned to the starting position a, the actuator 33 circulates within the first circumferential groove 42 formed in a straight line, and finally When the decomp reel 40 stops, it returns to the starting position a.

Note that when the decomp reel 40 rotates in reverse, the rotation speed of the decomp reel 40 becomes faster than when it rotates forward (starting rotation), so the ability of the actuator 33 to follow the guide groove 41 deteriorates. In the device, the influence of the running resistance of the actuator 33 on the guide groove 41 is minimized by making the actuator 33 run in the linear first circumferential groove 42 with the least running resistance during return rotation. We are trying to suppress it and improve its followability.

This combination reel 40 is fixed to the inner side surface 19a of the rope pulley 19 of the recoil starter 18, and the inner end side 40a of the combination reel 40 is inserted into the recessed portion 4C of the flywheel.

Therefore, the combination reel 40, the flywheel 4, and the crank pulley 12 are triple-coupled with each other in the axial direction.

The intermediate member Y is the lever member 50 of the combined shaft 30.
The link 32, which has one end hooked thereto, and the combined yoke shaft 31, in which the actuator 33 formed at one end of the link 32 is slidably fitted in the guide groove 41 of the decompression reel 40, are engaged with each other in an elongated hole. It is configured.

The decompression yoke shaft 31 is composed of a straight rod supported rotatably and slidably, and a short shaft-shaped actuator 33 is fixed to one end 31 a of the decompression yoke shaft 31 via an eccentric lever 53.
A substantially fan-shaped decompression yoke lever 34 having an arcuate elongated hole 35 is fixed to the other end 31b.

This combination yoke shaft 31 has its eccentric actuator 33 slidably fitted into the guide groove 41 of the combination reel 40, and the other end 32b of the link 32 is fitted into the elongated hole 35 of the decompression yoke lever 34. I'm putting it on.

At this time, the combination yoke shaft 31 is urged toward the guide groove 41 of the decomp reel 40 by the compression spring 52 fitted into the intermediate portion thereof.

Therefore, when the decombination reel 40 is rotated, the eccentric actuator 33 is guided by its guide groove 41 and rotates in the direction of arrow C-D, and accordingly, the decombination yoke shaft 31 also rotates in the direction of arrow C-D.
It will rotate in the D direction.

At this time, only when the combination yoke shaft 31 rotates in the direction of arrow C, one end 35a of the elongated hole 35 of the combination yoke lever 34 and the end 32b of the link 32 engage,
The decompression shaft 30 can be rotated in the direction of arrow G.

Next, to explain the operation of the internal combustion engine decompression device of the illustrated embodiment, when starting the internal combustion engine, first, the starter rope 36 of the recoil starter 18 is pulled out forcefully and the decompression reel 40 is rotated together with the engine shaft 2 in the direction of arrow A. .

When the tee comp reel 40 rotates, the decompression yoke shaft 31 is guided by the guide groove 41 of the tee comp reel 40 and first rotates in the direction of arrow C, and then rotates the decompression shaft 30 in the direction of arrow G via the link 32 to complete the decompression. Set the shaft 30 to the hinge position.

Therefore, in this state, since the exhaust valve is held open, the working chamber of the internal combustion engine is in a non-compressed state, and the engine shaft 2 can be easily rotated.

When the starter rope 36 is further pulled out from this state, the decompression yota shaft 31 is guided by the guide groove 41 and rotates in the direction of the arrow, returning to the predetermined position before starting.
The combination shaft 30 is held in a rotating state by the frictional force between the circumferential surface 38b of the protrusion 38 and the lower surface of the tappet 39, and the tappet 39 is held on the cam shaft (not shown).
When it is further lifted upward by the valve operating cam, it is returned to the direction of arrow H, that is, to the decompression release position, by the spring force of the return spring 51.

When the decompression shaft 30 is returned to the decompression release position, the working chamber becomes compressed and the engine starts.

After pulling out the starter lobe 36 and starting the engine, the tensile force of the starter rope 36 is released and the recoil starter 18 and decomp reel 40 are pulled out from the return spring 5.
The spring force of step 1 restores the state to the state before the starting operation.

This completes the engine starting operation.

In the illustrated embodiment, the decompression device Since the weight portion 4a and the circumferential wall 12a of the crank pulley 12 are overlapped three times in the direction of the engine axis, only the overlapping bones! The length of the coil starter mounting portion in the engine axis direction can be shortened.

As is clear from the above description, the decompression device for an internal combustion engine of the present invention consists of a drum-shaped Tekon reel for decompressing at the time of starting, a weight portion of a flywheel attached to one end of the engine shaft, and a weight portion of the flywheel attached to one end of the engine shaft. Since the crank pulley attached to the boss part of the engine is overlapped three times in the engine axial direction, the length of the internal combustion engine in the engine axial direction is shortened, making it possible to reduce the size and weight of an internal combustion engine equipped with such a combination device. This has the effect that it can be promoted.

[Brief explanation of the drawing]

FIG. 1 is a front view of an internal combustion engine with a combination device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of essential parts of the combination device shown in FIG. 1, and FIG. 3 is a guide for the decomp reel shown in FIG. 2. Developed view of the groove, Figure 4A. B and C are the A-A cross section and BB in Fig. 3, respectively.
It is a cross section and a CC sectional view. 2... Engine shaft, 2a... End of engine shaft, 4... Flywheel, 4a... Weight part of flywheel, 12... Crank pulley, 18... Recoil starter, 19... ... Rope pulley, 30... Tie combination shaft, 33... Actuator, 40... Tie combination reel,
41... Guide groove, Y... Intermediate member.

Claims (1)

[Scope of utility model registration request] A decompression shaft 30 that operates between two positions, a decompression position where the intake valve or the exhaust valve is held in an open state and a decompression release position where the decompression action is released, and a guide groove 41 of an appropriately shaped shape on the outer peripheral surface of the decompression shaft 30. A cylindrical decomp reel 40 that is coaxially attached to the inner surface of one of the rope pulleys of the recoil starter 18 and rotates in conjunction with the rope pulley 19 is guided by the guide groove 41 and is caused to move in conjunction with the actuator 33. One end 2 of the engine shaft 2 is connected via a suitable intermediate member Y that acts to transmit the decompression shaft 30 to the decompression shaft 30 from the decompression release position to the decompression position.
A flywheel 4 having a dish-shaped concave portion 4C on its outer surface and an annular weight portion 4a formed on its outer periphery is attached to the flywheel 4, and the crank pulley 12 of the recoil starter 18 is attached to the boss portion 4b of the flywheel 4. At the same time, insert the inner end 40a of the combination reel 40 between the weight portion 4a of the flywheel 4 and the crank pulley 12, and align the combination reel 40, flywheel 4, and crank pulley 12 with each other. An internal combustion engine with a decompression device characterized by a triple combination in the direction of the decompression device.