JPS6038010Y2 - Internal combustion engine decompression device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a decompression device used to make the combustion chamber in an uncompressed state when starting an internal combustion engine to facilitate rotation at the time of starting. and transmits the displacement of an actuator guided by and interlocked with the guide groove of the decomp reel rotating in conjunction with the rope pulley of the recoil starter to the decompression shaft to direct the decompression shaft from the decompression release position to the decompression position. This invention relates to a joint structure between the rope pulley and the decomp reel in a decompression device with a novel structure that is operated, and the decomp reel is integrally attached to the inner surface of the rope pulley and the boss of the rope pulley is used as the boss of the decomp reel. The purpose of this invention is to provide a decompression device for an internal combustion engine that can be used in common to ensure a reliable decompression effect at the time of startup and to promote downsizing and weight reduction of the internal combustion engine. It is.

Hereinafter, the decompression device for an internal combustion engine of the present invention will be explained based on the embodiment shown in Figs. 1 and 2. Fig. 1 shows a vertical water-cooled diesel engine having the decompression device according to the embodiment of the present invention. It is shown.

In FIG. 1, reference numeral 1 is the engine body, 2 is the engine shaft, 3 is the piston, 4 is the flywheel fixed to one end 2a of the engine shaft 2, and 5 is fastened to the side surface of the flywheel 4 on the side of the engine main body 1. A fixed cooling fan blade 6, a fan case disposed on the side of the engine body 1 so as to surround the outside of the flywheel 4 and the blades 5, 5...
Reference numeral 7 indicates a radiator device disposed within the fan case 6 above the flywheel 4.

Further, reference numeral 18 is a coil starter installed between the engine shaft 2 and the fan case 6 so as to be able to engage with the engine shaft 2 freely, and a rope pulley 19 installed on the outer wall of the fan case 6. and a bottomed cylindrical crank pulley 12 which is fastened to the boss end face 4a on the outer surface side of the flywheel 4.

The rope pulley 19 and the crank pulley 12 are engaged with each other by the dog 17 when the rope pulley 19 rotates in the engine starting direction (in the direction of arrow A in FIG. 2), so that the engine shaft 2 is rotated together with the crank boot 1J12. 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 returned to its pre-start position by the return spring 13 in the opposite direction (in the direction of arrow B in Fig. 2). ) is rotated back.

The rope pulley 19 is rotatably supported by a shaft member 15 fixed to the axial center of the recoil starter cover 14.

A decompression device X according to an embodiment of the present invention is disposed between the rope pulley 19 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 consisting of a link 32 and a decompression yoke shaft 31, which will be described in detail later.

The decompression shaft 30 is constituted by a rotatably supported straight bar body of an appropriate length, and has an angular sliding surface 38b formed by flattening the peripheral surface 38b of the decompression shaft at one end 30a side.
A corner protrusion 38 is formed.

This decompression shaft 30 has a corner sliding surface 3 on its one end 30a side.
The tappet 8a is disposed so as to closely face the lower surface of the tappet 39 at the lowest position.

In this case, when the decompression shaft 30 is rotated so that the circumferential surface 38b of the square projection 38 faces the lower surface of the tappet 39, the tappet 39 is lifted upward by the circumferential surface 38b, and the exhaust valve remains open. That is, the exhaust valve can be maintained in a decompressing state, and when the corner sliding surface 38a of the corner sliding protrusion is opposed to the lower surface of the tappet 39, the decompressing action on the exhaust valve is released.

On the other hand, there is a lever member 3 on the other end 30b side of the decompression shaft 30.
7 is fixed.

This lever member 37 is always biased by the return spring 22 so as to rotate in the direction of arrow H (decompression release direction).

Note that this decompression 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. That is, when the tappet 39 moves upward during the engine starting operation and the tappet 39 and the corner sliding projection circumferential surface 38b are separated from each other, the decompression shaft 30 is moved in the direction of arrow H by the spring force of the return spring 41. It is rotated to return to the decompression release position.

The decomp reel 40 is a drum-shaped member having a guide groove 41 of an appropriate depth formed on its outer peripheral surface, and is fixed to the side surface of the rope pulley 19 coaxially with the rope pulley 19.

This guide groove 41 has an actuator (in the illustrated embodiment, an eccentric actuator of the decompression yoke shaft 31, which will be described later, reference numeral 33 in FIG. 2) that is slidably fitted into the guide groove 41.
As the decomp reel 40 rotates, the decomp reel 4
This is for rotating the decompression shaft 30 by displacing it in the axial direction of the decompression reel, and three circumferential grooves 42, 43, and 44 are arranged in parallel in the axial direction of the decompression reel so that they can communicate with each other. It is configured.

Next, the detailed structure and function of the guide groove 41 will be explained with reference to FIGS. 3 and 4. In the following explanation,
When the recoil starter 18 starts the engine, the rope pulley 19 and decompletion reel 40 rotate in the forward direction (in the direction of arrow A in FIG. 2), which rotate based on the pull-out operation of the starter rope 36 (FIG. 2). is referred to as a forward rotation direction, and the opposite rotation direction, that is, the rotation of the rope pulley 19 and decomp reel 40 in the direction of winding the starter rope 36, is called a reverse rotation, and the rotation direction (direction of arrow B in FIG. 2) is called a reverse rotation direction. This is called the direction of rotation.

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 normal 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. (In Figures 3 and 4, the force direction of arrow B' is referred to as the reverse running direction.

The structure and function of the decomp reel guide groove 41 will be explained below according to the above definition. FIG. 3 shows a developed view of the decomp 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 trajectory of the actuator 33 with respect to FIG.

In addition, in Figure 3, the white groove part is a low bottom groove part with a low groove bottom, the double diagonal line groove part is a high bottom groove part with a high groove bottom, and the single diagonal line part is formed between a low bottom groove part and a high and 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. 2 and 3, this guide groove 41 is a first circumferential groove 42 formed at the axial center position of the decomp reel 40.
, 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 oblique groove 45, the second circumferential groove 43 when the decomp reel rotates forward
and the first circumferential groove 42, and a second oblique groove 46 that communicates the first circumferential groove 42 across the first circumferential groove 42;
It has a third oblique groove 47 that allows the circumferential groove 44 and the first circumferential groove 42 to communicate with each other.

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 $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 in the first circumferential groove 4 of the decomp reel 40.
The decomp reel 40 is positioned at a position a between the first diagonal groove 45 and the second diagonal groove 46 within the decompression reel 2 .

In this case, the position a becomes the starting position when the actuator 33 apparently moves relative to the guide groove 41, and
2, this start position a is the starting point, and the low bottom groove portion 42a1 is sequentially moved forward in the forward running direction (arrow A') of the actuator 33.
One side wall 42h (upright wall) of the first oblique groove 45, a high bottom groove 42k, and a slope groove 42 that slopes downward toward the front.
e1 low bottom groove portion 42d1 one side wall 42f of second oblique groove 46
(Upright wall), has a slope groove portion 42b that slopes downward toward the front of the high-bottomed groove portion 42c1, and is shaped to return to the starting position a.

The second circumferential groove 43 is a low bottom groove portion 43a that is continuous with the first oblique groove 45.
Following this, an upwardly sloping slope groove 43 is sequentially located in front of it.
b1 high bottom groove part 43c, one side wall 43d of the second oblique groove 46
(upright wall), a non-grooved portion 43e1, a low bottom load portion 43f, and a non-grooved portion 43g, and is shaped to return to the first diagonal groove 45.

The third circumferential groove 44 is a low bottom groove portion 44a that is continuous with the second oblique groove 46.
Next, in front of the third diagonal groove 47 is an upwardly inclined slope groove 44b, and a high bottom groove 4 which is the main part of the third diagonal groove 47.
4c, one side wall 44d (upright wall) of the third oblique groove 47, a non-grooved portion 44e, a low bottom groove portion 44f, and a non-grooved portion 44g, 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. The boundary is also an upright wall 42n.

Note that the low-bottom groove portion 43f of the second circumferential groove 43 and the low-bottom groove portion 44f of the third circumferential groove 44 do not have a guiding function for the actuator 33, and are simply formed to balance the rotation of the decomp 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 decomp reel 40 together with the rope pulley 19 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 guided by the vertical side wall 42h of the first circumferential groove 45 and moves from the first circumferential groove 42 into the second circumferential groove 443, and when passing through the second oblique groove 46, it is raised at the vertical wall 42m. It falls from the bottom groove part 43c to the low bottom groove part 46a.

When the decomp reel 40 rotates one more time, the actuator 33
enters the low bottom groove 42d of the first circumferential groove 42 from position d of the low bottom groove 44a of the third circumferential groove 44 via the third oblique groove 47,
Furthermore, it returns to the position d of the third circumferential groove 44 via the low-bottom groove portion 46a of the second oblique groove 46 (the travel path of the actuator 33 in the second rotation is hereinafter referred to as a 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
2n, it falls from the high bottom groove part 44c to the low bottom groove part 42d of the first circumferential groove 42, and the vertical side wall 4 of the second oblique groove
2f and moves from the first circumferential groove 42 into the third circumferential groove 44.

That is, the actuator 33 moves from the first circumferential groove 42 to the second circumferential groove 44 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, when the actuator 33 is in the third circumferential groove 44, it is guided by the vertical side wall 46b of the second oblique groove 46,
In addition, when it is in the first circumferential groove 42, it directly reaches the low bottom groove part 42d of the first circumferential groove 42, and furthermore, the first circumferential groove 42
The first groove passes through the second slope groove 42e and the high bottom groove 42k.
The starting position a in the circumferential groove 42 is reached.

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.

Note that this decompression reel 40 is not limited to the method of forming it as a single item and then integrally fixing it to the side of the rope pulley 19 as in the illustrated embodiment. The reel 40 and rope pulley 19 may be integrally formed.

The intermediate member Y includes a link 32 whose one end is hooked to the lever member 37 of the decompression shaft 30 and the decompression reel 4.
The decompression yoke shaft 31 has an actuator 33 formed at one end thereof slidably fitted in a guide groove 41 of 0, and the decompression yoke shaft 31 is engaged with the decompression yoke shaft 31 in a long manner.

The decompression yoke shaft 31 is configured as a straight rod that is rotatably and slidably supported on a bearing portion 29 formed in the fan case 6, and an eccentric lever 24 is attached to one end 31a of the straight rod.
While fixing the short shaft-like actuator 33 through the other end 31
A substantially fan-shaped decompression yoke lever 34 having an arcuate elongated hole 35 is fixed to b.

This decompression yoke shaft 31 has its eccentric actuator 33 slidably fitted into the guide groove 41 of the decompression reel 40, and the elongated hole 3 of the decompression yoke lever 34.
The other end 32b of the link 32 is inserted into the inside of the link 32.

At this time, the decompression yoke shaft 31 is urged toward the guide groove 41 of the decompression reel 40 by the compression spring 23 fitted into the intermediate portion thereof.

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

At this time, only when the decompression yoke shaft 31 rotates in the direction of arrow C, one end 3 of the elongated hole 35 of the decompression yoke lever 34
5a and the end portion 32b of the link 32 are engaged with each other, so that the decompression shaft 30 can be rotated in the direction of arrow G.

Note that these decompression yoke lever 34, link 32, and decompression shaft lever member 37 that constitute the intermediate member Y
is located outside the engine body 1, in other words, the decompression shaft 30
is connected to an intermediate member Y provided around the outside of the engine body 1.

Next, the operation of the internal combustion engine decompression device of the illustrated embodiment will be explained. When starting the internal combustion engine, first, the starter loaf 19 of the recoil starter 10 is pulled out vigorously and the decompression reel 4 is rotated together with the engine shaft 2 in the direction of arrow A. let

When the decomp reel 40 rotates, the decomp reel 40
The decompression yoke shaft 31 first rotates in the direction of arrow C while being guided by the guide groove 41 of the decompression yoke shaft 31 through the link 32.
0 in the direction of arrow G to set the decompression shaft 30 to the decompression 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 yoke shaft 31 is guided by the guide groove 41 and rotates in the direction of the arrow, returning to the predetermined position before the starting operation. It is held in a rotating state by the frictional force between the circumferential surface 38b of the tappet 38 and the lower surface of the tappet 39, and is returned only when the tappet 39 is further lifted upward by the valve drive cam of the camshaft (not shown). The spring force of the spring 22 returns the decompression release position in the direction of arrow H.

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 rope 36 to start the engine, the tensile force of the starter rope 36 is released and the recoil starter 18 and decomp reel 40 are returned to the state before the starting operation by the spring force of the return spring 22.

This completes the engine starting operation.

Further, the decompression device X of the illustrated embodiment includes a rope pulley 19.
A cylindrical decomp reel 40 is coaxially and integrally attached to the side of the decomp reel 4 to connect the boss of the lob pulley 19 to the decomp reel 4.
Since the decomp reel 40 can be used in common as a boss of 0, there is no need to provide a separate boss on the decomp reel 40, and the length in the engine axial direction can be reduced accordingly.

In addition, since the decomp reel 40 is integrally fixed to the rope pulley I) 19, the decomp reel 40 rotates together with the rope pulley 19 when the recoil starter 18 is started, thereby ensuring the decompression effect at the time of start. be able to.

Furthermore, when the recoil starter 18 is not operated, the free rotation of the decomp reel 40 is restricted along with the rope pulley 19 by the spring force of the return spring 13, so the decomp reel 40 is prevented from freely rotating due to vibration or the like during engine operation. There is no possibility that the decompression effect will be performed inadvertently.

As is clear from the above description, the decompression device for an internal combustion engine of the present invention includes a cylindrical decompression reel that is integrally attached to the side of the rope pulley of the recoil starter so that the boss of the rope pulley is shared as the boss of the decompression reel. As a result, the length of the decomp reel in the engine axial direction can be reduced by the dedicated boss forming portion, thereby promoting miniaturization and weight reduction of the internal combustion engine.

In addition, since the decompression reel is integrally attached to the rope pulley of the recoil starter, the decompression reel can be reliably rotated to perform the decompression action during starting operations using the recoil starter, improving the starting performance of the internal combustion engine. It has practical effects such as:

Furthermore, according to the present invention, the actuator is pivotally supported by the fan case, and the intermediate member Y that transmits the displacement of the actuator to the decompression shaft bypasses the outside of the engine body and is connected to the decompression shaft. There is no need to make any special modifications to the engine itself, and it has the advantage of being able to be applied to engines with conventional structures as is.

[Brief explanation of the drawing]

FIG. 1 is a front view of an internal combustion engine having a decompression device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of essential parts of the decompression device shown in FIG. 1, and FIG. 3 is a decompression reel shown in FIG. 2. Developed view of the guide groove, Figure 4 A, B, and C are respectively 3rd
They are an AA cross section, a B-B cross section, and a CC cross-sectional view in the figure. 19... Rope pulley, 30... Decompression shaft, 33... Operator, 40... Decompression 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 device that holds an intake valve or an exhaust valve in an open state and a decompression release position that releases the decompression action, and a guide groove 41 of an appropriately shaped shape on its outer peripheral surface. A cylindrical decompression reel 40 that has a cylindrical decompression reel 40 and rotates in conjunction with the rope pulley 19 of the recoil starter transmits the displacement of the actuator 33 guided by the guide groove 41 and moved to the decompression shaft 30. This is a decompression device for an internal combustion engine, in which the decompression reel 40 is connected to the inside of the rope pulley 19 of the recoil starter, and the decompression reel 40 is connected to the inside of the rope pulley 19 of the recoil starter. The actuator 3 is integrally attached to the side surface and coaxially with the rope pulley 19.
3, the intermediate member Y, which is pivotally supported by a fan case 6 that covers the outside of the engine cooling fan 5 and transmits the displacement of the actuator 33 to the decompression shaft 30, bypasses the outside of the engine body 1 and A decompression device for an internal combustion engine, characterized in that it is connected to a decompression shaft 30.