JPH0151889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compression device for a pre-combustion chamber in an internal combustion engine, and more particularly to a compression device in which a compression piston disposed in the pre-combustion chamber is driven by a cam.

The applicant of the present application previously provided an internal combustion engine equipped with a pre-combustion chamber (Japanese Patent Application No. 37950/1983). This internal combustion engine is equipped with a pre-combustion chamber that communicates with the main combustion chamber, and the homogeneous air-fuel mixture that is sucked into the main combustion chamber and further flows into the pre-combustion chamber is independently compressed by a compression piston installed in the pre-combustion chamber. The combustion gas is compressed and combusted there, and the combustion pressure in the pre-combustion chamber is used to inject the combustion gas in the pre-combustion chamber into the main combustion chamber, thereby combusting the homogeneous air-fuel mixture in the main combustion chamber.

The present invention provides a novel pre-combustion chamber compression device for such an internal combustion engine.

An embodiment in which the present invention is applied to a two-stroke engine will be described below with reference to the drawings. FIG. 1 shows the cylinder head portion of an engine, in which 1 is a cylinder and 9 is a piston. The upper end opening 1a of the cylinder 1 is hermetically closed by a head 3 attached to the upper end of the cylinder 1 with bolts 2. The head 3 has a bottom wall 3a extending horizontally and a side wall 3b extending vertically.
A compression device 4 is disposed at. The upper end opening 3c of the head 3 is hermetically closed by a cover 7 attached with screws 6 with a gasket 5 in between, thereby forming an airtight chamber 8 inside the head 3.
A predetermined amount of lubricating oil (not shown) is stored inside the head 3, and the amount of this lubricating oil can be checked using an oil level gauge 10. Further, a blind bolt 11 is screwed into the bottom wall portion 3a of the head, so that the lubricating oil can be replaced as necessary.

The compression device 4 mainly includes a cylinder block 12, a compression piston 13, a cam 14, and a tappet 1.
5 and a combustion adjustment valve 16. The cylinder block 12 is disposed directly above the cylinder 1 and is fixed to the bottom wall 3a of the head 3 with bolts 17. A cylinder hole 18 and a valve hole 19 are bored horizontally in the cylinder block 12 on the same axis as each other, and these cylinder holes 18 and valve hole 19 communicate with each other through a nozzle hole 52. An intake passage 20 and an ejection passage 21 communicate with a main combustion chamber 22 within the cylinder 1, respectively. The intake port 23 formed in the head bottom wall 3a is preferably located in a relatively high temperature part of the combustion chamber 22, thereby facilitating warm-up operation at low temperatures. Further, the position of the jet nozzle 24 formed in the head bottom wall portion 3a is preferably located at the center of the combustion chamber 22, so that the combustion chamber 22
It is possible to average the flame propagation time within 2. In FIG. 1, reference numerals 25 and 26 are gaskets fitted to the joints of the intake port 23 and the jet port 24, respectively.

A compression piston 13 is slidably and rotatably inserted into the cylinder hole 18 as shown in FIG. is formed. More specifically, as shown in FIG. 2, the compression piston 13 includes a hollow piston body 29 having a dish portion 28 formed at one end, and a cap-shaped piston head 3 screwed onto the outer periphery of the other end of the piston body 29.
Consists of 0. A guide 31 is rotatably fitted to the outer periphery of one end of the piston body 29, and a thrust bearing 32 is fitted between the guide 31 and the plate portion 28.

The guide 31 has a cylindrical portion 31a extending toward the piston head 22 and a ring-shaped bearing holding portion 31b.
It is slidably inserted into the outer periphery of 2a. Further, one side plate 32a of the thrust bearing 32 is fitted into the inner periphery of the bearing holding portion 31b.

In FIG. 2, 33 is a large oil hole formed along the axial direction in the piston body 29, and 34 is a plurality of small oil holes also formed along the radial direction. Reference numeral 35 denotes a plurality of first passages which are diagonally perforated from the vicinity of the entrance part 33a of the large oil hole 33 toward the surface of the dish part 28. This is for introducing lubricating oil. Further, 36 and 37 are second passages passing through the piston body 29 and the guide 31 in the radial direction, and 38 is a passage from the second passage 37 to the cylindrical portion
A third passage extending along the inside of 1a,
These second passages 37 and third passages 38 are connected to the cylindrical portion 3.
It is configured to function as a supply passage for lubricating oil to the inner circumferential surface of 1a, and to function as a vent to the inner space of the cylindrical portion 31a when the cylindrical portion 31a slides. Further, 39 and 40 are piston rings.

A spring receiving ring 44 is fitted and fixed to the base end of the cylindrical portion 12a of the cylinder block 12, as shown in FIG. And this spring retainer ring 4
A compression spring 45 is disposed between the piston 4 and the guide 31 of the compression piston 13, and the piston 13 is constantly urged in the direction of arrow a in FIG. On the other hand, a tappet 15 is disposed between the plate portion 28 of the compression piston 13 and the cam 14. This tapepet 15 consists of a shaft portion 15a and a dish portion 15b formed at one end of this shaft portion 15a. is slidably and rotatably inserted into the and,
The tip of the shaft portion 15a is connected to the plate portion 28 of the compression piston 13.
The plate portion 15b of the tappet 15 is in contact with the cam 14.
It is in contact with the outer peripheral surface of.

The cam 14 has a fan shape and is fixed to a cam shaft 51 disposed in the horizontal direction (in the front-rear direction in FIG. 1). This camshaft 51 is connected to the crankshaft of the engine via a transmission means such as a gear (not shown), and is configured so that when the crankshaft rotates once, the camshaft 51 also rotates once in conjunction with this. There is. The center line _L1 of the cam 14 is arranged slightly offset from the center line _L2 of the tappet 15 as shown in FIG. Therefore, the tappet 15 rotates little by little, and this rotation causes the compression piston 13 to rotate as well, thereby preventing the compression piston 13 from seizing.

The pre-combustion chamber 27 in the cylinder hole 18 is shown in FIG.
As shown in FIGS. 4 and 5, the nozzle hole 52 communicates with the tip of the valve hole 19. A combustion regulating valve 16 biased in the direction of arrow B by a spring 53 is slidably inserted into this valve hole 19 as shown in FIG. is closed by the tip of the However, in the middle part of the combustion adjustment valve 16,
As shown in the figure, a flange-shaped stopper part 54 is formed, and when this stopper part 54 comes into contact with the side wall 12b of the cylinder block 12, a fifth stopper part 54 is formed between the tip of the combustion regulating valve 16 and the nozzle hole 52. As shown in the figure, the structure is such that a slight gap A remains. This gap A is to prevent the nozzle hole 52 from being clogged with carbon or the like, but it is preferably set to a gap of 0.01 mm or less to prevent a pressure drop in the pre-combustion chamber 27 during compression. The outer circumferential surface 55 on the exit side of the nozzle hole 52 has a truncated conical shape as shown in FIG. The air-fuel mixture in the pre-combustion chamber 27 during compression is configured to be difficult to leak into the jet passage 21.

As shown in FIG.
It is housed in a cylindrical case 59 attached to. An insertion hole 60 through which the combustion adjustment valve 16 is inserted is formed at one end of the cylindrical case 59, and a tensioning bolt 6 for directing one end of the spring 53 is formed at the other end.
1 are screwed together. And this adjustment bolt 61
By adjusting the rotation of the spring 53, the setting force of the spring 53 can be adjusted. A fixing nut 62 for preventing loosening is screwed onto the adjustment bolt 61.

A screw hole 63 is formed in the adjustment bolt 61 along its central axis, and a stopper rod 64 is screwed into the screw hole 63. The tip 64a of the stopper rod 64 protrudes into the cylindrical case 59, and when the combustion adjustment valve 16 opens by sliding in the direction of arrow C in FIG. The receiving cap 65 is adapted to abut against the tip end 64a of the stopper rod 64. Therefore, by adjusting the rotation of the stopper rod 64, the maximum gap (indicated by ε in FIG. 4) between the tip of the combustion regulating valve 16 and the nozzle hole 52 can be adjusted.
are becoming regulated. Note that this gap ε
It is best to keep it below 3mm. A fixing nut 66 is screwed onto the stopper rod 64 to prevent it from loosening.

As shown in FIGS. 1 and 4, the combustion regulating valve 16 is formed with a small diameter portion 70 having a predetermined length.
On the other hand, the cylinder block 12 has this small diameter portion 70.
A passage 71 communicating with the outer peripheral gap is formed in the vertical direction, and a blow-by gas conduit 72 is connected to the upper end of this passage 71. This conduit 72 is connected to an intake port of the engine (not shown), so that the air-fuel mixture that has leaked to the small diameter portion 70 through the outer peripheral gap of the combustion adjustment valve 16 is sucked into the cylinder 1 again through the blow-by gas conduit 72. It's getting old.

Further, a blow-by gas plug 73 is attached to the cover 7 of the head 3.
It is also connected to an engine intake hole (not shown). The air-fuel mixture leaking into the airtight chamber 8 through the outer peripheral gap of the compression piston 13 is sucked into the cylinder 1 again through the plug 73. Note that a baffle plate 74 is provided below the plug 73 to prevent lubricating oil droplets from being sucked into the plug 73.

The compression device 4 of the pre-combustion chamber 27 is constructed as described above, and when the cam 14 rotates from the position shown by the chain line to the position shown by the solid line in FIG. The portion 15b is pressed by the cam 14, and the tappet 15 and compression piston 13 move forward in the direction of arrow d against the compression spring 45. Further, when the cam 14 rotates from the position shown by the solid line in FIG. 1 to the position shown by the chain line, the compression piston 13 and the tappet 15
It moves back in the direction of arrow a with the restoring force of. Note that the stroke of the compression piston 13 and the like are set so that the compression ratio of the pre-combustion chamber 27 is greater than the compression ratio of the main combustion chamber 22. The compression piston 13 continuously repeats such reciprocating motion, but since the compression piston 13 is driven by the cam 14 that is linked to the crankshaft, the operation of the compression piston 13 is extremely reliable. It is.

Next, the situation until the homogeneous air-fuel mixture introduced into the main combustion chamber 22 is ignited will be described. First, the compression piston 13 moves forward and its tip 13a is in the first position.
When the position shown by the chain line in the figure is reached, the pressure inside the pre-combustion chamber 27 becomes negative, and the intake passage 20 and the pre-combustion chamber 2
7 are communicated with each other, and a part of the homogeneous air-fuel mixture introduced into the main combustion chamber 22 is sucked into the pre-combustion chamber 27 through the intake port 23 of the head bottom wall 3a and the intake passage 20. Thereafter, as the piston 9 rises, the compression piston 13 moves forward in the direction of the arrow d in FIG. and pre-combustion chamber 27
The homogeneous air-fuel mixture within is independently compressed by the compression piston 13, and spontaneously ignites when the compression piston 13 moves forward to the position shown by the solid line in FIG. Note that until combustion starts in the pre-combustion chamber 27, the nozzle hole 52 is closed to the combustion adjustment valve 1, which is biased by a spring 53.
6, the homogeneous air-fuel mixture during compression will not leak from the nozzle hole 52 to the ejection passage 21.

Next, when combustion starts in the pre-combustion chamber 27, the pressure within the pre-combustion chamber 27 rises rapidly, and this combustion pressure causes the combustion regulating valve 16 to slide against the spring 53 as shown in FIG. Then, the nozzle hole 52 is opened.
At this moment, the flame in the pre-combustion chamber 27 is ejected from the nozzle hole 52, and this flame propagates into the main combustion chamber 22 through the ejection passage 21 and the ejection port 24, and is uniformly mixed in the main combustion chamber 22. Ignite your mind.

When combustion starts in the main combustion chamber 22, the piston 9 descends due to the combustion pressure, the nozzle hole 52 is closed again by the combustion adjustment valve 16, and the compression piston 13 returns in the direction of arrow a in FIG. The operation cycle described above is repeated continuously.

By disposing electric heating type heating plugs 77 and 78 in the intake passage 20 and the jetting passage 21 as shown in FIG. This improves the startability of the engine, especially in cold weather, and prevents the flame propagating through the jet passage 21 from being heated by the heating plug 78 and extinguished midway.

Next, a second embodiment of the present invention will be described based on FIGS. 6 to 9. In this second embodiment, as shown in FIG.
Compared to the first embodiment, the compression spring 45 is not required, and the compression piston 13 can be driven at high speed. It is also an applicable compression device. More specifically, as shown in FIG. 6, one disk 80 that slides on the positive cam 79 is fixed to the dish portion 28 of the compression piston 13 by four bolts 81 and nuts 82 on the upper, lower, left and right sides, and the positive cam 79 The other disc 83 that is in sliding contact with 79 is attached to the other ends of the four bolts 81 with nuts 84. The outer circumferential surfaces of the four bolts 81 are in sliding contact with the outer circumferential surface of the camshaft 51, as shown in FIGS. 6 and 7, and are configured to act as a guide when the compression piston 13 reciprocates. has been done. Note that the threaded portion 81a of the bolt 81 is formed slightly eccentrically with respect to the bolt body 81b as shown in FIG. It is configured so that it can be easily brought into sliding contact with the outer circumferential surface of the shaft 51.

According to the positive cam 79 configured as described above, the relationship between the rotation angle of the camshaft 51 and the stroke of the compression piston 13 is represented by the curve shown in FIG. Even if the number becomes quite high, it is not affected at all. Therefore, it becomes possible to apply the compression device according to the present invention to a high-speed rotation type engine.

According to experiments conducted by the inventors, the most stable operating results were obtained when the compression piston 13 was allowed to move forward by 20 to 40 mm while the camshaft 51 rotated from 60 degrees to 90 degrees. Obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. For example, in the above embodiments, the present invention was applied to a two-stroke gasoline engine, but it goes without saying that it is equally applicable to a four-stroke gasoline engine.

According to the compression device for the pre-combustion chamber according to the present invention, since the combustion adjustment valve is configured to have a slight interval even when closed, the mixture is mixed near the combustion adjustment valve to the extent that the compression efficiency by the compression piston is not reduced. This allows the combustion gas to constantly flow in a small amount without causing it to temporarily stagnate, thereby effectively preventing carbon from adhering to the vicinity of the combustion regulating valve, thereby stabilizing the combustion regulating valve. This makes it possible to ensure clean combustion in this type of internal combustion engine at all times, and to improve the maximum output.

[Brief explanation of drawings]

The drawings show embodiments of the invention,
Figures 1 to 5 show the first embodiment, Figure 1 is a longitudinal sectional view of the cylinder head of the engine, Figure 2 is a longitudinal sectional view of the compression piston, and Figure 3 is a plan view of the cam and tappet. 4 is a vertical sectional view showing the combustion regulating valve and its surroundings, and FIG. 5 is an enlarged sectional view of the tip portion of the combustion regulating valve. 6 to 9 show the second embodiment, in which FIG. 6 is a side view of the positive cam and its surroundings, FIG. 7 is a right side view of FIG. 6, and FIG. 8 is a side view of the positive cam and its surroundings. 9 is a side view of the bolt, and FIG. 9 is a curve diagram showing the relationship between the rotation angle of the camshaft and the stroke of the compression piston. 1... Cylinder, 3... Head, 12... Cylinder block, 13... Compression piston, 14...
Cam, 15... Tappet, 16... Combustion adjustment valve,
18...Cylinder hole, 19...Valve hole, 20...Intake passage, 21...Ejection passage, 22...Main combustion chamber,
23...Intake port, 24...Ejection port, 27...Precombustion chamber, 51...Camshaft, 52...Nozzle hole, 79
...Fixed cam.

Claims (1)

[Claims] 1. An intake passage that guides the air-fuel mixture from the main combustion chamber to the preheating chamber, a compression piston that independently compresses the air-fuel mixture that has entered the pre-combustion chamber, and combustion in the pre-combustion chamber that is compressed by the compression piston and ignited. In an internal combustion engine, the combustion adjustment valve is provided with an ejection passage that ejects gas into a main combustion chamber by the combustion pressure of the combustion gas, and a combustion adjustment valve that opens the ejection passage using the combustion pressure of the combustion gas. An internal combustion engine characterized by being configured to have a slight gap when closed.