JPH0385322A - Two-cycle engine - Google Patents

Abstract

PURPOSE:To greatly enhance output in a wide sped range by operating a main valve and an auxiliary valve with the same driving means, and changing the exhaust starting time of incombustible gas from a cylinder and an opening sectional area of a passage through which the incombustible gas passes at the same time. CONSTITUTION:As an arm member 30 is oscillated by turning a driving shaft 31, a main valve 20 is made to go forward and backward of a main exhaust passage 11, while a pair of auxiliary valves 22 are made to go forward and backward of an auxiliary exhaust passage 12. At this stage, when an engine is in the predetermined low speed area, for example, each valve 20, 22 is made to project inside each exhaust passage 11, 12. A height of an opening upper edge 11a' of the main exhaust passage 11 is lowered by a predetermined distance H by the projected main valve 20. The auxiliary valve 22 is projected by a distance L1 longer than the projection quantity L2 of the main valve 20 to seal the auxiliary exhaust passage 12. The output in a low speed range is thereby improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a two-stroke engine.

[Conventional technology]

In a typical two-stroke engine, a scavenging passage for supplying fresh air to the cylinder and an exhaust passage for discharging burned gas from the cylinder are each opened above the movement range of the piston in the cylinder, and the piston moves back and forth. By opening and closing these openings on the circumferential surface of the cylinder in a timely manner, the gas inside the cylinder is exchanged.

In such an engine, the position of the edge of the opening of the exhaust passage on the top dead center side determines when to start exhausting the burnt gas, and the cross-sectional area of the opening of the exhaust passage determines the exhaust flow rate of the burnt gas, i.e. This will determine the exhaust efficiency.

The start timing and exhaust efficiency of these burnt gases are uniquely determined when the exhaust passage is formed in the cylinder block, but the optimum timing for improving output is determined by the engine speed. It varies depending on the number.

In other words, it is preferable that the exhaust start time of burnt gas is late when the engine is in a low rotational speed range, and early when the engine is in a high rotational speed range.On the other hand, regarding the exhaust efficiency of burnt gas, It is preferable that it is low when the engine is in a low rotation speed range, and high when the engine is in a high rotation speed range.

Conventionally, in order to improve output in a wide rotation speed range from low rotation speed to high rotation speed, a valve body is movably disposed around the cylinder side opening of the exhaust passage. A two-stroke engine that changes the timing at which burned gas starts to be discharged by moving it forward and backward into the exhaust passage, and a cylinder that communicates with a sub-exhaust passage,
A two-stroke engine and the like have been provided in which a valve body is disposed in the sub-exhaust passage, and the exhaust efficiency is varied by opening and closing the sub-exhaust passage with the valve body.

[Problem to be solved by the invention]

By the way, in order to further improve the output of the two-stroke engine, it is preferable to set both the exhaust start timing and exhaust efficiency of the burnt gas to be appropriate for each rotational speed range.

However, when the above-mentioned 2-stroke engine that varies the start timing of exhausting burnt gas is combined with a 2-stroke engine that varies the exhaust efficiency, it is difficult to operate the valve bodies around the engine, especially the cylinders. Since driving means and means for transmitting the power of these driving means to each valve body are arranged, the structure becomes extremely complicated.

Furthermore, each of the above-mentioned valve bodies must be operated in synchronization, and control of the driving means for operating each valve body becomes extremely complicated.

In view of the above-mentioned circumstances, an object of the present invention is to provide a two-stroke engine with a simple structure that can further improve the output in a wide rotation speed range from low rotation speed to high rotation speed. be.

[Means to solve the problem]

In the two-stroke engine according to the present invention, a main exhaust passage opens into the cylinder, a sub-exhaust passage is arranged in parallel with the main exhaust passage and opens into the cylinder, and a sub-exhaust passage is arranged around the opening of the main exhaust passage on the cylinder side. a main valve element that varies the timing at which exhaust of burned gas starts to be discharged from the cylinder; a sub-valve element that is disposed in the sub-exhaust passage and opens and closes the sub-exhaust passage; a linking means that engages with the valve body and transmits power from the driving means to the main valve body and the auxiliary valve body, and causes the main valve body and the auxiliary valve body to act simultaneously according to the rotational speed of the engine. That's what I do.

[Effect]

According to the above configuration, the main valve body and the sub-valve body are actuated by the same driving means, and the timing at which burnt gas starts to be discharged from the cylinder and the opening cross-sectional area of the passage through which this burnt gas passes can be simultaneously varied. can be done.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail based on drawings showing embodiments.

1 to 3 conceptually show the main parts of a two-stroke engine according to the present invention, and as shown in FIG.
This engine has a main exhaust passage 11 in the cylinder block 10.
and a pair of sub-exhaust passages 12°12. As shown in FIG. 1, the main exhaust passage 11 has one end connected to a cylinder 13.
It opens into the inside of the cylinder block 10 and extends from there in the radially outward direction of the cylinder 13, and the other end is connected to the cylinder block 10.
It opens on the outer surface 10a of the. Sub-exhaust passage 12゜12
As shown in FIG.
1 and cylinder 13 are communicated with each other.

Openings 1 on the cylinder 13 side in these main exhaust passages 11
1a and the cylinder 13 in the auxiliary exhaust passage 12.12
As shown in Figure 1, the side openings 12a, 12a have a height of their respective upper edges (upper in the figure, edges on the top dead center side of the cylinder 13) lla'12a', 12a'. The main exhaust passage 1 is set to obtain the exhaust start timing of burned gas suitable for the high engine speed range.
The cross-sectional area of the first opening 11a is set to obtain exhaust efficiency suitable for the low rotational speed range of the engine.

On the other hand, this two-stroke engine includes a main valve body 20 in a portion of the cylinder block 10 located above the main exhaust passage 11. The main valve body 20 has an arcuate cross section along the cylinder 13 (as shown in FIG. 2).
, an opening 11 on the cylinder 13 side in the main exhaust passage 11
It fits into the sliding hole 14 formed near the upper edge of the cylinder 13 so that it can move forward and backward toward the main exhaust passage 11 at an angle of θ (15 to 45 degrees) from the axis A of the cylinder 13. It is accommodated.

As shown in FIG. 2, the main valve body 20 has a narrow upper end portion, and a linking pin 21 is provided in this narrow width portion. The linking pins 21 extend outward from both side surfaces of the upper end, and an arm member (linking means) 30 is linked thereto.

The arm member 30 has kerf grooves 30a, 30a opening at the tip of each of its bifurcated distal end portions, and the linking pin 21 is housed in these kerf grooves 30a, 30a, and the proximal end thereof is inserted and fixed to a drive III+31 connected to a drive means (not shown).

Further, the valve body 20 has arch-shaped sliding recesses 20a, 20a on both side surfaces of its lower end. Although these sliding recesses 20a, 20a are not clearly shown in the figure,
The axis is formed in such a manner that the axis is along the extending direction of the main valve body 2o, and each of the sub valve bodies 22, 22 has a cylindrical shape inside.
is slidably arranged.

As shown in FIG. 3, these sub-valve bodies 22, 22 have respective distal ends inserted into sliding holes 15.15 formed midway above the sub-exhaust passage 12.12. 1
It is fitted and housed so that it can move forward and backward toward the end.

As shown in FIG. 2, between the upper ends of these sub-valve bodies 22, 22, the central part is formed by the grooves 3Qa, 3O of the arm member 30.
They are connected to each other via a shaft member 23 housed in a. As is clear from the same figure and FIG. 1, the shaft member 23 is located outside the linking pin 21 within the grooves 30a, 30a. That is, as shown in FIG. 1(a), the distance Ma1 from the axis of the drive shaft 31 to the axis of the shaft member 23 is the distance Ma1 from the axis of the drive shaft 31 to the axis of the linking pin 21. It is longer than.

In the two-stroke engine configured as described above, when the drive shaft 31 is rotated by the drive means (not shown) described above, the arm member 31 fixed to the drive shaft 31 is rotated.
is swung, and the main valve body 20 is moved forward and backward into the main exhaust passage 11, and the pair of auxiliary valve bodies 22.22 are moved along with the main valve body 20, respectively, into the auxiliary exhaust passages 12.12. It is moved forward and backward.

At this time, as shown in FIG. 1(b), the main valve body 20 and the sub-valve body 22.22 in the most retracted state are completely immersed in the respective sliding holes 14 and 15.15, The bottom surface 20b of the main valve body 20 is aligned with the inner wall surface 11b of the main exhaust passage 11, and the bottom surfaces 22a, 22a of the auxiliary valve elements 22.22 are aligned with the inner wall surface 12b of the auxiliary exhaust passage 12 (shown in FIG. 3). be done.

Now, when this two-stroke engine is operated and its rotation speed is in a predetermined low rotation speed range, as shown in FIGS. 1(a) and 3, the main valve body 20 and the sub-valve bodies 22, 22
are the main exhaust passage 11 and the sub-exhaust passage 12 and 12, respectively.
protruded inward.

In this state, the height of the opening upper edge 11a' of the main exhaust passage 11 is lowered by a distance H due to the protruding main valve body 20.

Also, at this time, as described above, the distance intersection 1 from the axis of the drive shaft 31 to the axis of the shaft member 23 is longer than the distance intersection 2 from the axis of the drive shaft 31 to the axis of the linking pin 21. Therefore, when the main valve body 20 protrudes a distance L2, the sub-valve bodies 22, 22 protrude by a distance L1, which is longer than the distance L2, and these sub-valve bodies 22,22 cause the sub-exhaust passage 12. 12 will be blocked.

As a result, in the engine in this state, the burned gas in the cylinder 13 is exhausted at a later stage and only through the opening 11a of the main exhaust passage 11, improving the output in the low rotation speed range. .

On the other hand, when the engine speed increases from the above state and reaches a predetermined high speed range, the above-mentioned driving means (not shown) is operated in the opposite direction, as shown in FIG. 1(b). As shown in FIG. 2, the main valve body 20 and the sub-valve bodies 22, 22 are removed from the main exhaust passage 11 and the sub-exhaust passage 12, 12, respectively.

In the engine in this state, the burned gas in the cylinder 13 is released earlier by the distance H than in the low rotation speed range, and also at the opening 11a of the main exhaust passage 11 and the opening 12a of the auxiliary exhaust passage 12.12. , 12a, and the output in the high rotation speed range is improved.

Although the above embodiment employs the main valve body 20 and the sub-valve body 22 that act on the respective exhaust passages 11 and 12 by moving forward and backward, the present invention is not limited to these; for example, the shaft It may be a valve body that operates by rotating around the center. Further, although the main valve element 20 and the sub-valve element 22 have mutually different operating strokes, the main valve element and the sub-valve element 22 may be used that act on the respective exhaust passages with the same operating stroke.

Further, a swinging linking means 30 is applied, and the linking means 3
Although the operating strokes of the respective valve bodies 20 and 22 are made different by changing the distances from the swing center of the valve body 20 to the operating points of the main valve body 20 and the sub-valve body 22, the present invention is not limited to this. First, for example, it is also possible to apply a linking means that links the main valve element and the sub-valve element by means of a gear, and to vary the operating stroke of each valve element by changing the respective gear ratios.

Further, in the above embodiment, a two-stroke engine is exemplified which includes a pair of sub-exhaust passages 12 and 12 that communicate with the main exhaust passage 11 and are arranged on both sides of the main exhaust passage 11. The exhaust passages do not necessarily have to be a pair, nor do they need to communicate with the main exhaust passage.

Furthermore, in the above embodiment, the main valve body 20 is formed to have an arcuate cross section along the cylinder 13, and the main valve body 20 is
Since the main valve body 20 is arranged at an angle of 15 to 45 degrees from the axis A of the cylinder 13, the main valve body 20 is In addition, when the valve body 20 is retracted, the tip of the main valve body 20 can be completely immersed in the sliding hole 14 without causing the tip to separate significantly, thereby increasing the output in the high rotation speed range. Although it is possible to improve the output in the middle rotation speed range without causing a decrease, the present invention is not limited to this.

〔Effect of the invention〕

As described above, according to the two-stroke engine according to the present invention, the main valve body and the sub-valve body are operated by the same driving means, and the timing at which the combustion gas starts to be discharged from the cylinder and the passage of the combustion gas are determined. Since the cross-sectional area of the opening of the passage can be varied at the same time, it is possible to further improve the output in a wide rotation speed range from a low rotation speed range to a high rotation speed range with a simple structure.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view conceptually showing the main exhaust ventilation part of a two-stroke engine according to the present invention, in which FIG. 1(a) shows a state in a low rotation speed range, and FIG. This figure shows the conditions in the high rotation speed range. FIG. 2 is an enlarged perspective view conceptually showing a main valve body and a sub-valve body applied to a two-stroke engine according to the present invention, and FIG. 3 is a sub-exhaust passage section of a two-stroke engine according to the present invention. FIG. 2 is a cross-sectional view conceptually showing. DESCRIPTION OF SYMBOLS 11... Main exhaust passage, lla... Cylinder side opening of main exhaust passage, 12... Sub-exhaust passage, 13... Cylinder, 20... Main valve body, 22... Sub-valve body, 30...
Coordination means.

Claims (1)

[Claims] A main exhaust passage that opens into the cylinder; a sub-exhaust passage that is arranged in parallel with the main exhaust passage and opens into the cylinder; a main valve element that varies the timing at which combustion gas starts to be discharged from the cylinder; a sub-valve element disposed in the auxiliary exhaust passage that opens and closes the auxiliary exhaust passage; The main valve element and the auxiliary valve element are engaged with each other to transmit power from the drive means to the main valve element and the auxiliary valve element, and act on the main valve element and the auxiliary valve element at the same time according to the rotational speed of the engine. A 2-stroke engine with the following characteristics.