JPS63173815A - Method and device for scavenging two-cycle engine - Google Patents

Abstract

PURPOSE:To vary scavenging time of fuel mixture into a combustion chamber and increase output by providing a valve member for displacing an opening of the opening portion on the combustion chamber side of a scavenging passage formed on the side edge of a cylinder in the vicinity of the combustion chamber side opening portion. CONSTITUTION:A valve member 32 is disposed in a scavenging passage 30 in the vicinity of a scavenging port 28 opened on the side wall of a cylinder 10, and rotatably supported at its upstream end by the cylinder 10 through a rotary shaft 34. The free end 36 as the downstream end of the valve member 32 is formed like a circular-arc in such a manner as to agree with a peripheral portion of a combustion chamber 12 and moved in the axial direction of the combustion chamber 12 along a scavenging port 28 by pivotal motion of the valve member 32 on the rotary shaft 34. In this arrangement, the opening and closing timing of the scavenging port 28 can be determined to be optimum by a crank angle where the piston 14 passes the free end 36 to increase output of a two-cycle engine.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a scavenging method and device for a two-cycle engine, and in particular, to a scavenging method and device for a two-cycle engine, and in particular, a scavenging port formed on a cylinder side wall of a combustion chamber is variable in opening/closing timing. This article relates to a scavenging method and device for a two-stroke engine.

[Conventional technology]

Figures 10 and 11 for conventional two-cycle engines
This will be explained in the figure.

In FIG. 10, a cylinder 10 has a combustion chamber 12 therein, and one spark plug 13 is mounted on the top of the cylinder 10, with its discharge gap facing into the combustion chamber 12. The piston 14 defines a lower portion of the combustion chamber 12 and slides within the cylinder 10 . The crankcase 16 is joined to the lower end of the cylinder 10, and the crankshaft 18 has its axially central portion disposed within the crankcase 16, and both ends rotatably attached to the crankcase via ball bearings 20a and 20b. To 16! 11! supported.

The connecting rod 22 is rotatably connected to the piston 14 and the crankshaft 18 via pins at the upper and lower ends, respectively, and the seals 24a and 24b are connected to ball bearings 20a and 20b, respectively, in the axial direction of the crankshaft 18.
is fitted on the outside of the crankcase 16 to keep the inside of the crankcase 16 airtight. An exhaust port 26- and a pair of scavenging ports 28 below the exhaust port 26 are formed in the side wall of the cylinder 10 that partitions the combustion chamber 12 in the radial direction.

The scavenging passage 30 is formed in the cylinder 10 and the crankcase 16, communicates with the scavenging port 28 at the downstream end, and guides the mixed gas to the scavenging port 28.

FIG. 11 shows the opening/closing timing of the exhaust port 26 and the scavenging port 28 in terms of the rotation angle of the crankshaft 18. The opening/closing timing of the scavenging port 28 is fixed regardless of the operating conditions of the two-cycle engine.

[Problem that the invention seeks to solve]

When the two-cycle engine rotates at high speed, the opening and closing timing of the scavenging port 28 is preferably closer to the opening and closing timing of the exhaust port 26 because the scavenging effect and the efficiency of filling the mixture gas into the combustion chamber 12 are higher. During low-speed rotation, if the opening/closing timing of the exhaust port 26 is near, the scavenging port 28 will open before the gas pressure in the combustion chamber 12 is sufficiently low, and since the flow rate of the mixed gas is low, the combustion gas will be removed from the scavenging gas. The gas may flow back into the passage 30 or the efficiency of filling the combustion chamber 12 with the mixed gas may decrease, causing a decrease in the output of the two-cycle engine.

However, in conventional two-cycle engines, the opening and closing timing of the scavenging port 28 is fixed, making it difficult to control the opening and closing timing of the scavenging port 28 to an optimal value according to the rotational speed of the two-cycle engine. .

In addition, if there are multiple cylinders with different opening/closing timings of the scavenging ports,
To prepare those cylinders,
It requires a separate mold, which is disadvantageous in terms of cost, and
It is necessary to switch the cylinder used depending on the rotation speed of the two-cycle engine.

The effort increases.

An object of the present invention is to provide a two-cycle engine scavenging method and device that can optimally adjust the opening and closing timing of a scavenging port depending on the operating conditions of the two-cycle engine.

[Means for solving problems]

According to the scavenging method for a two-cycle engine of the present invention, a valve member is provided near the combustion chamber side opening of the scavenging passage formed on the side edge of the cylinder, and the valve member displaces the opening of the opening. , the timing at which the mixed gas is scavenged into the combustion chamber can be varied.

The scavenging device for a two-cycle engine according to the present invention includes a scavenging port formed on a cylinder wall surface of a combustion chamber, a scavenging passage that guides a mixed gas to the scavenging port, and a scavenging passage arranged outside the combustion chamber and having an edge on the side of the scavenging port. A valve member that defines the upper side of the effective opening of a scavenging port that introduces mixed gas from the scavenging passage into the combustion chamber and is movable in the axial direction of the combustion chamber along the scavenging port, and a valve member that is disposed outside the cylinder. and an operating member for operating the.

[Effect]

The valve member moves by operating the operating member or the like.

The edge of the valve member on the side of the scavenging port is displaced in the axial direction of the combustion chamber substantially along the scavenging port. The scavenging port side edge of the valve member becomes the upper edge of the effective opening of the scavenging port that introduces the mixed gas into the combustion chamber. Therefore, the opening/closing timing of the scavenging port is determined by the crank angle of the piston that passes the upper edge of the effective opening. The opening/closing timing of the scavenging port changes depending on the displacement of the edge of the member on the scavenging port side.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9.

In FIG. 1, the valve member 32 is arranged in the scavenging passage 30 in the vicinity of the scavenging port 28, and is rotatably supported by the cylinder 10 via a rotation shaft 34 at the upstream end. The free end 36 as the downstream end of the valve member 32 is
It is formed in an arc shape that matches the circumferential portion of the combustion chamber 12, and is movable in the axial direction of the combustion chamber 12 along the scavenging port 28 as the valve member 32 swings around the rotation shaft 34. It has become. The length of the free end 36 is equal to the length of the scavenging port 28 in the circumferential direction of the combustion chamber 12, and
2 partitions the space at the upper end of the scavenging passage 30, so
The free end 36 becomes the upper side of the effective opening of the scavenging port 28 that introduces the mixed gas into the combustion chamber 12. That is, the opening/closing timing of the scavenging port 28 is determined by the crank angle at which the piston 14 passes the free end 36. Valve member 32 in FIG.
The solid line position and the two-dot chain line position indicate different rocking positions of the valve member 32.

FIGS. 2(a) and 2(b) show in detail the joint between the valve member 32 and the rotating shaft 34, and the rotating shaft 34 with the rotating shaft 34 removed. The shaft 34 has an insertion portion 38 that is inserted into the cylinder 10, and this insertion portion 3.
8 and a base 40 integrally coupled to the end of the 8. The circumferential groove 42 and the screw hole 44 are formed at both axial ends and the intermediate portion of the insertion portion 38, respectively.

After the insertion portion 38 is inserted into the cylinder 10, a retaining ring 46 is fitted into the circumferential groove 42° 42 to prevent the insertion portion 38 from coming off from the cylinder 10. Screws 4g and 48 are
It is inserted into the insertion hole at the upstream end of the valve member 32 and then screwed into the screw hole 44 of the rotation shaft 34, whereby the valve member 32
is fixed to the rotation shaft 34 at its upstream end so as to be integrally rotatable therewith.

FIG. 3 is a perspective view showing another manner of coupling the valve member 32 and the rotating shaft 34. A square-shaped insertion hole 50 is formed at the upstream end of the valve member 32, and the rotation shaft 34 is formed to have the same circumferential outline as this square-shaped insertion hole 50, and is fitted into the square-shaped insertion hole 50. It has a rectangular insertion portion 52. In this coupling mode, the square insertion portion 52 of the rotation shaft 34 fits into the square insertion hole 50 of the valve member 32, thereby ensuring integral rotation of the valve member 32 and the rotation shaft 34. Therefore, the screw 48 in FIG. 2 can be omitted.

FIG. 4 is a side view of the cylinder 10 seen from the outside at the height of the scavenging port 28, and FIG. 5 is a cross-sectional view taken along the line ■--■ in FIG. Arm 54 turns! ! The bolt 56 is integrally fixed to the end of the base 40 of the + shaft 34 and the two arms 54
It is screwed onto the outer surface of the cylinder 10 at the center position. The operating lever 58 is rotatably inserted into the bolt 56 , and the compression coil spring 60 is fitted onto the shaft of the bolt 56 in a compressed state between the head of the bolt 56 and the operating lever 58 . It is pressed against the outer surface of the cylinder 10. Rotation of the operating lever 58 around the bolt 56 due to the compression of the operating lever 58 against the cylinder 10 by the compression coil spring 60 requires a rotational force of a predetermined value or more. That is, only when the operator grips and rotates the operating lever 58, a rotational force of a predetermined value or more is applied to the operating lever 58, and the operating lever 58 is rotated. When you let go,
The operating lever 58 is designed to maintain its rotational position. The coil springs 62,62 are each hooked at one end to both ends of the operating lever 58 and at the other end to the lower end of the arm 54,54. arrow 64
Rotation of the bolt 56 in the direction causes the pivot shaft 34 to rotate in the direction of the arrow 66, causing the free ends 36 of each valve member 32 to move along the scavenging port 28 while remaining at the same height as each other. Displaced in the axial direction of the combustion chamber 12.

FIG. 6 shows the position of the free end 36 at the scavenging port 28, which corresponds to the solid line position and the two-dot chain line position of the valve member 32 in FIG. The lower the free end 36 is, the lower the exhaust port 26 is.
The opening/closing timing of the scavenging port 28 is far away from the opening/closing timing of the scavenging port 28.

FIG. 7 shows the opening/closing timing of the exhaust port 26 and the scavenging port 28 using the rotation angle of the crankshaft 18, and FIG. It shows the time.

By rotating the operating lever 58, it is possible to adjust the opening/closing timing of the scavenging port 28. When the two-cycle engine rotates at high speed, the flow rate of the mixed gas flowing through the scavenging passage 30 is high, and the time during which the scavenging port 28 is in communication with the combustion chamber 12 is short, so in order to improve the scavenging effect and charging efficiency, By moving the free end 36 of the valve member 32 closer to the exhaust port 26, that is, raising it (as shown by the two-dot chain line in FIGS. 1 and 6), the opening/closing timing of the scavenging port 28 is adjusted to the opening/closing timing of the exhaust port 26. get closer to

When the two-cycle engine rotates at low speed, the flow rate of the mixed gas flowing through the scavenging passage 30 is low, so the combustion gas pressure in the combustion chamber 12 decreases slowly, and the opening/closing timing of the scavenging port 28 coincides with the opening/closing timing of the exhaust port 26. If the free end 36 of the valve member 32 is close to the exhaust port 26, the combustion gas will flow back into the scavenging passage 30 and the filling efficiency of the mixed gas into the combustion chamber 12 will be lowered.
(Figs. 1 and 6)
(solid line position in the figure), the opening/closing timing of the scavenging port 28 is separated from the opening/closing timing of the exhaust port 26.

FIG. 9 is a graph showing the relationship between engine rotational speed and horsepower in a two-cycle engine to which the present invention is applied and a conventional two-cycle engine. In this invention,
Since the opening/closing timing of the scavenging port 28 can be adjusted to an optimal value according to the engine rotation speed, the horsepower of the two-cycle engine increases over the entire engine rotation speed range, and engine performance can be improved.

〔Effect of the invention〕

As described above, according to the present invention, by operating the operating member or the like, the valve member moves, and the edge of the valve member on the scavenging port side moves within the scavenging port in the axial direction of the combustion chamber. The scavenging port side edge of the valve member defines the upper side of the effective opening of the scavenging port that introduces the mixed gas from the scavenging passage into the combustion chamber, and the displacement of the upper side of the effective opening determines the crank angle at which the piston passes through the upper side. Since the timing of opening and closing of the scavenging port can be adjusted by changing the displacement of the valve member. Therefore, the opening/closing timing of the scavenging port can be adjusted to an optimal value according to the rotational speed of the two-cycle engine, and the output of the two-cycle engine can be increased.

[Brief explanation of the drawing]

Figures 1 to 9 relate to this invention, Figure 1 is a structural diagram of the main part, Figures 2 (a) and (b) show the joint between the valve member and the rotating shaft, and the rotating shaft is removed. 3 is a perspective view showing another manner of coupling the valve member and the rotation shaft, and FIG. 4 is a view showing the cylinder from the outside at the level of the scavenging port. 5 is a sectional view taken along the line ■-■ in FIG. 4, and FIG. 6 is a side view of the valve member shown in FIG. 7 is a diagram showing the opening/closing timing of the exhaust port and the scavenging port in terms of the rotation angle of the crankshaft, and FIG. FIG. 9 is a diagram showing the relationship between engine speed and horsepower in a two-cycle engine to which the present invention is applied and a conventional two-cycle engine,
FIG. 10 is an overall schematic diagram of a conventional two-cycle engine, and FIG. 11 is a diagram showing the opening/closing timing of the exhaust port and the scavenging port in terms of the rotation angle of the crankshaft. 10-, Cylinder, 12... Combustion chamber, 28... Scavenging port (opening), 30... Scavenging passage, 32... Valve member, 36... Free end, 58... Operation Lever (operating member). 10...Cylinder 12...Combustion chamber 2 days...Scavenging Σ port (opening) 30...Scavenging passage 32...Valve member 36...Free end 44 4z b and Ob l (J 58 62
Figure 5 □ Engine rotational speed procedure manual (spontaneous) February 13, 1988 Commissioner of the Patent Office Black 1) Akio Yu 1, Indication of the incident 1988 Patent Application No. 003313 2, Name of the invention Relationship between scavenging method and device for cycle engines 3 and the case of the person making the amendment Patent applicant name Maruyama Seisakusho Co., Ltd. 4 Column for detailed explanation of the invention in the attorney's specification (6, Contents of amendment) In the specification l) No. 7' [Correct the "rotation shaft 34J" in the 7th line as follows [valve member 32] 2) Correct "large together" in the 7th line of page 10 as follows: "large together" 3 ) "Acupressure line" on page 12, line 16 is corrected as follows. 1 Acupressure diagram

Claims (3)

[Claims] (1) A valve member for displacing the opening of the opening of the scavenging passage formed on the side edge of the cylinder is provided near the combustion chamber side opening, and the displacement of this valve member causes the scavenging of the mixed gas to the combustion chamber. A two-stroke engine scavenging method that allows the timing of scavenging to be varied. (2) A scavenging port formed on the cylinder wall surface of the combustion chamber, a scavenging passage that guides the mixed gas to the scavenging port, and a scavenging passage arranged outside the combustion chamber, and an edge on the side of the scavenging opening from the scavenging passage to the combustion chamber. a valve member that defines the upper side of the effective opening of the scavenging port for introducing mixed gas into the combustion chamber and is movable in the axial direction of the combustion chamber along the scavenging port; and the valve member that is disposed outside the cylinder. A scavenging device for a two-cycle engine, comprising an operating member for operating the. (3) The scavenging device for a two-cycle engine according to claim 2, wherein the valve member is pivotably supported at an end opposite to the scavenging port.