JP3470483B2 - Reed valve device for two-cycle engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reed valve device of a two-stroke engine for preventing a backflow of an air-fuel mixture in an intake passage. 2. Description of the Related Art FIG. 7 is a longitudinal sectional view showing an example of a reed valve device conventionally used in a two-stroke engine. The reed valve device 51 is provided in a valve housing 52 of a two-stroke engine, and has a wedge-shaped valve body 53 narrowing toward the downstream side (engine side) of the valve housing 52; A valve passage 54 provided inside the valve body and a valve body
The valve hole 55 is formed on the slope of the valve 53 and a reed valve 56 for closing the valve hole 55 from outside is provided. A carburetor (not shown) and an air cleaner (not shown) are connected to the upstream side of the valve body 53 via an inlet pipe 57, so that an air-fuel mixture generated by the carburetor is supplied to a two-cycle engine via a reed valve device 51. ing. The reed valve 56 has a valve hole due to its elasticity.
Since it can be opened in a direction away from 55, it is pushed open by the mixture flow flowing toward the engine side in the valve passage 54 as shown by the arrow, but closes when the mixture flows backward. Therefore, backflow of the air-fuel mixture from inside the crankcase during the primary compression stroke of the two-cycle engine is prevented. [0005] By the way, many motorcycles equipped with a two-stroke engine often inject oil stored in an oil tank into a carburetor, an inlet pipe 57 or the like little by little to form an air-fuel mixture. A separate refueling system is used, which mixes and atomizes the oil to supply it into the engine. However, during low-speed operation or the like in which the flow rate of the air-fuel mixture is relatively low, the oil contained in the air-fuel mixture is not completely atomized but remains in a liquid state.
Or flow in the valve passage 54. Further, the fuel in the air-fuel mixture may flow through the inlet pipe 57 and the valve passage 54 in a liquid state without being completely atomized. [0007] Since the liquid oil or fuel in the liquid state enters the crankcase as it is, there is a concern that the lubrication state in the crankcase is deteriorated, and the concentration of the mixture becomes uneven, resulting in engine malfunction. . In addition, if the inlet pipe 57 is curved in the lateral direction due to, for example, the layout of the vehicle body, the liquid oil or fuel is biased in the centrifugal direction in the inlet pipe 57 by the centrifugal force, and the valve passage 54 is left as it is. This concern is even more acute as it flows into the crankcase through one side. A reed valve device for a two-stroke engine according to the present invention has been made in order to solve such a problem, and an object thereof is to completely remove oil or fuel flowing through an intake passage in a liquid state. And then supply it to a two-stroke engine. [0010] To achieve this object, a reed valve device for a two-stroke engine according to the present invention is installed in a valve housing of a two-stroke engine, and is provided downstream of the valve housing. a valve body formed headed narrowed wedge, a valve passage provided in the interior of the valve body, to close the valve hole formed in the inclined surface of the valve body from the outside through the valves passage on the engine side In a reed valve device of a two-stroke engine having a reed valve pushed and opened by a mixed airflow flowing toward the upstream side of the valve passage,
Provide a gentle climbing slope, and use this slope
By causing break at the end face of the Ujingu, the weir to the bottom surface of the valve passage lying perpendicular to the passage direction of the valves passage provided in a V-shape and the engine side in the widthwise central portion of the weir
A notch that gradually became shallower was formed. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a left side view of a two-stroke engine to which the reed valve device according to the present invention is applied, and FIG. 2 is a schematic plan view corresponding to FIG. The two-stroke engine 1 is a single-cylinder engine mounted on the front half of a body frame 2 of a motorcycle, for example, and has a cylinder assembly 4 on a top surface of a crankcase 3 with a slight inclination toward the front. is set up. In the crankcase 3, a crankshaft 5 extending in the vehicle width direction is supported by two left and right bearings 6,7. At the rear upper portion of the crankcase 3, a valve housing 8 that opens rearward is provided.
Here, a reed valve device 10 is incorporated, a carburetor 12 is connected via an inlet pipe 11, and an air cleaner 13 is connected to a rear portion of the carburetor 12. The air cleaner 13 includes, for example, a cleaner box 14, a cleaner duct 15 extending forward from the cleaner box 14 and connected to the carburetor 12, and a cleaner duct 15.
15 and a cleaner element 16 provided at the entrance of the device. As shown in FIG. 2, since a cushion unit 18 for rear wheel suspension is located in front of the air cleaner 13, the carburetor 12 is offset, for example, to the left so as to avoid the cushion unit 18. The intake side (rear part) is angled so that it is diagonally left behind, and the discharge side (front part) is diagonally right forward. The cleaner duct 15 of the air cleaner 13 bypasses the left side of the cushion unit 18 and connects to the suction side of the carburetor 12. On the other hand, the inlet pipe 11 connects the discharge side of the carburetor 12 to the valve housing 8.
It is curved to the left to connect to. FIG. 3 is an exploded perspective view of the reed valve device 10 and the inlet pipe 11. FIG. 4A is a longitudinal sectional view of the reed valve device 10 and the inlet pipe 11, and FIG.
(B) is a reed valve device taken along the line IVB-IVB in FIG. 4 (A).
It is a rear view of 10. FIG. 5 is a cross-sectional view of the reed valve device 10 and the inlet pipe 11 taken along the line VV in FIG. The main body of the reed valve device 10 is a wedge-shaped valve body 20 narrowing toward the downstream side of the valve housing 8. A flange-shaped fixed flange 21 is formed at the base of the valve body 20, and a valve passage 22 having a square cross section is provided inside the valve body 20. A pair of left and right rectangular valve holes 25 are formed in the upper and lower slopes 23 and 24 of the valve body 20, respectively. In the valve passage 22, for example, a horizontal rectifying fin 26 that bisects the passage space vertically and a vertical rectification fin 27 that bisects the passage space left and right are provided. The four valve holes 25 of the valve body 20 are closed from the outside by reed valves 30, respectively. The reed valve 30 is a thin plate having elasticity, and is applied to the slopes 23 and 24 in accordance with the position of the valve hole 25.
Fixed to 4. Note that the reed valve stopper 32 is
It is a plate that regulates the opening of 30. The fixed flange 21 of the valve body 20 is sandwiched between an end face of the valve housing 8 and a fixed flange 35 formed at the end of the inlet pipe 11 and several flanges inserted from the fixed flange 35 side. Bolt 36 is fixed flange 21
Boss formed on the end face of the valve housing 8
37, the valve housing 8, the reed valve device 10, and the inlet pipe 11 are connected. On the bottom surface of the valve passage 22, there is provided a weir 40 lying perpendicular to the direction of the valve passage 22. The weir 40 has a shape in which, for example, a slope gently climbing toward the upstream side (the inlet pipe 11 side) is provided on the bottom surface of the valve passage 22, and the slope is cut off at the end face of the fixed flange 21. Therefore, the valve passage 22
And a step between the bottom surface of the inlet pipe 11 and the bottom surface of the passage of the inlet pipe 11. Further, a V-shaped notch 41 is formed at the center of the weir 40 in the width direction. The notch 41 is formed so as to gradually become shallower toward the engine side. When the two-cycle engine 1 operates, outside air is sucked from the air cleaner 13, and the outside air is removed of dust and the like by the cleaner element 16 and flows to the carburetor 12 through the cleaner duct 15. In the carburetor 12, the fuel is mixed with the outside air to generate a mixture, and the oil is further mixed little by little. The air-fuel mixture containing the oil flows through the inlet pipe 11 and the valve passage 22 of the reed valve device 10, pushes and opens the reed valve 30, flows into the crankcase 3 through the valve housing 8, and continues for two cycles. While the engine 1 is operating, lubricating parts such as the bearings 6 and 7 of the crankshaft 5 are lubricated. At the time of the primary compression stroke of the two-cycle engine 1, the air-fuel mixture tends to flow backward from the inside of the crankcase 3, but at that time, the reed valve 30 is closed, so that the air-fuel mixture is prevented from flowing backward. In a low-speed operation where the flow rate of the air-fuel mixture is relatively low, the oil and fuel components contained in the air-fuel mixture cannot be completely atomized. It may flow on the bottom inside the pipe 11. This liquid oil or fuel is temporarily blocked by a weir 40 provided in the reed valve device 10, and gradually flows out to the engine side from a notch 41 formed in a central portion of the weir 40. Then, it receives a relatively fast airflow flowing through the central portion of the valve passage 22 to atomize and spread uniformly, and then enters the crankcase 3. Therefore, even during a low-speed operation, the oil or fuel does not enter the crankcase 3 in a liquid state, and the lubrication state in the crankcase 3 is kept good. Further, the concentration of the air-fuel mixture is also kept uniform, thereby avoiding engine malfunction. In addition, when the inlet pipe 11 is curved in the horizontal direction due to the layout of the motorcycle body as in this embodiment, the liquid oil and fuel flowing through the inlet pipe 11 receive centrifugal force. Although the oil and fuel flowing in the inlet pipe 11 in such a manner tend to be offset, notch and the weir 40 of the reed valve device 10 are notched.
Since it enters the crankcase 3 after being gathered and atomized by the center 41, deterioration of the lubrication state and engine malfunction can be more effectively prevented. Since the weir 40 and the notch 41 can be formed integrally with the valve body 20, the manufacturing cost of the reed valve device 10 does not increase when the weir 40 and the notch 41 are provided. In the present embodiment, the weir 40 is formed in the shape of a slope on the bottom surface of the valve passage 22. However, the shape is not limited to this. , A semicircular cross section or the like. Further, the shape of the notch 41 is not limited to the V-shape, and may be a U-shape, a small hole, or the like. Further, in this embodiment, the height of the weir 40 is constant over the entire width, but the liquid oil or fuel is biased to the right by the centrifugal force in the inlet pipe 11 curved to the left. In consideration of the flowing, the height of the weir 40 may be increased toward the right side in the traveling direction. As described above, the reed valve device of the two-stroke engine according to the present invention is installed in the valve housing of the two-stroke engine and has a wedge shape narrowing toward the downstream side of the valve housing. a valve body which is formed, a valve passage provided in the interior of the valve body, the mixing airflow to close the valve hole formed in the inclined surface of the valve body from the outside flows through the valves passage on the engine side in reed valve device of the two-stroke engine having a reed valve which is pushed open, the valve passage
Slope gently climbing toward the upstream of the passage at the bottom of the road
And cut this slope at the end face of the valve housing.
By giving is, the weir to the bottom surface of the valve passage lying perpendicular to the passage direction of the valves passage provided gradually I shallower toward the V-shape and the engine side in the widthwise central portion of the weir
A notch is formed. According to this structure, oil or fuel flowing in a liquid state in the intake passage such as the inlet pipe is temporarily blocked by a weir provided in the valve passage, and then is cut off from the notch at the center of the weir. Pour little by little and let it completely atomize, then 2
Since the oil can be supplied to the cycle engine, the lubricating state can be kept good, and the concentration of the air-fuel mixture can be made uniform to avoid engine malfunction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a reed valve device according to the present invention;
The left view of a cycle engine. FIG. 2 is a schematic plan view corresponding to FIG. FIG. 3 is an exploded perspective view of a reed valve device and an inlet pipe. FIG. 4A is a longitudinal sectional view of a reed valve device and an inlet pipe, and FIG. 4B is a rear view of the reed valve device taken along the line IVB-IVB of FIG. FIG. 5 is a cross-sectional view of the reed valve device and the inlet pipe along the line VV in FIG. 4 (A). FIG. 6 is a cross-sectional view showing the operation of the reed valve device. FIG. 7 is a longitudinal sectional view of a reed valve device and an inlet pipe showing a conventional technique. [Description of Signs] 1 Two-cycle engine 8 Valve housing 10 Reed valve device 11 Inlet pipe 20 Valve body 22 Valve passage 23, 24 Slope of valve body 25 Valve hole 30 Reed valve 40 Weir 41 Notch

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 35/10 F02M 29/00

Claims (1)

(57) [Claim 1] A wedge-shaped valve body which is installed in a valve housing of a two-stroke engine and narrows toward the downstream side of the valve housing. a valve passage provided, two-stroke engine having a reed valve which is pushed open to and closes the valve hole formed in the inclined surface of the valve body from the outer valves in the passage to the mixing airflow flowing toward the engine side in the reed valve device, the passage upstream to the bottom surface of the valve passages
Set up a slope that climbs slowly
By causing break at the end face of the valve housing, the weir to the bottom surface of the valve passage lying perpendicular to the passage direction of the valves passage provided, V-shaped and end in the widthwise central portion of the weir
A reed valve device for a two-stroke engine, wherein a notch that gradually becomes shallower toward the gin side is formed.