JPH10220234A - Reed valve device for two cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a reed valve device by inducing intake air into an engine interior after uniformly distributing intake air to each reed valve window and straightening it with a compartment plate even if an intake passage from a carburetor to the reed valve is curved. SOLUTION: With regard to an intake passage of the two cycle engine, whose intake pipe 30 is curved, a valve body 26 includes a reed valve fitting surface facing the downstream side in the intake flow direction and inclined towards the flow direction, while the reed valve fitting surface is provided with a reed valve and compartment plate 40 partitioning asjoining windows 32, 32 toward the upstream side is formed inside the intake passage of the valve body 26, while respective distances from the carburetor fitting surface 30a of the intake pipe 30 to the respective compartment plate 40 upstream ends 40a are made in approximately the same length A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reed valve device, and more particularly to a reed valve device suitable for use in a two-cycle engine for a motorcycle.

[0002]

2. Description of the Related Art In a two-stroke engine, a reed valve (device), that is, a check valve in which a thin elastic plate fixed on one side is provided in an intake passage from a carburetor to a crank chamber is provided in the intake passage. Is provided. With this reed valve, while the pressure in the crank chamber is lower than that on the manifold side, the reed valve is opened and the intake period is started, so that the air-fuel mixture can be sucked into the crank chamber.

In this reed valve, a partition forming plate is provided inside a valve body to which the reed valve is attached, and the partition forming plate rectifies intake air supplied from a carburetor (Japanese Patent Laid-Open No. 6-58155). Gazette).

[0004]

As for the straightening of the intake air in the reed valve, the valve body a of the reed valve is opened and closed by the reed valve b as disclosed in the above-mentioned publication, as seen in cross section in FIG. If two windows c (shown from the inside of the window in the figure) are provided on each side,
The flow of intake air (fresh air) in the left and right passages of the partition forming plate d in the valve body a is not so uneven. In addition, the code | symbol e is an engine case.

However, when three or more windows c are provided on one side of the valve body a as shown in a sectional view of FIG. 9A, the flow of intake air passing through each window c becomes uneven depending on the position. (The outside is slow and the center is easy to be fast). As a result, the durability of the reed valve b or the valve body a outside the intake flow, that is, the durability of the reed valve device may be reduced. In particular, when the intake passage f upstream of the reed valve is significantly bent due to the influence of the rear suspension g and the like, as shown in a sectional view of FIG. There are problems such as the amount of fresh air (intake) flowing through c1 to c3 is c1 <c2 <c3.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. Even if the intake passage from the carburetor to the reed valve is bent, the intake air is evenly distributed to each window of the reed valve. An object of the present invention is to provide a reed valve device of a two-cycle engine that can be introduced into the engine after rectification by a plate, and thus can improve durability of the reed valve device.

[0007]

The present invention has the following arrangement to solve the above-mentioned problems. According to a first aspect of the present invention, there is provided a reed valve in which one end of a resilient reed valve is fixed to a carburetor and a valve body forming a part of an intake passage, and the operation of the reed valve prevents intake air from flowing back toward the carburetor. In the intake passage of the two-stroke engine, which is connected to the device by an intake pipe, and the intake pipe is bent, the valve body has a lead facing the downstream side in the intake flow direction and inclined with respect to the flow direction. Forming three or more windows through which intake air passes through the valve mounting surface, and providing a reed valve for each window,
In the intake passage of the valve body, two or more partition plates partitioning adjacent windows are formed toward the upstream side, and each distance from the carburetor mounting surface of the intake pipe to the upstream end of each partition plate in the valve body is increased. A reed valve device for a two-stroke engine, wherein the reed valve device has substantially the same length.

According to the first aspect of the present invention, since the intake pipe is bent, the distance from the carburetor mounting surface of the intake pipe to the upstream end of each partition plate in the valve body is substantially the same length. The intake air has a substantially identical flow velocity from the interp pipe to the end of each partition plate. That is, the flow of the intake air is affected by the bending of the intake passage.In the present invention, the intake passage flows almost linearly from the carburetor mounting surface to the end of each partition plate. Flows straight without being affected by bending.

Therefore, the intake air can be regarded as having substantially the same flow velocity at each portion of the right-angled cross section. (In the very vicinity of the inner peripheral surface of the intake pipe, the intake air touches the inner peripheral surface, and the flow velocity is slowed down to some extent. It is expected to have very little effect). Therefore, since the intake air flows out from each window of the volve body at a substantially uniform flow velocity, the flow velocity does not increase unevenly depending on the window as in the conventional case, so that the flow velocity of the intake air hitting the reed valve is almost uniform in any window. Therefore, the durability of all the reed valves is improved. Particularly, the durability of the reed valve located at the outside of the bend is improved.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1 to 7 are illustrations of a reed valve device for an intake system of a two-cycle engine mounted on a motorcycle according to this embodiment.

As shown in FIG. 1, in this engine unit, an intake port 10a of an engine case 10
The reed valve device 12 is bolted, and the carburetor 14 is bolted upstream of the reed valve device 12. Air cleaner 1 on the intake side of carburetor 14
6 are connected. In addition, in the upper part of the engine case 10,
The cylinder block 18 is erected and the engine case 1
A drive sprocket 20 is provided at the rear of the vehicle so as to drive the chain 22. The chain 22 drives a driven sprocket 24 of a rear wheel (not shown).

The intake passage flows from the air cleaner 16 through the carburetor 14, through the reed valve device 12, and into the engine case 10. A detailed description of the structure inside the engine case 10 and the cylinder block 18 is omitted.

Here, the reed valve device 12 in the intake passage
2 is shown in FIG. One end of a resilient reed valve 28 is fixed to the carburetor 14 and a valve body 26 forming a part of an intake passage with a screw 34, and the reed valve 28 operates to prevent the intake air from flowing back toward the carburetor 14. Intake pipe 3 between valve device 12
0, and the intake pipe 30 is bent.

The valve body 26 has a reed valve mounting surface 26a facing the downstream side in the intake flow direction and inclined with respect to the flow direction. The number of the mounting surfaces 26a may be one or two, but in the embodiment, the pair of mounting surfaces 26a, 26a facing each other at an angle has a roof shape, and the roof tip direction is directed to the downstream side.

On each of the mounting surfaces 26a, 26a, four windows 32 are formed to allow air to pass therethrough.
2, one reed valve 28 is provided. This window 32
Each have a substantially rectangular shape whose long sides extend along the intake air flow direction, and have substantially the same dimensions.

The reed valve 28 is fastened with a screw 34 for each window 32, and a reed valve stopper (a stopper for restricting the reed valve from being excessively opened) 36 is fastened together with the screw 34 via a spacer 36a. Is done.

At the same time, each mounting surface 26a, 26a
The portion 38 between the windows 32 has a linear shape, and the upstream side of the portion 38 has the windows 32, 3 adjacent to the upstream side in the intake passage of the valve body 26.
A partition plate 40 for partitioning the two is formed. In the embodiment, there are three partition plates 40.

The three partition plates 40 are plate-shaped walls and extend in parallel toward the intake side of the valve body 26. As will be described below, the extension lengths of the partition plates 40 will be described. Is different. That is, as shown in a side view in FIG. 3 and a cross-sectional view in FIG. 4, the reed valve device 12 has a bent intake pipe 30, and the valve body 26 extends from the mounting surface 30 a of the carburetor 14 of the intake pipe 30.
Each of the distances to the upstream end 40a of each of the partition plates 40 is substantially the same length A. In addition, intake pipe 3
A bend of 0 preferably has a radius of curvature of the pipe centerline of 90
mm to 1000 mm, and if it exceeds 1000 mm, the tendency of the intake pipe to be closer to a straight line increases.

When the intake pipe 30 is mounted on the carburetor 14, the carburetor mounting surface 30a is tightened and fixed with a tightening band 42 so that the carburetor mounting surface 30a is aligned with the intake outlet side of the carburetor 14, as shown in FIGS. A flange 26b is formed on the intake inflow side of the valve body 26, and the flange 26b is used to fasten the flange 30b on the downstream side of the intake pipe 30 together with a screw 44. The intake pipe 30 is mainly formed of a resin elastic body such as rubber, and a metal core 30c is formed on the flange 30b so as to rise up into the valve body 26.

The valve body 26 is mainly formed of a lightweight metal such as aluminum. As shown in detail in FIGS. 5 and 7, an elastic film layer such as rubber is provided on the surface of the mounting surface 26a. 26c is thin (for example, about 2mm)
It is formed so as to absorb the impact when the reed valve 28 comes into contact. In FIGS. 5 to 7, reference numeral 26 d denotes a beam-shaped metal portion formed on the back side of the distal end portion of the valve body 26 on the downstream side of the intake air.

In the embodiment, the intake pipe 30 is bent, but each partition plate 40, 4 in the valve body 26 is separated from the carburetor mounting surface of the intake pipe 30.
Since the respective distances to the upstream ends 0a, 40a, 40a, 40a are substantially the same length A, the intake air coming out of the carburetor 14 is supplied from the intake pipe 30 to the partition plates 40, 40,
Approximately the same flow velocity is obtained up to 40 tips. That is, each partition plate 40, 40, 4 from the carburetor mounting surface 30a.
Since the intake air flows almost linearly up to the 0 upstream end, even if the intake pipe 30 is bent, the intake air flows linearly without being affected by the bending.

Therefore, the intake air can be regarded as having substantially the same flow velocity in each section of the right-angled cross section.
2, the intake air flows out at a substantially uniform flow rate, and depending on the window 32, it is almost impossible for the flow rate to be unevenly increased. Therefore, the flow velocity of the intake air impinging on the reed valve 28 becomes substantially uniform in any window 32, and the durability of all the reed valves 28 is improved.

In the above embodiment, four windows 32 of the valve body 26 are formed on each mounting surface 26a. However, the number of windows of the present invention is not limited to three or five. It can be applied to the above number. Although the valve body has two reed valve mounting surfaces, the present invention can be applied to the valve body with one mounting surface, and the effects of the present invention can be achieved.

[0024]

As described above, according to the first aspect of the present invention, since the intake air flows from each window of the volve body at a substantially uniform flow velocity, the flow velocity may be unevenly increased depending on the window as in the related art. Since there is no air flow, the flow velocity of the intake air impinging on the reed valve is almost uniform in any window, and the durability of all the reed valves is improved. In particular, the durability of the reed valve located at the outside of the bend is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a two-cycle engine unit for a motorcycle according to an embodiment of the present invention.

FIG. 2 is an exploded view of the reed valve device.

FIG. 3 is an external view explanatory diagram of the reed valve device.

FIG. 4 is an explanatory view in cross section of the reed valve device of FIG. 3;

FIG. 5 is an explanatory view of a reed valve body, and is a cross-sectional view taken along line VV of FIG. 6;

FIG. 6 is an explanatory view of the reed valve body as viewed from an intake inflow side.

FIG. 7 is an explanatory view of a reed valve body, and is a detailed view of a portion indicated by VII in FIG. 5;

FIG. 8 is an explanatory diagram of an example of a conventional reed valve device.

FIG. 9 is an explanatory view of another example of the conventional reed valve device.
(A) is a diagram in which the intake pipe is close to a straight line, and (b) is a diagram in which the intake pipe is bent.

[Explanation of symbols]

 Reference Signs List 10 engine case 12 reed valve device 14 carburetor 16 air cleaner 26 valve body 26a reed valve mounting surface 28 reed valve 30 intake pipe 32 window 40 partition plate 40a partition plate upstream end

Claims (1)

[Claims] 1. A carburetor and a reed valve device for fixing one end of a resilient reed valve to a valve body forming a part of an intake passage so as to prevent intake air from flowing back in the direction of the carburetor by operation of the reed valve. In a two-stroke engine intake passage in which the intake pipe is bent and the intake pipe is bent, the valve body faces the downstream side in the intake flow direction and is inclined with respect to the flow direction. Three or more windows through which air passes are formed on the surface, and a reed valve is provided corresponding to each window, and a partition plate for partitioning adjacent windows toward the upstream side in the intake passage of the valve body. While two or more are formed, the respective distances from the carburetor mounting surface of the intake pipe to the upstream ends of the respective partition plates in the valve body are substantially the same length. Reed valve device of a two-stroke engine, wherein the door.