JPH09209768A - Reed valve device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten a function as the reed valve of an engine, particularly operate excellently even at a low speed time in which intake negative pressure is small so as to secure low speed performance, and simultaneously heighten following characteristics at a high speed time, and heighten limit number of revolutions. SOLUTION: A reed valve 5 is equipped with a reed valve body 6, and a reed valve plate 10 the base end of which is fixed to the reed valve body 6 in a state where the valve opening 6a is covered. The reed valve plate 10 is so formed as the thickness of the tip side thereof is thin, the thickness is gradually increased from the rip to the intermediate portion, the thickness of the intermediate portion and a portion to the base end therefrom is thick, and in the vicinity of the base end a low stiffness portion composed of a slit 13 and the like exist.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reed valve device provided in an intake passage of an engine and opened / closed according to the operation of the engine.

[0002]

2. Description of the Related Art Conventionally, in a two-cycle engine or the like, a reed valve that opens and closes according to the operation of the engine is provided in an intake passage communicating with a crankcase of the engine, and intake is performed through the reed valve. Those that have been done are generally known. In addition to this, there is also an intake system of a two-cycle engine in which intake is performed through a rotary valve that rotates in synchronization with the engine. Therefore, it is difficult to change the opening / closing timing, and it is not always possible to obtain the opening / closing timing adapted to various operating conditions. On the other hand, when a reed valve is used, it opens and closes in response to pressure fluctuations in the crankcase, etc., so the opening and closing timing changes depending on the engine speed, etc., and it is expected that the opening and closing timing suited to the operating conditions will be obtained. .

The reed valve device has a reed valve body having a valve opening and a reed valve plate whose base end is fixed to the reed valve body so as to cover the valve opening. The reed valve body is fixed to the communicating intake passage.

In such a reed valve device, the reed valve plate is made of resin, as disclosed in Japanese Utility Model Laid-Open No. 62-190175, for example, in order to improve followability and durability. In some cases, the reed valve plate tip portion that abuts the valve seat on the tip side of the valve port is formed thick, and the reed valve plate from the base end portion to the thick portion is thinly ground. According to this reed valve device, most of the reed valve plate is made thin and light in weight, so that responsiveness is improved and damage to the tip of the reed valve plate that contacts the valve seat is prevented.

[0005]

By the way, the reed valve device of this type needs to satisfy the responsiveness and the followability to the operation of the engine from the low speed region to the high speed region of the engine. Especially when it is applied to a small model engine such as a model helicopter or a model airplane, in order to ensure low-speed performance, it operates well at low speed,
In order to increase the torque, it is required to improve the followability at high speed and increase the limit rotational speed, but the following problems remain in response to such a demand.

That is, since the suction negative pressure acting on the reed valve plate is relatively small when the engine speed is low, it is preferable that the reed valve plate be thin and flexible in order to operate the reed valve favorably at low speed. , Like this,
At high engine speeds, the suction negative pressure increases and the valve opening / closing operation speed increases, which causes a so-called waviness in which the reed valve plate bends and deforms into a wavy shape during operation, resulting in poor followability and closing operation. The engine output cannot be increased because the air-fuel mixture is blown back due to the delay. Therefore, it is difficult to increase the limit rotation speed. On the other hand, in order to suppress such waviness and improve followability at high speed,
Although it is necessary to make the reed valve plate thicker and stiffer, this makes it difficult to open the reed valve plate at low speed when the suction negative pressure is small, and the low speed performance is impaired.

As described above, when the conventional reed valve device is used over a wide range of rotational speeds, it is difficult to achieve both low speed operability and high speed followability. Even the structure shown could not be fully resolved. Recently, a reed valve has been developed that uses FRP (fiber reinforced plastic) as a material to improve the followability, but even with this FRP, the limit speed is 15,000 rpm. This is a degree, and further improvement of the limit rotational speed is required for small model engines.

In view of the above-mentioned circumstances, the present invention is capable of ensuring good low speed performance by operating well even at low speed when the suction negative pressure is small, while at the same time improving the followability at high speed and increasing the limit rotational speed. It is an object of the present invention to provide an engine reed valve device capable of achieving the above.

[0009]

To achieve the above object, the present invention provides a reed valve body having a valve opening, and a reed valve having a base end fixed to the reed valve body in a state of covering the valve opening. A reed valve device having a plate attached to an intake passage of an engine so that the reed valve plate opens and closes a valve opening according to the operation of the engine. The rigidity of the side is low, and the rigidity gradually increases from the tip to the middle part, and the rigidity is a certain high in the middle part and the part near the base end, and in the vicinity of the base end, the rigidity is lower than the middle part. It was done.

According to this structure, the tip end side of the reed valve plate becomes supple, so that the tip end side of the reed valve plate can be properly opened and closed according to the pressure fluctuation even when the engine speed is low when the suction negative pressure is small. Also, at high engine speeds, the vicinity of the base end portion bends greatly in response to the suction negative pressure, and almost all of the reed valve plate opens and closes. The valve is prevented from being bent in a wavy shape during operation, and the followability is enhanced.

In the present invention, the reed valve plate has a thin wall thickness on the front end side, and the wall thickness gradually increases from the front end to the middle portion, and the middle portion and the portion near the base end become thicker. It may be formed so as to have a low-rigidity portion having a shape that reduces rigidity near the end.

In the present invention, the low-rigidity portion near the base end portion of the reed valve plate is formed by, for example, providing a groove extending in the width direction of the reed valve plate, or near the base end portion of the reed valve plate. It may be formed by forming a hole or by forming a notch near the base end of the reed valve plate.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a state in which a reed valve device according to an embodiment of the present invention is incorporated in a two-cycle engine. In the figure, reference numeral 1 is a crankcase of a two-cycle engine, 2 is an intake passage opening into the crankcase, and a carburetor 3 is assembled on the upstream side of the intake passage 2. A reed valve 5 is incorporated in the intake passage 2 downstream of the carburetor 3.

The reed valve 5 is, as shown in FIG.
It is composed of a reed valve body 6 and a pair of reed valve plates 10. The reed valve body 6 has a substantially V-shaped cross section, valve openings 6a are formed in both inclined wall portions of the reed valve body 6, and a flange portion 6b is provided on the base end side. The flange portion 6b is a passage of the intake passage 2. It is attached to the wall with bolts 7 etc. Further, the pair of reed valve plates 10 are located outside both inclined wall portions of the reed valve body 6, and the valve opening 6a is formed.
The base end of the reed valve body 6 with screws 8 etc.
Attached to. In addition, 81 is a screw insertion hole provided in the base end part of the reed valve plate 10, and 82 is a screw hole provided in the reed valve body 6.

In the example shown in FIG. 2, the reed valve 5 is a six-leaf type. That is, three valve openings 6a are provided in parallel on both inclined wall portions of the reed valve body 6, and correspondingly, the pair of reed valve plates 10 are respectively provided with three pieces arranged in parallel. Has a structure that is connected at the base end.

A stopper 9 is formed on the inner wall surface of the intake passage 2 at a position corresponding to each piece of the reed valve plate 10.

The reed valve plate 10 has low rigidity on the distal end side and gradually increases rigidity from the distal end to the intermediate portion, and has a predetermined high rigidity in the intermediate portion and a portion near the proximal end, and the proximal end portion. In the vicinity, it is formed so as to have lower rigidity than the intermediate portion. In this embodiment, the reed valve plate 10 is made of synthetic resin, and the rigidity is changed as described above by changing the wall thickness of each part as shown in FIG.

That is, in the portion 11 (hereinafter referred to as the tip side portion) on the tip side from the predetermined position in the intermediate portion of the reed valve plate 10, one surface (front side) is an inclined surface, so that the wall thickness of the tip is The thickness is the thinnest and gradually changes so as to become the maximum at a predetermined position in the middle portion. Further, a portion 12 (hereinafter, referred to as a portion near the base end), which is on the base end side from the predetermined position of the intermediate portion and excluding the vicinity of the base end portion, has a substantially constant thickness corresponding to the maximum thickness. . A low-rigidity portion is formed by providing a groove 13 having an arcuate cross-section extending in the width direction of the reed valve plate near the base end portion.

Of the above-mentioned tip end side portion 11, the portion near the tip end is supple enough to bend in the valve opening direction even with a relatively small negative pressure during idle operation of the engine. The material and the wall thickness of each portion of the reed valve plate are set so that the lean portion 12 has a sufficiently high rigidity.

The operation of the reed valve device of this embodiment as described above will be described below.

During operation of the engine, the pressure in the crankcase fluctuates according to the vertical movement of the piston and the like, and the reed valve plate 10 opens and closes according to the pressure fluctuation. That is, the reed valve plate 10 is opened when the inside of the crankcase 1 has a negative pressure (see FIG. 4), and is closed when the pressure inside the crankcase 1 becomes high.

By the way, when the engine is rotating at a low speed, the suction negative pressure acting on the reed valve plate 10 is small, but the thickness of the tip side portion 11 of the reed valve plate 10 is thinner toward the tip, and the portion near the tip is supple. Therefore, the tip end side portion 11 bends in the valve opening direction (two-dot chain line in FIG. 4) even with a small suction negative pressure during low speed rotation, and the opening / closing operation according to the pressure fluctuation is favorably performed. .

As described above, when the suction negative pressure is small, the distal end side portion 11 mainly bends, but the low rigidity portion near the base end portion where the groove 13 is formed also bends to some extent according to the suction negative pressure. As the suction negative pressure increases, the degree of bending near the base end increases.

At the time of high-speed rotation, a large suction negative pressure acts on the reed valve plate 10, so that the low-rigidity portion near the base end portion largely bends, and substantially the entire reed valve plate 10 contacts the stopper 9. Such a state is opened (solid line in FIG. 4), and substantially the entire reed valve plate 10 is opened / closed according to the pressure fluctuation. In this case, since the suction negative pressure becomes large and the reed valve plate 10 is opened and closed at high speed during high-speed rotation, if the reed valve plate 10 is supple, a so-called wavy state in which the reed valve plate 10 is bent and deformed into a wavy shape during operation. Become,
Although the followability to the operation of the engine is deteriorated, since the portion 12 near the base end of the reed valve plate 10 is thick and sufficiently high in rigidity, the above wavy state is suppressed and the followability is improved. Is increased.

As described above, according to the reed valve device of the present embodiment using the reed valve plate 10, the operation performance at low speed rotation is kept good, and the followability at high speed rotation is improved. The limit rotational speed of the reed valve 5 is significantly increased. According to what the inventor confirmed experimentally,
A conventional reed valve (for example, a reed valve plate formed by FRP with a constant thickness) has a limit rotational speed of 15,000 rp.
In contrast to m or less, the reed valve device according to the above-described embodiment was able to increase the limit rotational speed to 20000 rpm or more.

In the device of the present invention, the reed valve 5
Is not limited to the six-leaf type as shown in the above embodiment, and may be, for example, a two-leaf type in which a pair of reed valve plates is provided with one piece or a four-leaf type with two pieces. However, if the number of leaves is increased, it is advantageous in improving followability.

Further, as the low-rigidity portion provided in the vicinity of the base end portion of the reed valve plate 10, the groove 13 having an arcuate cross section is formed in the above embodiment, but the V-shaped groove 13 as shown in FIG.
1. Grooves having various cross-sectional shapes such as a square groove 132 as shown in FIG. 6 can be adopted. Instead of such a groove, a window hole 133 as shown in FIG. 7 and a round hole 134 as shown in FIG.
For example, the low-rigidity portion may be formed by arranging a hole having an arbitrary shape, or the low-rigidity portion may be formed by providing the notch 135 as shown in FIG.

As a shape in which the thickness of the tip side portion 11 of the reed valve plate 10 is gradually changed, the front surface side is an inclined surface in the above embodiment, but the back surface side or the front and back surfaces may be an inclined surface. Instead of such an inclined surface, a gently curved surface or a stepped surface may be formed on one side or both sides.

In the above embodiment, the portion 12 of the reed valve plate 10 near the base end has a substantially constant thickness. However, as shown in FIG. The part 12 near the base end so that the thickness gradually becomes thinner.
1 may be formed, or as shown in FIG. 11, it may be formed so as to extend from the distal end side portion 11 to the proximal end portion 122 and gradually become thicker toward the vicinity of the proximal end portion.

In order to increase the rigidity of the portion near the base end and gradually change the rigidity of the tip end side portion, ribs are provided instead of changing the wall thickness as in the above embodiment. The amount of protrusion, the arrangement, etc. may be changed in each part, or a plurality of types of materials may be joined to change the joining state in each part.

Further, when the reed valve device of the present invention is applied to a small single-cylinder two-cycle engine used for a model helicopter, a model airplane, etc., low speed performance can be ensured and a limit rotational speed can be increased. It has a great effect in that it can generate torque, etc., but it can also be applied to two-cycle engines for motorcycles, etc., and can also be applied to four-cycle engines, etc., as long as it has a reed valve. Is.

[0032]

As described above, according to the present invention, the rigidity of the reed valve plate in the reed valve device of the engine is low on the tip side and gradually increases from the front end to the middle portion, and the middle portion and the portion closer to the base end. Since it is formed to have a predetermined high rigidity and lower rigidity in the vicinity of the base end part than in the middle part, the tip side of the reed valve plate becomes supple, and even at low engine speeds with low suction negative pressure Respond and again
At the time of high engine speed in which the suction negative pressure increases, the vicinity of the base end portion of the reed valve plate is largely bent, and the intermediate portion has a relatively large rigidity, so that the followability on the engine high speed side can be improved. Therefore, it is possible to increase the limit rotational speed while ensuring the low speed performance of the engine.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a state in which a reed valve device according to an embodiment of the present invention is installed in an intake passage.

FIG. 2 is an exploded perspective view of a reed valve.

FIG. 3 is an enlarged sectional view of a reed valve plate.

FIG. 4 is a sectional view of the reed valve in an open state.

FIG. 5 is a partially cutaway perspective view showing a second embodiment of a reed valve plate.

FIG. 6 is a partially cutaway perspective view showing a third embodiment of a reed valve plate.

FIG. 7 is a partially cutaway perspective view showing a fourth embodiment of a reed valve plate.

FIG. 8 is a partially cutaway perspective view showing a fifth embodiment of a reed valve plate.

FIG. 9 is a partially cutaway perspective view showing a sixth embodiment of a reed valve plate.

FIG. 10 is a partially cutaway perspective view showing a seventh embodiment of a reed valve plate.

FIG. 11 is a partially cutaway perspective view showing an eighth embodiment of a reed valve plate.

[Explanation of symbols]

 5 reed valve 6 reed valve body 10 reed valve plate 11 tip side portion 12 proximal end portion 13 groove provided near the proximal end portion

Claims (5)

[Claims] 1. A reed valve body having a valve opening, and a reed valve plate having a base end fixed to the reed valve body so as to cover the valve opening. The reed valve plate is configured such that the reed valve plate opens and closes the valve opening in accordance with the operation of, and the rigidity of the reed valve plate is low on the tip side and gradually increases from the tip to the intermediate part. The reed valve device for an engine, wherein the intermediate portion and a portion near the base end have a predetermined high rigidity, and the rigidity is lower in the vicinity of the base end than in the intermediate portion. 2. The reed valve plate has a thin wall thickness on the front end side, and the wall thickness gradually increases from the front end to the middle portion, and the middle portion and the portion near the base end become thicker, and the base end portion. The reed valve device for an engine according to claim 1, wherein the reed valve device is formed so as to have a low-rigidity portion having a shape that reduces rigidity in the vicinity thereof. 3. The reed valve device for an engine according to claim 2, wherein a low-rigidity portion is formed by providing a groove extending in the width direction of the reed valve plate near the base end portion of the reed valve plate. . 4. The reed valve device for an engine according to claim 2, wherein a low-rigidity portion is formed by forming a hole in the vicinity of the base end portion of the reed valve plate. 5. The reed valve device for an engine according to claim 2, wherein a low-rigidity portion is formed by providing a notch near the base end of the reed valve plate.