JP2001182617A - Air cleaner and rotary opening and closing valve for two-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple, compact and low-cost opening and closing valve, such as a choke valve, with improved operativity for a two-cycle engine for supplying thick air-fuel mixture for a combustion chamber and for producing high negative pressure at the start. SOLUTION: This two-cycle engine comprises: an air supply passage for transmitting scavenging air from an air cleaner to a scavenging passage; and an air-fuel mixture supply passage for transmitting air-fuel mixture generated at a carburetor to a crank chamber. The air cleaner comprises: a first air passage communicating with the air supply passage; a second air passage connected with an air intake of the carburetor for supplying air to the carburetor so as to generate air-fuel mixture; and a choke valve for opening and dosing the first and second air passages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air supply passage connected to a scavenging passage that connects a scavenging port and a crank chamber and supplying scavenging air from an air cleaner to the scavenging passage, and an air supply passage formed by a carburetor. The present invention relates to an air cleaner device in a two-stroke engine provided with a mixture supply path for supplying the mixture mixture to the crank chamber and a rotary on-off valve used for a choke valve of the air cleaner.

[0002]

2. Description of the Related Art In a stratified scavenging two-cycle engine, a scavenging passage communicating between a scavenging port provided in a cylinder side and a crank chamber, and scavenging air from an air cleaner connected in the middle of the scavenging passage are provided. An air supply passage for supplying the scavenging passage, and a mixture supplying passage for supplying the mixture generated by the carburetor to the crank chamber; prior to supplying the mixture to the combustion chamber from the scavenging port, The leading air filtered by the air cleaner is introduced into the combustion chamber through the air supply passage, the scavenging passage and the scavenging port to perform a scavenging action, thereby improving scavenging efficiency and combustion efficiency.

Such a stratified scavenging two-cycle engine is disclosed in JP-A-9-125966 and JP-A-10-2525.
Inventions such as No. 65 are provided. JP-A-9-1259
In the invention of No. 66, two air cleaners are provided,
The outlet of one of the air cleaners is connected to a mixture supply passage through a carburetor, and the outlet of the other air cleaner is connected to an air supply passage for supplying leading air to a scavenging passage via an air control valve.

Further, in the invention of Japanese Patent Application Laid-Open No. Hei 10-252565, a mixture supply path for supplying mixture from a carburetor to a crank chamber and an air supply path for supplying leading air to a scavenging path are arranged in parallel. The air inlet of the carburetor and the inlet of the air supply path are directly connected to the air outlet of the air cleaner.

[0005]

In such a stratified scavenging two-stroke engine, when starting, the amount of air passing through the air supply passage is limited and the negative pressure is increased, so that the combustion proceeds from the mixture supply passage through the crank chamber and the scavenging passage. By increasing the amount of air-fuel mixture supplied to the chamber to a rich mixing ratio,
It is required to improve the startability.

However, in the invention of Japanese Patent Application Laid-Open No. 9-125966, the air supply valve is closed at the start to shut off the air supply passage, and the air passage on the carburetor side is opened to supply the mixture from the carburetor to the mixture supply passage. Although it is possible to increase the air-fuel mixture to achieve a rich mixture ratio, it is necessary to equip two air cleaners, and there is a problem that the structure becomes complicated and large, and the equipment cost increases. .

In the invention of Japanese Patent Application Laid-Open No. 10-252565, the air inlet of the carburetor and the inlet of the air supply path are directly connected to the air outlet of the air cleaner. It is difficult to completely shut off the air flowing to the side, that is, the air supply path side. For this reason, in such an invention, there is a problem that it is not possible to supply an air-fuel mixture of a rich mixture ratio to the combustion chamber, and it is difficult to obtain a high negative pressure. .

Further, in the above-described prior art, the choke valve that closes the air supply passage when the engine is started generally rotates an oscillating choke valve around a valve axis. When working in connection with a working machine such as a bush cutter, the operation lever of the choke valve interferes with the start operation by the recoil starter, and the swing radius of the operation lever is large and it is difficult to operate. This leads to reduced operability.

The present invention has been made in view of the problems of the prior art,
Simple and compact in a two-stroke engine,
It is a first object of the present invention to improve startability by enabling a mixture of a rich mixture ratio to be supplied to a combustion chamber at the time of starting and obtaining a high negative pressure by a low-cost structure.

It is another object of the present invention to provide an on-off valve such as a choke valve having a simple and compact structure and improved operability.

[0011]

According to the present invention, there is provided a scavenging passage which connects a scavenging port provided in a cylinder side portion to a crank chamber, and a scavenging passage for the scavenging passage. An air supply passage connected midway to supply scavenging air from the air cleaner to the scavenging passage;
A two-stroke engine including a mixture supply passage for supplying the mixture generated by the carburetor to the crank chamber.
The air cleaner is connected to a first air supply passage.
And a second air passage connected to an air inlet of the carburetor and supplying the air for generating the air-fuel mixture to the carburetor is arranged in parallel, and a first air passage of the air cleaner and An air cleaner device for a two-cycle engine, comprising: a choke valve that opens and closes a second air passage.

The inventions according to claims 2 to 6 relate to a specific structure of the choke valve according to the invention, and the invention according to claim 2 is
2. The choke valve according to claim 1, wherein the choke valve is a rotary valve body that opens and closes an inlet opening of each of the first air passage and the second air passage by rotation, and a rotary knob for rotating the valve body. And characterized in that:

According to a third aspect of the present invention, in the second aspect, the choke valve has the valve body rotatably fitted to a case portion of the air cleaner, and a tip end surface of the choke valve is the first air passage. And a seat surface detachably attached to an inlet opening of the second air passage. A fluid seal inside the air cleaner is formed around the shaft of the valve body, and the seat of the valve body is elastically resilient. A seal ring made of an elastic body that presses a surface against the entrance opening is inserted.

According to a fourth aspect of the present invention, in the third aspect, the case portion of the air cleaner is formed with a stopper projection protruding from an outer surface of the case portion, and the rotary knob of the choke valve is provided with an elasticity of the seal ring. The seal ring is configured to be able to rotate over the protrusion, to be restored by the elasticity of the seal ring, and to be locked to a portion of the outer surface of the case portion where the protrusion is not provided.

According to a fifth aspect of the present invention, in the third aspect, a protrusion having a tapered surface is formed on an inner surface of the case portion of the air cleaner, and the rotation knob of the choke valve rides on the protrusion. The seat surface of the valve body is configured to be pressed against an inlet opening of the first air passage or the second air passage.

According to this invention, when the engine is started, the rotary knob of the choke valve is rotated to rotate the rotary valve body, thereby the second air of the air cleaner connected to the air inlet of the carburetor. The engine is started by fully closing the passage and opening only the choke hole and fully closing the first air passage of the air cleaner connected to the air supply passage for leading air supply. By this operation, the air from the air cleaner is supplied to the carburetor through the second air passage narrowed by the choke hole, and a mixture is formed in the carburetor.
The gas is supplied into the combustion chamber via a scavenging passage and a scavenging port.

At this time, since the first air passage of the air cleaner is completely closed by the choke valve,
The supply of the leading air into the combustion chamber is cut off, and only the air-fuel mixture from the vaporizer is supplied, so that the air-fuel mixture having a rich mixture ratio can be charged into the combustion chamber. Thereby, the startability of the engine is improved.

Further, the choke valve is formed so that the seat surfaces of the rotary valve body are respectively attached to and detached from the inlet openings of the two air passages. Since the seat surface is pressed against the inlet opening by the elasticity of a seal ring such as an O-ring inserted into the outer periphery of the shaft of the valve body, the choke valve causes the inlet opening of the air passage on the leading air side to move. As a result, the air-fuel mixture is reliably closed to maintain the above-described rich air-fuel mixture forming operation, and a high negative pressure can be maintained.

Further, according to the third and fourth aspects of the present invention, since the seal ring as described above is provided and a stopper projection is provided on the outer surface of the case portion of the air cleaner, the starting of the choke valve is started. When the two air passages are switched by rotation from the position to the normal operation position, the rotary knob of the choke valve can be easily rotated over the protrusion against the elasticity of the seal ring, and can be appropriately rotated. A friction force is added to improve the operational feeling of the choke valve, and when the choke valve is released, the choke valve is automatically moved to a portion of the outer surface of the case portion having no protrusion by the elasticity of the seal ring and the stopper function of the protrusion. In this way, the return can be prevented and locking can be achieved, and high operability can be obtained.

Further, when the choke valve is rotated in the direction of the starting position, a projection having a tapered surface is formed on the inner surface of the case portion of the air cleaner. When the knob rides on the projection, the seat surface of the valve body is pressed against the inlet opening of the leading air passage by the elasticity generated by the bending of the valve body itself, so that the sealing property of the seat surface is improved, and In addition, the startability can be improved.

The invention according to claim 6 relates to the invention of a rotary on-off valve applied to the choke valve according to any one of claims 1 to 5, wherein the rotary on-off valve is rotatably fitted to a case by rotation. A rotary valve body for opening and closing the two passages provided in the case, and a rotary knob for rotating the valve body, and a tip end surface of the valve body is provided at an inlet opening of the two passages. A seal formed of an elastic body which is formed on a seat surface to be detached and attached to the shaft portion of the valve body and forms a fluid seal inside the case and presses the seat surface of the valve body against the inlet opening by elasticity. A rotary on-off valve characterized by being fitted with a ring.

The rotary on-off valve having such a configuration is not limited to the choke valve for an air cleaner of an engine as described above, and a rotary knob is rotated to rotate a rotary valve body, and two fluid passages are formed. It can be widely applied to open / close valves that switch between open and closed. .

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and other relative arrangements of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Not just.

FIG. 1 is a cross-sectional view of a structure of an air cleaner device and an intake device of a two-stroke engine according to an embodiment of the present invention, taken along a line perpendicular to the crankshaft center. FIG.
3 is a view taken in the direction of arrows BB in FIG. 1, FIG. 4 is a view taken in the direction of arrows CC in FIG. 2, and FIG. 5 is a cross-sectional view of the air cleaner cover and the choke valve.
FIG. 6 is a view taken in the direction of the arrow D--D in FIG. 5, and FIG.
FIG. 7 is an EE cross-sectional view of FIG.

The two-stroke engine to which the present invention shown in FIG. 1 is applied is configured as follows. Reference numeral 2 denotes a cylinder, and reference numeral 5 denotes a crankcase. The cylinder 2 and the crankcase 5 are fastened by a plurality of bolts via a gasket 05 on their fastening surfaces. 4 is a piston, 3 is a connecting rod, 8 is a spark plug, 1
3 is an exhaust port and 25 is a combustion chamber.

Reference numeral 9 denotes a scavenging port opened to the side of the cylinder 2, and reference numeral 5a denotes a crank chamber formed in the crank case 5. Reference numeral 12 denotes a vaporizer, and reference numeral 30 denotes an insulator interposed between the vaporizer and the cylinder 2. Reference numeral 15 denotes an air-fuel mixture supply passage which can communicate with the crank chamber 5a from the throttle passage of the carburetor 12 through the inside of the insulator 30 and the inside of the cylinder 2. Reference numeral 10 denotes an air supply path, which passes through the inside of the insulator 30 and the check valve 16 from the air passage of the carburetor 12,
The scavenging passage and the scavenging port 9 can communicate with each other. The check valve 16 is a reed valve which is opened and closed by a negative pressure on the scavenging passage side. The above configuration is the same as that of the conventional two-stroke engine.

In the present invention, an air cleaner device and a choke valve used for the same are improved. That is, 1
Reference numeral 00 denotes an air cleaner, which is configured as follows. Reference numeral 101 denotes a cleaner case, which is fixed to the vaporizer 12 by bolts (not shown). A cleaner cover 102 is fixed to the cleaner case 101 by a plurality of bolts 109, and a cleaner element 108 is loaded inside the cleaner case 101.

The cleaner case 101 has two air passages, a first air passage 106 and a second air passage 107.
Are juxtaposed. The first air passage 106 is connected to the air supply passage 10 having the check valve 16, and the second air passage 107 is connected to the mixture supply passage 15. 1
Reference numeral 20 denotes the first air passage 106 and the second air passage 107
This is a choke valve that switches the opening and closing of the valve, and is configured as follows.

1 to 7, reference numeral 104 denotes a first valve body 10.
4a and a second valve body 104b.
The cleaner cover 102 is rotatably fitted in a hole formed in a substantially central portion thereof, and the inlet openings of the first air passage 106 and the second air passage 107 are connected to a first valve body 104a and a second valve body. 104b. Reference numeral 103 denotes a rotary knob for rotating the valve element 104, which is fixed to an end of the valve element 104. Second
A choke hole 150 is formed in the valve body 104b. Further, protruding pieces 151 and 152 are formed integrally with the first valve body 104a and the second valve body 104b on the side opposite to the engine.

The distal end surface of the valve body 104 is formed on a seat surface 110 which is a flat surface which is attached to and detached from the inlet openings of the first air passage 106 and the second air passage 107, respectively. As shown in FIG. 1, the rotation of the valve body 104 causes the first air passage 10 to rotate.
6 and the second air passage 107 are formed in such an outer shape that the inlet opening can be completely closed.

Reference numeral 105 denotes an O-ring fitted on the outer periphery of the shaft portion of the valve body 104.
13 and the step portion 122 of the shaft portion of the valve body 104,
The valve body 104 is compressed so as to be compressible in the axial direction to form a fluid seal inside the air cleaner 100, and the elasticity of the valve body 104 urges the seat surface 110 of the valve body 104 between the first air passage 106 and the second air passage 107. It is pressed against the entrance opening.

As shown in FIG. 2, the rotary knob 103 integrated with the valve body 104 is set so as to be in a normal operation position when rotated about 90 ° clockwise from a start position shown in FIG. ing. Reference numeral 123 denotes a stopper projection protruding from the outer surface of the cleaner cover 102.
As shown in FIGS. 3 to 5, while rotating the rotary knob 103 from the starting position to the normal operation position, the end surface of the rotary knob 103 rotates over the projection 123 against the elasticity of the O-ring 105. The projecting pieces 151 and 152 of the valve element 104 are connected to stopper pieces 153 and 154 shown in FIG.
, Respectively, and is restored to a state before the vehicle gets over by the elasticity of the O-ring 105 so that the cleaner cover 102 can be locked to a portion of the outer surface of the cleaner cover 102 where the protrusion 123 is not provided.

As shown in FIGS. 6 and 7, a projection 111 having a tapered surface 112 is formed on the inner surface of the cleaner cover 102. When the rotary knob 103 is placed at the starting position shown in FIG. 2, the end surface of the rotary knob 103 rides on the tapered surface 112 of the projection 111, and the projection 111 extends the seat surface 110 of the valve body 104 to the first position. The first air passage 106 is configured to be completely closed by being pressed against the inlet opening of the first air passage 106.

In the air cleaner device for a two-stroke engine having such a configuration, when the engine is started, the rotary knob 103 of the choke valve 120 is rotated to a start position (choke position) shown in FIG.
By rotating the rotary valve body 104 fixed to the air inlet, the second air passage 107 connected to the air inlet of the carburetor 12 and the air-fuel mixture supply passage 15 is fully closed (however, the choke hole 150 Only the small holes are open), the first air passage 106 connected to the air supply passage 10 for leading air supply is fully closed, and the engine is started.

By the operation of the choke valve 120, the air filtered by the cleaner element 108 of the air cleaner 100 enters the second air passage 107 through the choke hole 150, and is connected to the second air passage 107 from the second air passage 107. Is supplied to the main nozzle side of the vaporizer 12. Then, in the carburetor 12, an air-fuel mixture is formed by atomizing the fuel in the air, and the air-fuel mixture is supplied to the air-fuel mixture supply path 1
5 through a crank chamber 5a, a scavenging passage and a scavenging port 9, and is supplied into a combustion chamber 25 to ignite and burn,
The engine starts.

At the time of such starting, the air cleaner 10
0 is completely closed by the valve element 104 of the choke valve 120, the first air passage 106
6 and the supply of the leading air through the air supply passage 10 into the combustion chamber is cut off, and only the air-fuel mixture produced in the carburetor 12 by the air which is throttled by the choke hole 150 and passed through the second air passage 107 is cut off. Is supplied. As a result, the air-fuel mixture having a rich mixture ratio can be charged into the combustion chamber 25, and the startability of the engine is improved.

The choke valve 120 is configured such that the seat surface 110 of the rotary valve body 104 is connected to the two air passages 10.
6 and 107 are formed so as to be attached to and detached from the entrance openings, respectively, and the inner surface 113 of the cleaner cover 102 is formed.
Between the valve body 104 and the step 122 of the shaft of the valve body 104.
4 so that it can be compressed in the axial direction.
Since the seat surface 110 of the valve body 104 is pressed against the inlet openings of the first air passage 106 and the second air passage 107 by the elasticity of the O-ring 105 forming an internal fluid seal, the choke valve 120 The inlet opening of the first air passage 106 on the leading air side is securely closed,
The mixture formation effect of the rich mixture ratio as described above is maintained, and a high negative pressure can be maintained.

In addition to the provision of the O-ring 105 and the projection 123 for a stopper projecting from the outer surface of the cleaner cover 102, the choke valve 120 is provided.
When the rotary knob 103 is rotated from the start position to the normal operation position during the switching operation of the two air passages 106 and 107 by rotation from the start position to the normal operation position, the end face of the rotary knob 103 Ring 1
05 can rotate over the protrusion 123 against the elasticity of the choke valve 120, the operational feeling of the choke valve 120 can be improved by adding an appropriate frictional force, and the rotary knob 10
3 release the elasticity of the O-ring 105 and the protrusion 1
By the stopper function of 23, the choke valve 120 can be locked automatically and prevented from returning to a portion of the outer surface of the cleaner cover 102 where there is no protrusion.

When the choke valve 120 is rotated in the direction of the starting position as shown in FIG. 2, the projection 111 having the tapered surface 112 is formed on the inner surface 113 of the cleaner cover 102. When the knob 103 is in the starting position, the end surface of the rotary knob 103 rides on the tapered surface 112 of the projection 111, and the valve body 1
04 is pressed against the inlet opening of the first air passage 106. Thereby, the sealing property of the seat surface 110 of the valve element 104 is improved, and the first air passage 10
6 can be completely closed.

The rotary choke valve 120 having the above configuration is not limited to the above-described choke valve for an air cleaner. It can be widely applied to an on-off valve configured to switch between opening and closing of two fluid passages.

[0041]

As described above, according to the present invention, at the time of starting, the first air passage of the air cleaner is securely completely closed by the choke valve, so that the supply of the leading air into the combustion chamber is prevented. The air-fuel mixture is shut off and only the air-fuel mixture is supplied from the vaporizer, so that the air-fuel mixture having a rich mixture ratio can be charged into the combustion chamber. Thereby, the startability of the engine is improved.

Further, the choke valve is formed such that the seat surface of the rotary valve body is detachably attached to the inlet openings of the two air passages, respectively. Since the seat surface is pressed against the inlet opening by the elasticity of a seal ring such as an O-ring inserted into the outer periphery of the shaft of the valve body, the choke valve causes the inlet opening of the air passage on the leading air side to move. As a result, the air-fuel mixture is reliably closed to maintain the above-described rich air-fuel mixture forming operation, and a high negative pressure can be maintained.

In addition, since the seal ring is provided and the stopper projection is provided on the outer surface of the case portion of the air cleaner as in the third and fourth aspects of the present invention, the choke valve is normally moved from the starting position. When switching between the two air passages by rotation to the operating position, the rotary knob of the choke valve can be easily rotated over the projection against the elasticity of the seal ring,
An appropriate frictional force is added to improve the operational feeling of the choke valve, and when the choke valve is released, the elasticity of the seal ring and the stopper function of the protrusion move the choke valve to a portion on the outer surface of the case portion having no protrusion. The lock can be locked automatically and with return prevented, and operability is improved.

Further, when the choke valve is rotated in the direction of the starting position, a projection having a tapered surface is formed on the inner surface of the case portion of the air cleaner. When the knob rides on the projection, the seat surface of the valve body is pressed against the inlet opening of the leading air passage by the elasticity generated by the bending of the valve body itself, so that the sealing property of the seat surface is improved, and In addition, the startability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a structure of an air cleaner device and an intake device of a two-stroke engine according to an embodiment of the present invention, which is perpendicular to a crankshaft center.

FIG. 2 is a view as viewed in the direction of the arrow A in FIG.

FIG. 3 is a view taken in the direction of arrows BB in FIG. 1;

FIG. 4 is a view taken in the direction of arrows CC in FIG. 2;

FIG. 5 is a sectional view of an air cleaner cover and a choke valve.
FIG. 2 is a detailed view of a portion Z in FIG. 1.

FIG. 6 is a view as viewed in the direction of the arrow DD in FIG. 5;

FIG. 7 is a sectional view taken along the line EE of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 4 Piston 5 Crankcase 5a Crankcase 6 Crankshaft 9 Scavenging port 10 Air supply path 12 Vaporizer 13 Exhaust port 15 Mixture supply path 25 Combustion chamber 30 Insulator 100 Air cleaner 101 Cleaner case 102 Cleaner cover 103 Rotary knob 104 Valve body 105 O-ring 106 First air passage 107 Second air passage 108 Cleaner element 110 Seat surface 111 Projection 112 Tapered surface 120 Choke valve 123 Projection 150 Choke hole

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 35/024 521 F02M 35/024 521Z // F16K 11/074 F16K 11/074 Z

Claims (6)

[Claims] 1. A scavenging passage that connects a scavenging port provided in a cylinder side portion to a crank chamber, and an air supply passage that is connected in the middle of the scavenging passage and supplies scavenging air from an air cleaner to the scavenging passage. And a mixture supply path for supplying a mixture produced by the vaporizer to the crank chamber.
In the cycle engine, the air cleaner includes a first air passage that communicates with the air supply passage, and a second air that is connected to an air inlet of the carburetor and supplies the air for generating the air-fuel mixture to the carburetor. An air cleaner device for a two-stroke engine, comprising: a passage provided in parallel with a choke valve that opens and closes a first air passage and a second air passage of the air cleaner. 2. The choke valve according to claim 1, wherein said choke valve is rotated by said first valve.
2. A rotary valve body for opening and closing the inlet openings of the air passage and the second air passage, respectively, and a rotary knob for rotating the valve body. Air cleaner for two-stroke engines. 3. The choke valve, wherein the valve body is rotatably fitted to a case portion of the air cleaner,
The tip surface is formed on a seat surface which is detachably attached to the inlet openings of the first air passage and the second air passage, and a fluid seal inside the air cleaner is provided on the outer periphery of a shaft portion of the valve body. 3. The air cleaner device for a two-stroke engine according to claim 2, wherein a seal ring made of an elastic body that presses the seat surface of the valve body against the inlet opening by elasticity is inserted. 4. A stopper projection is formed on an outer surface of a case portion of the air cleaner, and a rotary knob of the choke valve rotates over the projection against the elasticity of the seal ring. 4. A structure which is restored by the elasticity of the seal ring and can be locked to a portion of the outer surface of the case portion where the protrusion is not provided.
An air cleaner device for a two-stroke engine according to claim 1. 5. A case having a tapered surface formed on an inner surface of a case portion of the air cleaner. When a rotary knob of the choke valve rides on the protrusion, the seat surface of the valve body is moved to a first air passage. 4. The air cleaner device for a two-stroke engine according to claim 3, wherein the air cleaner device is configured to be pressed against an inlet opening of the second air passage. 6. A rotary valve body rotatably fitted to a case by rotation to open and close two passages provided in the case, and a rotary knob for rotating the valve body. The valve body has a front end surface formed on a seat surface detachably attached to the entrance opening of each of the two passages, and a fluid seal inside the case is formed around the shaft portion of the valve body by elasticity. A rotary on-off valve, wherein a seal ring made of an elastic body that presses a seat surface of the valve body against the inlet opening is inserted.