JP2007046483A - Carburetor for stratified scavenging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate a change in valve opening start timing of a scavenging air valve with respect to an opening of a throttle valve in a carburetor for stratified scavenging. <P>SOLUTION: A first lever 8 is fixed to a throttle valve shaft 5a of a throttle valve. A second lever 9 is rotatably provided to the throttle valve shaft. A third lever 10 is fixed to an air valve shaft 7a of an air valve. The second lever and third lever are coupled to each other through the medium of a coupling rod 11. The first lever is provided with an adjustment screw 12 abutted to an engagement piece 9a of the second lever through the rotation in the valve opening direction. The throttle valve opening for starting the opening of the air valve (rotary valve) can be adjusted. By so doing, even if an error in manufacturing caused by independent manufacturing of a carburetor and an engine to be mounted, adjustment can be made after mounting the carburetor in the engine. A carburetor for stratified scavenging with high versatility can be provided at low cost. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stratified scavenging carburetor having a throttle valve as a butterfly valve and a scavenging air valve as a rotary valve.

Conventionally, a stratified scavenging carburetor of a two-cycle engine has been provided with a carburetor throttle valve and a scavenging air control valve (scavenging air valve) for supplying a mixture, and scavenging air at the initial stage of acceleration. In order to avoid acceleration failure due to the dilution of the air-fuel mixture due to the introduction of the air-fuel mixture, there is a structure in which a phase is provided in conjunction with the throttle valve and the scavenging air valve (see, for example, Patent Document 1). .
JP 2000-186559 A

  In order to provide a phase (a delay in starting the opening of the air valve) in the opening timing between the two valves in the stratified scavenging carburetor (the opening start timing of the air valve with respect to the opening of the throttle valve), the conventional structure is shown In the thing of patent document 1, the gear was used or the play of a lever and a lever was used. However, in such a structure, only one phase can be handled, and if it is better to control the product with a phase different from the design phase, it is necessary to change the phase by performing component replacement or reassembly. There was a problem that there was.

  In order to solve such a problem and to make it possible to easily change the opening timing of the scavenging air valve relative to the opening of the throttle valve in the stratified scavenging carburetor, in the present invention, In the stratified scavenging carburetor, the throttle valve that opens and closes the mixture passage for sending the mixture is a butterfly valve, and the scavenging air valve that opens and closes the air passage for sending the scavenging air is a rotary valve. An interlocking mechanism is provided between the two valves for interlocking and opening the first lever fixed to the throttle valve shaft that supports the butterfly valve, and coaxially to the throttle valve shaft. A second lever rotatably supported; a third lever fixed to an air valve shaft that supports the rotary valve; and a connecting rod that connects the second lever and the third lever. An interlock provided between the first lever and the second lever to adjust the predetermined opening so that the rotary valve starts to open after the butterfly valve opens to the predetermined opening. The opening degree adjusting means and a return spring that elastically urges the third lever to the fully closed position of the rotary valve are provided.

  In particular, the interlock start opening adjusting means is supported by the first lever so that the second lever can be rotated by the rotational force of the first lever so as to be able to be screwed and unscrewed, and hits a part of the second lever. It is preferable to have an adjusting screw provided so that it can contact.

  Thus, according to the present invention, the butterfly valve has a large change rate of the opening area with respect to the opening change in the low opening range, and the rotary valve has a change in opening in the low opening range. The change rate of the opening area with respect to the opening change is contradictory in both valves, that is, the change rate of the opening area with respect to the opening is small, but the change rate of the opening area with respect to the opening change is large in the high opening range. In consideration of the above, a stratified scavenging carburetor was constructed in which the throttle valve was a butterfly valve and the scavenging air valve was a rotary valve, and both valves were linked. As a result, the effect of the scavenging air is reduced during low-speed rotation of the engine and the low-speed rotation and acceleration operation are stabilized, and the rate of change of the area with respect to the opening change of the butterfly valve that controls the air-fuel mixture is small during high-speed rotation of the engine. Because the change in the opening area of the rotary valve that controls the scavenging air is larger than the change in the opening, the supply amount of the scavenging air is larger than the supply amount of air-fuel mixture. Air can be supplied.

  Then, as an interlocking opening degree adjusting means for interlocking mechanism that interlocks the opening of both valves, a first lever is provided integrally with the throttle valve shaft, a second lever is provided rotatably, and a third lever is integrated with the air valve shaft. A lever is provided, the third lever and the second lever are connected by a connecting rod, and the second lever starts to be interlocked by opening the throttle valve (butterfly valve) between the first lever and the second lever. By providing the mechanism for adjusting the opening position of the valve, the opening degree of the throttle valve that starts opening the air valve (rotary valve) can be adjusted. As a result, even if production errors occur due to the separate production between the carburetor and the engine to be installed, it can be adjusted after the carburetor is installed in the engine, making it a highly versatile laminar scavenging A vaporizer can be provided at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a fragmentary sectional side view of a stratified scavenging vaporizer to which the present invention is applied. The carburetor 1 is used for an engine 2 of a stratified scavenging two-cycle internal combustion engine, and includes an air-fuel mixture passage 1 a for sending air-fuel mixture to the engine 2 and an air passage 1 b for sending scavenging air to the engine 2. And have. The passages 1a and 1b extend in parallel with each other, and an air cleaner 3 is disposed on the upstream side thereof.

  A choke valve 4 and a throttle valve 5 are arranged in this order from the upstream side of the air-fuel mixture passage 1a, and a fuel nozzle port 6 is provided between the valves 4 and 5. A scavenging air valve 7 is provided in the air passage 1b. As shown in the figure, the throttle valve 5 comprises a butterfly valve in which a disc-like valve body 5b is fixed to a throttle valve shaft 5a provided so as to cross the air-fuel mixture passage 1a in the radial direction. Is provided integrally with a cylindrical valve body 7b that is coaxial with an air valve shaft 7a provided parallel to the throttle valve shaft 5a and along the radial direction of the air passage 1b having a circular cross section, and that crosses the air passage 1b. It consists of a rotary valve in which a radial through hole 7d is provided in the valve body 7b to open and close the air passage 1b by rotation of 7b.

  As shown in FIG. 2 showing the appearance of the vaporizer 1 and FIG. 3 as viewed along the line III-III in FIG. 2, the axial centers of the throttle valve shaft 5a and the air valve shaft 7a are parallel to each other. It is provided so as to extend, and one end in the axial direction of both valve shafts 5 a and 7 a protrudes outward on the same side of the vaporizer 1. A first lever 8 extending radially outward is fixed to the protruding end of the throttle valve shaft 5a, and a third lever 10 extending radially outward is also fixed to the protruding end of the air valve shaft 7a. Has been. Further, a second lever 9 is provided on the throttle valve shaft 5a so as to be coaxial and relatively rotatable. The second lever 9 and the third lever 10 are connected via a connecting rod 11.

  The first lever 8 is provided with a screw support portion 8a formed by bending a part of the first lever 8 so as to be substantially parallel to the throttle valve shaft 5a. The screw support portion 8a has an adjustment screw 12 to some extent. It is supported in a screwed state. A compression coil spring 13 is coaxially interposed between the head of the adjustment screw 12 and the screw support portion 8a, so that the adjustment screw 12 is set at an arbitrary position where the adjustment screw 12 is screwed back. It can be stopped without any hesitation. The tip of the adjustment screw 12 can be engaged with an engagement piece 9a formed by extending a part of the second lever 9 outward in the radial direction. The abutment direction is such that when the throttle valve 5 is rotated in the valve opening direction indicated by the arrow A in FIG. 2, the engagement piece 9 a is pushed and the second lever 9 is integrated with the first lever 8. This is the direction to be interlocked (rotated) with. In this way, the opening degree adjusting means is configured.

  1 to 3 show the fully opened state of the throttle valve 5. In the state shown in FIGS. 1 to 3, the first lever 8 is formed to extend outward in a radial direction different from the lever body. The fully arm 8b is in contact with a protruding stopper 1c formed on the body of the vaporizer 1.

  Further, as shown in FIG. 3, a throttle lever 14 to which a throttle wire for remote operation (not shown) is connected is fixed to an axial end opposite to the first lever 8 side of the throttle valve shaft 5a. . A return spring 17 that elastically biases the throttle valve shaft 5a to the fully closed position is interposed in a portion of the throttle valve shaft 5a exposed from the vaporizer body to the first lever 8 side.

  Further, a return spring 15 is provided between the third lever 10 and the rotary valve case 7c which is a part of the body of the carburetor 1 to elastically bias the air valve shaft 7a in the fully closed direction of the air valve 7. It is disguised. Thereby, the valve body 7b of the air valve 7 is always elastically biased toward the fully closed position that shields the air passage 1b.

  FIG. 4 and FIG. 5 show the throttle valve 5 and the scavenging air valve 7 in the fully closed state before engine operation. 4 corresponds to FIG. 2 and FIG. 5 corresponds to FIG. 1, and the same reference numerals are given to the same parts as in the illustrated example, and detailed description thereof will be omitted.

  In the fully closed state, as described above, the return spring 17 returns the valve body 5b of the throttle valve 5 to the position where the mixture passage 1a is shielded. Although FIG. 5 shows a state where the valve body 5b is completely shielded, the opening at the time of idling is at a predetermined position of the body of the vaporizer 1 as shown in FIGS. It can be adjusted by a screwed idle opening adjusting screw 16.

  A tapered surface 16a is provided at a portion between the head portion and the threaded portion of the idle opening adjusting screw 16 so that the arm 8b of the first lever 8 contacts the tapered surface 16a when the throttle valve 5 is idling. It has become. When the idle opening adjusting screw 16 is screwed back, the position of the taper surface 16a that contacts the arm 8b is displaced in the radial direction. Accordingly, the arm as shown by the arrow B in FIG. 4 corresponds to the deviation in the radial direction. 8b rotates, and the opening degree of the throttle valve 5 changes accordingly. Thus, the opening degree of the throttle valve 5 at the time of idling can be adjusted.

  In the fully closed state, in the illustrated example, the tip of the adjustment screw 12 and the engagement piece 9a are separated. When the valve body 5b is opened in the fully open direction by operating the throttle lever 14 from the fully closed state, the first lever 8 rotates in the direction of arrow A in FIG. Then, when the first lever 8 rotates to the position shown in FIG. 6, the tip of the adjusting screw 12 that is integrally displaced comes into contact with the engagement piece 9 a of the second lever 9. The opening of the throttle valve 5 at this time is, for example, 30 degrees, and FIG. 7 shows the opened state. In this state, the tip end of the adjusting screw 12 has just abutted against the engagement piece 9a, the second lever 9 has not yet started rotating, and the valve body 7b is elastically biased to the fully closed position by the return spring 15. As shown in FIG. 7, the air valve 7 is in a fully closed state. The opening degree of the throttle valve 5 in this state may be, for example, 30 degrees.

  When the throttle valve 5 is further opened from the state shown in FIGS. 6 and 7, the tip of the adjustment screw 12 continues to contact the engagement piece 9a as the first lever 8 rotates until the throttle valve 5 is fully opened. The second lever 9 rotates in the direction indicated by the arrow A in FIG. Then, the connecting rod 11 connected to the second lever 9 is pulled in the direction indicated by the arrow B in FIG. 6, and the third lever 10 is directed in the direction indicated by the arrow C against the spring force of the return spring 15. And the air valve 7 is opened. The change in the opening degree relative to the opening degree of the throttle valve 5 after the air valve 7 starts to open is due to the link mechanism between the levers 9 and 10 and the connecting rod 11. The interlocking mechanism is not limited to the link mechanism shown in the drawing, and may be a transmission mechanism using gears or a timing belt.

  FIG. 8 shows the characteristics of the opening area with respect to the opening degree in the carburetor having this structure. As shown in the figure, in the low opening range, the opening area of the scavenging air valve 7 is zero until the opening is about 30 degrees, and the valve starts to open after the opening is exceeded. . As a result, the supply of scavenging air in the low opening range is stopped, so that operation with a richer air-fuel mixture can be performed, and in the high opening range, the characteristics of the rotary valve are utilized, Then, since the increasing rate of the opening area of the scavenging air valve 7 is larger than that of the butterfly valve, it is possible to supply a large amount of scavenging air corresponding to the opening change of the throttle valve 5, Blow-through to the exhaust port can be prevented. In this way, when it is desired to stop the supply of scavenging air to a predetermined valve opening angle, the design and manufacture of such a carburetor is facilitated and the interlock start position after assembly can be adjusted as described above. Therefore, even if a manufacturing error occurs between the engine 2 and the carburetor 1, an opening characteristic as designed can be obtained.

It is a principal part fracture side sectional view of a layered scavenging vaporizer to which the present invention was applied. It is a figure which shows the mechanism of the outer surface of the vaporizer | carburetor of FIG. It is the principal part fracture | rupture side view seen along the arrow III-III line | wire of FIG. It is a figure corresponding to FIG. 2 which shows the fully closed state of a throttle valve. It is a figure corresponding to FIG. 1 which shows the fully closed state of a throttle valve. It is a figure corresponding to Drawing 4 which shows the state where the throttle valve opened about 30 degrees. It is a figure corresponding to Drawing 5 which shows the state where the throttle valve opened about 30 degrees. It is a figure which shows the change of the opening area with respect to the opening degree of a throttle valve and the scavenging air valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 carburetor 2 engine 5 throttle valve, 5a throttle valve shaft, 5b valve body 7 scavenging air valve, 7a air valve shaft, 7b valve body 8 1st lever, 8a screw support part, 8b arm 9 2nd lever, 9a Joint 10 Third lever 11 Connecting rod 15 Return spring

Claims (2)

In the stratified scavenging carburetor, the throttle valve that opens and closes the mixture passage for sending the mixture is a butterfly valve, and the scavenging air valve that opens and closes the air passage for sending the scavenging air is a rotary valve. In order to open and close in conjunction with each other, a linkage mechanism is provided between the two valves,
The interlock mechanism includes a first lever fixed to a throttle valve shaft that supports the butterfly valve, a second lever that is coaxially and rotatably supported on the throttle valve shaft, and an air valve that supports the rotary valve. A third lever fixed to the shaft, a connecting rod that connects the second lever and the third lever, and the rotary valve starts to open after the butterfly valve opens to a predetermined opening degree. In order to adjust the predetermined opening, the interlock start opening adjusting means provided between the first lever and the second lever, and the third lever are elastically applied to the fully closed position of the rotary valve. A stratified scavenging vaporizer comprising a return spring for biasing.   The interlock start opening adjusting means is supported by the first lever so that the second lever can be rotated by the rotational force of the first lever so that the second lever can be screwed and unscrewed, and can be in contact with a part of the second lever. The stratified scavenging carburetor according to claim 1, further comprising an adjusting screw provided as described above.

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