JP5534513B2 - Two-stroke engine carburetor and method of assembling the valve member to the carburetor body - Google Patents

Description

  The present invention relates to a carburetor of a stratified scavenging type two-stroke engine and a method of assembling the valve member to the carburetor body, and more particularly, it is convenient to be incorporated in a small-sized two-stroke engine mounted on a portable work machine. The carburetor which can be reduced in size and a method for assembling a valve member included in the carburetor.

  Although portable working machines such as chainsaws, mowers, and power blowers are known to carry on the back or on the hand, a small two-stroke engine is generally employed as a drive source. In this type of two-stroke engine, a carburetor is usually incorporated in the intake system.

  Patent Document 1 discloses that a first and second passages are formed by providing a partition wall in a single throttle bore of a carburetor body. This carburetor is incorporated in a stratified scavenging two-stroke engine (Patent Document 2), and an air-fuel mixture is supplied to the engine through a first passage and air is supplied to the engine through a second passage.

  Specifically, the carburetor of Patent Document 1 mainly discloses a carburetor that employs a rotary valve as a throttle valve. The rotary valve has a cylindrical valve body. The cylindrical valve body includes a first opening interposed in the first passage (mixture passage) and a second opening interposed in the second passage (air passage). 2 openings are formed. In the rotary valve, the opening degree of the first passage and the second passage of the vaporizer is controlled simultaneously by rotating the cylindrical valve body.

  Patent Document 1 discloses a carburetor adopting a butterfly valve as a throttle valve in FIG. More specifically, the vaporizer has a partition wall that divides a single hole of the vaporizer body into first and second passages, and the partition wall is fixedly attached to the vaporizer body. .

  First and second butterfly valves are disposed in the first and second passages, respectively. The first and second butterfly valves are supported by a common shaft, and the common shaft is rotated. The first and second butterfly valves can be opened and closed. That is, the common shaft extends through the carburetor body and through the partition wall. The common shaft is rotatably supported by both the vaporizer body and the partition wall. According to this configuration, the first and second butterfly valves can be opened and closed by rotating the common shaft.

  Since the carburetor disclosed in Patent Document 1 described above has first and second passages, the elastic connector disclosed in Patent Document 3 is provided between the carburetor and the engine. Is preferably interposed. The elastic connector of Patent Document 3 is an integrally molded product having first and second passages partitioned by a partition wall and made of an elastic material.

US Patent No. 7,261,281 WO 2008/033062 A1 Publication US 2009/0188461 A1 Publication

  As proposed in Patent Document 1, a partition wall is provided in a single throttle bore of the carburetor body to form the first and second passages. The air passage of the stratified scavenging engine is formed inside the carburetor. Since the increase in size of the carburetor can be suppressed while being incorporated, there is an advantage that the structure around the engine can be simplified. Of course, this advantage can increase the merchantability of the work machine since the work machine on which the engine is mounted is portable.

  The butterfly valve type carburetor has a simple structure, and thus can be reduced in size more easily than the rotary valve type carburetor. The above-described butterfly valve type carburetor disclosed in Patent Document 1 is a concept-level proposal, and in order to put it to practical use, how to use two butterfly valves and a common shaft that supports them is a carburetor. There is a problem of how to adjust the attachment position of the butterfly valve when assembling to the body. In particular, in the structure shown in FIG. 8 of Patent Document 1, it is practically impossible to assemble two butterfly valves and a common shaft in the carburetor body.

  An object of the present invention is to provide a small carburetor mounted on a stratified scavenging two-stroke engine.

  A further object of the present invention is to provide a partition member for partitioning a single throttle bore of the carburetor body into first and second passages, and a butterfly valve is disposed in each of the first and second passages. It is an object of the present invention to provide a carburetor that can easily assemble a partition member and first and second butterfly valves to a carburetor main body and a method for assembling the valve member to the carburetor main body.

  A further object of the present invention is to provide a carburetor capable of adjusting the mounting position of the carburetor body relative to the throttle bore when the partition member and the first and second butterfly valves are assembled, and the assembly of the valve member to the carburetor body. It is to provide a method.

The above technical problem is, according to one aspect of the present invention,
A vaporizer body (2) with a single throttle bore (4);
A shaft (40, 72, 74) extending across the throttle bore (4) and supported on the carburetor body (2) and rotatable about the shaft;
A partition member (10 or 12) disposed in the single throttle bore (4) to partition the air-fuel mixture passage (18) and the air passage (20);
A first butterfly valve (22) disposed in the mixture passage (18);
Wherein a second butterfly valve disposed in the air passage (20) and (24),
In the two-stroke engine carburetor (100) in which the first and second butterfly valves (22, 24) are opened and closed by rotating the shaft (40).
A valve member (34) in which the partition member (10 or 12) and the two butterfly valves (22, 24) are integrated;
An opening (38) formed in the partition member (10 or 12) included in the valve member (34) and through which the shaft can be inserted;
A screw (42) passing through a screw insertion hole (36) formed in one of the two butterfly valves (22, 24) included in the valve member (34);
A screw hole (50) formed in a semicircular section of the shaft (40),
The shaft (40) is inserted into the opening (38) formed in the central portion of the partition member (10 or 12), and the valve member (34) is inserted into the screw hole (50) of the shaft (40). The valve member (34) can be attached to and detached from the shaft (40) by screwing the screw (42) into the screw hole (50) in a state where the screw insertion hole (36) is aligned. Screwed to
By rotating the shaft (40), the partition member (10 or 12) rotates on the same plane around the shaft (40), and the two butterfly valves (22, 24) are respectively the mixture passage (18) is achieved by providing a 2 for stroke engines carburetor characterized by opening and closing the air passage (20).

  That is, according to the present invention, the valve member (34) in which the partition member (10 or 12) and the two butterfly valves (22, 24) are integrated is prepared, and the valve member (34) is connected to the shaft (40, 72, 74), it is possible to secure the assembling property to the vaporizer body (2) by adopting the structure in which the screw is fixed.

  According to a preferred embodiment of the present invention, the diameter of the screw insertion hole (36) is set to be larger than the diameter of the shaft portion of the screw (42), whereby the valve member (34) is connected to the shaft (40, 72). , 74), the mounting position of the valve member (34) can be adjusted with respect to the throttle bore (4) of the carburetor body (2).

The above technical problem is, according to the second aspect of the present invention,
A vaporizer body (2) with a single throttle bore (4);
A shaft (40, 72, 74) extending across the throttle bore (4) and supported on the carburetor body (2) and rotatable about the shaft;
A partition member (10 or 12) disposed in the single throttle bore (4) to partition the air-fuel mixture passage (18) and the air passage (20);
A first butterfly valve (22) disposed in the mixture passage;
Wherein a second butterfly valve disposed in the air passage and (24),
The partition member (10) is connected to the carburetor body (2) of the carburetor (100) for a two-stroke engine in which the first and second butterfly valves (22, 24) are opened and closed by rotating the shaft (40). Or 12) and a method of assembling the first and second butterfly valves (22, 24),
A valve member (34) in which the partition member (10 or 12) and the two butterfly valves (22, 24) are integrated, and the partition member (10 or 12) included in the valve member (34). 12) and through which the shaft (40) can be inserted, and a screw insertion hole (36) formed in one of the two butterfly valves (22, 24) included in the valve member. ) And a screw hole (50) formed in a semicircular section of the shaft (40), and the diameter of the screw insertion hole (36) is the screw (42). Prepare a valve member (34) larger than the diameter of the shaft part ,
A shaft insertion step of inserting the shaft ( 40 ) into the opening (38) formed in the partition member (10 or 12) of the vaporizer body (2);
While positioning the valve member (34) with respect to the single throttle bore (4) using the screw insertion hole (36) having a diameter larger than the diameter of the shaft portion of the screw, the shaft (40, 72, And a valve member fixing step for fixing the valve member (34) with a screw to the semicircular section of the cross section of 74). Is achieved by providing

  In a preferred embodiment of the invention of the second aspect, the valve member (34) is positioned with respect to the single throttle bore (4) in the valve member fixing step.

  The above and other objects and advantages of the present invention will become apparent from the detailed description of the preferred embodiments of the present invention.

It is a perspective view of the vaporizer | carburetor of an Example. It is sectional drawing of the vaporizer | carburetor of FIG. 1, and is the figure cut | disconnected along the plane in which a partition plate is located. It is sectional drawing of the vaporizer | carburetor of FIG. 1, and is the figure cut | disconnected along the air-fuel mixture channel | path. It is sectional drawing which cut | disconnected the vaporizer | carburetor of FIG. 1 along the throttle valve mechanism. It is a figure for demonstrating the extrusion material for making the valve member which consists of a partition plate and the 1st, 2nd butterfly valve plate of an integral structure with this. It is a figure for demonstrating one process which makes a valve member, and is the figure which cut one board surface of the extrusion material, and formed the circular partition plate. The other plate surface of the extruded material is cut to form the first and second throttle valve plates, and a substantially semicircular opening for passing the shaft through the center of the partition plate is formed. It is the figure which formed the screw insertion hole in the center of the substantially circular plate which consists of a 2nd throttle valve plate. It is a perspective view of the shaft main body provided with the semicircular part for improving the assembly | attachment property of the valve member with respect to a carburetor main body, and the shaft for rotating this. It is a disassembled perspective view of a shaft, It is a figure for demonstrating that the shaft is comprised with the shaft main body and the semicircle member integrated with this. It is a perspective view of the assembly of the shaft and valve member which was extracted and drawn from the vaporizer body. It is sectional drawing which shows the modification of a valve member, (A) is a figure which shows the example which inclined (angle (theta) 1) only one half part half in the semicircle part by the side of the air passage of a butterfly valve plate, (B) is a view showing an example in which one half portion in the semicircular portion on the air passage side of the butterfly valve plate is inclined (angle θ2) and the other half portion is also inclined (angle θ3). It is a perspective view of the shaft contained in a modification. It is a figure for demonstrating the modification of the assembly of a shaft and a valve member. It is a perspective view of the assembly of the shaft and valve member of the further modification. FIG. 15 is a side view of the assembly of FIG. 14. It is a perspective view of the modification of the assembly shown in FIG. FIG. 17 is a side view of the assembly of FIG. 16. FIG. 17 is a perspective view of a modified example of the assembly illustrated in FIG. 16. FIG. 19 is a side view of the assembly of FIG. 18.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a vaporizer according to an embodiment. The illustrated carburetor 100 is installed in an intake system of a stratified scavenging two-stroke single cylinder engine.

  The carburetor 100 has a single throttle bore 4 that extends through the carburetor body 2. In this single throttle bore 4, a choke valve mechanism 6 and a throttle valve mechanism 8 are incorporated in order along the air flow direction. In FIG. 1, the carburetor 100 viewed from the downstream side in the air flow direction is depicted.

  The choke valve mechanism 6 and the throttle valve mechanism 8 have the same basic configuration for valve opening / closing, and therefore the throttle valve mechanism 8 will be described as a representative example.

  Referring to FIG. 2 in which the carburetor of FIG. 1 is cut obliquely in the longitudinal direction along the flow direction of the airflow, the choke valve mechanism 6 and the throttle valve mechanism 8 are respectively circular partition plates 10 and 12 as partition members. The circular first and second partition plates 10 and 12 are arranged on the same plane.

  The space between the first and second partition plates 10 and 12 is filled with a wall surface that defines the throttle bore 4 of the carburetor body 2. Specifically, a wall 2a including arcuate contours 14 and 16 for receiving the two partition plates 10 and 12 between the two partition plates 10 and 12 arranged on the same plane (FIG. 2, FIG. 2). 3) is filled. The wall 2a is located on a plane including the partition plates 10 and 12, and the single throttle bore 4 of the carburetor body 2 is formed by the wall 2a and the two partition plates 10 and 12 into the first and second two. It is divided into two passages 18 and 20 (FIG. 1). The first passage 18 is an air-fuel mixture passage, and the second passage 20 is an air passage.

  The first and second partition plates 10, 12 both functioning as partition members are disposed offset from the central axis of the throttle bore 4, so that the air-fuel mixture passage 18 is relative to the air passage 20. The effective area is large.

  Referring to FIG. 4, both the choke valve mechanism 6 and the throttle valve mechanism 8 have first and second butterfly valve plates 22 and 24 that are substantially semicircular, and the first and second butterfly valve plates. 22 and 24 function as butterfly valves for opening and closing the first and second passages 18 and 20.

  The first and second butterfly valve plates 22, 24 both functioning as butterfly valves are integrated with one partition plate 10 (12). The first butterfly valve plate 22 is disposed in the first passage or mixture passage 18, and the second butterfly valve plate 24 is disposed in the second passage or air passage 20.

  5-7 is a figure for demonstrating an example of the manufacturing method of one partition plate 10 (12) and the 1st, 2nd butterfly valve plates 22 and 24 integrated with this. is there. First, a metal extrusion material 26 shown in FIG. 5 is prepared. The extruded material 26 is made of a long member having a cross-shaped cross section composed of two plate surfaces 28 and 30 orthogonal to each other.

  With reference to FIG. 6, in the extruded material 26 having a cross section of one cross section, one plate surface 28 is first formed into a circular shape. One plate surface 28 formed in this circular shape constitutes the partition plate 10 (12). The next process will be described with reference to FIG. 7. The other plate surface 30 orthogonal to the one plate surface 28 is also formed in a substantially circular shape as a whole, and thereby the two plate surfaces 10 (12 ), 22 and 24, the cross-sectional valve member 34 is manufactured.

  Of course, the first and second butterfly valve plates 22 and 24 are respectively prepared, and the first and second butterfly valve plates 22 and 24 are joined to one partition plate 10 (12) to be a valve member. 34 may be made. Contrary to this, two partition plate elements obtained by dividing the partition plate 10 (12) in half are prepared, and a substantially circular plate in which the first and second butterfly valve plates 22 and 24 are integrated is prepared. The valve member 34 may be made by joining two substantially semicircular partition plate elements to the substantially circular plate. Needless to say, the cross-shaped valve member 34 may be manufactured by a mold forming method. When the mold forming method is adopted, there is an advantage that the degree of freedom in design is high with respect to the valve shape and the shape of the partition plate 10 (12).

  As described above, the valve member 34 includes the partition plate 10 and the first and second butterfly valve plates 22 and 24 that are integral with and perpendicular to the partition plate 10. The first butterfly valve plate 22 is relatively larger than the second butterfly valve plate 24, and the first butterfly valve plate 22 constitutes a throttle valve for engine output control, and does not appear in FIG. The two butterfly valve plates 24 constitute an air amount adjusting valve.

  In other words, the valve member 34 composed of two substantially circular plate surfaces orthogonal to each other in a cross shape is arranged with the partition plate 10 being offset, whereby the first butterfly valve plate 22 for relatively large output control, This also forms a small butterfly valve plate 24 for adjusting the air amount. The substantially circular plate surfaces constituting the first and second butterfly valve plates 22 and 24 have a screw insertion hole 36 at the center thereof, and the circular partition plate 10 has a substantially semicircular opening at the center thereof. 38.

  The valve member 34 is fastened with a screw 42 to a shaft 40 having a circular cross section disposed through the vaporizer body 2 (FIG. 10). 8 and 9 show an example of the shaft 40, and the illustrated shaft 40 has a divided structure. FIG. 8 shows a shaft body 44, part of which is a semicircular cross section. Specifically, the one end portion 44a has a circular cross section, and the remaining portion 44b has a semicircular cross section. The shaft 40 is configured by superimposing a semicircular member 46 (FIG. 9) on the other end of the shaft main body 44. The semicircular member 46 and the shaft main body 44 may be coupled by a conventionally known coupling means such as a C ring 48 as illustrated in FIG. Reference numeral 48 a in FIGS. 8 and 9 indicates a groove for receiving the C-ring 48. A screw hole 50 is formed in the central portion of the shaft main body 44 in the longitudinal direction, and the valve member 34 is attached using a screw 42 (FIG. 10) screwed into the screw hole 50 as described below. Is called.

  FIG. 10 shows a state where the valve member 34 is assembled to the shaft 40. The valve member 34 can be assembled to the shaft 40 as follows. First, the other end portion (semicircular portion) of the shaft main body 44 is inserted into the substantially semicircular opening 38 (FIG. 7) of the valve member 34. Next, after the screw insertion hole 36 of the valve main body 34 is aligned with the screw hole 50 (FIG. 8) of the shaft main body 44, the screw 42 is screwed into the screw hole 50. Thereby, the valve member 34 is fixed to the shaft main body 44. Note that the screw insertion hole 36 of the valve member 34 has a slightly larger diameter than the shaft portion of the screw 42, so that the mounting position of the valve member 34 with respect to the shaft 40 can be finely adjusted. As a result, the valve member 34 can be easily assembled to the wall surface of the throttle bore 4 of the carburetor body 2 without a gap.

The assembling operation of the valve member 34 to the single throttle bore 4 of the carburetor body 2 is performed according to the following procedure.
(1) With the valve member 34 disposed in the throttle bore 4 of the carburetor body 2, the shaft hole (not shown) of the carburetor body 2 and the substantially semicircular opening 38 (FIG. 7) of the valve member 34. The shaft body 44 (FIG. 8) is inserted. This insertion is performed with the semicircular remaining portion 44b side of the shaft body 44 as a tip. By performing this operation, the shaft main body 44 is in a state of crossing the single throttle bore 4 of the carburetor main body, and the valve member 34 is hung from the shaft main body 44.

(2) The semicircular member 46 (FIG. 9) is inserted into the shaft hole (not shown) of the carburetor main body 2 where the other end portion of the shaft main body 44 is located, and then the semicircular member 46 is inserted into the C ring 48. To be integrated with the other end of the shaft body 44.
(3) Next, the valve member 34 is fixed to the central portion in the longitudinal direction of the shaft main body 44 using the screw 42 (FIG. 10). When this fixing is performed, the position of the valve member 34 with respect to the wall surface of the throttle bore 4 of the carburetor body 2 is adjusted.

  The above operation is performed in the same procedure for the choke valve mechanism 6, whereby the assembly operation of the choke valve mechanism 6 and the valve body 34 of the throttle valve mechanism 8 to the single throttle bore 4 of the carburetor 100 is completed. .

  The valve body 34 of each of the choke valve mechanism 6 and the throttle valve mechanism 8 assembled in this way is a single throttle bore 4 of the carburetor 100 by a partition plate 10 (12) positioned orthogonal to each shaft 40. Is divided into two first and second passages 18 and 20. The first and second butterfly valve plates 22 and 24 orthogonal to the partition plate 10 (12) constitute a throttle valve for controlling engine output and an air amount adjusting valve, respectively, and the shaft 40 is axially rotated. By doing so, the throttle valve and the air amount adjusting valve can be opened and closed in an interlocked state. Of course, even if the shaft 40 is rotated, the partition plate 10 (12) only rotates on the same plane with the shaft 40 as the center. Keep the function to partition.

  As described above, since the first and second butterfly valve plates 22 and 24 functioning as the butterfly valve are integrated with one partition plate 10 (12), the mixture passage 18 and the air passage 20 are connected to each other. The partition plate 10 (12) to be partitioned can exhibit a partition function for partitioning the air-fuel mixture passage 18 and the air passage 20 in any of the operation states of idle operation, partial operation, and high speed operation. Accordingly, the carburetor can be reduced in size in the stratified scavenging engine, and a carburetor suitable for stratified scavenging can be provided at a relatively low cost.

  In the illustrated example, as best seen in FIG. 4, a first step 54 is formed to position the partition plate 10 (12) on the wall surface defining the single throttle bore 4 of the carburetor body 2. In addition, second and third step portions 56 and 58 for defining the fully open positions of the throttle valve (first butterfly valve plate 22) and the air amount adjusting valve (second butterfly valve plate 24) are formed. However, whether or not to install any of these three steps 54, 56, 58 is arbitrary.

  Referring to FIG. 4, reference numeral 60 denotes a return coil spring, and the first and second throttle valve plates 22 and 24 are always urged in the valve closing direction by the return coil spring 60 as in the conventional case.

  1 and 10, reference numeral 62 indicates an idle passage hole formed in the first butterfly valve plate 22 included in the throttle valve mechanism 8, and the first butterfly valve plate 22 is fully closed. At this time, a slight air-fuel mixture is supplied to the engine through the idle passage hole 62.

  In the above embodiment, the crossing angle between the partition plate 10 (12) and the first and second butterfly valve plates 22 and 24 is set to 90 degrees, but as a modification, the choke valve mechanism 6 and the throttle valve mechanism As for either one or both, idle operation can be achieved by slightly tilting at least one of the first and second butterfly valve plates 22 and 24 to increase the clearance with the wall surface of the throttle bore 4 of the carburetor body 2. You may make it adjust supply_amount | feed_rate of the air or air-fuel | gaseous mixture in. FIG. 11A shows an example in which one half portion of the semicircular portion on the air passage side of the butterfly valve plate 24 included in the choke valve mechanism 6 is inclined by the angle θ1. 11B, one half portion in the semicircular portion on the air passage side of the butterfly valve plate 24 included in the choke valve mechanism 6 is inclined (angle θ2), and the other half portion is also inclined (angle θ3). FIG.

  As another modification, a notch is formed in a peripheral portion of at least one of the first, second first and second butterfly valve plates 22, 24, and this notch causes air or The supply amount of the air-fuel mixture may be adjusted.

  FIG. 12 shows a modification of the shaft 40 described above, and FIG. 13 shows a modification of the valve member 34 described above. Reference numerals 70 and 72 in FIGS. 12 and 13 show valve members and shafts of modified examples. In these drawings, the same reference numerals are given to the same elements as those in the above-described embodiment, and the description thereof will be made. Omitted.

  First, the shaft 72 will be described with reference to FIG. 12. The shaft 72 has both one end portion 72a and the other end portion 72b circular in cross section, and the longitudinal central portion 72c of the shaft 72 has a semicircular cross section. The valve member 70 is screwed to the semicircular portion 72c as in the above-described embodiment. In FIG. 13, the screw 42 is not shown.

  Referring to FIG. 13, the valve member 70 has an opening 38 formed in the partition plate 10 (12), that is, an opening 38 through which the shaft 72 is passed, which is sufficient to pass the circular end 72 b of the shaft 72. It has a substantially semi-oval shape.

The assembly comprising the valve member 70 and the shaft 72 can be attached to the vaporizer body 2 in the following procedure.
(1) With the valve member 70 disposed in the throttle bore 4 of the carburetor body 2, the shaft body 72 is inserted into the shaft hole of the carburetor body 2 and the substantially semi-circular opening 38 of the valve member 70.
(2) Next, the valve member 70 is fixed to the central portion in the longitudinal direction of the shaft 72 using the screw 42 (not shown in FIG. 13). When this fixing is performed, the position of the valve member 70 with respect to the wall surface of the throttle bore 4 of the carburetor body 2 is adjusted.

  14 and 15 show modifications of the shafts 40 and 72. FIG. FIG. 14 is a perspective view of an assembly including the valve member 34 and the two shaft members 74a and 74b, and FIG. 15 is a side view thereof. The shaft 74 shown in FIGS. 14 and 15 is composed of first and second shaft members 74a and 74b that are coaxially spaced apart from each other, and the first and second shaft members. Each of the ends of 74a and 74b facing each other is connected to the valve member 34 via a screw 42.

  More specifically, the first shaft member 74a is connected to the air-fuel mixture butterfly valve plate 22 of the valve member 34, and the second shaft member 74b is connected to the air amount adjusting butterfly valve plate 24.

  Although not shown in the drawing, the above-described screw insertion hole 36 is formed in the mixture passage butterfly valve plate 22 and the air amount adjustment butterfly valve plate 24, and the screw insertion hole 36 is a shaft portion of the screw 42. Is larger than. As a result, when the first and second shaft members 74a and 74b are fixed to the mixture passage butterfly valve plate 22 and the air amount adjusting butterfly valve plate 24, the valve against the wall surface of the throttle bore 4 of the carburetor body 2 is secured. The position of the member 34 can be adjusted.

  FIGS. 16 and 17 are views showing a further modification. In this modification, the valve member 34 is cantilevered by the first shaft member 74a, and the second shaft member 74b described above is omitted. . Preferably, a spherical member 76 may be installed on the air amount adjusting butterfly valve plate 24 by welding or the like instead of the second shaft member 74b. Although not shown, a hemispherical recess for receiving the spherical member 76 is formed on the wall surface of the throttle bore 4 of the carburetor main body 2, and a spherical bearing for receiving the spherical member 76 is formed in the hemispherical recess. It may be.

  18 and 19 show modifications to the examples shown in FIGS. 16 and 17, the first shaft member 74a is fixed to the mixture passage butterfly valve plate 22 using the screw 42. However, in the modified examples of FIGS. 18 and 19, the first shaft member 74a is fixed. The end surface of the member 74a is fixed to the partition plate 10 (12) using screws 42. The partition plate 10 (12) is formed with the above-described screw insertion hole 36 for inserting the screw 42 (not shown in the drawing for reasons of drawing). Of course, the screw insertion hole 36 has a diameter larger than that of the shaft portion of the screw 42, so that when the first shaft member 74 a is fixed to the valve member 34, the valve with respect to the wall surface of the throttle bore 4 of the carburetor body 2. The position of the member 34 can be adjusted.

  The carburetor of the present invention is assembled to a small internal combustion engine which is a drive source of a portable work machine. The carburetor of the present invention is suitably applied to a stratified scavenging two-stroke engine. Typical examples of portable work machines are chainsaws and mowers, and most of the engines of this kind of work machines are single cylinder engines.

DESCRIPTION OF SYMBOLS 100 Vaporizer 2 Vaporizer main body 4 Throttle bore of vaporizer main body for allowing airflow to pass 6 Choke valve mechanism 8 Throttle valve mechanism 10 Partition plate (partition member on choke side)
12 Partition plate (Throttle side partition member)
18 First passage (mixture passage)
20 Second passage (air passage)
22 Mixture passage butterfly valve plate (Butterfly valve for output control)
24 Air passage butterfly valve plate (Air amount adjustment butterfly valve)
26 Cross-section extruded material 34 Valve member 36 Screw insertion hole 38 Substantially semicircular opening (for shaft insertion)
40 Shaft 42 Screw for fixing the valve member to the shaft 44 Shaft body 44a One end of the shaft body (circular cross section)
44b Remaining semicircular cross section of shaft body 46 Semicircular member 48 C ring 50 Screw hole (screw is screwed)
70 Valve member of modified example 72 Shaft of modified example

Claims (8)

A carburetor body with a single throttle bore;
A shaft extending across the throttle bore and supported by the carburetor body and rotatable about the shaft;
A partition member disposed in the single throttle bore to partition the mixture passage and the air passage;
A first butterfly valve disposed in the mixture passage;
And a second butterfly valve disposed in the air passage,
In the two-stroke engine carburetor in which the first and second butterfly valves are opened and closed by rotating the shaft.
A valve member in which the partition member and the two butterfly valves are integrated;
An opening formed in the partition member included in the valve member and through which the shaft can be inserted;
A screw passing through a screw insertion hole formed in one of the two butterfly valves included in the valve member;
A screw hole formed in a semicircular section of the shaft,
The shaft is inserted into the opening formed in the central portion of the partition member, and the screw is screwed into the screw hole in a state where the screw insertion hole of the valve member is aligned with the screw hole of the shaft. By doing so, the valve member is detachably screwed to the shaft,
By pivoting the shaft, and wherein the partition member around the said shaft to rotate on the same plane, the two butterfly valves, respectively, said mixture passage, opens and closes the air passage A two-stroke engine carburetor. The carburetor for a two-stroke engine according to claim 1 , wherein the valve member is made of an extruded material having two plate surfaces intersecting each other. 3. The shaft according to claim 1, wherein one end portion of the shaft has a circular cross section and the remaining portion has a semicircular cross section, and is configured by connecting a semicircular member to the other end portion of the shaft. Vaporizer for stroke engine. The carburetor for a two-stroke engine according to claim 3, wherein the semicircular member is connected to the other end of the shaft by a C-ring. The carburetor for a two-stroke engine according to claim 1 or 2 , wherein a diameter of the screw insertion hole is larger than a diameter of a shaft portion of the screw. And a choke valve mechanism and the throttle valve mechanism, these choke valve mechanism and a throttle valve mechanism, both have the valve member which is screwed to the shaft, according to any one of claims 1 3 2 Vaporizer for stroke engine. A choke valve mechanism and a throttle valve mechanism, both the choke valve mechanism and the throttle valve mechanism having the valve member screwed to the shaft;
The first partition member included in the choke valve mechanism and the second partition member included in the throttle valve mechanism are disposed on the same plane, and the space between the first and second partition members is between The air passage and the air-fuel mixture passage are partitioned by a wall including an arcuate outline that receives the first and second partition members, and the wall and the first and second partition members define the air passage and the mixture passage. The carburetor for a two-stroke engine according to claim 4. A carburetor body with a single throttle bore;
A shaft extending across the throttle bore and supported by the carburetor body and rotatable about the shaft;
A partition member disposed in the single throttle bore to partition the mixture passage and the air passage;
A first butterfly valve disposed in the mixture passage;
And a second butterfly valve disposed in the air passage,
A method of assembling the partition member and the first and second butterfly valves to the carburetor body of a carburetor for a two-stroke engine in which the first and second butterfly valves are opened and closed by rotating the shaft. ,
The valve member in which the partition member and the two butterfly valves are integrated , the opening formed in the partition member included in the valve member and through which the shaft can be inserted, and included in the valve member A screw passing through a screw insertion hole formed in one of the two butterfly valves; and a screw hole formed in a semicircular section of the shaft, the diameter of the screw insertion hole being the screw Prepare a valve member larger than the diameter of the shaft part ,
A shaft insertion step of inserting the shaft into the opening formed in the partition member of the vaporizer body;
The valve member is fixed to the semicircular section of the shaft while positioning the valve member with respect to the single throttle bore using the screw insertion hole having a diameter larger than the diameter of the shaft portion of the screw. And a valve member fixing step. The valve member assembling method of the two-stroke engine carburetor to the carburetor body.

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