JP2007056801A - Stratified scavenging carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cope with types of machines having different amount of scavenging air without changing parts. <P>SOLUTION: A valve element 7b like a circular column constituting an air valve composed of a rotary valve is provided so as to displace freely in the direction of axial line, and a plurality of channels 19a to 19c in the peripheral direction are provided in a valve shaft 7a being coaxial with the valve element at an interval in the direction of axial line to assemble a clip 20 in any one of them and energize the valve shaft springily in the direction of axial line by a return spring 15. The valve element is positioned by abutting of the clip on a boss part 18b formed in a case 18 for displacement of the valve element due to springy energization. Opening area of both holes when opened fully can be set in accordance with a position of displacement in the direction of axial line of the valve element. Consequently, amount of scavenging air corresponding to type of machine can be set by simple setting for changing a position in the direction of axial line of the valve element in accordance with difference in type of machine of engine and it is unnecessary to change parts individually as in a conventional case, thereby reducing manufacturing cost. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stratified scavenging carburetor having a throttle valve and a scavenging air valve, wherein the scavenging air valve is a rotary valve.

Conventionally, in a stratified scavenging carburetor of a two-cycle engine, a carburetor throttle valve for supplying a mixture and a scavenging air control valve (scavenging air valve) are provided, and the air valve relative to the opening of the throttle valve is provided. There is one in which the opening degree is controlled by an interlocking mechanism (for example, see Patent Document 1).
JP 2000-136755 A

  On the other hand, there is a throttle valve as a butterfly valve and a pneumatic valve as a rotary valve. As a result, the opening area of the throttle valve increases relatively quickly in the low opening range of the throttle valve, and the opening area of the scavenging air valve Is relatively small so that a relatively rich mixture can be supplied to the engine. Since the rate of increase in the opening area of the scavenging air valve is large in the high opening range, a large amount of Since scavenging air can be supplied, it is possible to prevent the air-fuel mixture from being blown into the exhaust port.

  Further, the amount of scavenging air when the stratified scavenging is fully opened is determined by the communication area in which the air passage formed in the case for receiving the valve body and the through hole provided in the valve body are aligned in the rotary valve. In the conventional rotary valve type air valve, the cross-sectional area of the air passage and the cross-sectional area of the through hole are formed to be equal to each other, and both holes are coaxially aligned when fully opened.

  However, there are various types of engines depending on the application. For example, if the displacement is the same, there may be a case where the throttle valve (air mixture valve) can be made common. Even in such a case, the amount of scavenging air may be changed depending on the model (specification), and there has been a problem that the number of parts increases because the parts constituting the air valve are changed.

  In order to solve such a problem and realize a stratified scavenging carburetor that can cope with different types of scavenging air without changing the parts, in the present invention, mixing for sending the air-fuel mixture is performed. A throttle valve for opening and closing the air passage, a scavenging air valve for opening and closing an air passage for sending scavenging air, and an interlocking mechanism provided between the valves for interlocking and opening the both valves In the stratified scavenging carburetor, the scavenging air valve includes a cylindrical support hole formed in a case so as to cross the air passage, and a columnar valve body rotatably supported coaxially in the support hole. The valve body comprises a rotary valve having a through hole provided so as to penetrate the valve body in the diameter direction thereof, and the valve body is arbitrarily changed at least when the air passage and the through hole are fully opened. The axial direction of the support hole Displaceably provided, and the position in the axial direction relative to the supporting hole of the valve body and that provided the valve body positioning means for arbitrarily positioned.

  In particular, the valve body positioning means includes a plurality of circumferential grooves provided at predetermined intervals in the axial direction on a valve shaft provided coaxially with the valve body, and any of the plurality of circumferential grooves. An engagement member that can be fitted into one and has a portion that protrudes radially outward of the valve shaft; and a resilient biasing means that resiliently biases the valve body in one of the axial directions; It is good to have a stopper part provided in the case to stop the engagement member displaced by the bullet urging force.

  As described above, according to the present invention, the air valve is a rotary valve, and the valve body is formed in a cylindrical shape so that the valve body can be provided to be displaceable in the axial direction. The communication ratio at the time of full opening with the hole can be set by the axial displacement of the valve body, and the opening area of both holes at the time of full opening can be set according to the position of the axial displacement of the valve body. As a result, it is possible to set the scavenging air amount corresponding to each model with a simple setting of changing the axial position of the valve body depending on the model of the engine, and it is necessary to change the parts individually as in the past Product costs can be reduced because they are eliminated.

  In particular, a plurality of circumferential grooves are provided in the valve shaft, and for example, a circlip or a C (E) ring is used as an engaging member, and the valve body is elastically moved in one axial direction by a coil spring as an elastic biasing means. By changing the axial displacement position of the valve body in accordance with the attachment of the engagement member to an arbitrary circumferential groove by forming a stopper portion on the case that biases and stops the displacement of the engagement member in the same direction Can do. When changing the axial displacement position of the valve body, it is only necessary to replace the engaging member with another circumferential groove, and it is possible to provide a stratified scavenging carburetor that can easily cope with engines of different models.

  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 mixture passage 1a having a circular cross section in the radial direction. The scavenging air valve 7 has an air valve shaft 7a provided on an axis parallel to the throttle valve shaft 5a, and a columnar shape formed integrally with the air valve shaft 7a coaxially and across the air passage 1b. It consists of a rotary valve having a valve body 7b. The valve body 7b is rotatably provided in a valve case 18 as a case where the air passage 1b is formed. The valve body 7b is formed with a through hole 7d penetrating in the diameter direction of the valve body 7b so as to open and close the air passage 1b by the rotation of the valve body 7b.

  As described above, and in addition to FIG. 3 showing the external appearance of the vaporizer 1, and FIG. 3 viewed along the line III-III in FIG. 2, the shafts of the throttle valve shaft 5a and the air valve shaft 7a are shown. The cores are provided so as to extend in parallel with each other and are arranged in the height direction of the vaporizer 1 (vertical direction in the figure). The axial ends of the valve shafts 5a and 7a protrude outward from the same side of the body of the carburetor 1, and a first lever that extends radially outward from the protruding end of the throttle valve shaft 5a. 8 is fixed, and a second lever 9 extending radially outward is also fixed to the projecting end of the air valve shaft 7a. The first lever 8 and the second lever 9 are connected via a connecting rod 11.

  One end of the connecting rod 11 is rotatably connected to the second lever 9 via a pin 11a formed at the one end. Further, as shown in FIG. 2, the first lever 8 is formed in a substantially L-shape that extends in the radial direction and is bent in the circumferential direction at the extended end portion thereof. An arcuate guide slot 8 a centering on the throttle valve shaft 5 a is provided at the circumferentially bent portion of the first lever 8, and an engagement provided at the other end of the connecting rod 11 in the guide slot 8 a. A mating pin 11b engages with the slot in the longitudinal direction so as to be displaceable. In this way, the connecting rod 11 and the first lever 8 are connected so that a lost motion is generated in the rotation direction of the first lever 8.

  1 to 3 show the throttle valve 5 in a fully opened state. In the fully opened state, the arm 8b formed to extend outward in the radial direction on the first lever 8 is in contact with a protruding stopper 1c formed on the body of the vaporizer 1. The first lever 8 rotates in the direction indicated by the arrow A in FIG. 2 from the fully closed side, and stops rotating at the above position.

  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.

  Between the second lever 9 and the valve case 18 that is a part of the body of the carburetor 1, a return spring 15 that elastically biases the air valve shaft 7a in the fully closed direction of the air valve 7 is interposed. ing. 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. The return spring 15 also acts as a compression coil spring, thereby elastically displacing the second lever 9, that is, the valve shaft 7 a outward (in the direction of arrow B in FIG. 3) that is one of the axial directions. It constitutes a biasing means.

  The valve body 7b is supported by a cylindrical support hole 18a in the valve case 18 so as to be coaxially rotatable and displaceable in the axial direction. The base end portion, which is the valve body 7b side portion of the valve shaft 7a, is exposed in the support hole 18a, and the exposed portion of the valve shaft 7a has three predetermined intervals in the axial direction in the illustrated example. Circumferential grooves 19a, 19b and 19c are provided. FIG. 3 shows a structure in which a thin plate C-shaped clip 20 as an engaging member is assembled by fitting into the first circumferential groove 19a on the most projecting end side of the valve shaft 7a. The clip 20 only needs to have an outer diameter larger than the outer diameter of the valve shaft 7a, and a circlip or an E-ring can be applied.

  In addition, an annular boss portion 18b that surrounds the valve shaft 7a and protrudes toward the valve body 7b is formed in the support hole 18a of the valve case 18 as a stopper portion. The valve shaft 7a is elastically biased by the return spring 15 in the direction of the arrow B in FIG. 3, which is the direction in which the valve body 7b is displaced to the boss portion 18b, whereby the clip 20 is attached to the protruding end of the boss portion 18b. The valve shaft 7a (valve element 7b) is displaced until the valve element 7 contacts, and the axial displacement of the valve element 7b is positioned at the contact position. These circumferential grooves 19a (19b and 19c), the clip 20, and the boss portion 18b constitute valve body positioning means.

  In the fully closed state of the throttle valve 5 and the scavenging air valve 7 before the engine is operated, the operation is as shown in FIGS. 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 a 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 shifts in the radial direction, so that the arm as shown by the arrow C in FIG. 4 corresponds to the radial shift. 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, the other end side (the lower side in FIG. 2) opposite to the longitudinal end (the upper side in FIG. 2) of the guide slot 8a engaged with the engaging pin 11b of the connecting rod 11 when fully open. Side). Therefore, when the valve body 5b is opened in the fully open direction (the direction of arrow A in FIG. 5) by operating the throttle lever 14 from the fully closed state, the first lever 8 starts to rotate in the direction indicated by the arrow A in FIG. However, until the first lever 8 rotates by a certain angle, the engaging pin 11b is relatively displaced toward one end in the longitudinal direction of the guide slot 8a. Since the valve shaft 7a of the air valve 7 is elastically biased in the fully closed direction (the direction of arrow D in FIG. 4) by the return spring 15 as described above, the engagement pin 11b is relatively moved in the guide slot 8a. During the displacement, the air valve 7 is held in a fully closed state.

  When the first lever 8 is rotated by a predetermined angle from the fully closed position, the engaging pin 11b is engaged with the other longitudinal end of the guide slot 8a. Since the rotational force of one lever 8 is transmitted to the second lever 9 via the connecting rod 11, the second lever 9 rotates in the direction opposite to the arrow D against the spring force of the return spring 15, and the air Valve 7 opens. 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 8 and 9 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.

  The air valve 7 of the stratified scavenging carburetor configured as described above will be described below. FIG. 6A shows the fully opened state of the air valve 7. In this case, the air passage 1b and the through hole 7d are perfectly aligned and formed with the same inner diameter, so that scavenging through the air passage 1b is in a fully connected state through the 100% through hole 7d.

  On the other hand, when it is better to set the scavenging amount when fully opened due to the difference in model, for example, as shown in FIG. 6 (b), the clip 20 is moved to the third circumferential direction closest to the valve body 7b during assembly. It is assembled in the groove 19c. 6 (a) is displaced by the distance between the first circumferential groove 19a and the third circumferential groove 19c with respect to the entire communication state of FIG. As shown in b), the overlapping portion in the communication state between the air passage 1b and the through hole 7d is limited to be small, and the amount of scavenging air decreases due to the reduction in the communication portion.

  Also, as shown in the figure, by providing three circumferential grooves 19a to 19c, the assembly position of the clip 20 is set to the first circumferential groove 19a in the fully connected state, and in the minimum connected state, the first circumferential groove 19a. 3 circumferential grooves 19c, and in an intermediate communication state between them, an intermediate second circumferential groove 19b can be used to provide a communication state corresponding to each, and for laminar scavenging composed of the same parts The carburetor 1 can cope with a plurality of different models. The circumferential grooves for assembling the clip 20 are not limited to the three shown in the figure, and four or more may be provided, and each interval is arbitrarily set according to the design.

  The connecting rod 11 is translated in the axial direction of the valve shaft 7a relative to the first lever 8 by the amount that the valve shaft 7a is displaced in the axial direction. In any state, the pin 11b connected to the first lever 8 has a shaft portion with a predetermined length in order to maintain the coaxiality of the pins 11a and 11b with respect to the corresponding pivot holes of the levers 8 and 9 in any state. The two flat washers 21a and 21b having a thickness corresponding to the amount of movement are fitted to the shaft portion of the pin 11b. Each of the pins 11a and 11b may have the same shape, and has a large-diameter portion to a small-diameter shaft portion formed on the main body side of the connecting rod 11 and a tapered enlarged head portion. Also, as representatively shown on the first lever 8 side, the enlarged head of the pin 11b can be inserted when assembled to the pivot hole 8c provided in the first lever 8 to pivotally support the shaft portion of the pin 11b. Thus, the pin 11b is formed in, for example, a split shape.

  In the fully connected state, as shown in FIG. 7A, the first lever 8 and the second lever 9 are located on the same line when viewed from the side (direction perpendicular to the axis). In this case, the pin 11b The plain washers 21a and 21b are interposed between the head extension of the first lever 8 and the first lever 8. In the minimum communication state, as shown in FIG. 7B, the second lever 9 is displaced in a direction away from the carburetor body with respect to the first lever 8, and in this case, the enlarged head of the pin 11b is A plain washer 21 a and 21 b are interposed between the first lever 8 and the first lever 8 in sliding contact with the first lever 8. In this way, the levers 8 and 9 and the connecting rod 11 can be held in parallel in each case. In the intermediate communication state, the plain washers 21a and 21b may be provided on both sides of the first lever 8 one by one. In the illustrated example, two plain washers 21a and 21b are used. However, it is also possible to prepare collars having different thicknesses and to interpose them at predetermined positions according to the respective communication states. In addition, the length of the shaft portion of the pin 11b may be the same as that of the pin 11a, and in that case, the main body (bar-shaped portion) of the connecting rod 11 according to the amount of displacement of the second lever 9 relative to the first lever 8. ) Can be bent.

  Thus, for example, a large number of parts such as preparing a plurality of types of valve bodies having different through-hole sizes is not increased, and a reduction in the number of parts compared to the conventional one can be achieved. Moreover, since it can respond by changing the assembly position of the common parts, there is no increase in inventory due to prospective production when parts of different shapes are used.

  The valve body positioning means is not limited to the illustrated example, and even if the clip body is assembled in the circumferential groove provided in the valve shaft 7a as shown in the illustrated example, A directional groove may be provided in a portion of the valve shaft 7a exposed to the outside of the valve case 18.

  Further, in the illustrated example, the return spring 15 of the second lever 9 is also used as a spring urging force for positioning with respect to the axial displacement of the valve shaft 7a (valve element 7b). Two levers 9 may be provided for returning, and a separate compression coil spring may be provided so as to be wound twice together with, for example, the return spring 15 in order to urge the valve shaft 7a.

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. (A) is a principal part expanded partial sectional view which shows the full communication state in the fully open state of an air valve, (b) is a figure corresponding to (a) which shows the minimum communication state. (A) is a fragmentary sectional view which shows the connection point of the 1st lever and connecting rod which show all the communication states, (b) is a figure corresponding to (a) which shows the minimum communication state.

Explanation 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, 7d through hole 8 first lever, 8a guide slot, 8b arm 9 second lever DESCRIPTION OF SYMBOLS 11 Connecting rod, 11b Engaging pin 15 Return spring 18 Valve case, 18a Support hole 19a * 19b * 19c Circumferential groove | channel 20 Clip

Claims (2)

A throttle valve that opens and closes an air-fuel mixture passage for sending air-fuel mixture, a scavenging air valve that opens and closes an air passage for sending scavenging air, and a valve between the valves for opening and closing the valves in conjunction with each other In a stratified scavenging vaporizer having an interlocking mechanism provided,
The scavenging air valve has a cylindrical support hole formed in the case in a direction crossing the air passage, a columnar valve body rotatably supported coaxially in the support hole, and a diameter direction of the valve body A rotary valve having a through hole provided so as to penetrate through,
The valve body is provided so as to be displaceable in the axial direction of the support hole, and the position of the valve body in the axial direction with respect to the support hole in order to arbitrarily change the communication ratio at least when the air passage and the through hole are fully opened. A stratified scavenging vaporizer comprising valve body positioning means for arbitrarily positioning the valve.   The valve body positioning means includes a plurality of circumferential grooves provided at predetermined intervals in the axial direction on a valve shaft provided coaxially with the valve body, and any one of the plurality of circumferential grooves. An engagement member having a portion protruding radially outward of the valve shaft, a bullet urging means for urging the valve body in one of the axial directions, and the bullet The stratified scavenging carburetor according to claim 1, further comprising a stopper portion provided in the case to stop the engaging member displaced by the urging force.

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