JP2005282471A - Carbureter for two cycle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to install a carbureter in a small space and eliminate possibility of interference with other parts by operating an interlocking device making scavenging air flow rate roughly proportional to air fuel mixture by an air valve interlocking with a throttle valve in an side zone of the carbureter. <P>SOLUTION: A rotatable intermediate lever 20 is arranged between a throttle valve lever 8 fixed on a throttle valve shaft 5, an air valve lever 14 fixed on the air valve shaft 12. And those valves are arranged in such a manner that the same can rotate in a side surface zone of a carbureter body 1. The intermediate lever 20 does not rotate the air valve lever 14 until the throttle valve 4 is slightly opened from an idling position. When the throttle valve 4 is opened more than that, a driven edge 21 and a drive edge 22 of the intermediate lever 20 abut on a push edge 9 of the throttle lever 8 and a receiving edge 15 of the air valve lever 14 to open the air valve 11, and the air valve is made to reach a full open position simultaneously with the throttle valve 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a carburetor for supplying fuel to a two-cycle engine in which scavenging air is introduced into a combustion chamber prior to an air-fuel mixture.

  Two-cycle engines in which scavenging air is introduced into the combustion chamber when the piston is lowered and the combustion gas is discharged and then the air-fuel mixture is introduced into the combustion chamber are widely known. The scavenging air is fed into the scavenging passage connected to the cylinder and the mixture is fed into the crank chamber, or the scavenging air is fed into the combustion chamber and the mixture is fed into the crank chamber. The working air and the air-fuel mixture are introduced into the combustion chamber in the order described above.

  The scavenging air and the air-fuel mixture must be approximately proportional in flow rate to prevent incomplete combustion and stabilize engine operation. For this purpose, an air valve is provided in the air passage that supplies the scavenging air to the engine. It is interlocked with a throttle valve of a carburetor that is an air-fuel mixture generating means. In this case, when the throttle valve has a butterfly shape, the air valve also has a butterfly shape. For example, Japanese Utility Model Laid-Open No. 52-1912, Japanese Patent Laid-Open No. 9-125966, Japanese Patent Laid-Open No. 2000-314350, As described in Japanese Unexamined Patent Application Publication No. 2002-242679, it is common to link the throttle valve lever fixed to the throttle valve shaft and the air valve lever fixed to the air valve shaft by a link mechanism in which the rod is connected. is there.

  Such a link mechanism is one in which the air passage is separated from the carburetor, such as those described in Japanese Utility Model Laid-Open No. 52-1912 and Japanese Patent Laid-Open No. 9-125966, or in Japanese Patent Laid-Open No. 2000-314350. An air passage adjacent to the carburetor as described, but an air valve installed outside the overlapping area with the carburetor can be easily accommodated by increasing the length of the rod. However, if there is an installation restriction that the link mechanism cannot be extended greatly, the air valve installation portion of the air passage is adjacent to the carburetor as described in JP-A-2002-242679. It can be easily handled by installing the link mechanism along the side surfaces.

However, in the case where the air valve installation portion of the air passage is adjacent to the carburetor, in order to install without linking the link mechanism outward from the side surfaces thereof, it is arranged at the intake passage outlet portion of the carburetor. It is necessary to rotate the throttle valve lever toward the intake passage inlet. However, if the carburetor is equipped with a choke valve at the intake passage inlet portion in this way, a link mechanism must be installed so that the throttle valve lever and rod do not interfere with the choke valve shaft and choke valve lever. Problems arise. That is, the throttle valve lever and the air valve lever rotate on one plane, and the rod moves on a different plane, so that the throttle valve lever that moves on different planes in the area close to the choke valve and It is necessary to install the rod so that it does not come into contact with the choke valve shaft or choke valve lever. For this reason, there is a concern that the installation is greatly restricted and smooth interlocking becomes difficult.
Japanese Utility Model Publication No. 52-1912 JP-A-9-125966 JP 2000-314350 A JP 2002-242679 A

  The present invention provides a two-cycle engine carburetor in which an air valve is interlocked with a throttle valve to obtain interlocking means that operates in a lateral region of the carburetor to smoothly interlock the throttle valve and the air valve. In order to solve the above-mentioned problem that there is a case where the air valve is difficult, a carburetor having a choke valve can also open and close the air valve smoothly and appropriately in conjunction with the throttle valve. The purpose is to provide interlocking means.

  The present invention has an intake passage in which a throttle valve is installed and supplies air-fuel mixture to the engine, and an air passage in which an air valve is installed and supplies scavenging air to the engine. The air valve is linked to the throttle valve by the interlocking means. The above-described problem of the two-cycle engine carburetor that is supposed to open and close is solved as follows.

  That is, the interlock means is a throttle valve lever fixed to the throttle valve shaft, an air valve lever fixed to the air valve shaft, and is disposed between these two levers and is freely supported by the carburetor body. And the intermediate lever transmits the rotation of the throttle valve lever to the air valve lever after the throttle valve has slightly opened from the idle position to open the air valve from the closed position. The throttle valve lever is pushed and rotated so that the valve is in the fully open position at the same time.

  As described above, according to the present invention in which the throttle valve lever and the air valve lever are linked with each other instead of being linked with each other through the intermediate lever, according to the present invention, the shape of each lever and the rotation center of the intermediate lever There is a great degree of design freedom in terms of position, so the carburetor with the choke valve is installed without worrying about interference, and the air valve is linked to the throttle valve. Thus, the opening / closing operation can be performed smoothly and appropriately.

  Here, according to one of the preferred means for achieving the object of the present invention, the throttle valve lever has a pushing edge that rotates in contact with the intermediate lever, and the air valve lever rotates in contact with the intermediate lever. The intermediate lever has a driven edge that contacts the pushing edge and a driving edge that contacts the receiving edge. Until the throttle valve is slightly opened from the idle position, at least one of the driven edge and the driven edge is not in contact with the push edge and the receiving edge, and thereafter the push edge and the driven edge until the throttle valve reaches the fully open position. The driving edge and the receiving edge are in contact with each other to open the air valve from the closed position to the fully open position.

  This mixes the scavenging air above a certain opening of the throttle valve without supplying scavenging air that dilutes the air-fuel mixture at the idle position and small opening position of the throttle valve and makes engine operation unstable. The original function of supplying approximately in proportion to the energy can be provided accurately.

  Further, according to the embodiment of the present invention, the air valve is provided with the return spring that urges the valve closing force, so that the air valve can reliably follow the operation in the throttle valve closing direction. Alternatively, according to another embodiment, the throttle valve lever, the air valve lever and the intermediate lever are arranged on one plane in the side region of the carburetor body where the intake passage and the air passage are provided and rotate in the side region. As a result, the objective of eliminating the risk of interference with the choke valve can be reliably achieved as well. It becomes.

  According to the present invention, the air valve can be opened and closed smoothly and appropriately in conjunction with the throttle valve without causing a concern that the carburetor projects outward from the side region or interferes with the choke valve.

  An embodiment of the present invention will be described with reference to the drawings. A laterally extending intake passage 2 for supplying an air-fuel mixture to an engine and a side for supplying scavenging air to an engine disposed above the intake passage 2. An air passage 3 extending in the direction is formed in one carburetor body 1, and a manual starter pump, a pulse pressure type fuel pump, and a diaphragm type constant fuel chamber (not shown) are provided on the lower surface of the carburetor body 1. . The carburetor body 1 may be formed by superposing a carburetor body provided with the intake passage 2 and an air passage body provided with the air passage 3.

  1 and 2, an accelerator lever 6 is attached to one shaft end of a throttle valve shaft 5 to which a butterfly-shaped throttle valve 4 provided near the outlet of the intake passage 2 is fixed, and the valve is closed. A valve closing spring 7 acting in the direction is applied, and a throttle valve lever 8 is fixed to the other shaft end. Further, the air valve lever 14 is fixedly attached to the shaft end of the air valve shaft 12 to which the butterfly-shaped air valve 11 provided near the inlet of the air passage 3 is fixed on the same plane as the throttle valve lever 8. In addition, a return spring 13 acting in the valve closing direction is applied to the air valve lever 14.

  Further, an intermediate lever 20 is rotatably mounted on a boss 18 projecting from a pedestal 17 provided on the side surface of the carburetor body 1 so as to be positioned on the same plane as the throttle valve lever 8. It is held on the pedestal 17 so as not to come out from the base. The intermediate lever 20 is disposed between the throttle valve lever 8 and the air valve lever 14, and the pedestal 17 is located in a portion near the inlet of the intake passage 2.

  A straight side edge portion facing the intermediate lever 20 of the throttle valve lever 8 and a subsequent arc-shaped tip edge portion form a pushing edge 9. The arcuate tip edge portion of the air valve lever 14 facing the intermediate lever 20 forms a receiving edge 15. Further, a side edge portion facing the pushing edge 9 of the intermediate lever 20 forms a driven edge 21 curved in an arc shape, and a side edge portion facing the receiving edge 15 forms a linear drive edge 22. These throttle valve lever 8, air valve lever 14, and intermediate lever 20 constitute interlocking means for the throttle valve 4 and the air valve 11.

  The throttle valve lever 8, the air valve lever 14, and the intermediate lever 20 are disposed on a vertical plane along one side surface of the carburetor body 1, and the throttle valve lever 8 extends toward the inlet of the intake passage 2, The lever 14 and the intermediate lever 20 extend toward the outlet of the intake passage 2.

  1 and 2 show a state when the throttle valve 4 is in the idle position. The intermediate lever 20 is automatically rotated so that the tip end portion is placed on the boss 8A of the throttle valve lever 8, and the driven edge 21 and the driving edge are shown. 22 is in a state of being separated from both the pushing edge 9 and the receiving edge 15.

  When the throttle valve 4 is opened from the idle position by the driver's accelerator operation, the throttle valve lever 8 rotates counterclockwise in FIG. 1 and when the pushing edge 9 contacts the driven edge 21, the intermediate lever 20 is rotated clockwise in FIG. The drive edge 22 comes into contact with the receiving edge 15 and is in the state shown in FIG. During this time, the opening of the throttle valve 4 is small, and the air valve 11 is maintained in the closed position, so that only the air-fuel mixture from the intake passage 2 is supplied to the engine when the engine is idling and when the load is low, thereby diluting the air-fuel mixture. Stable operation can be performed without doing.

  When the throttle valve 4 is opened, the air valve lever 14 is rotated clockwise in FIG. 1 by the intermediate lever 20 to open the air valve 11, and the throttle valve 4 and the air valve 11 are simultaneously opened as shown in FIG. Reach the fully open position.

  When the throttle valve 4 returns to the idle position by the valve closing spring 7, the air valve lever 14 causes the receiving edge 15 to contact the drive edge 22 by the return spring 13 as the throttle valve lever 8 rotates in the opposite direction. After the intermediate lever 20 is pushed and rotated in the opposite direction and returned to the position shown in FIG. 3, the throttle valve lever 8 and the intermediate lever 21 are rotated to the position shown in FIG. That is, between FIG. 3 and FIG. 4, the air valve 11 opens and closes in conjunction with the throttle valve 4, and scavenging air supplied from the air passage 3 to the engine is mixed with the air-fuel mixture supplied from the intake passage 2 to the engine. The flow rate is almost proportional.

  In the present embodiment, the distance between the pushing edge 9 and the driven edge 21 at the idle position of the throttle valve 4 and the distance between the driving edge 22 and the receiving edge 15 at the closed position of the air valve 11 are set appropriately. Thus, the opening timing of the air valve 11 can be easily made appropriate. Further, by appropriately setting the positions of the air valve shaft 12 and the boss 18 with respect to the throttle valve shaft 5 and the dimensions and shapes of the throttle valve lever 8, the air valve lever 14 and the intermediate lever 20, these rotation ranges are vaporized. It can be in the side region of the device body 1 and can be installed and used in a place where there is not enough space.

  Further, in the case where the carburetor has the choke valve 25 as shown by a two-dot chain line in FIG. 1, even if the choke lever 27 is installed on the same side as the throttle valve lever 8 or the like, the choke lever 27 By disposing on a different plane from the throttle valve lever 8, there is no fear that the throttle valve lever 8 and the intermediate lever 20 interfere with the choke lever 27. Further, the throttle valve lever 8 only needs to be rotated by the intermediate lever 20, so that it does not need to be lengthened. Therefore, the throttle valve lever 8 can be used without worrying about interference with the choke valve shaft 26.

The side view which shows embodiment of this invention. FIG. 2 is a partially cut end view seen from the right side of FIG. 1. The side view which shows the state which begins the air valve opening of the form shown in FIG. The side view which shows the state of the air valve full open of the form shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vaporizer body, 2 Air intake passage, 3 Air passage, 4 Throttle valve, 5 Throttle valve shaft, 8 Throttle valve lever, 9 Push edge, 11 Air valve, 12 Air valve shaft, 13 Return spring, 14 Air valve lever, 15 Receiving edge, 20 intermediate lever, 21 driven edge, 22 driving edge

Claims (4)

An intake passage for supplying an air-fuel mixture to the engine with a throttle valve and an air passage for supplying scavenging air to the engine with an air valve, and the air valve is interlocked with the throttle valve by an interlocking means; In a two-cycle engine carburetor that is designed to open and close,
The interlock means includes a throttle valve lever fixed to the throttle valve shaft, an air valve lever fixed to the air valve shaft, and an intermediate member disposed between the two levers and rotatably supported by the carburetor body. With a lever,
The intermediate lever transmits the rotation of the throttle valve lever to the air valve lever after the throttle valve is slightly opened from the idle position to open the air valve from the closed position, and the throttle valve and the air valve At the same time, the throttle valve lever is pushed and rotated so as to be in the fully open position.
A two-cycle engine carburetor characterized by that. The carburetor for a two-cycle engine according to claim 1,
The throttle valve lever of the interlocking means has a pushing edge that rotates in contact with the intermediate lever, the air valve lever has a receiving edge that rotates in contact with the intermediate lever, and the intermediate lever A driven edge that contacts the push edge and a driving edge that contacts the receiving edge;
Then, until the throttle valve is slightly opened from the idle position, at least one of the driven edge and the driving edge is not in contact with the push edge and the receiving edge, and thereafter the throttle valve reaches the fully open position. The pushing edge and the driven edge and the driving edge and the receiving edge are in contact with each other to open the air valve from the closed position to the fully opened position.
A two-cycle engine carburetor characterized by that.   The carburetor for a two-cycle engine according to claim 1 or 2, wherein a return spring that urges a valve closing force is provided on the air valve. The throttle valve lever, the air valve lever, and the intermediate lever are arranged on a single plane in the side region of the carburetor body in which the intake passage and the air passage are provided, and rotate within the side region. The carburetor for a two-cycle engine according to claim 1, 2 or 3.

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