JP2005307863A - Carburetor for universal engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carburetor for a universal engine, in which a cable connected to an acceleration lever manually operated by a driver and a throttle valve lever fixed to a throttle valve shaft at both ends changes its direction without generating sliding friction around the carburetor. <P>SOLUTION: A direction changing member 21 having an overlap surface 25 at least part of which is curved is rotatably supported by a carburetor main body 1, and the cable 12 is overlapped with the overlap surface 25. The direction changing member 21 is rotated as the cable 12 moves in accordance with accelerating operation without generating slip to an overlapped part of the cable 12. In the direction changing member 21, distance of the rotation center to an acceleration lever side end part of the overlap surface 25 is set larger than distance to a throttle valve lever 9 side end part. The throttle valve lever 9 is formed compact compared to total operation quantity in the acceleration lever, thereby its installation is facilitated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention mainly relates to a carburetor suitable for a small general-purpose engine mounted on a portable work machine.

  A brush cutter, one of the portable work machines, is equipped with a fuel tank, carburetor, engine, and disc blade at the end of the handle, and it can follow the handle by operating the accelerator lever (trigger) on hand. The throttle valve of the carburetor is opened and closed through a cable arranged in the above manner. The handle is slanted with respect to the end equipment for workability and safety, so the cable that connects both ends to the throttle valve lever and accelerator lever fixed to the throttle valve shaft changes direction near the carburetor. Arranged.

  The above-mentioned direction change is performed by installing a curved pipe and inserting the cable therethrough, so sliding friction cannot be avoided, the operating force of the accelerator lever can be fluctuated, and excessive force is applied to the cable. There is a concern that it may act or cause wear, leading to premature deterioration. Also, the total amount of operation of the accelerator lever that opens the throttle valve from the idle position to the fully open position, that is, the total stroke of the cable at the coupling position with the accelerator lever, and the total stroke of the cable at the coupling position with the throttle valve lever are equal to each other. . Therefore, in order to reduce the throttle valve opening / closing operation amount corresponding to a certain amount of operation of the accelerator lever and prevent stable acceleration and deceleration and unstable engine rotation, the accelerator lever can be operated. If the total operation amount is increased, the connecting portion of the cable to the throttle valve lever must be positioned far away from the throttle valve shaft, which may cause the throttle valve lever to be large and unable to be installed in a narrow space.

  In the present invention, firstly, a cable for transmitting and closing the operation of the accelerator lever to the throttle valve is subjected to sliding friction which cannot be avoided at the direction change point. Second, the accelerator lever and the throttle valve lever are in a one-to-one relationship. It was made to solve the above-mentioned problem that the throttle lever would become too large to be installed if the engine operation stability was achieved because of the corresponding movement, and the direction of the cable without sliding friction Another object of the present invention is to provide a general-purpose engine carburetor in which conversion is performed, and in addition, the throttle valve lever is small and easy to install with respect to the total operation amount of the accelerator lever.

  The above-mentioned general-purpose engine carburetor has a cable in which both ends of an accelerator lever manually operated by the driver and a throttle valve lever fixed to the throttle valve shaft are connected to change the direction in the vicinity of the carburetor. In order to solve the problems, the present invention is as follows.

  That is, the problem that the cable is subject to sliding friction at the direction changing portion in the vicinity of the carburetor is the cable in which the direction changing member having an overlapping surface with at least a part of the curved surface is supported on the carburetor body freely. And the direction changing member is rotated without causing any slip between the cable overlapping portion corresponding to the movement of the cable according to the operation of the accelerator lever. did.

  As described above, the direction changing member rotates in response to the movement of the cable at the direction changing portion, thereby achieving the object of preventing the generation of sliding friction.

  In addition, the problem is that the throttle valve lever becomes large when the total operation amount of the accelerator lever is large. The distance between the rotation center of the direction changing member and the end of the overlapping side of the accelerator lever is the side of the throttle valve lever. It was decided to solve the problem by making the distance larger than the distance from the end.

  When the direction change member rotates, the ratio of the movement amount (stroke) of the accelerator lever side end portion to the movement amount (stroke) of the throttle valve lever side end portion is equal to the ratio of the distance from the rotation center to them. . Therefore, the opening / closing operation amount of the throttle valve is reduced with respect to the operation amount of the accelerator lever, and the object that the throttle valve lever can be downsized even if the total operation amount of the accelerator lever is increased is achieved.

  For the support shaft that freely supports the direction changing member, it is advantageous in terms of reducing the number of parts to use a mounting bolt for coupling the carburetor body to the engine.

  Further, the overlapping surface of the direction change member includes a guide portion that is curved toward the direction change member rotation center at the end portion of the throttle valve lever, and a plane portion that extends linearly with a gradually increasing distance from the rotation center. The direction change part curved toward the rotation center and the arc part centering on the rotation center, and the throttle valve lever side of the cable is the area of the guide part between the idle position and the fully open position of the throttle valve The contact and separation of the accelerator lever within the arcuate area within the arcuate area keep the driver's accelerator operation amount and the opening position of the throttle valve at a predetermined ratio, and the cable. This is effective in preventing sliding friction at all.

  According to the present invention, the cable is not subjected to sliding friction at the direction changing portion, and therefore, the accelerator operation can be smoothly performed without worrying about fluctuations in the accelerator operation force or premature deterioration of the cable. In addition to this, the throttle valve lever can be downsized with respect to the total operation amount of the accelerator lever, so that both ease of operation of the accelerator and ease of installation of the throttle valve lever can be achieved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. A manual starter pump, a pulse pressure type fuel pump, a diaphragm type constant fuel (not shown) are provided on the lower surface of a carburetor body 1 having a laterally extending intake passage. A chamber is provided, and the fuel sent from the fuel tank to the constant fuel chamber by the start pump or the fuel pump is sent to the intake passage from the idle port, the slow port, and the main nozzle and supplied to the engine 2. The carburetor body 1 is coupled to the engine 2 with a heat insulating material 3 sandwiched between a plurality of mounting bolts 4 inserted from the air cleaner side.

  One end of a cable 12 is coupled to a post 10 of a throttle valve lever 9 fixed to one end protruding from the carburetor body 1 of a throttle valve shaft 8 to which a butterfly-shaped throttle valve 7 is consolidated, and the other end of the cable 12 is operated. It is connected to an accelerator lever (trigger) (not shown) that is manually operated by a person. The throttle valve 7 is opened by pulling the cable 12 by the accelerator lever, and is closed by the valve closing spring 11.

  As in the present embodiment, when the intake passage 6 extends in the horizontal direction substantially horizontally in a normal posture, the throttle valve lever 9 rotates on a substantially vertical plane, and the cable 12 moves in the vertical direction. On the other hand, when the handle equipped with devices such as a carburetor and engine at the tip is inclined like a brush cutter, the cable 12 must change direction in the vicinity of the carburetor main body 1, In the present embodiment, the direction changing member 21 is rotatably installed in the upper region of the post 10 of the throttle valve lever 9.

  The direction changing member 21 has a plate-like bracket 23 protruding from a boss 22 having a shaft hole 22A through which the support shaft 13 serving as the center of rotation is inserted, and a plate-like overlapping piece 24 is attached along the tip edge of the bracket 23. The surface of the overlapping piece 24 forms an overlapping surface 25 on which the cable 12 is overlapped. According to one of the features of the present invention, the overlapping surface 25 may be generally arcuate centered on the center of rotation, but in this embodiment, the overlapping surface 25 is at the end of the end facing the post 10. The guide portion 25A curved toward the boss 22, the flat portion 25 B extending gradually in a straight line by gradually increasing the distance from the boss 22, the direction changing portion 25 C curved toward the boss 22, and the center line of the boss 22 And a circular arc part 25D centered at.

  Then, the direction changing member 21 is supported by the carburetor body 1 so as to protrude upward and downward from one side by fitting a boss 22 on the support shaft 13 attached to the carburetor body 1, and is freely supported. The cable 12 is brought into close contact with the entire length from the throttle valve lever side end to the accelerator lever side end.

  The distance between the center line of the support shaft 13, which is the center of rotation, and the guide portion 25A and the circular arc portion 25D is smaller in the former, which is another feature of the present invention. 1 and 3A show the posture of the direction changing member 21 when the throttle valve 7 is in the idle position. The cable 12 is in contact with the overlapping surface 25 at the end of the guide portion 25A, and the end of the arc portion 25D. And away from the overlapping surface 25 to the accelerator lever.

  When the cable 12 is pulled by the driver operating the accelerator lever, the direction changing member 21 rotates with the movement of the cable 12 without causing any slip between the cable 12 and the overlapping portion. When the throttle valve 7 is in the fully open position, as shown in FIG. 3B, the cable 12 contacts the overlapping surface 25 at the starting end of the guide portion 25A and leaves the overlapping surface 25 at the starting end portion of the arc portion 25D. That is, between the idle position and the fully open position of the throttle valve 7, the throttle valve lever side of the cable 12 contacts and separates from the overlapping surface 25 within the region of the guide portion 25A, and the accelerator lever side within the region of the arc portion 25D. It contacts / separates from the overlapping surface 25. Since the cable 12 does not slip between the overlapping surface 25, sliding friction does not occur.

  On the other hand, when the direction changing member 21 rotates, the ratio of the moving amount (stroke) of the arc portion 25D that is the accelerator lever side end portion to the moving amount (stroke) of the guide portion 25A that is the throttle valve lever end portion is , Equal to the ratio of the distance from the center of rotation. For this reason, the opening / closing operation amount of the throttle valve 7 with respect to the operation amount of the accelerator lever, that is, the amount of change in opening is reduced, and the total operation amount of the accelerator lever is made sufficiently large by appropriately setting the ratio value. However, the throttle valve lever 9 can be made smaller and easier to install, and the throttle valve 7 can be opened and closed in response to slight operation of the accelerator lever to make the engine rotation unstable, or the throttle valve 7 can be opened and closed more than the target. Thus, unexpected acceleration / deceleration is not performed.

  Next, an example of attaching the direction changing member 21 to the vaporizer main body 1 will be described with reference to FIGS. 4 and 5. The boss 22 is fitted to the corner portion of the vaporizer main body 1 so as to open to one side and the upper surface. A mounting hole 31 is provided, and a groove 32 into which the accelerator lever side end of the bracket 23 enters is provided open on the upper surface of the vaporizer body 1, and an axis passing through the center line of the mounting hole 31. A hole 33 is provided in the vaporizer body 1. Then, the boss 22 is fitted into the mounting hole 31 from the open portion, and the support shaft 13 is inserted into the boss 22 through the shaft hole 33, whereby the direction changing member 21 is rotatably supported by the vaporizer body 1.

  The support shaft 13 may be a dedicated one, but the mounting bolt 4 is used in the present embodiment. In this case, since the carburetor is assembled to the engine by the engine manufacturer, the carburetor manufacturer ships with the direction changing member 21 temporarily attached to the carburetor main body 1. For this purpose, in this embodiment, a retaining projection 14 is provided on the throttle valve lever 9, and the retaining projection 14 is positioned in front of the boss 22 in the idle position so that it completely comes out of the mounting hole 31 and falls off. It was supposed to prevent. The retainer projection 14 is retracted from the front region of the mounting hole 31 to the side by turning the throttle valve lever 9 in the valve opening direction, and the directional change member 21 can be temporarily assembled to the vaporizer body 1. .

  Further, in this embodiment, the direction changing member 21 is provided with a positioning protrusion 26 that contacts the side surface of the carburetor body 1 at the idle position, and the protrusions 27 and 28 are provided on both side edges of the overlapping surface 25. . The positioning projection 26 is brought into contact with the side surface of the carburetor main body 1 so that the cable 12 is coupled to the accelerator lever and the throttle valve lever 9 in the idle position and overlaps the overlapping surface 25, whereby the idle position and the fully open position of the throttle valve 7 are set. The operation amount of the accelerator lever and the opening change amount of the throttle valve 7 can be maintained at a set ratio. Further, the protrusions 27 and 28 are prevented from coming off from the overlapping surface 25 when the cable 12 is assembled, thereby facilitating the assembly.

The front view which shows embodiment of this invention. The left view of FIG. The form (A) of FIG. 1 is an idle position, (B) is the side surface fragmentary part which shows the state of a full open position. (A) of the form of FIG. 1 is a partially cutaway front view of the direction changing member, (B) is a front view of the mounting hole, and (C) is a cross-sectional view of (B). The longitudinal cross-sectional view which shows the state which assembled | attached the direction change member of the form of FIG. 1 to the vaporizer main body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vaporizer body, 4 Mounting bolt, 7 Throttle valve, 8 Throttle valve shaft, 9 Throttle valve lever, 12 Cable, 13 Support shaft, 21 Direction change member, 22 Boss, 24 Stack piece, 25 Stack surface, 25A Guide part, 25B plane part, 25C direction change part, 25D arc part

Claims (4)

In a general-purpose engine carburetor in which a cable that couples both ends to an accelerator lever that is manually operated by a driver and a throttle valve lever that is fixed to the throttle valve shaft is disposed in the vicinity of the carburetor.
A direction changing member having an overlapping surface with at least a curved surface is rotatably supported by the vaporizer body, and the cable is overlapped on the overlapping surface, and the direction changing member is responsive to an operation of the accelerator lever. In addition, it is supposed to rotate without causing a slip between the overlapping portions of the cables corresponding to the movement of the cables,
This is a general-purpose engine carburetor. In a general-purpose engine carburetor in which a cable that couples both ends to an accelerator lever that is manually operated by a driver and a throttle valve lever that is fixed to the throttle valve shaft is disposed in the vicinity of the carburetor.
A direction changing member having an overlapping surface with at least a curved surface is rotatably supported by the vaporizer body, and the cable is overlapped on the overlapping surface, and the direction changing member is responsive to an operation of the accelerator lever. In addition, in response to the movement of the cable, it rotates without causing a slip between the overlapping portions of the cables, and the rotation center of the direction changing member and the end portion on the accelerator lever side of the overlapping surface Is greater than the distance to the throttle valve lever side end,
This is a general-purpose engine carburetor.   The general-purpose engine carburetor according to claim 1 or 2, wherein the support shaft that freely supports the direction changing member is a mounting bolt that couples the carburetor body to the engine. A guiding portion in which the overlapping surface of the direction changing member is curved toward the turning center of the direction changing member at the end portion on the throttle valve lever side, and a plane extending linearly by gradually increasing the distance from the turning center Part, a direction changing part curved toward the rotation center, and a circular arc part centering on the rotation center, and the throttle valve lever side of the cable between the idle position and the fully open position of the throttle valve 3. The general-purpose engine according to claim 2, wherein is in contact with or separated from the overlapping surface in the region of the guiding portion, and the accelerator lever side is in contact with or separated from the overlapping surface in the region of the arc portion. Vaporizer.

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