JP2005146980A - Throttle valve supporting shaft dust-proof seal for turning throttle valve type carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a throttle valve supporting shaft dust-proof seal for a turning throttle valve type carburetor. <P>SOLUTION: The dust-proof seal 31 protects a clearance between a supporting shaft 24 of a turning valve body 3 and a shaft supporting part 23a for supporting the shaft from dust. The dust-proof seal 31 is formed to be a cylindrical shape whose diameter is enlarged at the intermediate part, and an outward flange part 23b is provided at an intermediate part of the shaft supporting part 23a. Thereby, as the dust-proof seal can be engaged with and mounted to the turning support shaft and the shaft supporting part at three points, its both ends and its intermediate diameter-enlarged part 31a, it can retain a dust-proof performance more securely than that engaging only at its both ends can. The diameter of the both ends of the dust-proof seal is made smaller than that of the intermediate part, which can prevent an opening end of the shaft supporting part side from moving over a radial direction outwardly projecting part so as to make the clearance between the turning support shaft and the shaft supporting part always covered with the dust-proof seal. As the durability of the dust-proof seal is improved as well as the dust-proof function, the seal need not to be changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a throttle valve support shaft dustproof seal of a rotary throttle valve type vaporizer.

  Conventionally, in a carburetor using a rotary throttle valve, the intake passage is opened and closed by the rotation of the rotary valve body, and the fuel injection amount from the fuel injection nozzle is controlled by the axial displacement of the rotary valve body. I have to. In such a rotary throttle valve type carburetor, the rotary support shaft of the rotary valve body protrudes outward from the carburetor body, and an operation lever is fixed to the protruding end portion, so that it can be operated by throttle operation. When the lever is rotated, the rotating valve body is rotated, and accompanying this, the cam means is displaced in the axial direction (see, for example, Patent Document 1).

  A valve shaft dustproof seal for sealing a gap between the support shaft and the lid body of the rotary throttle valve is mounted.

Japanese Utility Model Publication No. 4-8294 (page 2-3, Fig. 1)

  In the above rotary throttle valve type vaporizer, in order to prevent dust and the like from entering the gap between the rotary support shaft projecting outward of the vaporizer body and the corresponding shaft support portion of the vaporizer body. A dustproof seal is provided to cover that part. In the installation procedure of the dust-proof seal, the dust-proof seal is formed into a cylindrical shape by an elastic material, and one end of the opening is elastically brought into close contact with the rotation support shaft and engaged with the other, for example, an annular boss. Engage in close contact with the shaft support.

  However, when the engine is left idle for a long time, the rotary valve body remains in the initial position (the lowest position when the axial direction is the vertical direction), and in this state, the distance between the operation lever and the shaft support portion Is the shortest, the dust-proof seal is in the most crushed state. Therefore, if the above-mentioned neglected state lasts for a long time, the dustproof seal may be deteriorated and deformed when it is made of rubber.

  If the engine is restarted without replacing the dust-proof seal, and the rotating valve body rises to the highest point so that the engine is fully rotated and the maximum fuel injection amount is achieved, the dust-proof seal is fully extended in the axial direction. Become. In this case, if the deformation due to the deterioration occurs, the elastic holding force of the dustproof seal is reduced and the engagement force is lowered. For example, the opening end on the shaft support side cannot stay at the initial position, and the shaft support side The opening end portion moves upward. For this reason, if the opening end on the shaft support side is removed from the protruding end of the shaft support, the dustproof function is lost. As a countermeasure, it is necessary to replace the dustproof seal, which causes problems such as maintenance costs and troublesome inspection.

  In order to solve such a problem and improve the durability of the throttle valve support shaft dustproof seal of the rotary throttle valve type carburetor so that it is not necessary to replace it. The rotary valve body is provided on the carburetor body so as to be rotatable about an axis perpendicular to the intake passage and is displaced in the axial direction, and protrudes into the through hole coaxially with the rotary valve body. A rotary throttle valve type having a fuel injection nozzle fixed to the body of the carburetor, and a needle valve integrated with the rotary valve body so as to face the fuel injection nozzle and be coaxially immersed therein The carburetor has a dust-proof seal made of an elastic body for dust-proofing a gap between a rotation support shaft integrated with the rotation valve body and a shaft support portion supporting the rotation support shaft in the vaporizer body. A ring projecting outwardly from a surface covering the rotating valve body. It is formed in a boss shape and has a radially outward projection at its middle part, the middle part of the dust-proof seal is enlarged in diameter, and one end of the dust-proof seal is outside the vaporizer body of the rotating support shaft The other end is elastically engaged with the shaft support, and the middle portion of the dust-proof seal is engaged with the radially outward projection, It was assumed that the dustproof seal was attached.

  As described above, according to the present invention, the diameter of the intermediate portion of the dust-proof seal is increased and the radially outward protrusion is provided at the intermediate portion of the corresponding shaft support portion, and the diameter-expanded portion of the dust-proof seal is engaged with the radial protrusion. By combining, the dustproof seal can be attached to the pivot support shaft and the pivot support at three points, both ends and the middle part, so that it is more reliable than the one that is engaged at only two points at both ends. Dustproofness can be maintained. In addition, since both ends of the dust-proof seal are reduced in diameter with respect to the intermediate portion, it is possible to prevent the opening end on the side of the shaft support portion from moving over the outward projecting portion in the radial direction. The gap between the support shaft and the shaft support portion can always be covered with the dustproof seal. In addition, a tensile load can always be applied to the dust-proof seal by the radially outward projection, and the deterioration of the dust-proof seal can be prevented by the tensile load. Thereby, since durability improves with the improvement of the dust-proof function of a dust-proof seal, it is possible to prevent the necessity of replacing the dust-proof seal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing the entire rotary throttle valve type vaporizer. As shown in FIG. 1, the carburetor body 1 is provided with an intake passage 2 that communicates an upstream portion and a downstream portion of an intake pipe (not shown) so as to open in the front and back direction in the figure, A rotary valve body 3 for opening and closing the intake passage 2 is received.

  The rotary valve body 3 is formed by molding a synthetic resin material, for example, and is provided so as to be rotatable around an axis perpendicular to the intake passage 2. Further, in the rotary valve body 3, the upper part in the drawing that is one end in the axial direction protrudes above the carburetor body 1, and the lower part in the drawing that is the other axial end is in the carburetor body 1. Immersive.

  A pulsation pressure chamber 4 communicating with the crank chamber is provided in the carburetor body 1 so that the pulsation pressure of the crank chamber of the engine acts, and a pump membrane 5 is provided in the pulsation chamber 4. . A pump chamber 6 is provided on the side of the pump membrane 5 opposite to the pulsation chamber 4. The pump chamber 6 communicates with an external fuel tank (not shown) via a flow path provided in the carburetor body 1 and a check valve 7. When the pump membrane 5 is reciprocally displaced by pulsation pressure, the fuel in the fuel tank Is sucked into the pump chamber 6.

  The pump chamber 6 communicates with the fuel control chamber 11 via the check valve 8 and the inflow fuel control valve 9. When the pump membrane 5 is operating on the fuel suction side, the check valve 8 is closed and the fuel on the fuel tank side is sucked. When the pump membrane 5 is operating on the fuel discharge side, the check valve 8 is opened and the fuel in the pump chamber 6 is discharged. The fuel is discharged into the fuel control chamber 11.

  A part of the fuel control chamber 11 is closed by a diaphragm 12. An air chamber 13 is provided outside the diaphragm 12. A lever 15 is pivotally supported in the fuel control chamber 11 by a pivot 14 fixed in place. The inflow fuel control valve 9 is connected to one end of the lever 15, and the other end of the lever 15 is positioned to face the central protrusion of the diaphragm 12. Due to the deformation of the diaphragm 12, the central protrusion is displaced in the axial direction, whereby the other end of the lever 15 is pushed and the lever 15 rotates clockwise in the figure, whereby the inflow fuel control valve 9 is opened. The lever 15 is elastically biased in a direction to close the inflow fuel control valve 9.

  A fuel passage extending from the fuel control chamber 11 to the intake passage 2 is a fuel jet erected on the carburetor body 1 so as to protrude into the communication passage portion of the carburetor body 1 and the vent hole 3a of the rotary valve body 3. It is formed by the axial hole of the nozzle 16. Between the fuel control chamber 11 and the nozzle 16 in the fuel passage, a check valve 17 and a main jet 18 are disposed from the fuel control chamber 11 side. In addition, a main nozzle hole 16 a that communicates with the axial hole of the nozzle 16 is formed in a portion of the nozzle 16 that is positioned at the center of the vent hole 3 a.

  In the axial direction hole of the nozzle 16, the distal end portion of the fuel adjustment needle valve 19, whose base end portion is coupled to the upper portion of the rotating valve body 3 and suspended in the vent hole 3 a, is immersed. The state shown in FIG. 1 is a state in which the throttle valve in the carburetor is fully closed. In this state, the main nozzle 16a is closed by the tip of the fuel adjustment needle valve 19.

  On the lower surface of the rotating valve body 3, a cam body 21 as a rotating cam for performing a cam action as the rotating valve body 3 rotates is assembled. The cam body 21 is received in a recessed portion 1 a that is recessed in a corresponding portion of the vaporizer body 1. On the lower surface of the cam body 21 (the surface facing the bottom surface of the recessed portion 1a), as shown in FIG. 2, a cam surface 21a formed of a pair of inclined surfaces having a point-symmetric shape with respect to the axis is formed. . A pair of hard spheres 22 that are partially protruded from the bottom surface are embedded in the bottom surface of the recessed portion 1a so as to contact the cam surface 21a.

  A lid body 23 is fixed on the upper surface of the vaporizer body 1 so as to cover the upper part of the rotary valve body 3. A support shaft 24 integrated with the rotary valve body 3 is supported by the lid body 23 so as to be rotatable and axially displaceable. The upper portion of the support shaft 24 protrudes outward from the lid body 23, and an operation lever 25 is fixed to the protruding end portion of the support shaft 23.

  The support shaft 24 is coaxially provided with an axial hole 24a, and the base end portion of the fuel adjustment needle valve 19 is screwed into an internal screw provided in the axial hole 24a and is axially Is spring-biased. The fuel adjustment needle valve 19 is coaxially fixed to the support shaft 24 by its screw connection and spring bias, but by adjusting the screwing amount, the amount of penetration of the fuel adjustment needle valve 19 with respect to the nozzle 16 in the axial direction is reduced. Can be adjusted.

  A compression coil spring 26 is provided between the upper surface of the rotary valve body 3 and the lid body 24 to elastically bias the rotary valve body 3 downward in FIG. Thereby, the cam surface 21a of the cam body 21 assembled | attached to the rotation valve body 3 can always contact | abut to the hard ball | bowl 22 by the side of the carburetor main body 1. FIG. Further, one coil end of the compression coil spring 26 is engaged with the lid body 23 and the other coil end is engaged with the rotating valve body 3, whereby the rotating valve body 3 is closed. Is being energized.

  A throttle operating lever is connected to the operating lever 25 via a wire or a link (not shown), and the support shaft 24, that is, the rotary valve body 3 rotates according to the amount of throttle operation. Since the cam body 21 is also integrally rotated by the rotation of the rotary valve body 3, the hard ball 22 is relatively moved up and down on the cam surface 21a, whereby the rotary valve body 3 is displaced in the axial direction. Then, the fuel adjustment needle valve 19 is also integrally displaced by the axial displacement of the rotary valve body 3, and the position where the tip of the needle valve 19 crosses the main nozzle 16a of the nozzle 16 changes. The opening area can vary. The lid body 23 is provided with an adjusting screw 27 for adjusting the valve closing position of the rotary valve body 3 by contacting a part of the operation lever 25.

  In the rotating valve body 3, for example, a recessed portion 3 f is formed in the lower portion on the inner side of the carburetor body 1 by forming a wall in a portion forming the wall of the vent hole 3 a, and the vent hole 3 a On the other hand, a plurality of radial ribs 3b are provided as shown in FIG. 3 in order to prevent molding distortion with respect to the thin wall portion.

  The radial rib 3b is formed so as to extend from an annular boss portion 3c provided at the center portion to penetrate the nozzle 16 to a peripheral wall 3d as an outer peripheral wall of the recessed portion 3f. In addition, axial ridges 3e are arranged at at least three locations at equal pitch angles on the inner peripheral surface of the peripheral wall 3d. In addition, a pair of engaging pieces 28 as protrusions toward the movable valve body 3 are integrally provided on the outer peripheral surface of the cam body 21 at symmetrical positions in the diameter direction, and the peripheral wall 3d of the rotating valve body 3 is provided. A corresponding portion is provided with a pair of engagement recesses 29 as recesses for receiving the engagement pieces 28.

  As shown by the arrow in FIG. 2, the cam body 21 is assembled to the rotary valve body 3 with both engagement pieces 28 protruding into both engagement recesses 29. As shown in FIG. 4, the outer diameter d <b> 1 of the cam body 21 and the diameter D <b> 1 of the circle passing through the projecting ends of the three axial ridges 3 e of the rotary valve body 3 are the same. Thereby, centering at the time of the assembly of the cam body 21 with respect to the rotary valve body 3 is performed. An axial hole 21b having a size surrounding the annular boss 3c of the rotary valve body 3 is provided at the center of the cam body 21.

  Further, the axial position of the rotary valve body 3 in the radial rib 3b (for example, the length h from the axial center of the vent hole 3a) is made the same in all the radial ribs 3b, and the cam body 21 is assembled. By contacting the radial rib 3b, the axial position of the cam body 21 with respect to the rotary valve body 3 is regulated. The positioning of the cam body 21 with respect to the rotary valve body 3 is performed with high accuracy by the restriction of the axial position and the centering.

  Further, the engagement piece 28 is provided with a circumferential convex portion 28a, and a circumferential concave portion 29a is provided in a corresponding portion of the engagement concave portion 29, whereby the cam body 21 is attached to the rotary valve body 3. Combined means are configured. In assembling the cam body 21, the engagement piece 28 a and the engagement recess 29 a are aligned, and the cam body 21 is pushed into the rotary valve body 3, whereby the circumferential protrusion 28 a of the engagement piece 28 is engaged. The cam body 21 is coupled to the rotary valve body 3 by engaging with the circumferential recess 29 a of the joint recess 29. Thus, the cam body 21 can be assembled to the rotary valve body 3 with one action. Moreover, since the rotation valve body 3 can be handled in the state which integrated the cam body 21, the assembly | attachment to the vaporizer body 1 can be performed easily.

  Further, since the rotation valve body 3 and the cam body 21 are made of a synthetic resin material, the engagement of the engagement convex portion 28a and the engagement concave portion 29a can be elastic. It can be made to contact elastically. Thereby, the position accuracy in the axial direction when the cam body 21 is assembled can be easily ensured.

  The present invention is particularly characterized by the following configuration. A dustproof seal 31 made of an elastomer material is attached between the operation lever 25 and the lid 23 of the support shaft 24. As shown in FIG. 5, the dust-proof seal 31 has a shape in which the diameter of the intermediate portion in the axial direction of the cylindrical shape is expanded. The lid body 23 is provided with an annular boss-shaped shaft support portion 23a that encloses the upper projecting portion of the support shaft 24 over a predetermined length. An outward flange portion 23b as a radially outward projection is formed at an axially intermediate portion of the shaft support portion 23a.

  The upper opening of the dustproof seal 31 is elastically adhered to the outer peripheral surface of the support shaft 24 exposed from the shaft support portion 23a, and the lower opening of the dustproof seal 31 is attached to the outer peripheral surface of the base end portion of the shaft support portion 23a. The inner diameters of the opening ends of the dust-proof seal 31 are set so that they adhere elastically. Similarly, the maximum inner diameter of the intermediate enlarged portion 31a of the dustproof seal 31 is also set smaller than the outer diameter of the outward flange portion 23b, and the inner diameter of the intermediate enlarged portion 31a is engaged with the outward flange portion 23b and attached. In this state, a tensile load is generated on the dustproof seal 31.

  As shown in FIG. 5, the support shaft 24 is inserted into the shaft support portion 23a, and the portion of the support shaft 24 that protrudes outward (upward in the drawing) of the shaft support portion 23a and the shaft support portion 23a is enclosed. 31 is fitted. Thereby, the clearance gap between the support shaft 24 and the shaft support part 23a can be covered by the dust-proof seal 31.

  During operation, the rotary valve body 3 rotates according to the operation of the operation lever 25, opens according to the rotation angle, and the fuel adjustment needle valve 19 rises to open the main nozzle 16a. The fuel in the nozzle 16 is sucked out according to the flow of the intake air passing through the intake passage 2 and the vent hole 3a, and the engine rotates. At this time, even if the support shaft 24 is similarly displaced in accordance with the axial displacement of the rotating valve body 3 and the rotating valve body 3 rises to the highest position during high-speed rotation, for example, the upper portion of the dust-proof seal 31 remains Dustproofness is maintained because it is in sliding contact with the support shaft 24 in close contact.

  Further, since a tensile load is generated in the dust-proof seal 31 in the attached state as described above, an appropriate tensile load can always be applied to the dust-proof seal 31. Due to this moderate tensile load, when the dust-proof seal 31 is made of, for example, rubber, the deterioration can be suitably prevented. In this way, not only the dustproof function of the dustproof seal 31 but also the durability can be improved.

  The throttle valve support shaft dustproof seal of the rotary throttle valve type vaporizer according to the present invention improves the dustproof function and durability of the dustproof seal, and is useful for a rotary throttle valve type vaporizer.

It is a longitudinal cross-sectional view which shows the vaporizer in which this invention was explained. It is a fragmentary perspective view which shows the assembly | attachment point of the cam body to a rotation valve body. FIG. 3 is a bottom view of the rotary valve body as seen from the arrow III line in FIG. 2. It is a principal part longitudinal cross-sectional view of a rotation valve body and a cam body. It is a sectional side view which shows the attachment point of the dustproof seal based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vaporizer body 3 Rotating valve body 16 Fuel injection nozzle 19 Fuel adjustment needle valve 23 Cover body, 23a Shaft support part, 23b Outward flange part 24 Support shaft 31 Dust-proof seal, 31a Intermediate diameter expansion part

Claims (1)

A rotary valve body provided on the carburetor main body so as to be rotatable about an axis perpendicular to the intake passage and provided in an axial displacement, and the vaporization so as to protrude coaxially with the rotary valve body into the through hole. A rotary throttle valve type carburetor having a fuel injection nozzle fixed to the body of the vessel and a needle valve integrated with the rotary valve body so as to oppose and coaxially enter the fuel injection nozzle In
A dust-proof seal made of an elastic body for dust-proofing a gap between a rotation support shaft integrated with the rotation valve body and a shaft support portion supporting the rotation support shaft in the vaporizer body;
The shaft support portion is formed in an annular boss shape projecting outward from a surface covering the rotating valve body, and has a radially outward projection at an intermediate portion thereof,
The middle part of the dust-proof seal is expanded,
One end of the dustproof seal is elastically engaged with a portion of the rotation support shaft that protrudes outward of the vaporizer body, and the other end is elastically engaged with the shaft support, and the dustproof seal A throttle valve support shaft dustproof seal of a rotary throttle valve type carburetor, wherein the dustproof seal is attached with an intermediate portion of the seal engaged with the radially outward projection.

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