JP2006242122A - General-purpose engine carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a main jet securely fixed to a main well part in a normal state and maintain a sealing property for a general-purpose engine carburetor having a main well part made of a synthetic resin, and to be easily detached during maintenance. Is an issue.
SOLUTION: In a general-purpose engine carburetor 1A in which a main jet 35A is inserted into a mounting hole 33a formed in a predetermined position on an outer wall of a main well portion 33A that is suspended in a constant fuel chamber 20, the main jet 35A is inserted. An O-ring 40 that secures internal and external airtightness is fitted between the inner portion and the inner peripheral surface of the mounting hole 33a, and the fall prevention wall 21b that regulates the movement of the main jet 35A in the removal direction is provided in the chamber 21A. It is assumed that the main jet 35A is detachable from the bottom wall before the chamber 21A is mounted, and at least the main jet 35A is not dropped from the main well portion 33A after the chamber 21A is mounted.
[Selection] Figure 1

Description

  The present invention relates to a carburetor disposed in a fuel supply for a general-purpose engine, and more particularly, to a carburetor for a general-purpose engine in which a main well portion provided with a fuel passage is formed of a synthetic resin.

  Conventionally, metal die-cast molded products such as aluminum have been frequently used for the main body and main well portion (columnar portion) of a carburetor used in a general-purpose engine. On the other hand, as described in Japanese Patent Application Laid-Open No. 2001-27156, synthetic resin molded products are used for each part including the main well portion from the viewpoint of weight reduction, ease of manufacture, and manufacturing cost. There are many things. However, synthetic resin products tend to be problematic in that mechanical strength and heat resistance are inferior to those made of metal, and joints between components are likely to loosen.

  For example, as shown in FIG. 5, in the carburetor 1D for a general-purpose engine, when the columnar main well portion 33D inserted into the constant fuel chamber inside the chamber 21C (fuel container) is made of metal, It is assumed that 35D is not easily dropped by screwing. Further, since the main well portion 33D and the main jet 35D are made of metal, a sheet surface is provided at the contact portion to ensure airtight holding by metal touch.

  However, if the main well is made of synthetic resin, there is a problem that it becomes difficult to hold the main jet in the main well due to the effect of creep due to heat. Can not do it.

  Therefore, as shown in FIG. 6, in a general-purpose engine carburetor 1E employing a synthetic resin main well portion 33E, the main jet 35A is generally attached via an O-ring 40. In other words, the O-ring 40 seals between the main jet 35A and the inner wall of the mounting hole of the main well portion 33E, thereby ensuring airtightness. However, fixing to the main well portion 33E only by the O-ring 40 tends to cause a problem that the main jet 35A is dropped due to vibration during use.

To solve this problem, a method of completely fixing the main jet to the main well portion made of synthetic resin by using high-frequency welding or adopting insert molding for the mounting structure can be considered. However, this causes inconvenience that it is inconvenient at the time of maintenance such as replacement of the main jet, and the cost for replacement increases, so that the market needs cannot be met.
Japanese Patent Laid-Open No. 2001-27156

  The present invention is intended to solve the above-described problems, and in a general-purpose engine carburetor having a synthetic resin main well portion, the main jet is normally securely fixed to the main well portion. It is an object of the present invention to maintain airtightness and to facilitate the detachment during maintenance.

In view of the above, the present invention provides a main well portion which is provided with a fuel passage inside and is formed of a synthetic resin in a constant fuel chamber, and a main jet is formed in a mounting hole formed at a predetermined position on the outer wall of the main well portion. In the general-purpose engine carburetor inserted,
Sealing means is provided between the insertion portion of the main jet and the inner peripheral surface of the mounting hole to ensure internal and external airtightness, and a drop-off preventing structure that restricts the movement of the main jet in the removal direction is provided. Thus, at least after the chamber is installed, the main jet does not fall out of the main well portion.

  In this way, even if the main well portion is made of resin and the main jet is easily loosened, the main jet does not fall off at least after the chamber is attached, while ensuring airtightness inside and outside by the sealing means. As a result, the main jet can be attached to the main well portion without being dropped during use, and can be surely hermetically sealed, and can be removed during maintenance with the chamber removed.

  Further, in the above-described carburetor for a general-purpose engine, the drop-off prevention structure is projected upward from the bottom wall side of the chamber, and is located on the extraction orbit of the main jet when the chamber is mounted. If the main jet can be removed before the chamber is installed, the main jet can be easily removed during assembly and maintenance. It will be possible to reliably prevent the dropout.

  Alternatively, the drop-off prevention structure is a drop-off prevention claw composed of an arm portion protruding in the centrifugal direction from the periphery of the main jet mounting hole opening of the main well portion and a flange portion that hooks the main jet proximal end portion at the distal end side thereof. By restricting the movement in the removal direction by hooking the main jet, it is possible to detach the main jet before installing the chamber.If the arm is bent before installing the chamber, the same as above The main jet can be detached and the main jet can be reliably prevented from falling off after the chamber is installed.

  According to the present invention, the attachment of the main jet to the main well portion is fixed without dropping in the normal state to ensure the airtightness, and can be easily attached and detached during the maintenance.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1 showing a longitudinal sectional view of a general-purpose engine carburetor according to the present embodiment, a main body made of synthetic resin has a lateral intake passage 2 penetrating in the front-rear direction. Are provided with a choke valve 3, a venturi 4 and a throttle valve 5 in order from the inlet to the outlet. The valve shafts 3a and 5a of the choke valve 3 and the throttle valve 5 are fitted and supported in bearing holes provided in the main body. The choke valve lever 6 and the throttle valve lever 7 united with these valve shafts are used for the choke valve 3, The opening / closing operation of the throttle valve 5 is the same as that of a normal carburetor.

  In addition, a circular lower surface 8 whose diameter is the passage length of the intake passage 2 is formed in the main body, and a synthetic resin chamber (fuel container) 21A is fixed to this portion, and a main nozzle 32 is provided at the inner center thereof. A columnar main well portion 33A that is fitted and supported is provided vertically. Further, the main well portion 33A integrally has a disc-shaped flange 12 having the same diameter as the lower surface 8 at the upper end, and the upper surfaces of the main well portion 33A and the flange 12 are formed in a circular plane.

  The constant fuel chamber 20 is formed inside the chamber 21A, and the main well portion 33A is inserted into the central portion thereof. A float 24 supported in a cantilever manner on a pin 23 is inserted into the constant fuel chamber 20, and a fuel valve 25 attached to the float 24 is fitted into a valve seat body 26 fixed to the flange 12.

  A fuel passage 31 is provided inside the main well portion 33A, and a main jet 35A is inserted from the side into a mounting hole 33a formed in the outer peripheral surface on the front end side of the main well portion 33A. The fuel passage 31 is communicated with the fuel at a predetermined flow rate. The main jet 35A is a substantially cylindrical member made of metal, and is provided with an annular flange 35a on the base end side so that insertion is stopped at a predetermined position.

  The main jet 35A is inserted into and fixed to the main jet mounting hole 33a formed in the resin main well portion 33A. The fixing is mainly performed in the circumferential direction on the outer periphery of the insertion portion of the main jet 35A. This is due to the elasticity of the O-ring 40 fitted between the provided annular groove 35b and the inner peripheral surface of the mounting hole 33a, thereby ensuring internal and external airtightness.

  Also, a substantially square drop-off prevention wall 21b protrudes upward from the bottom wall of the chamber 21A. After the chamber 21A is mounted, the main jet 35A comes close to the base end face side on the withdrawal track, and moves in the removal direction. The feature of the present embodiment lies in that the main jet 35A is prevented from falling off during use because the main jet 35A is prevented from coming off. The drop prevention wall 21b can be formed at the same time as the molding of the chamber 21A, and therefore can be easily provided without increasing the manufacturing cost.

  Referring to the exploded view of vaporizer 1A in FIG. 2, there is nothing to block the main jet 35A from being attached to or detached from the main well portion 33A before the mounting of the chamber 2A at the time of manufacturing assembly, maintenance or the like. The position where the inner surface of the flange 35a comes into contact with the outer surface of the main well portion 33A and stops as a result of the insertion becomes the fixed position. After the chamber 21A is mounted, the drop-off prevention wall 21b reliably prevents the main jet 35a from falling off, and the internal and external airtightness is ensured.

  FIG. 3 shows a second embodiment of the present invention. Instead of the drop-off prevention wall 21b as the drop-off prevention structure in the vaporizer 1A of FIG. 1, a set of drop-off prevention claws from the main well portion 33B. The carburetor 1B is formed by projecting 33b and 33b so as to face each other.

  The drop-off preventing claw 33b is directed toward the inside of the mounting hole 33a at the distal end side of the arm portion 331 projecting in the centrifugal direction from the opposing position around the opening portion of the mounting hole 33a of the synthetic resin main well portion 33B. It is made of a synthetic resin composed of a protruding flange 332, and is relatively easily created by being integrally formed or retrofitted with the main well 33B. After the main jet 35A is inserted and fixed, the flanges 332 and 332 latch the main jet 35A base end face side to restrict the movement in the removal direction to prevent the drop off.

  Referring to the exploded view of the vaporizer 1B in FIG. 4, as shown in FIG. 4 (A), the main jet 35A is attached to and detached from the main well portion 33B before the chamber 21B is installed during manufacturing assembly and maintenance. It is the same as the carburetor 1A in that the flange 35a of the main jet 35A can be easily pinched without any obstruction, and the position where the inner surface of the flange 35a abuts the outer surface of the main well is the fixed position. . Further, as shown in the figure (B), since the movement in the removal direction is regulated by the drop-out preventing claw 33b after the chamber 21B is mounted, the drop-out of the main jet 35A is surely prevented.

  Referring to FIG. 4C, when the main jet 35A is attached / detached, the drop-off preventing claws 33b, 33b are easily bent in the direction in which the arm portions 331, 331 made of an elastic resin increase the interval. Therefore, the main jet 35A can be easily expanded and inserted simply by pushing in the main jet 35A at the time of mounting, and the main jet 35A can be easily removed simply by pulling it in the direction of spreading with a finger or the like at the time of withdrawal. In addition, even if it is not one set which opposed this fall-off prevention nail | claw 33b, for example, the predetermined drop-off prevention effect can be exhibited.

The longitudinal cross-sectional view which shows 1st embodiment in this invention. The exploded view for demonstrating the removal | desorption operation | work of the main jet in the vaporizer | carburetor of FIG. The longitudinal cross-sectional view which shows 2nd embodiment in this invention. (A) is an exploded view for explaining the main jet desorption operation in the vaporizer of FIG. 3, (B) is a longitudinal sectional partial view showing a state after fixing the main jet, and (C) shows a state during the main jet desorption operation. FIG. The longitudinal cross-sectional view which shows the prior art example in case a main well part is metal. The longitudinal cross-sectional view which shows the prior art example in case the main well part is resin.

Explanation of symbols

1A, 1B carburetor, 20 constant fuel chamber, 21A, 21B chamber, 21b drop-off prevention wall, 32 main nozzle, 33A, 33B main well portion, 33a mounting hole, 33b drop-off prevention claw, 35A main jet, 35a flange, 35b annular groove , 40 O-ring, 331 arm, 332 buttocks

Claims (3)

A general-purpose engine having a fuel passage inside and a main well portion formed of a synthetic resin in a constant fuel chamber, and a main jet inserted in a mounting hole formed in a predetermined position on the outer wall of the main well portion In the vaporizer,
Sealing means is provided between the insertion portion of the main jet and the inner peripheral surface of the mounting hole to ensure internal and external airtightness, and a drop-off preventing structure that restricts the movement of the main jet in the removal direction is provided. A general-purpose engine carburetor for preventing the main jet from falling off from the main well portion at least after the chamber is installed.   The drop-off prevention structure protrudes upward from the bottom wall side of the chamber, and protrudes from the chamber that is positioned on the extraction orbit of the main jet and restricts movement in the extraction direction when the chamber is mounted. The general-purpose engine carburetor according to claim 1, wherein the carburetor is a drop-off prevention protrusion. The drop-off prevention structure is composed of an arm portion protruding in the centrifugal direction from the periphery of the main jet attachment hole opening of the main well portion and a flange portion that hooks the main jet base end portion on the distal end side of the arm portion, The general-purpose engine carburetor according to claim 1, wherein the main-jet is a drop-off prevention claw that restricts movement in a removal direction by hooking the main jet.

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