JP2674690B2 - Lubricating oil supply structure for carburetor of two-cycle engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil supply structure for a carburetor of a two-cycle engine, and more particularly to a carburetor using lubricating oil supplied into a crank chamber together with intake air. The present invention relates to a lubricating oil supply structure for a carburetor of a two-cycle engine which lubricates the piston valve of the above. (Prior Art) Generally, a two-cycle engine employs a method in which a lubricating oil pump guides the lubricating oil to an intake passage, and the lubricating oil is supplied into the crank chamber together with the intake air to lubricate each part of the engine. Then, conventionally, an oil passage for guiding the lubricating oil to the intake passage is opened at a position separated from the carburetor. Therefore, in a carburetor equipped with a piston valve that appears in and out of the intake passage and adjusts the intake air amount, when such an oil passage is opened at an intake passage location downstream of the piston valve, lubricating oil from the oil passage is removed. Therefore, the piston valve cannot be lubricated. Further, when the oil passage is opened in the intake passage portion upstream of the piston valve, the piston valve can be lubricated with the lubricating oil from the oil passage. In this case, however, the lubricating oil simply flows into the piston valve together with the intake air. Since it only hits, it is hard to say that the piston valve can be lubricated sufficiently. (Problems to be Solved by the Invention) The present invention has been devised in view of the above circumstances, and an object of the present invention is to use a lubricating oil supplied into the crank chamber together with intake air to form a piston valve of a carburetor. (EN) A lubricating oil supply structure for a carburetor of a two-cycle engine that can lubricate the engine and can supply the lubricating oil to the engine side in a quick response to the operating condition of the engine. (Means for Solving the Problems) In order to achieve the above-mentioned object, the structure of the present invention is such that: the body 3 in which the intake passage 5 is formed; and the cylinder 15 formed in the body 3 slides to form the intake passage 5 Piston valve 17 that appears and disappears inside to adjust the intake amount
A needle jet 19 that extends below the intake passage 5 and is immersed in the fuel;
In a carburetor of a two-cycle engine equipped with a jet needle 33 that axially moves inside to adjust the injection amount of fuel, and a peripheral surface 15 of a cylinder 15 that slides and guides a piston valve
The opening 41 of the lubricating oil passage 39 is provided in A, and it is connected to the opening 41 on the peripheral surface 15A of the cylinder 15 and has a width of 4 mm.
A vertical groove 47 having a diameter larger than 1 and extending to the upper edge of the sliding surface and having an open surface facing the piston valve 17 is formed, and an opening 41 is formed.
The lubricating oil from is introduced to the intake passage 5. (Function) The lubricating oil derived from the lubricating oil passage 39 passes through the vertical groove 47, reaches the intake passage 5 while lubricating the cylinder peripheral surface 15A and the piston valve outer peripheral surface 17A, and the lubricating oil is sent to the engine side together with the intake air. To be done. Therefore, the piston valve 17 can be lubricated by utilizing the lubricating oil fed to the engine side together with the intake air. Further, the flow passage area of the intake passage 5 is narrowed by the piston valve 17, and the intake passage portion where the piston valve 17 is disposed.
The negative pressure on the engine side acts most on 5A, and this negative pressure acts on the lubricating oil, so that it is possible to quickly supply the lubricating oil to the engine side in response to the operating state of the engine. The lubricating oil flows smoothly because the piston valve 17 does not block the opening in the vertical groove 47.
Further, the vertical groove 47 extends to the upper edge of the sliding surface, and the piston valve
Due to the open side facing 17
47 forms an oil passage with the piston valve 17 to flow lubricating oil, and even if the piston valve 17 loosens in the circumferential direction, the positional relationship between the opening 41 and the vertical groove 47 does not change, and the lubricating oil Since it does not adversely affect the passage, the groove width does not need to be increased excessively. Secondly, regardless of the position with the outer peripheral surface 17 of the piston valve, for example, even in the upper position of the cylinder 15 where icing is likely to occur, in which water vapor contained in intake air freezes on the piston valve 17 and the jet needle 33 in cold regions. The lubricating oil is supplied, and good lubrication can be performed between the cylinder peripheral surface 15A and the piston valve 17A. (Examples) Examples of the present invention will be described below with reference to the accompanying drawings. First, the first embodiment will be described. FIG. 1 is a sectional side view of an essential part of a carburetor according to the first embodiment, FIG. 2 is a sectional plan view of the same part, and FIG. FIG. 4 is a sectional view taken along line III-III, and FIG. 4 is a sectional view of an intermediate portion of the intake passage. Reference numeral 1 is a carburetor, 3 is its body, and an intake passage 5 extending in the left-right direction is formed in the body 3, and a case 9 in which a float chamber 7 is defined is attached to the lower portion of the body 3. An intermediate portion 5A of the intake passage 5 has a vertically elongated elliptical shape, and one end 5B of the intake passage 5 is connected to the air cleaner side and the other end 5C is connected to the engine side. Cylindrical parts are provided above and below the body 3 that defines the intermediate part 5A.
11, 13 are bulged to form a cylinder 15 extending over the lower surface of the intermediate portion 5A and the upper cylindrical portion 11, and a piston valve 17 is slidably fitted into the cylinder 15. Further, a needle jet 19 is incorporated in the lower cylinder portion 13. The needle jet 19 is disposed with its axis aligned with the axis of the cylinder 15, the needle jet 19 is immersed in the fuel in the float chamber 7, the main jet 21 is installed below the needle jet 19, and 23 in the figure is a float. , 25 is a main air jet, and 27 is a bypass road. A skirt 29 is formed at the bottom of the piston valve 17,
A notch 31 is formed on the front surface of the skirt portion 29. From the lower part of the piston valve 17, a jet needle 33 is hung vertically with its axis aligned with the axis of the cylinder 15, and the jet needle 33 is inserted into the needle jet 19. A wire 35 connected to a throttle grip is connected to the piston valve 17, and the piston valve 17 is urged by a spring 37 in a direction to close the intake passage 5. The lower limit position of the piston valve 17 is regulated by a stop screw (not shown). Then, by operating the throttle grip, the piston valve 17 is moved up and down, the piston valve 17 is retracted in the intake passage 5, the flow passage area of the intermediate portion 5A is increased or decreased to adjust the intake air amount, and the jet needle 33 is used as a needle jet.
It is moved up and down within 19 to adjust the injection amount of fuel into the intake passage 5. Reference numeral 39 denotes a lubricating oil passage, and the lubricating oil passage 39 is an upper cylinder portion of the body 3.
The cylinder 11 is formed so as to be inclined toward the engine side as shown in FIG. 2, and the lubricating oil passage 39 faces the upper outer peripheral surface of the piston valve 17 at the lower limit position of the piston valve 17, that is, at the fully closed position of the piston valve 17. It communicates with the opening 41 of the peripheral surface 15A. A pipe 43 is connected to the lubricating oil passage 39, and the lubricating oil in the lubricating oil tank is fed through the pipe 43 by a lubricating oil pump.
Supply to 39. An upper end is connected to the opening 41 on the peripheral surface of the cylinder 15, and in the embodiment, a vertical groove 47 extending downward from the upper end of the tubular portion 11 and having a lower end 47A facing the side surface 45 of the intermediate portion 5A is formed. As shown in FIG. 4, the vertical groove 47 is provided with the piston valve 17 having at least 30% of the flow passage area of the intermediate portion 5A open.
The lower end 47A is formed so as to be exposed in the flow path. Since this embodiment is configured as described above, the lubricating oil passage 39,
The lubricating oil derived from the opening 41 passes through the vertical groove 47, and lubricates the cylinder peripheral surface 15A and the piston valve outer peripheral surface 17A, and the middle portion.
At the 5A side, lubricating oil is sent to the engine side together with the intake air. Therefore, the piston valve 17 can be lubricated by utilizing the lubricating oil fed to the engine side together with the intake air. Further, since the vertical groove 47 is opened in the piston valve 17 portion where the negative pressure on the engine side acts most, it is possible to quickly supply the lubricating oil to the engine side in response to the operating state of the engine. . Further, since the vertical groove 47 can be integrally formed during body casting, the piston valve 17 can be lubricated while suppressing an increase in the number of processing steps. Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a sectional side view of a main part of the vaporizer according to the second embodiment,
FIG. 6 is a sectional view of an intermediate portion of the intake passage, and FIG. 7 is a sectional view of a downstream portion of the intake passage. In the second embodiment, in addition to the first embodiment, the intake passage 5
A lateral groove 51 extending from the side surface 45 to the upper surface 49 of the vertical groove 47 and extending to the downstream side along the extending direction of the intake passage 5 is formed. In the second embodiment, the lower end 47A of the vertical groove 47 is connected to the side surface 45 of the intermediate portion 5A.
Formed facing the top. Then, the horizontal groove 51, the upstream end 51A connected to the lower end 47A of the vertical groove 47 and formed with a small vertical width, and the upstream portion 51B extending from the upstream end 51A by gradually increasing the vertical width,
It is composed of a downstream portion 51C extending from the upstream portion 51B and having a constant vertical width. According to the second embodiment, in addition to the effect of the first embodiment, the lateral groove 51 allows a negative pressure substantially the same as the negative pressure on the engine side to act on the lubricating oil. Lubricating oil can be supplied more quickly in response to engine operating conditions. Further, in the second embodiment, since the lateral groove 51 extending from the cylinder 15 to the downstream side is formed, there is no possibility that lubricating oil will enter the float chamber 7 through the bypass passage 27 or the like. Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a sectional side view of a main part of the vaporizer according to the third embodiment,
FIG. 9 is a sectional plan view of the same main part, and FIG. 10 is XX of FIG.
FIG. In FIG. 10, 61 is a stop screw that restricts the lower limit position of the piston valve 17, 63 is a notch formed at the lower end of the piston valve 17 with which the stop screw 61 abuts, and the stop screw 61 is orthogonal to the extending direction of the intake passage 5. It is arranged in the direction. In the third embodiment, the lubricating oil passage 39 is formed on the stop screw 61 side in a direction orthogonal to the extending direction of the intake passage 5. Then, by connecting to the opening 41 of the lubricating oil passage 39, the vertical groove 34
7 is extended downward, and the lower end 347A of the vertical groove 347 is formed so as to face the upper portion of the notch 63 at the lower limit position of the piston valve 17. According to the third embodiment, the lubricating oil sent to the engine side together with the intake air can be used to lubricate the piston valve 17, and the lubricating oil is supplied from the direction orthogonal to the flow direction of the intake air. Therefore, the lubricating oil can be evenly attached to the outer peripheral surface 17A of the piston valve, and the piston valve 17 can be efficiently lubricated. Further, since the piston valve 17 can be made to have a negative pressure substantially the same as the negative pressure on the engine side from full closing to full opening, the lubricating oil can be supplied to the engine side from idling to high speed rotation. It can be carried out. Next, a reference example will be described with reference to FIGS. 11 and 12. FIG. 11 is a schematic side view of the vaporizer according to the reference example, and FIG. 12 is a view taken along the arrow XII of FIG. In the reference example, the lubricating oil passage 39 is formed in the direction orthogonal to the extending direction of the intake passage 5 as in the third embodiment.
Vertical groove 44 connected to the opening 41 of 39 to guide the lubricating oil to the intake passage 5 side
7 is formed on the outer peripheral surface 17A of the piston valve. The upper end 447B of the vertical groove 447 is located at a position orthogonal to the extending direction of the intake passage 5 on the piston valve outer peripheral surface 17A, and the lower end 447A is located on the piston valve outer peripheral surface 17A.
Located on the downstream side, with a curved section between the upper end 447B and the lower end 447A
Connected at 447C. The height of the lower end 447A is appropriately selected according to the opening degree of the piston valve 17 and the negative pressure on the engine side. According to the reference example, the piston valve 17 can be lubricated by utilizing the lubricating oil fed to the engine side together with the intake air, and the vertical groove 447 is formed by being curved, so that the piston valve 17 and the cylinder 15 The lubricating oil can be efficiently supplied over a wide range. Next, a fourth embodiment of the present invention will be described with reference to FIGS. 13 and 14. FIG. 13 is a sectional side view of a main part of the vaporizer 1 according to the fourth embodiment, and FIG. 14 is a sectional plan view of the same part. In the fourth embodiment, similarly to the third embodiment, the lubricating oil passage 39 is formed in a direction orthogonal to the extending direction of the intake passage 5 and is connected to the opening 41 of the lubricating oil passage 39 to supply the lubricating oil to the intake passage 5 side. A vertical groove 547 leading to the vertical groove 547 is formed on the cylinder peripheral surface 15A, and a horizontal groove 551 is formed by being connected to the vertical groove 547 as in the second embodiment. The vertical groove 547 extends downward while being curved toward the lower end of the intake passage 5. The lower end 547A of the vertical groove 547 is formed at a height such that the piston valve 17 is exposed in the flow path at an opening of 30% or less. The horizontal groove 551 is the lower end 54 of the vertical groove 547 as in the second embodiment.
An upstream end 551A connected to 7A and formed with a small vertical width, and an upstream portion 551B extending from the upstream end 551A by gradually increasing the vertical width,
It is composed of a downstream portion 551C extending from the upstream portion 551B and having a constant vertical width. According to the fourth embodiment, the piston valve 17 can be lubricated by utilizing the lubricating oil fed to the engine side together with the intake air, and the vertical groove 547 is curved so that the piston valve 17 Lubricating oil can be efficiently supplied over a wide range between the cylinders 15. Further, by the lateral groove 551, a negative pressure substantially the same as the negative pressure on the engine side is applied to the lubricating oil, so that the lubricating oil can be supplied to the engine side in a quick response to the operating state of the engine. In addition, since the lateral groove 551 is formed, the lubricating oil is
There is also no risk of entering the float chamber 7 from 7 and the like. (Effects of the Invention) As is apparent from the above description, according to the present invention, the piston valve of the carburetor can be lubricated by utilizing the lubricating oil supplied to the crank chamber together with the intake air, and the operating condition of the engine can be quickly changed. Accordingly, it is possible to obtain a lubricating oil supply structure for a carburetor of a two-cycle engine that can supply lubricating oil to the engine side. The lubricating oil flows smoothly because the opening in the vertical groove is not blocked by the piston valve. Further, since the vertical groove extends to the upper edge of the sliding surface and the surface facing the piston valve is open, the vertical groove forms an oil passage with the piston valve to flow lubricating oil, Even if the piston valve rotates in the circumferential direction due to backlash, the positional relationship between the opening and the vertical groove does not change, and the oil passage of the lubricating oil is not adversely affected.Therefore, it is not necessary to increase the groove width. Demonstrate. Secondly, lubricating oil is supplied even at a position above the cylinder where icing that freezes the piston valve or jet needle is likely to occur, and good lubrication can be performed between the cylinder peripheral surface and the piston valve outer peripheral surface. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side view of an essential part of a vaporizer according to the first embodiment, FIG. 2 is a sectional plan view of the same part, and FIG. 3 is a III-III section of FIG.
FIG. 4 is a sectional view taken along the line, FIG. 4 is a sectional view of an intermediate portion of the intake passage, FIG.
FIG. 7 is a sectional view of an intermediate portion of the intake passage, FIG. 7 is a sectional view of a downstream portion of the intake passage, FIG. 8 is a sectional side view of a main part of a carburetor according to the third embodiment, and FIG. 9 is the same.・ Main section cross-sectional plan view, No.
10 is a sectional view taken along line XX of FIG. 9, FIG. 11 is a schematic side view of a vaporizer according to a reference example, and FIG. 12 is a view taken along the arrow XII of FIG.
FIG. 3 is a sectional side view of the main part of the vaporizer according to the fourth embodiment, FIG.
The figure is a sectional plan view of the same main part. In the figure, 1 is a carburetor, 3 is a body, 5 is an intake passage, 15 is a cylinder, 15A is a cylinder peripheral surface, 17 is a piston valve, 1
9 is a needle jet, 33 is a jet needle, 39 is a lubricating oil passage, 47,347,447,547 are vertical grooves, and 51,551 are horizontal grooves.

Claims (1)

(57) [Claims] A body with an intake passage, a piston valve that slides in a cylinder formed in the body and appears in and out of the intake passage to adjust the intake amount, and extends below the intake passage and is immersed in fuel. A cylinder that slides and guides a piston valve in a carburetor for a two-cycle engine that includes a needle jet and a jet needle that is vertically installed from the piston valve and axially moves inside the needle jet to adjust the fuel injection amount. The opening of the lubricating oil passage is provided on the peripheral surface of the cylinder, and the surface of the cylinder that is connected to the opening is wider than the diameter of the opening, extends to the upper edge of the sliding surface, and faces the piston valve. A lubricating oil supply structure for a carburetor of a two-cycle engine, characterized in that a vertical groove is formed to guide the lubricating oil from the opening to an intake passage.