JP3994578B2 - Ventilator air vent device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a carburetor that adjusts the concentration and amount of an air-fuel mixture supplied to an engine, and in particular, opens a liquid level upper chamber above a certain fuel level formed in a float chamber of the carburetor to the atmosphere. The present invention relates to an air vent device related to an air vent passage.
[0002]
[Prior art]
A conventional carburetor air vent device is shown in FIG. Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes laterally, and a throttle valve guide tube 3 is continuously provided upward from an intermediate portion of the intake passage 2, and an upper end of the throttle valve guide tube 3. 3A opens upward. A sliding throttle valve 4 that opens and closes the intake passage 2 is movably disposed in the throttle valve guide cylinder 3, and an upper end 3 </ b> A of the throttle valve guide cylinder 3 is closed by a top cover 5. The sliding throttle valve 4 opens and closes the intake passage 2 when the driver mechanically operates an accelerator wire (not shown). On the other hand, a bottomed cup-shaped float chamber body 6 is disposed corresponding to the lower recess 1A of the vaporizer body 1, and a float chamber 7 is formed by the lower recess 1A and the float chamber body 6. In the float chamber 7, a float 8 and a float valve that moves synchronously with the float 8, a valve seat that is opened and closed by the float valve, and a constant liquid level control mechanism are arranged. As a result, a constant fuel level FF is formed in the float chamber 7. The float valve and valve seat are not shown. An air vent passage is provided to maintain the upper liquid level chamber F1 above the fuel level FF in the float chamber 7 at atmospheric pressure. The first air vent passage A1 opens toward the atmosphere above the liquid upper chamber F1. The second air vent passage A2 opens toward the atmosphere on the side of the upper liquid chamber F1 or the first air vent passage A1. The first air vent passage A1 and the second air vent passage A2 are respectively formed on the sides of the intake passage 2, and L-shaped first pipes P1 and P1 are connected to the first air vent passage A1, respectively. L-shaped second pipes P2 and P2 are connected to the air vent passage A2. The first and second pipes P1 and P2 are provided in order to set the opening at a preferred position of the vehicle so that foreign matter such as mud does not enter the air vent passages A1 and A2.
[0003]
[Problems to be solved by the invention]
Here, there is a problem when the carburetor having the air vent passage is mounted on an off-road vehicle that travels on a wasteland other than a general public road such as a two-wheeled vehicle or a three-wheeled vehicle. According to such a vehicle, the vehicle repeats sudden jumps and landings when traveling on rough land or the like, and at this time, the fuel in the float chamber 7 moves rapidly in the vertical direction due to its inertia. Particularly when the vehicle jumps, the fuel in the float chamber 7 moves upward and enters the first air vent passage A1 and the second air vent passage A2, while the first, second, and air vents when the vehicle lands. The fuel in the passages A <b> 1 and A <b> 2 tries to return into the float chamber 7. Here, the air vent passages A1 and A2 are considered to have a relatively small diameter (for example, 3 millimeters). There is a risk that the fuel that has entered A1 and A2 when jumping will not be completely discharged from the air vent passages A1 and A2 and will remain when landing. According to the above, at the time of operation after landing, the desired differential pressure between the main nozzle, the low speed nozzle and the upper liquid surface chamber F1 opening in the intake passage 2 cannot be secured, and good fuel supply is hindered, There is a risk that good drivability may not be obtained. That is, the air vent passages A1 and A2 are those whose effective area is reduced or blocked by the fuel remaining inside, and the inside of the liquid level chamber F1 cannot be maintained at a sufficient atmospheric pressure. This is because it is difficult to maintain a sufficient differential pressure with respect to the main nozzle or the low-speed nozzle that opens to 2 and the fuel supply tends to decrease.
[0004]
On the other hand, in order to solve the above problem, it is conceivable that the diameter of the air vent passages A1 and A2 is made sufficiently large. According to this, a large amount of fuel flows out from the air vent passages A1 and A2 toward the atmosphere. Therefore, the fuel liquid level in the float chamber 7 is greatly lowered immediately after landing. This is not preferable (because a large amount of fuel in the float chamber 7 has flowed to the outside during the jump).
[0005]
The air vent device for a carburetor according to the present invention has been made in view of the above-mentioned problems, and the air vent passage is not blocked by fuel when the vehicle jumps and lands, and the upper liquid level chamber in the float chamber It is a first object of the present invention to provide the above-described apparatus that can maintain the engine operability satisfactorily by maintaining the pressure at an atmospheric pressure.
[0006]
[Means for solving the problems]
In order to achieve the above object, the air vent device for a carburetor according to the present invention has a carburetor body in which an intake passage penetrates the inside, and a throttle valve guide tube is bored upwardly in connection with the intake passage. And a fixed fuel level in the float chamber formed by the slide throttle valve, which is disposed in the slide throttle guide cylinder and variably controls the opening of the intake passage, and the carburetor body and the float chamber body. In the carburetor having a float as a constant liquid level control mechanism, the bottom of the carburetor body is recessed at the bottom of the buoyancy chamber side at the side of the throttle valve guide tube and with a bottom. An air vent chamber recess having an opening at the upper position and an opening at the second path at the lower position is provided, while the passage forming portion includes a large-diameter cylindrical portion that closes the lower opening of the air vent chamber recess, A small-diameter cylindrical portion protruding upward from the radial cylindrical portion, and a small-diameter cylindrical portion A third passage penetrating from the end toward the lower end of the large-diameter cylindrical portion, and inserting the passage-forming portion into the air vent chamber concave portion of the carburetor body, thereby opening the lower opening of the air vent chamber concave portion to the large-diameter cylinder A first chamber formed at a position above the upper end of the small-diameter cylindrical portion; and a first chamber that is formed above the upper end of the small-diameter cylindrical portion. It is in a lower position and is formed in an annular second chamber formed on the outer peripheral side of the small-diameter cylindrical portion. The first passage opens into the first chamber and the second passage opens into the second chamber. This is the first feature.
[0007]
In addition to the first feature, the second feature of the present invention is that the effective area of the annular second chamber is larger than the effective area of the third passage.
[0008]
[Action]
According to the first feature, when the vehicle jumps, the fuel in the float chamber enters the air vent chamber via the third passage. The fuel overflowing from the upper end of the third passage into the air vent chamber overflows into the first chamber of the air vent chamber, and then falls downward in the annular second chamber due to its own mass, and this fuel passes through the second passage. Discharged outside. The overflowed fuel does not stagnate into the first chamber, and the upper liquid level chamber of the float chamber communicates with the atmosphere through the third passage, the first chamber, and the first passage. It can be maintained at atmospheric pressure.
[0009]
According to the second feature, the fuel overflowing from the third passage into the air vent chamber is immediately discharged to the atmosphere through the second passage without stagnation in the annular second chamber.
[0010]
【Example】
An embodiment of an air vent device for a vaporizer according to the present invention will be described below with reference to FIG. Reference numeral 10 denotes a carburetor body in which the intake passage 11 penetrates in the horizontal direction. The carburetor main body 10 is connected to the intake passage 11 and has a throttle valve guide cylinder 12 opened upward. Reference numeral 13 denotes an air vent chamber recess, which is recessed in the vaporizer body 10 as follows. That is, the air vent chamber recess 13 is located on the side of the intake passage 11 and is recessed in a bottomed shape upward from the float chamber side bottom 10 </ b> A of the carburetor body 10. A first passage 14 is opened above the air vent chamber recess 13 and a second passage 15 is opened below the air vent chamber recess 13. In this example, the air vent chamber recess 13 is formed on both sides of the intake passage 11.
[0011]
Reference numeral 16 denotes a float chamber main body disposed at the lower end of the vaporizer main body 10, which forms a float chamber 17. The float chamber 17 includes a float 18, a valve seat (not shown), and a float valve. A constant fuel level FF is formed by the constant level control mechanism. A sliding throttle valve 19 for opening and closing the intake passage 11 is disposed in the throttle valve guide cylinder 12, and a needle 21 to be inserted into the nozzle 20 is attached to the sliding throttle valve 19. . Further, the upper opening of the throttle valve guide cylinder 12 is closed by a cover 22.
[0012]
The passage forming portion T has a large-diameter cylindrical portion 23A that closes the lower opening 13A of the air vent chamber recess 13, a small-diameter cylindrical portion 23B that protrudes further upward from the large-diameter cylindrical portion 23A, and a large diameter from the upper end 23C of the small-diameter cylindrical portion 23B. And a third passage 23E penetrating toward the lower end 23D of the diameter cylinder portion 23A. The passage forming portion T is inserted into the air vent chamber recess 13 so that the lower opening 13A of the air vent chamber recess 13 is closed by the large-diameter cylindrical portion 23A to form the air vent chamber V. In the air vent chamber V, a first chamber V1 is formed above the upper end 23C of the small diameter cylindrical portion 23B, and an annular second chamber V2 is formed on the outer periphery of the small diameter cylindrical portion 23B. Here, the first passage 14 opened to the air vent chamber V opens to the first chamber V1, and the second passage 15 opens to the annular second chamber V2.
[0013]
Next, the operation will be described. When the vehicle jumps suddenly during operation, the fuel in the float chamber 17 is largely displaced upward, and quickly flows into the third passage 23E via the upper liquid level chamber F1 above the fuel level FF. Fuel enters at a speed. On the other hand, the air vent chamber V communicates with the atmosphere by the first passage 14 and the second passage 15 and is maintained at atmospheric pressure, and the third passage 23E is opened to the air vent chamber V in the atmospheric pressure state. According to this, the fuel that has entered the third passage 23E is discharged well into the air vent chamber V without receiving any resistance from the upper opening of the third passage 23E (in other words, the upper end 23C of the small diameter cylindrical portion 23B). Is done. The fuel discharged into the air vent chamber V enters the first chamber V1 above, but immediately flows downward in the second chamber V2 due to its own mass. According to the above, the fuel flowing down in the second chamber V2 is immediately discharged to the outside from the second passage 15, and the fuel does not stay in the air vent chamber V. Atmospheric air is always introduced through the third passage 23E, the first chamber V1, and the first passage 14, and the upper liquid level chamber F1 can be maintained at atmospheric pressure. Therefore, the liquid level chamber F1 can be maintained at the atmospheric pressure state as described above even when the vehicle has finished jumping and the vehicle has descended and landed again, or even after driving after landing. The pressure difference between the nozzle 20 opening inside, the low-speed nozzle (not shown) and the upper liquid level chamber F1 can be maintained in a predetermined pressure state, thereby enabling good fuel supply. The driving performance can be satisfied.
[0014]
Further, the air vent chamber V formed of the first chamber V1 and the annular second chamber V2 is recessed in the carburetor body 10, and a passage forming portion including a large diameter cylindrical portion 23A and a small diameter cylindrical portion 23B. According to the formation by T, the production can be performed by lathe processing, so that the manufacturing cost can be greatly reduced.
[0015]
Further, according to the second chamber V2 having an annular shape, the fuel overflowing from the upper end 23C of the small diameter cylindrical portion 23B can overflow into the second chamber V2 from all the circumferences, and into the small diameter cylindrical portion 23B. It is effective in improving the exhaustability of the fuel that has entered.
[0016]
Furthermore, if the effective area of the annular second chamber V2 is made larger than the effective area of the third passage 23E, the fuel overflowing from the third passage 23E may rise to a position above the second chamber V2. This is effective in enhancing the discharge performance of the fuel that has entered the third passage 23E.
[0017]
【The invention's effect】
According to the air vent device for a carburetor of the present invention, the bottom of the carburetor body is located on the side of the float chamber and is recessed in a bottomed shape on the side of the throttle valve guide tube and upward. An air vent chamber recess in which the first passage opens and the second passage opens in a lower position is provided. On the other hand, the passage forming portion includes a large diameter cylinder portion 17A that closes the lower opening 13A of the air vent chamber recess 13 and a large diameter cylinder. A small diameter cylindrical portion 17B protruding upward from the portion 17A, and a third passage 17E penetrating from the upper end 17C of the small diameter cylindrical portion 17B toward the lower end 17D of the large diameter cylindrical portion 17A. By inserting T into the air vent chamber recess 13 of the carburetor body 10, the lower opening 13A of the air vent chamber recess 13 is closed by the large diameter cylindrical portion to form an air vent chamber V and the small diameter cylindrical portion 17B is A first chamber V1 formed above the upper end 17C of the small diameter cylindrical portion 17B and a position below the first chamber V1, and the outer periphery of the small diameter cylindrical portion 17B. Since the first passage is opened in the first chamber V1 and the second passage 15 is opened in the second chamber V2, it is always on the liquid surface. The chamber can be maintained at atmospheric pressure through the third passage, the first chamber, and the first passage, so that proper fuel supply is possible even when the vehicle makes a sudden jump or a drastic operation that repeats landing. It is possible to obtain a good engine operating performance.
[0018]
In addition, by forming the air vent chamber by the air vent chamber recess provided in the vaporizer main body, the large diameter cylindrical portion, the small diameter cylindrical portion, and the passage forming portion consisting of the third passage,
[0019]
Further, by making the second chamber an annular shape, it is possible to improve the discharge performance of the fuel that has entered the small diameter cylindrical portion.
[0020]
Furthermore, when the effective area of the annular second chamber is made larger than the effective area of the third passage, the fuel discharge performance of the third passage can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of an air vent device for a vaporizer according to the present invention.
FIG. 2 is a longitudinal sectional view showing an air vent device of a conventional carburetor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Vaporizer body 10A Float chamber side bottom 12 of carburetor body Throttle valve guide tube 13 Air vent chamber recess 13A Lower opening 14 of air vent chamber recess 14 First passage 15 Second passage T Passage formation portion 23A Large diameter tube portion 23B Small diameter tube portion 23E Third passage V Air vent chamber V1 First chamber V2 Second chamber

Claims (2)

An intake passage passes through the inside, a carburetor body that is continuous with the intake passage and has a throttle valve guide cylinder drilled upward, and a sliding throttle valve guide cylinder that is disposed in the opening of the intake passage. A carburetor comprising: a sliding throttle valve that is variably controlled; and a float as a constant liquid level control mechanism that forms and holds a constant fuel liquid level in a float chamber formed by a vaporizer body and a float chamber body. The bottom portion 10A of the main body 10 is located on the side of the throttle valve guide tube 12 and is recessed in a bottomed shape toward the upper side. On the other hand, the air vent chamber recess 13 in which the second passage 15 opens is provided, while the passage forming portion T has a large diameter cylindrical portion 17A that closes the lower opening 13A of the air vent chamber concave portion 13 and an upward direction from the large diameter cylindrical portion 17A. The small-diameter cylindrical portion 17B and the small-diameter cylindrical portion 17 Is formed by a third passage 17E penetrating from the upper end 17C to the lower end 17D of the large-diameter cylindrical portion 17A, and the air vent chamber is formed by inserting the passage forming portion T into the air vent chamber recess 13 of the carburetor body 10. The lower opening 13A of the recess 13 is closed with a large-diameter cylindrical portion to form an air vent chamber V, and a small-diameter cylindrical portion 17B is disposed so as to protrude into the air vent chamber. The air vent chamber is arranged from the upper end 17C of the small-diameter cylindrical portion 17B. The first passage V1 is formed in a first chamber V1 formed in an upper position and an annular second chamber V2 in a position below the first chamber V1 and formed on the outer peripheral side of the small-diameter cylindrical portion 17B. Is opened in the first chamber V1 and the second passage 15 is opened in the second chamber V2. The air vent device for a carburetor according to claim 1, wherein an effective area of the annular second chamber V2 is larger than an effective area of the third passage 17E.

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