JP3504779B2 - Vaporizer accelerator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor accelerating device equipped with a piston type acceleration pump, and more particularly to a carburetor accelerating device in which a piston is smoothly pushed by a cam of a throttle valve shaft.

[0002]

2. Description of the Related Art Japanese Examined Patent Publication No. 4-72063 and Shokai 6
As disclosed in Japanese Patent Laid-Open No. 1-58662, a carburetor equipped with an accelerating pump inside a carburetor body for supplying a rich air-fuel mixture during acceleration of an engine has a small accelerating pump and a simple structure. There is an advantage that foreign matter does not enter the inside of the fuel pump from the outside.

As shown in FIG. 5, in the above-described conventional carburetor acceleration pump D, the throttle valve shaft 21 that crosses the intake passage 15 of the carburetor main body B has a throttle valve 25 for adjusting the passage area of the intake passage 15. While the cylinder 22 is supported, the cylinder 22 orthogonal to the throttle valve shaft 21 is formed inside the body away from the intake passage 15 of the main body B, and the end of the cylinder 22 is closed by the plug 16.
The throttle valve shaft 21 that fits in the shaft hole 40 is cut out to form the cam 21.
a is formed. The piston 41 with the seal member 43 attached is fitted into the cylinder 22 and the end of the piston 41 is engaged with the cam 21a by the force of the spring 44.

At the idle position of the illustrated throttle valve 25, the acceleration pump D is supplied with fuel from the constant pressure fuel chamber to the cylinder 22 through the check valve. When the throttle valve shaft 21 is rotated counterclockwise in order to increase the opening degree of the throttle valve 25 during acceleration of the engine, the piston 41 causes the spring 44 to move by the edge portion (lower edge portion in FIG. 5) of the cam 21a. The fuel in the chamber 22a is pushed to the high-speed fuel injection hole through the acceleration passage 23, and a rich air-fuel mixture is supplied to the engine, improving the accelerating performance of the engine. It

However, the conventional acceleration pump D described above is
In forming the cam 21a on the throttle valve shaft 21, a notched groove having a rectangular cross section orthogonal to the throttle valve shaft 21 is cut on the peripheral surface of the throttle valve shaft 21 to obtain a flat cam surface. The machining is troublesome, burrs are likely to occur, and notching more than half of the shaft diameter causes stress concentration especially at the corners where the flat cam surface of the notch groove and both side walls intersect, and the throttle valve shaft 21 There is a problem of impairing the strength of. Due to the above-mentioned problem in strength, the stroke of the acceleration pump D is regulated by the throttle valve shaft 21 and the discharge amount of the acceleration pump D is also limited, which is not suitable for a large engine. Since the rubber seal member 43 is fitted onto the piston 41, the end portion of the piston 41 and the cam 2 are
The resistance of the engagement portion with 1a is large, and the operation force of the throttle valve shaft 21 is large. Further, since the strong return spring 44 is used to move the piston 41 back, there is a problem that the operability of the throttle valve shaft 21 is poor.

[0006]

[0007]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a carburetor accelerating device having a larger piston stroke and a lighter operation of the throttle valve shaft.

[0008]

In order to achieve the above object, according to the present invention, a cam is formed by a notch surface in a portion of the throttle valve shaft located inside the body of the carburetor body, and the throttle valve is formed inside the body. A cylinder that is orthogonal to the axis is formed, a piston that engages with the cam is fitted in the cylinder, and the piston that reciprocates following the rotation of the throttle valve shaft sucks fuel from the constant pressure fuel chamber into the cylinder and In a carburetor accelerating device for delivering to a high-speed fuel injection hole through an internal accelerating passage, a hemispherical cross-section provided on the cam and the piston head or
A ball is interposed between the conical recess and the cam force is transmitted to the piston via the ball.

[0009]

According to the present invention, the end portion of the piston is engaged with the cam formed by cutting out the throttle valve shaft by the force of the spring housed in the cylinder via the ball.
The end of the piston is formed with a conical or spherical recess that engages the ball. With the rotation of the throttle valve shaft, the ball that makes point contact with the notch surface of the cam moves radially outward from the axial center of the throttle valve shaft at the contact point with the notch surface of the cam. at the same time,
The ball pushes the piston in the axial direction of the cylinder while rotating. In other words, the ball and the notch surface of the cam make rolling contact, so there is less friction and wear at the contact portion, and it is smooth.
A smooth acceleration operation of the throttle valve shaft can be obtained.

[0010]

[0011]

1 is a cross-sectional side view of a membrane vaporizer equipped with an accelerator according to the present invention, and FIG. 2 is an enlarged side sectional view of the accelerator of the vaporizer. The carburetor main body B, through which the intake passage 15 penetrates, is connected to the cover 3 with the membrane 7 sandwiched on the upper end wall to form the fuel pump A, while the carburetor main body B has the cover 18 sandwiched with the membrane 30 on the lower end wall. To form a constant pressure fuel supply mechanism C.

The fuel pump A is located on the upper side of the membrane 7 from the pipes 5 to 2
A pulsating pressure introducing chamber 8 for introducing the pulsating pressure of the crank chamber of the stroke engine is defined, and a pump chamber 6 is defined below the membrane 7. The pump chamber 6 is connected to the fuel tank via a suction valve 4, which is integral with the membrane 7, an inlet pipe 2, and a pipe (not shown). The pump chamber 6 can communicate with the constant pressure fuel chamber 31 via the discharge valve 10, strainer 12, passage 13 and inflow valve 14.

The constant pressure fuel supply mechanism C is divided into a constant pressure fuel chamber 31 on the upper side of the membrane 30 and an atmosphere chamber 19 on the lower side. A lever 33 supported by a support shaft 34 is disposed inside the constant pressure fuel chamber 31, and the left end of the lever 33 is engaged with a protrusion provided at the center of the membrane 30 by the force of the spring 20 to allow the lever 3 to move.
The right end of 3 is engaged with the inflow valve 14. When the amount of fuel in the constant pressure fuel chamber 31 becomes low, the membrane 30 is pushed up against the force of the spring 20 by the atmospheric pressure, the lever 33 is rotated clockwise around the support shaft 34, and the inflow valve 14 moves through the passage 13. open. Therefore, the fuel is fed from the fuel pump A to the constant pressure fuel chamber 3
It is replenished to 1. When the fuel fills the constant pressure fuel chamber 31, the membrane 30 is pushed down, the lever 33 is rotated counterclockwise by the force of the spring 20, and the inflow valve 14 closes the passage 13. Thus, the constant pressure fuel chamber 31 always stores a substantially constant fuel under a predetermined pressure.

The fuel in the constant pressure fuel chamber 31 is sucked into the intake passage 15 through the passage 32, the low speed fuel adjusting needle valve 17, and the low speed fuel injection hole 27 due to the negative pressure in the intake passage 15. Further, the fuel in the constant pressure fuel chamber 31 is sucked into the intake passage 15 through the passage 29, the high speed fuel adjusting needle valve 28, and the high speed fuel injection hole 24 provided with the check valve 24a.

As shown in FIG. 2, the acceleration pump D according to the present invention is adjacent to the intake passage 15 and inside the carburetor main body B, that is, inside the body, a cylinder 22 orthogonal to the throttle valve shaft 21.
Is equipped with. The left end of the cylinder 21 is closed by the plug 16, and the right end of the cylinder 21 is communicated with the high-speed fuel injection hole 24 through the acceleration passage 23. A throttle valve 25 for adjusting the passage area of the intake passage 15
The throttle valve shaft 21 for coupling the above is formed with a cam 21a by cutting out a portion facing the cylinder 22.

As shown in FIG. 4, specifically, the cam 21
Reference symbol a is formed as a notch groove having an arcuate cross section orthogonal to the throttle valve shaft 21. The notch groove is machined by rotating a shaft-shaped tool having a cutting blade on the shaft circumferential surface so as to be orthogonal to the throttle valve shaft 21. The notch surface of the cam 21a is engaged with the piston 41 via the ball 26. The piston 41 is fitted with a seal member 43 such as rubber, and has a conical or spherical recess 42 that stably holds the ball 26 on the left end surface.
The force of a spring 44 interposed between the piston 41 and the end wall of the cylinder 22 causes the piston 41 to move the ball 26 to the cam 2
It is pressed against the cutout surface of 1a. The chamber 22 a of the cylinder 22 communicates with the acceleration passage 23.

At the idle position of the throttle valve 25, the ball 2
Reference numeral 6 makes a point contact with substantially the center of the notch surface of the cam 21a, that is, a portion close to the axis of the throttle valve shaft 21. When the throttle valve shaft 21 is rotated counterclockwise during the acceleration operation of the engine, the cam 2
The ball 26 is pushed to the right by the notch surface of 1a, and pushes the piston 41 to the right against the force of the spring 44. At this time, the ball 26 transmits the force of the cam 21a to the piston 41 while rotating between the notch surface 21a of the cam and the recess 42.

As shown in FIG. 3, at the fully open position of the throttle valve 25, the outer diameter portion of the throttle valve shaft 21 contacts the ball 26 .

In the structure of the present invention, it is not necessary to decenter the center axis of the cylinder 22 with respect to the center of the throttle valve shaft 21, and the notch surface or notch of the cam 21a is not perpendicular to the center axis of the piston 41. Even if the ball 21 is slightly inclined, the ball 26 makes point contact with the notch surface of the cam 21a substantially at the center in the radial direction.
The value is almost equal to the radius of.

[0020]

Since the cam of the throttle valve shaft is formed as a cutout groove having an arcuate cross section, machining is easier than in the conventional cutout groove having a rectangular cross section, less burr is generated, and stress concentration is reduced. Since there is no corner to bring and the amount of machining of the cam groove (volume of the meat part to be shaved off) is small, even if the cam groove is deepened by that much, that is, the stroke of the piston of the acceleration pump is increased, The reduction in strength of the throttle valve shaft can be avoided.

[0022]

As described above, according to the present invention, since the cam of the throttle valve shaft and the balls make rolling contact with each other, friction and wear of the contact portion are small, and the operation of the throttle valve shaft is light and smooth. Further, since the lubricant is retained in the recess provided in the end portion of the piston, the operation of the ball is smoother.

[Brief description of drawings]

FIG. 1 is a side sectional view of a carburetor accelerator according to the present invention.

FIG. 2 is a side sectional view showing, in an enlarged manner, a main part of the accelerator at an idle position of the throttle valve.

FIG. 3 is a side cross-sectional view showing an enlarged main part of the accelerator when the throttle valve is at the fully open position.

FIG. 4 is a plan cross-sectional view showing an enlarged main part of the accelerator.

FIG. 5 is a side sectional view showing a main part of a conventional accelerator.

[Explanation of symbols]

A: Fuel pump D: Accelerating pump B: Vaporizer body
C: constant pressure fuel supply mechanism 2: inlet pipe 3: cover 4:
Suction valve 5: Pipe 6: Pump chamber 7: Membrane 8: Pulsating pressure introduction chamber 10: Discharge valve 12: Filter 13: Passage 1
4: Inflow valve 15: Intake passage 16: Plug 17: Low speed fuel adjustment needle valve 18: Cover 19: Atmosphere chamber 20: Spring
21: Throttle valve shaft 21a: Cam 22: Cylinder 22
a: chamber 23: acceleration passage 24: high-speed fuel injection hole 24
a: check valve 25: throttle valve 26: ball 27: low speed fuel injection hole 28: high speed fuel adjusting needle valve 29: passage 3
0: Membrane 31: Constant pressure fuel chamber 32: Passage 33: Lever 34: Spindle 40: Shaft hole 41: Piston 42: Recess 43: Seal member 44: Spring

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 7/08 F02M 17/04 F02D 9/10

Claims (2)

(57) [Claims] 1. A cam is formed by a notch surface in a portion of the throttle valve shaft located inside the body of the carburetor body, and a cylinder is formed inside the body so as to be orthogonal to the throttle valve shaft, and the cylinder is engaged with the cam. The carburetor acceleration that fits the piston to reciprocate by following the rotation of the throttle valve shaft, sucks fuel from the constant pressure fuel chamber into the cylinder, and delivers it to the high-speed fuel injection hole through the acceleration passage inside the fuselage In the device, the cam and the piston head have a hemispherical cross section or a conical cross section.
Ball interposed the acceleration device of the carburetor, characterized in that as the force of the cam is transmitted to the piston through a ball between the depressions. 2. The carburetor acceleration device according to claim 1, wherein the cam of the throttle valve shaft is a notched groove having an arcuate cross section orthogonal to the throttle valve shaft.