JP2001153049A - Diaphragm type pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm type pump capable of preventing change in fuel discharge characteristics by always harmonizing the manipulated variable of a manipulating member with the stroke of a diaphragm valve. SOLUTION: In this diaphragm type acceleration pump 5, the upper end part 6a of a pump rod 6 placed so as to be axially movable is linked to a throttle grip (manipulating member), its lower end part 6b is made to abut on the center part of a diaphragm valve 7 and the diaphragm valve 7 is pressingly driven through the pump rod 6 in accordance with the manipulated variable of the throttle grip. A recessed part 27 is formed on the head part 25a of a bolt member 25 mounted to the center part of the diaphragm valve 7, and a projecting part 28 abutting on the recessed part 27 is formed on the lower end part 6b of the pump rod 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a diaphragm type pump, for example, a diaphragm type acceleration pump used for a carburetor of a vehicle engine.

[0002]

2. Description of the Related Art For example, a carburetor of a vehicle engine may be equipped with a diaphragm-type acceleration pump for increasing the amount of fuel corresponding to the operation amount of an accelerator operation member by a diaphragm valve and supplying the fuel to the engine during acceleration.

As a diaphragm type acceleration pump of this type, for example, as shown in FIG. 4, an upper end of a pump rod 50 arranged to be able to advance and retreat in an axial direction is provided with an operation member (not shown) operated by a throttle grip. There is a structure in which the lower end surface 50a of the pump rod 50 is connected to the center portion 52 of the diaphragm valve 51. In this acceleration pump, when the throttle grip is rapidly opened, the pump rod 50 moves in the axial direction according to the operation amount and presses the diaphragm valve 51, whereby fuel corresponding to the operation amount is discharged.

In such an acceleration pump, from the viewpoint of minimizing the contact area between the pump rod 50 and the center part 52, conventionally, the lower end face 50a of the pump rod 50 is made flat, and the center part 52 is made convex, Or, generally, both have a convex shape.

[0005]

However, in the above-mentioned conventional acceleration pump, since the diaphragm valve 51 itself has a structure capable of swinging right and left, the center portion 52 moves to the left, for example, and the pump rod 50 is moved. There is a case where the diaphragm valve 51 is deviated from the axis C when pressed by the pump rod 50 (see a two-dot chain line in FIG. 4).
As a result, the stroke amount of the diaphragm valve 51 varies with respect to the operation amount of the throttle grip, and the fuel discharge amount characteristic may change.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and provides a diaphragm pump which can prevent a change in fuel discharge amount characteristics by always making an operation amount of an operation member coincide with a stroke amount of a diaphragm valve. It is intended to provide.

[0007]

According to the present invention, an operating member is connected to one end of a pump rod disposed so as to be able to advance and retreat in the axial direction, and the other end is brought into contact with the center of a diaphragm valve. In a diaphragm pump in which the diaphragm valve is pressed and driven via the pump rod according to the operation amount of the member, a concave portion is formed at one of the other end of the pump rod or the center of the diaphragm valve, and the other is formed at the other end. It is characterized in that a convex portion which contacts the concave portion is formed.

A second aspect of the present invention is characterized in that, in the first aspect, the contact surfaces of the concave portion and the convex portion are each formed in a spherical shape.

[0009]

According to the diaphragm type pump of the present invention, a concave portion is formed at one of the center portions of the pump rod or the diaphragm valve, and a convex portion is formed at the other portion so as to be in contact with the concave portion. The center portion is less likely to deviate from the axis of the pump rod, so that the diaphragm valve can be prevented from tilting. As a result, the operation amount of the operation member and the stroke amount of the diaphragm valve can always be matched, and a stable fuel discharge amount characteristic can be obtained. Is obtained.

In the second aspect of the present invention, since the contact surfaces of the concave portion and the convex portion are spherical, the spherical surfaces of the pump rod and the central portion are in contact with each other, so that the inclination of the diaphragm valve can be more reliably reduced. Can be prevented.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 are views for explaining a diaphragm type acceleration pump according to an embodiment of the present invention. FIG. 1 is a side view of a carburetor having a built-in diaphragm type acceleration pump, and FIG. 2 is a diaphragm type acceleration pump. FIG. 3 is an enlarged sectional view of a main part of a diaphragm type acceleration pump.

In FIG. 1, reference numeral 1 denotes a carburetor disposed in an intake system of a vehicle engine (not shown), which has a schematic structure in which an intake passage 2a and a float chamber 2b are formed in a cab body 2. A piston valve (not shown) for changing a passage area is provided in the intake passage 2a.

A throttle pulley 3 is rotatably supported on the upper portion of the cab body 2, and a throttle cable 3a is connected to the throttle pulley 3.
An extended end of the throttle cable 3a is connected to a throttle grip (not shown) mounted on a steering handle. By rotating the throttle grip, the throttle pulley 3 is rotated, and the piston valve is turned. It moves up and down.

The cab body 2 has a built-in diaphragm type acceleration pump 5. This acceleration pump 5
When the throttle grip is suddenly opened, the amount of fuel is increased and is forcibly supplied into the intake passage 2a.

The cab body 2 is formed with a cylindrical rod storage portion 2c extending in the vertical direction.
The pump rod 6 is inserted and disposed in the section c so as to be able to advance and retreat in the axial direction. The upper end 6a of the pump rod 6 is
It is connected to the throttle pulley 3 via second link levers 10 and 11.

The first link lever 10 is rotatably urged by a shaft member 12 and rotated counterclockwise by a spring (not shown), and the upper end 6a of the pump rod 6 is attached to the link lever 10. Abut. In addition, the first
The link lever 10 is connected to the second link lever 11 via a spring 13, and the second link lever 11 is engaged with a pin 15 fixed to the throttle pulley 3.

When the throttle pulley 3 is rapidly rotated in the direction indicated by the arrow mark in FIG. 1 by the rapid opening operation of the throttle grip, the second link lever 11 is rotated clockwise together with the first link lever 10 about the shaft member 12. Thereby, the first link lever 10 presses the pump rod 6 downward.

At the lower end of the rod housing portion 2c of the cab body 2, a vertically divided pump housing 17 in which the diaphragm valve 7 is housed is provided, and the outer peripheral edge of the diaphragm valve 7 is formed by the pump housing 17. It is pinched. The interior of the pump housing 17 is defined by the diaphragm valve 7 into an air chamber 17a and a fuel chamber 17b.
A spring 18 for urging the air toward the air chamber 17a is provided. The air chamber 17a of the pump housing 17
The lower end 6 of the pump rod 6 is inserted into the inside.

The float chamber 2b is provided in the fuel chamber 17b.
A fuel suction passage 19 communicating with the intake passage 2a is formed with a check valve 20 interposed therebetween, and a fuel discharge passage 21 communicating with the intake passage 2a is formed. When the diaphragm valve 7 is pressed downward by the pump rod 6, the fuel in the fuel chamber 17b is pressurized, and the pressurized fuel is discharged to the intake passage 2a through the fuel discharge passage 21. When the pressing force by the pump rod 6 is removed, the diaphragm valve 7 is raised by the spring 18, and the fuel is sucked from the fuel suction passage 19 into the fuel chamber 17b.

A pair of disk flanges 23, 24 are disposed at the center of the diaphragm valve 7 so as to face each other with the diaphragm valve 7 interposed therebetween.
A bolt member 25 is inserted through the shaft core portion of No. 4. The flanges 23 and 24 are fixed so as to sandwich the diaphragm valve 7 by a fastening flange 26 formed integrally with the bolt member 25 and a head 25a formed by caulking at the upper end.

The head 25 of the bolt member 25
a, a spherical concave portion 27 is formed in the lower end portion 6b of the pump rod 6, and a spherical convex portion 28 is formed on the lower end portion 6b of the pump rod 6 so that the convex portion 28 is coaxial with the concave portion 27. In contact. The diameter of the head 25a is the pump rod 6
, And the radius of curvature of the concave portion 27 is set to be larger than the radius of curvature of the convex portion 28.

Next, the operation and effect of this embodiment will be described. In the diaphragm type acceleration pump 5 according to the present embodiment, when the throttle grip is rotated, the pump rod 6 moves downward via the first and second link levers 11 and 10 to press the diaphragm valve 7, whereby the fuel is The fuel in the chamber 17b is pressurized and discharged from the fuel discharge passage 21 to the intake passage 2a.

According to this embodiment, a spherical concave portion 27 is formed in the bolt member 25 mounted on the axis of the diaphragm valve 7, and a spherical concave portion 27 abuts on the lower end portion 6 b of the pump rod 6. Since the convex portion 28 is formed, the center of the diaphragm valve 7 is hardly displaced from the axis C of the pump rod 6,
The diaphragm valve 7 can be prevented from tilting left and right. As a result, the operation amount of the throttle grip and the stroke amount of the diaphragm valve 7 can always be matched, and a stable fuel discharge amount characteristic can be obtained.

In this embodiment, the pump rod 6 and the bolt member 25 have a structure in which the convex spherical surface and the concave spherical surface are in contact with each other. Therefore, even if the pump rod 6 is slightly swung in the direction perpendicular to the axis, the above-described operation is performed. The displacement of the center can be prevented to prevent the diaphragm valve 7 from tilting, and a stable fuel discharge amount characteristic can be obtained.

In this embodiment, the concave portion 2 of the bolt member 25 is used.
Since the radius of curvature of the protrusion 7 is larger than the radius of curvature of the projection 28 of the pump rod 6, the swing of the pump rod 6 in the direction perpendicular to the axis and the inclination of the diaphragm valve 7 can be more reliably prevented.

In the above embodiment, the diaphragm type acceleration pump used in the carburetor of the vehicle engine has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention can be applied to any diaphragm pump in which the center of the diaphragm valve is pressed and driven by the axial movement of the pump rod.

In the above embodiment, the case where the concave portion and the convex portion are spherical has been described. However, in the present invention, the contact surface of the concave portion and the convex portion may be conical. The same effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a carburetor employing a diaphragm type acceleration pump according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the diaphragm type acceleration pump.

FIG. 3 is a sectional view showing a main part of the diaphragm type acceleration pump.

FIG. 4 is a diagram showing a main part of a conventional general diaphragm type acceleration pump.

[Explanation of symbols]

 Reference Signs List 5 diaphragm type fuel pump 6 pump rod 6a upper end 6b lower end 7 diaphragm valve 27 concave part 28 convex part

Claims (2)

[Claims] An operation member is connected to one end of a pump rod disposed so as to be able to advance and retreat in the axial direction, and the other end is brought into contact with a center portion of a diaphragm valve. In a diaphragm type pump configured to drive the diaphragm valve via a pump rod,
A diaphragm type pump, wherein a concave portion is formed at one of the other end of the pump rod or the center portion of the diaphragm valve, and a convex portion is formed on the other side to contact the concave portion. 2. The diaphragm pump according to claim 1, wherein the contact surfaces of the concave portion and the convex portion are each formed in a spherical shape.