JPH0329565Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention arranges a fuel nozzle and a negative pressure responsive valve opposite to the fuel nozzle in the intake passage upstream of the throttle valve, and uses the negative pressure responsive valve to control the negative pressure generated in the intake passage. This relates to a constant vacuum vaporizer that is controlled to open and close according to changes. In this type of constant vacuum carburetor, the negative pressure applied to the fuel nozzle is always properly controlled by the automatic opening and closing of the negative pressure responsive valve, so the negative pressure can be maintained at a substantially constant level regardless of engine operating fluctuations. It is often used in two-wheeled vehicles, four-wheeled vehicles, etc. due to its excellent characteristics of stable oil injection from the fuel nozzle.

A commonly used constant vacuum vaporizer will be explained with reference to FIG. Reference numeral 1 denotes a carburetor body through which an intake passage 2 passes, and a guide cylinder 3 is provided on the upper side connected to the intake passage 2, and a negative pressure responsive valve 4 is installed in the guide cylinder 3.
are arranged so as to be slidable. A diaphragm 5 is disposed at the upper end of the negative pressure responsive valve 4, and a pressure receiving chamber 7 is formed by the diaphragm 5 and a top 6 covering the upper part of the diaphragm 5. A chamber 8 is sectioned. A fuel nozzle 10 connected below a constant liquid level in the float chamber 9 opens in the intake passage 2 facing the lower end of the negative pressure responsive valve 4 . A moving jet needle 11 is inserted. In addition, the intake passage negative pressure generated in the intake passage 2 is introduced into the pressure receiving chamber 7 through a small hole 12 formed at the bottom of the negative pressure responsive valve 4, while the atmospheric chamber 8 is introduced through an atmospheric passage (not shown). Connected to the atmosphere. Reference numeral 13 denotes a spring that presses the negative pressure responsive valve 4 downward in the figure to reduce the intake passage area.

The diaphragm 5 and the negative pressure responsive valve 4 must be securely fixed in order to separate the pressure receiving chamber 7 and the atmospheric chamber 8 by the diaphragm 5. For this purpose, a stepped portion 4A is provided at the top of the negative pressure responsive valve 4, and a lower retainer 14A is placed on top of the stepped portion 4A.
Next, the diaphragm 5 was placed, the upper retainer 14B was placed on top of the diaphragm 5, and the upper part was caulked and fixed.

According to such a conventional structure, although the diaphragm 5 and the negative pressure responsive valve 4 can be firmly fixed together,
The lower, upper, and retainers 14A, 14B are required, which increases the number of parts, and the crimping process requires time, leading to higher costs. Furthermore, during crimping work, for example, when performing rolling crimping, the upper retainer 14B may rotate, and this rotation may apply unnecessary force to the diaphragm 5, causing the diaphragm 5 to be twisted.
Furthermore, there is a risk that it may be scratched and damaged.

The constant vacuum type vaporizer of the present invention was developed in view of these points, and its purpose is to reduce the number of parts and work hours for the diaphragm 5 and the negative pressure responsive valve 4, and to ensure that they are firmly fixed. The point is to get a vaporizer.

An embodiment of the constant vacuum type vaporizer according to the present invention will be described below with reference to FIGS. 2, 3, and 4.
(Only the negative pressure responsive valve and diaphragm part will be explained, and other parts will be omitted.) 20 is a negative pressure responsive valve, and its upper part has an outer diameter of φA.
A small diameter portion 20A having a smaller diameter φB is provided,
Together, a stepped portion 20B is formed. Also, the small diameter part 20A
For example, an arc-shaped positioning groove 20C is bored on the outer periphery of the groove.

On the other hand, the diaphragm 21 is formed into a cup shape from an elastic material such as rubber, and has a cylindrical thick walled part 21A with a diameter somewhat smaller than the outer diameter φB of the small diameter part 20A of the negative pressure responsive valve 20 in the center thereof. The membrane portion 21 is sufficiently thinner than the thickness t of the thick portion 21A from the outer periphery of the thick portion 21A.
B extends outward. Further, a mandrel 22 made of a cylindrical metal body is disposed within the thick portion 21A, and the mandrel 22 is integrally molded by inserting it into the diaphragm 21 when it is molded.

Furthermore, a protrusion 21D that is fitted into the positioning groove 20C of the negative pressure responsive valve 20 is provided on the inner circumferential surface of the fitting hole 21C of the thick portion 21A.

In order to fix the diaphragm 21 to the negative pressure responsive valve 20, first apply a load outward to the fitting hole 21C of the thick portion 21A of the diaphragm 21 to expand its inner diameter. The protrusion 21D of the diaphragm 21 is inserted into the small diameter portion 20A, and the protrusion 21D of the diaphragm 21 is fitted into the positioning groove 20C of the small diameter portion 20A of the negative pressure responsive valve 20.

At this time, the membrane portion 21B and thick wall portion 21A of the diaphragm 21 on the outside of the mandrel 22 are connected to the mandrel 22.
2 prevents the load from being applied outwards, so there is no deformation at all, and only the portion inward from the mandrel 22 expands.

In this way, the diaphragm 21 and the negative pressure responsive valve 2
By fixing 0, upper, lower,
Since a retainer is completely unnecessary, the number of parts can be reduced. In addition, in the fixation, the fitting hole 21 of the thick portion 21A of the diaphragm 21 is simply
Since C is fitted into the small diameter portion 20A of the negative pressure responsive valve 20, extreme mechanical force is not applied to the diaphragm 21, and there is no fear of damage to the diaphragm 21, improving reliability. At the same time, it is possible to reduce the number of work steps, reduce costs, and improve quality.

Furthermore, by arranging the mandrel 22 within the thick walled portion 21A of the diaphragm 21, the rigidity of the thick walled portion 21A is increased, and the stepped portion 20B and the positioning groove 20C are
This allows for more reliable connectivity.

Furthermore, when the diaphragm 21 is attached to the carburetor and used, the outer peripheral end of the diaphragm 21 is held between the carburetor main body 1 and the top 6, and the negative pressure responsive valve 20 operates at the center of the diaphragm 21. Therefore, the repeated bending force of the membrane portion 21B of the diaphragm 21 is applied to the thick wall portion 21A outside the core metal 22.
The bending force is absorbed by the joint hole 21C of the thick wall portion 21A and the fitting hole of the small diameter portion 20A of the negative pressure responsive valve 20, and the bending force is not transmitted to the fitting hole 21C of the thick wall portion 21A and the fitting hole of the small diameter portion 20A of the negative pressure responsive valve 20, ensuring a secure fit even during long-term use. It is possible to guarantee that the

As described above, according to the constant vacuum type vaporizer of the present invention, a small-diameter stepped portion is provided at the upper end of the negative pressure responsive valve, and a positioning groove is bored on the outer periphery of the small-diameter portion. A cylindrical thick-walled part is provided in the thick-walled part, and a mandrel made of a cylindrical metal body is inserted into the thick-walled part, and the positioning groove of the negative pressure responsive valve is fitted into the fitting hole in the center of the thick-walled part. Since a protrusion is provided and the fitting hole in the thick part of the diaphragm is fitted into the small diameter part of the negative pressure responsive valve, the number of parts and work hours can be reduced and an inexpensive constant vacuum type vaporizer can be obtained. I can do it.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an example of a conventional constant vacuum type vaporizer commonly used, and Fig. 2 shows a negative pressure responsive valve portion of the constant vacuum type vaporizer according to the present invention. 3 is a vertical sectional view showing the diaphragm of the constant vacuum vaporizer according to the present invention, and FIG. 4 is a vertical sectional view showing the state of connection between the negative pressure responsive valve and the diaphragm according to the present invention. It is. 1... Carburetor main body, 20... Negative pressure responsive valve, 20
A...Small diameter part, 20B...Step part, 20C...Positioning groove, 21...Diaphragm, 21A...Thick wall part, 21B...Membrane part, 21C...Fitting hole, 22
... core metal, 21D ... protrusion.

Claims (1)

[Scope of utility model registration request] A negative pressure responsive valve 20 is disposed in a guide tube 3 connected to an intake passage 2 passing through the carburetor body 1, and a diaphragm 5 disposed at the end of the negative pressure responsive valve connects a pressure receiving chamber 7 and an atmospheric chamber 8. In addition, a spring 13 is provided in the pressure receiving chamber 7 to bias the negative pressure responsive valve 20 toward the side that closes the intake passage 2, thereby directing the negative pressure generated in the intake passage 2 into the pressure receiving chamber 7. In a constant vacuum type vaporizer that controls a negative pressure responsive valve 4 by introducing a small diameter portion 20A having an outer diameter φB smaller than an outer diameter φA of the negative pressure responsive valve 20 at the upper end of the negative pressure responsive valve 20. is erected upward, a stepped portion 20B is formed by this small diameter portion 20A and the outer diameter φB of the negative pressure responsive valve 20, and a positioning groove 20C is bored on the outer periphery of the small diameter portion 20A. , on the other hand, the center of the diaphragm 21 is thicker than the membrane portion 21B and has a negative pressure responsive valve 2.
Fitting hole 21C with a smaller diameter than the outer diameter of the small diameter portion 20A of 0
A thick wall portion 21B is provided, and a mandrel 22 made of a cylindrical metal body is inserted into the thick wall portion, and a negative pressure responsive valve 20 is positioned in the inner diameter portion of a fitting hole 21C of the thick wall portion 21A. A protrusion 21D that fits into the groove 20C is provided, and the fitting hole 21C of the thick wall portion 21A of the diaphragm 21 is fitted into the small diameter portion 20A of the negative pressure responsive valve 20, and at the same time, the protrusion 21D of the diaphragm 21 is activated to respond to negative pressure. Positioning groove 2 of valve 20
Constant vacuum type vaporizer fitted with 0C.