JPH0125817Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a needle valve used in a carburetor of an internal combustion engine, etc., which is formed by fixing an elastic material such as rubber to the tip of a columnar valve body.

(Prior art) Conventionally, needle valves have been provided with a rubber-like elastic part especially at the tip of the plunger to ensure wear resistance and sealing performance due to the usage conditions, and from the viewpoint of valve assembly and operation. The plunger part is required to be free from deformation.

In order to meet this requirement, the applicant has already proposed the following method for manufacturing a needle valve (Japanese Patent Publication No. 35782/1982). That is, as shown in FIG. 3, a biasing member 34 such as a disc spring is disposed at the bottom of a plunger insertion hole 33 for inserting a plunger (valve body) 32 provided in a fixed mold 31, and the cavity 3
5 and the fixed mold 31 are clamped, and the shoulder portion 37 of the plunger 32 is pressed against the cavity inner surface 38 of the movable mold 36 by the elastic force of the biasing member 34. A valve head 40 made of an elastic material is molded in the cavity formed between the distal end surface of the valve 32 and the inner surface 38 of the cavity.
Therefore, when the mold is clamped, the excessive pressing force applied to the plunger 32 due to variations in the length of the plunger 32 is absorbed by the urging member 34,
Preventing the plunger 32 from being plastically deformed,
Shoulder portion 37 of plunger 32 and cavity inner surface 38
This prevents burrs from forming due to gaps between the two.

(Problems to be Solved by the Invention) However, in the case of such a conventional technique, the biasing member 34 absorbs the excessive pressing force applied to the plunger 32 during mold clamping, and also prevents the movable mold 36 and the plunger 32 from collapsing during molding. It is necessary to prevent the elastic molding material from leaking from between the two, making it extremely difficult to set the elastic constant. In addition, plunger 32
Due to variations in length, when clamping the mold,
In some cases, the excessive pressing force applied to the plunger 32 cannot be sufficiently absorbed by the urging member 34, and the deformation of the plunger 32 is insufficiently prevented. especially,
As shown in FIG. 4, when a hollow narrow-diameter portion 41 and a flange portion 42 are formed at the assembly portion at the end of the plunger 32, a large pressing force is applied to the thin-walled narrow-diameter portion 41 during mold clamping. As a result, the narrow diameter portion 41 is deformed into a spindle shape, the outer diameter R increases, and a positive dimensional error occurs. In addition, the support member 43 that the flange portion 42 abuts is provided with a through hole 45 for fitting the protrusion 44 protruding from the center of the back surface of the flange portion 42 . An upward bending moment acts on the outer peripheral portion of the flange portion 42 due to the pressing force acting downward on the flange portion 42 . As a result, the outer peripheral end of the flange portion 42 is deformed upward, and the length L from the tip of the narrow diameter portion 41 to the outer peripheral end of the flange portion 42 becomes smaller, resulting in a negative dimensional error. Therefore, when assembling,
When assembling the plunger 32 to another member, as described above, there is a dimensional error in the narrow diameter portion 41 and the flange portion 42, so it may not be possible to assemble accurately, resulting in a defective assembly, which may result in malfunction. There was a problem.

The present invention was devised to solve the problems of the prior art, and its purpose is to:
To provide a needle valve that reliably prevents deformation of a portion of a plunger that requires dimensional accuracy, eliminates assembly defects, and eliminates the risk of malfunction.

(Means for Solving the Problems) Therefore, in order to achieve the above object, the present invention provides a needle valve having a valve head made of an elastic material at the distal end of a valve body, in which the valve head is formed. The shoulder portion of the valve body, which comes into pressure contact with the mold, is formed by a thin pressure-receiving flange portion.

(Example) The present invention will be explained below based on the illustrated example. In Fig. 1, 1 indicates a fixed type,
This fixed mold 1 is combined with a movable mold 3 with a plunger 2 as a valve body inserted, and a conical valve head 4 made of an elastic material is integrally molded at the tip of the plunger 2 to form a needle. It is for manufacturing valves.

The plunger 2 includes a cylindrical portion 5 on the distal end side, a narrow diameter portion 6 and a flange portion 7 coaxially connected to an assembly portion on the distal side of the cylindrical portion 5. An annular groove 9 is carved in the vicinity of the shoulder 8 of the cylindrical part 5 that comes into pressure contact with the movable mold 3 during molding of the valve head, and the shoulder 8 of the cylindrical part 5 is formed by a thin pressure-receiving flange. It is formed in the section 10. Further, an engagement protrusion 11 having a substantially arrow-shaped cross section for engaging the valve head 4 is protruded from the center of the tip of the columnar part 5, and a guide protrusion 11 is provided on the outer periphery of the columnar part 5. A plurality of strips 12 are provided extending along the axial direction from slightly below the tip. On the other hand, an annular protruding part 13 is formed on the back surface of the flange part 7, and a mounting hole 14 is bored from the flange part 7 side to the middle of the columnar part 5. is hollow. Note that since the tip of the plunger 2 is the portion where the valve head 4 is provided, the shoulder portion 8 of the cylindrical portion 5 and the like do not require dimensional accuracy and may be deformed. On the other hand, since the assembly part on the distal side of the plunger 2 is a part to be assembled to another member, the wall thickness T of the narrow diameter part 6, the outer diameter R of the narrow diameter part 6, The length L from the tip to the outer peripheral end of the flange portion 7, etc. requires high dimensional accuracy.

The fixed mold 1 is provided with a plunger insertion hole 15 into which the plunger 2 is inserted, and a large-diameter bottom 16 of the plunger insertion hole 15 has a hole for urging the end of the plunger 2 in one direction. A biasing member 17 is provided inside. The lower end of the plunger insertion hole 15 is closed by a stop member 18 fixed to the fixed mold 1, and a biasing member 17 made of a disc spring is placed on the stop member 18. A support member 1 supporting the end of the plunger 2 is provided between the biasing member 17 and the plunger 2.
9 is interposed, and the support member 19 has a through hole 20 into which the protrusion 13 of the plunger 2 is fitted.
is drilled. Note that a preload force is applied to the biasing member 17 in a state where the fixed mold 1 and the movable mold 3 are not clamped.

On the other hand, a conical cavity 21 is formed in the movable mold 3, and a molding material supply path 22 is communicated with the top of the cavity 21. By clamping the movable mold 3 and the fixed mold 1, the shoulder portion 8 of the plunger 2 is urged by the urging member 17 and pressed against the cavity inner surface 23 of the movable mold 3. A cavity is formed between the tip end surface and the cavity inner surface 23.

With the above configuration, the needle valve of the present invention is manufactured as follows. That is, as shown in FIG. 1, after inserting the plunger 2 into the plunger insertion hole 15 of the fixed mold 1, the fixed mold 1 and the movable mold 3 are clamped, and the urging force of the urging means 17 is applied. Therefore, the plunger 2 is urged upward in the axial direction,
The shoulder portion 8 is brought into pressure contact with the cavity inner surface 23. At this time, if the pressing force applied to the plunger 2 due to the pressing force of the movable die 3 cannot be completely absorbed by the urging member 17 and an excessive pressing force is directly applied to the plunger 2, the shoulder of the plunger 2 The pressure receiving flange portion 10 forming the flange 8 deforms toward the groove 9 and absorbs the excessive pressing force. However, an elastic molding material such as rubber is injected under pressure into the cavity formed between the upper end surface of the plunger 2 and the inner surface 23 of the cavity 21 through the supply path 22, and is heated and hardened to form a conical valve. Shape head 4. The biasing force acting on the plunger 2 by the biasing means 17 is applied to the plunger shoulder against the pressure applied downward in the axial direction to the upper end surface of the plunger 2 as the elastic molding material is injected under pressure. The preload force of the biasing member 17 is set to be sufficient to maintain the pressure contact state between the biasing member 8 and the cavity inner surface 23. Therefore, no gap is created between the plunger shoulder 8 and the cavity inner surface 23, and no burrs are generated.

FIG. 2 shows another embodiment of the apparatus used for manufacturing the needle valve according to the present invention, and the same parts as in the embodiment shown in FIG. 1 are given the same reference numerals. To explain, in this embodiment, a coil spring is used as the biasing member 17, and the support member 19 is provided with a recess 25 instead of the through hole 20 in which the protrusion 13 of the plunger 2 is fitted. The only difference is in this point, and the other configurations and functions are the same as those in the embodiment shown in FIG. 2, so their explanation will be omitted.

In the illustrated embodiment, an injection molding method is used, but a compression molding method may be used depending on the characteristics of the molding material used for the valve head. In this case, in order to release the excess portion of the valve head molding material placed on the plunger, it is necessary to take measures such as providing a small diameter relief hole at the position of the supply channel 22 in the embodiment shown in FIG. It is.

Further, in the illustrated embodiment, a case has been described in which a disc spring and a coil spring are used as the biasing member 17, but the present invention is not limited to this.
For example, it goes without saying that an elastic rubber ring or the like may be used as the biasing member 17.

(Effects of the invention) The present invention consists of the above-mentioned structure and operation.
The shoulder part of the valve body that comes into pressure contact with the mold during molding of the valve head is formed by a thin pressure-receiving flange, so that due to variations in the length of the valve body, etc. Even when a large pressing force is applied, the pressure-receiving flange part of the plunger shoulder that does not require dimensional accuracy deforms and absorbs the excessive pressing force, so dimensional accuracy is required such as the plunger assembly part. deformation can be reliably prevented. Therefore, when assembling the needle valve to other members, the assembly work can be carried out without any hindrance, making it possible to eliminate assembly defects and preventing the needle valve from malfunctioning.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of a needle valve and its manufacturing apparatus according to the present invention, Fig. 2 is a longitudinal sectional view showing another embodiment of the invention, and Fig. 3 is a longitudinal sectional view showing a conventional needle valve and its manufacturing device. FIG. 4 is a longitudinal sectional view showing the manufacturing apparatus, and FIG. 4 is a longitudinal sectional view showing the main part of the plunger of the needle valve. Explanation of symbols, 1...Fixed type, 2...Plunger (valve body), 3...Movable type, 4...Valve head, 8...Shoulder part, 10...Pressure receiving flange part, 15...Plunger insertion Hole, 17... biasing member, 21... cavity, 23... cavity inner surface.

Claims (1)

[Scope of utility model registration request] In a needle valve having a valve head made of an elastic material at the distal end of the valve body, the shoulder of the valve body that comes into pressure contact with the mold during molding of the valve head is formed by a thin pressure-receiving flange. Features a needle valve.