JP2005307909A - Method for manufacturing throttle valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict generation of a weld line on the surface of a throttle valve along the axial line without specifically devising the position of a resin injection gate or a resin injection direction in a method for manufacturing a throttle valve by charging resin around a throttle shaft. <P>SOLUTION: Resin is injected from a resin injection gate 30 to be charged around a rod-shaped shaft member 20, while semicircular valve members 11 are integrally formed to hold the shaft member 20 in this method for manufacturing the throttle valve 10. Through holes 21 are diametrically provided in the shaft member 20 corresponding to the number and the interval of the resin injection gates 30 for charging the resin. The shaft member 20 is disposed to put the through holes 21 and the resin injection gates 30 to correspond to each other. Resin is thus injected from the resin injection gates 30 to be charged for formation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a throttle valve. In particular, the present invention relates to a method of manufacturing a throttle valve that is disposed in an intake air amount control device of an internal combustion engine (engine) and controls the intake air amount.

  2. Description of the Related Art Conventionally, in internal combustion engines such as automobiles, peripheral parts are made of resin for the purpose of weight reduction. As a part of that, a resin of a throttle valve that is rotatably disposed in the intake passage of the intake air amount control device and opens and closes the intake passage is also achieved (for example, see Patent Document 1). Patent Document 1 discloses a process of molding a throttle shaft and a throttle valve by filling resin around the circumference of a rod-shaped shaft member (hereinafter referred to as “throttle shaft”).

6 to 8 show a method of manufacturing a throttle valve according to a conventional process. 6 is a conceptual diagram showing a state of molding of a throttle valve manufactured in the conventional process, FIG. 7 is a bottom view of the throttle valve manufactured in the above process, and FIG. 8 is a case where the resin injection direction is inclined in the conventional process. It is a conceptual diagram which shows the mode of shaping | molding of a throttle valve.
In FIG. 6, a resin injection gate 30 that opens downward is provided at the top of a predetermined cavity (space) 50 defined by an injection mold, and the throttle valve 10 (FIG. 7) is shown. The molten resin injected from the resin injection gate 30 first flows in the direction of the arrow 31 and then branches after hitting the rod-shaped metal throttle shaft 20. On the other hand, it flows in the direction of the arrow 31 a and reaches the end of the cavity 50. The semicircular plate portion 11b (see FIG. 7) of the valve body 11 is formed, and on the other hand, the shaft covering portion 11a of the valve body 11 is turned around the circumference of the lower half of the throttle shaft 20 in the direction of the arrow 31b. Form. Finally, the resin forming the valve body 11 is cured, and the throttle valve 10 in which the valve body 11 having the bottom surface shown in FIG. 7 and the throttle shaft 20 are integrated is manufactured.

  What should be noted here is the presence of a weld line (weld mark) 32 generated on the surface of the shaft covering portion 11a of the valve body 11 (see FIG. 7). The weld line 32 is a thin linear molding defect on the resin surface, and is generated at a portion where two or more flows of the molten resin meet. For example, as shown in FIG. 6, since the molten resin flows in the direction of the arrow 31b and meets at the site 32 on the axis of the lower surface of the throttle shaft 20, a weld line 32 is generated at the site. As shown in FIG. 7, the weld line 32 appears on the bottom surface of the valve body 11 in a substantially linear shape at a site on the axis of the shaft covering portion 11a.

When the weld line 32 is generated on the surface of the resin product, the weld line 32 forms a notch and causes stress concentration, so that the strength of the portion is generally lowered. For this reason, it is not preferable that the weld line 32 is generated at a site on the axis of the shaft covering portion 11a. Due to the structure of the throttle valve 10 in which the semicircular disk portions 11b are extended on both sides of the throttle shaft 20, the bending stress due to the pressure of the intake air applied to the semicircular disk portions 11b is the axis of the throttle shaft 20 as a fulcrum. It is because it concentrates on the part on the line.
In addition, the resin injection gate 30 shown in FIG. 6 may be provided at two or more points on the axis line at a predetermined interval at the top of the cavity 50 provided around the circumference of the throttle shaft 20. May be provided only. In either case, the weld line 32 is generated at the portion 32 where the molten resin injected from the resin injection gate 30 is branched by the throttle shaft 20 and then reassociates as shown in FIGS.

Although the generation of the weld line 32 is conventionally known, it is difficult to completely eliminate the weld line 32 in the resin injection molding. Therefore, the position where the resin injection gate 30 is provided on the cavity 50 or the resin injection direction is changed. Attempts have been made to control the site where the weld line 32 is generated (for example, see Patent Document 2 or 3). Patent Document 2 discloses a method of changing the wall thickness of the weld line 32 for the purpose of improving the roundness of the throttle valve 10 that is molded with resin, and Patent Document 3 discloses a seat. A method is disclosed in which the weld line 32 is prevented from being generated in a straight line with the injection direction of the molten resin as an oblique direction in the resin molding of the shaped product.
Japanese Patent Laid-Open No. 11-294203 (see claim 9, second embodiment, FIG. 6B) JP 2000-8888 A (refer to claim 1). Japanese Patent Laying-Open No. 2003-340889 (see claim 1, FIG. 1)

  However, since the inventions disclosed in Patent Documents 2 and 3 are different in the shape of a product to be resin-molded, the throttle valve 10 manufactured by filling and forming a resin around the throttle shaft 20 targeted by the present invention. It cannot be applied as it is. Further, even if the method of inclining the injection direction of the molten resin disclosed in Patent Document 3 is applied to the resin molding step shown in FIG. 6, the position of the weld line 32 remains at the throttle shaft 20 as shown in FIG. The weld line 32 does not change in a straight line on the surface of the shaft covering portion 11a of the valve body 11 which is a problem in strength. Further, by changing the position of the resin injection gate 30 with respect to the cavity 50, the generation site of the weld line 32 should be changed to a site with no problem in strength such as the vicinity of the semicircular plate portion 11b of the valve body 11. Even so, the degree of freedom in which the position of the resin injection gate 30 can be changed is not so great. Further, since it is desirable that the shape of the valve body 11 is symmetric, there is also a demand for disposing the resin injection gate 30 on the axis of symmetry of the valve body 11.

  The present invention was devised to solve the above-mentioned conventional problems, and the problem to be solved by the present invention is in a method of manufacturing a throttle valve by filling a resin around a throttle shaft. The purpose of this is to prevent the occurrence of a weld line on the surface of the throttle valve on the axial line without any particular ingenuity in the position of the resin injection gate or the resin injection direction.

As means for solving the above problems, the present invention takes the following means.
First, the manufacturing method of the throttle valve according to the first invention takes the following means. That is, the resin is injected and filled from the resin injection gate, and the resin is filled around the circumference of the rod-shaped shaft member, and the semicircular valve body is integrally filled on both sides of the shaft member. A method of manufacturing a throttle valve, wherein a through hole is provided in the shaft member in a radial direction corresponding to the number and interval of resin injection gates for filling the resin, the through hole and the resin injection The shaft member is disposed at a position facing the gate, and the resin is injected from the resin injection gate to be filled.
According to the first aspect of the invention, in addition to the flow of the molten resin injected from the resin injection gate and circulated in the circumferential direction of the shaft member, the resin flows through the through hole from the resin injection gate in the radial direction of the shaft member. It is possible to create a flow of molten resin that goes around in the circumferential direction of the shaft member using the hole as a resin outlet.

The method for manufacturing a throttle valve according to the second invention takes the following means. That is, in the method for manufacturing a throttle valve according to the first aspect of the present invention, the resin injection gate and the shaft member have one through hole.
According to the second invention, the molten resin injected from the resin injection gate and circulated in the circumferential direction of the shaft member and the through hole at the symmetrical position of the resin injection gate with respect to the shaft member are used as the resin outlet to make a circle of the shaft member. The molten resin that goes around in the circumferential direction spreads radially in the planar direction of the valve body with the through-hole portion as the center, so that a throttle valve can be formed.

The present invention can obtain the following effects by taking the above-described means.
First, according to the first invention, even if the position of the resin injection gate is on the axis of the shaft member, the injected molten resin is branched by the shaft member, and from both the left and right directions around the circumference of the shaft member. Since it does not meet on the axis of the surface of the wraparound shaft member, it is possible to suppress the occurrence of a weld line in a straight line on the axis of the surface of the shaft member. As a result, the strength of the throttle valve does not decrease along the axis where stress tends to concentrate.
In addition, according to the second invention, there is no portion where the molten resins that can be generated when injected from a plurality of resin injection gates are associated, and at the same time, the molten resins are associated around the circumference of the shaft member. Therefore, the number of weld lines generated can be minimized, and the generation of linear weld lines around the circumference of the shaft member can be prevented. Further, since only one resin injection gate is required, there is an effect that molding management becomes easy.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  This embodiment is shown in FIGS. FIG. 1 is a plan view of a throttle valve according to the present embodiment, FIG. 2 is a sectional view taken along line II-II in FIG. 1, a longitudinal sectional view of an intake air amount control device provided with the throttle valve, and FIG. 4 is a side view of the valve, FIG. 4 is a longitudinal sectional view corresponding to FIG. 2 showing the manufacturing method of the throttle valve in relation to the molding die, and FIG. 5 shows the manufacturing method of the throttle valve in relation to the flow of molten resin. FIG. 5 is an enlarged view of FIG. 4. In the present embodiment, parts corresponding to the parts related to the conventional method for manufacturing the throttle valve shown in FIGS.

First, the structure of the throttle valve according to this embodiment will be described with reference to FIGS.
The throttle valve 10 has a structure in which a rod-shaped metal throttle shaft 20 penetrates in the direction of the axis of symmetry of the disc-shaped valve body 11 made of resin, that is, in the diameter direction in the plane of the disc. The valve body 11 has a resin-made shaft covering portion 11 a cast around the circumference of the throttle shaft 20. In the shaft covering portion 11a, a semi-disc-shaped resin-made semi-disc portion 11b is integrally formed in a direction facing both sides of the throttle shaft 20 therebetween. Further, on both front and back surfaces of the valve body 11, a plurality of reinforcing ribs 13 are integrally formed with the valve body 11 at a predetermined interval in a direction orthogonal to the axial direction of the throttle shaft 20. The ribs 13 extend from the shaft covering portion 11a toward the end of the semicircular disc portion 11b so that the height decreases in a slope shape and joins the surface of the semicircular disc portion 11b.

Further, both end portions in the axial direction of the shaft covering portion 11a are respectively provided with well-known bearing portions (not shown) that are provided in the bore portion 15 (see FIG. 2) of the intake air amount control device and support the throttle shaft 20. The bearing contact part 11c which contacts is provided. On the other hand, the semicircular peripheral portions of the semicircular disk portions 11b that are opposed to each other with the throttle shaft 20 interposed therebetween are in contact with the inner wall surface of the cylindrical bore portion 15 that forms the intake passage of the intake air amount control device. A bore contact surface 14 is formed.
As shown in FIG. 2, the throttle valve 10 is configured to rotate in the opening direction (counterclockwise direction) about the throttle shaft 20 as a central axis to open the intake passage. The throttle valve 10 is in contact with and locked to the cylindrical bore portion 15 in the fully closed position (horizontal position) at a position where the bore portion contact surface 14 and the bore portion 15 of the throttle valve 10 are opposed to each other. The taper which expands in 10 opening directions is attached.
The inflow direction of the intake air is a direction from top to bottom in FIG.

Here, the throttle shaft 20 will be described with reference to FIGS. 1 and 3.
The throttle shaft 20 is a rod-shaped metal, and bearing engaging portions 22 are provided at both ends in the axial direction. The both bearing engaging portions 22 are supported by a pair of bearings (not shown) disposed in the bore portion 15 (see FIG. 2) and penetrate the bore portion 15. Further, in a portion where the valve body 11 is formed on the throttle shaft, a through hole 21 is provided in the portion corresponding to the approximate center in the axial direction of the throttle shaft 20 in the radial direction. At the time of resin molding, the through hole 21 is filled with resin so that both the front and back surfaces of the valve body 11 communicate with each other, and the shaft through portion 12 of the valve body 11 is formed. With this configuration, since the throttle shaft 20 and the valve body 11 are coupled to each other in the throttle valve 10, even when the valve body 11 is not fixed on the surface of the throttle shaft 20, the valve body 11 is not rotated by the throttle shaft 20. Can follow the movement.
In the valve body 11, the shaft covering portion 11a, the semicircular disc portion 11b, the bearing abutting portion 11c, the shaft penetrating portion 12, and the rib 13 are filled with molten resin in the molding die during resin molding. , Integrally formed at one time.

Next, based on FIG.4 and FIG.5, the manufacturing method of the throttle valve 10 which concerns on a present Example is demonstrated.
As shown in FIG. 4, the throttle shaft 20 is inserted into the valve molding die 40 to mold the valve body 11 with resin. The valve molding die 40 includes an upper mold 41, a lower mold 42, a plurality of side molds 43, an upper auxiliary mold 44, and a lower auxiliary mold 45 so as to form a cavity 50 for molding the valve body 11. The upper auxiliary mold 44 has an opening of a resin injection gate 30 communicating with a cavity 50 provided in the lower part thereof. When viewed from above, the resin injection gate 30 is located at the center of the valve body 11 having a substantially circular shape, and is provided so as to face the through hole 21 of the throttle shaft 20 (see FIG. 1).

The specific resin molding process is as follows.
First, the throttle shaft 20 is inserted into the valve molding die 40 and fixed so as to be disposed at a predetermined position of the cavity 50, and the molds 41 to 45 are closed to define the cavity 50. The valve body 11 is resin-molded by injecting and filling molten resin from the resin injection gate 30 into 50.
Second, after the valve body 11 is cured, the molds 41 to 45 are opened, and the product, that is, the throttle valve 10 is taken out.

Here, the manner in which the molten resin is injected from the resin injection gate 30 and filled into the cavity 50 in the above-described process will be described with reference to FIG.
First, the molten resin injected at a predetermined pressure from the resin injection gate 30 in the direction of the arrow 31 flows in the direction of the arrow 31c through the through hole 21 provided immediately below the resin injection gate 30 of the throttle shaft 20. Due to the inflow, the flow of molten resin that immediately overflows from the through hole 21 (flow in the direction of arrow 31a) and the flow of molten resin that flows in the direction of arrow 31c as it is and then branched by the lower auxiliary mold 45 (in the direction of arrow 31d). Flow).
Next, the flow in the direction of the arrow 31a flows along the circumference of the upper half of the throttle shaft 20 when viewed from the cross-sectional view shown in FIG. 5 (planar radial direction centered on the resin injection gate 30 when viewed from the upper surface of the cavity 50). . On the other hand, the flow in the direction of the arrow 31d flows along the circumference of the lower half of the throttle shaft 20 when viewed from the cross-sectional view shown in FIG. 5 (when viewed from the lower surface of the cavity 50, the bottom radial direction centered on the through hole 21).
Next, the flow in the direction of the arrow 31 a and the flow in the direction of the arrow 31 d meet in the cavity 50. The meeting part is a part (see FIG. 2) in the vicinity of the base of the semicircular disk part 11b of the valve body 11. Thereafter, the molten resin reaches the periphery of the cavity 50, and the shape of the valve body 11 is formed.

The portion where the above-mentioned molten resin is associated is described quantitatively as follows.
First, the association site depends on the ratio of the flow rate of the molten resin flowing in both directions. For example, if the molten resin flow rate in the direction of the arrow 31a is larger than the molten resin flow rate in the direction of the arrow 31d, the meeting portion is shifted to the lower half side of the throttle shaft 20 in the cross-sectional view shown in FIG. Next, the ratio of the flow rate of the molten resin flowing in both directions depends on various conditions such as the temperature of the molten resin, the diameter and injection pressure of the resin injection gate 30, the flow characteristics of the resin, and the size of the through hole 21 of the throttle shaft 20. To do. In this embodiment, the resin used is PPS (polyphenylene sulfide) resin reinforced with glass fiber, the molten resin temperature is 285 ° C., the injection pressure from the resin injection gate 30 having a diameter of 1 mm is 70 MPa, and the throttle is 7 mm in diameter. The diameter of the through hole 21 provided in the shaft 20 is 3 mm.

As is apparent from the above conditions, the diameter of the through hole 21 of the throttle shaft 20 is three times the diameter of the resin injection gate 30, and all the molten resin injected from the resin injection gate 30 is guided into the through hole 21. Therefore, the molten resin flowing into the cavity 50, on the other hand, flows from the center of the through hole 21 in the direction of the arrow 31c according to the injection pressure from the resin injection gate 30, and then flows from the direction of the arrow 31d, On the other hand, it is rebounded by the lower auxiliary mold 45 and flows upward in the through-hole 21 and overflows from the through-hole 21, and then flows in the direction of the arrow 31a.
For this reason, the flow rate of the molten resin in the direction of the arrow 31a does not directly receive the injection pressure, but flows from the entire periphery of the upper portion of the through hole 21, whereas the flow rate of the molten resin in the direction of the arrow 31d directly receives the injection pressure. However, it flows from only the central part below the through-hole 21. That is, the effect of the injection pressure and the effect of the inflow path cancel each other. As a result, compared with the flow rate of the molten resin in the direction of the arrow 31a, the flow rate of the molten resin in the direction of the arrow 31d is slightly larger or substantially equal, and the resin flowing in the direction of the arrow 31a and the flow direction of the arrow 31c The flowing resin associates in the cavity 50 at a site near the base of the semi-disc portion 11b of the valve body 11.

Therefore, in this embodiment, the weld line 32 as shown in FIG. 7 is not generated on the surface of the shaft covering portion 11a of the valve body 11. Even if a thin linear molding defect such as the weld line 32 occurs due to the molten resin meeting in the vicinity of the base of the semicircular disk portion 11b of the valve body 11, the generation site Since the inside of the valve body 11, the weld line 32 is notched on the surface of the valve body 11, and there is no possibility of stress concentration. Even if it occurs on the surface of the valve body 11, there is no problem in strength because there are a plurality of reinforcing ribs 13 provided in the vicinity of the base.
In the present embodiment, no weld line 32 was observed on any surface of the shaft covering portion 11a and the semicircular disc portion 11b of the valve body 11.

Although the embodiments of the method for manufacturing the throttle valve according to the present invention have been described above, the present invention can be implemented in various other forms.
For example, in the above embodiment, only one through hole 21 is provided in the throttle shaft 20, but two or three in the radial direction of the throttle shaft 20 may be provided. At this time, the resin injection gate 30 is provided at a position facing each through hole 21. The plurality of resin injection gates 30 are effective when the volume of the cavity 50 is large.
In this case, there is a concern that the weld line 32 is generated at a portion where the molten resin flowing into the cavity 50 from each of the plurality of resin injection gates 30 meets, but the weld line 32 is in the axial direction of the throttle shaft 20. Therefore, it is possible to avoid occurrence in the axial direction on the surface of the throttle shaft 20 which is a problem in strength.

It is a top view of the throttle valve concerning the example of the present invention. FIG. 2 is a sectional view taken along line II-II in FIG. 1 and a longitudinal sectional view of an intake air amount control device provided with a throttle valve according to an embodiment of the present invention. 1 is a side view of a throttle valve according to an embodiment of the present invention. It is a longitudinal cross-sectional view equivalent to FIG. 2 which shows the manufacturing method of the throttle valve based on the Example of this invention in relation to a shaping die. FIG. 5 is an enlarged view of FIG. 4 showing a throttle valve manufacturing method according to an embodiment of the present invention in relation to the flow of molten resin. It is a conceptual diagram which shows the mode of shaping | molding of the throttle valve manufactured by the conventional process. It is a bottom view of the throttle valve manufactured by the conventional process. It is a conceptual diagram which shows the mode of shaping | molding of the throttle valve at the time of making the resin injection direction diagonal in the conventional process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Throttle valve 11 Valve body 11a Shaft coating | coated part 11b Semi-disc part 11c Bearing contact part 12 Shaft penetration part 13 Rib 14 Bore part contact surface 15 Bore part 20 Throttle shaft (shaft member)
21 Through-hole 22 Bearing engaging portion 30 Resin injection gate 31 Resin inflow direction 32 Weld line (molten resin association site)
40 Valve mold 41 Upper mold 42 Lower mold 43 Side mold 44 Upper auxiliary mold 45 Lower auxiliary mold 50 Cavity (space)

Claims (2)

A throttle that injects and fills resin from a resin injection gate, fills and forms resin around the circumference of a rod-shaped shaft member, and integrally fills and forms semi-disc shaped valve bodies on both sides of the shaft member A method for manufacturing a valve, comprising:
The shaft member is provided with a through hole in the radial direction corresponding to the number and arrangement interval of the resin injection gates for filling the resin, and the shaft member is positioned so that the through hole and the resin injection gate face each other. A method for manufacturing a throttle valve, comprising: arranging and injecting resin from a resin injection gate. A method of manufacturing a throttle valve according to claim 1,
A method for manufacturing a throttle valve, wherein the resin injection gate and the shaft member have one through hole.

Images